Tuesday, April 30, 2019

Avengers Endgame And a Couple of Very Good Days

Speaking for Mrs. Graybeard and I, it has been a very good couple of days, and I've only barely been watching the circus that passes for news. 

Two weeks ago, I updated her injury recovery from her fractured thigh bone back on March 2nd.  She was told she could start putting some weight on that leg, easing away from using her walker and switching over to a cane.  That was Monday the 8th.  That Wednesday she stopped using the walker and hasn't used it since.  Yesterday, three weeks since the last visit, we were back for a checkup with a final x-ray taken last Thursday.  The PA gave us the best words one could hear at this point: she's healed.  No need to rely on the cane to protect it, the bone has grown back well enough to give nearly zero chance of displacing at this point.  She can try to do whatever she wants, guided by the pain.  (By my guesstimate, it took her four hours to overdo it and get too sore)  

One of the ideas behind that two week old post was that we had done what we would have done back when she hurt herself, and gone to the movies.  Today we were back at the theater to see Avengers: Endgame, the movie that broke the world record opening with over $1.2 Billion through Sunday night.  Only $357 Million of that was in the USA, so if that doesn't tell Hollywood that the world likes fun-filled, escapist, - did I say fun? - entertainment, I don't know what will.

Here is the closest I'm going to get to a spoiler in this posting, and you can read this on the IMDB page without spoiler warnings.  The movie is almost exactly three hours long - 181 minutes, 3:01.  I read one article about the movie that said they promised to not give anything away.  That guy's first point was: "the movie is three full hours long.  Go to the bathroom before you go to the theater.  Once you have your seats, drinks and what not, go to the bathroom again".  Sound advice.  DAMHIK. Along the same line of advice, unlike the other movies in the Marvel Universe up 'til now, there are no sneak-previews during or after the credits.  When the credits end (and the 3:01 hours includes the credits), the screen goes dark.  That five minutes of credits means a lot when you really have to use the bathroom.

While I'm a fan of the Marvel movies, I'm not a "fan boy."  I don't read movie or entertainment magazines or websites trying to figure out what's coming.  I actively tried to avoid any spoilers on this; I want my 3 hours of escapism and want to be surprised in the movie. Stopping short of spoilers, while I didn't actively go searching for information on the movie, I did see references to this being the 22nd and final film in the MCU story arc.  There has been talk about some of the stars of the series being off contract once this was done and that led to speculation of how the movie turns out: who gets killed and who doesn't.  I will only say I was surprised at who didn't make the end of the film and how one main character chose to end his involvement in the Avengers.   

There is still a Marvel Cinematic Universe.  They appear to be starting a new group of stories, "Phase 4" that there are only hints about.  In the same theater, there was a poster for a new Spiderman movie opening July 2nd.  Spiderman was killed off in Infinity War, so you know he is rescued and survives the movie.  Or else, I suppose, it could be a prequel that was before Infinity War.  In the IMDB listings, you can look at the cast listing, click on their biography page, and see if a new movie is announced, in production, or being readied for release.

Listen, if you haven't seen any of these movies, skip this.  You'll never keep up with who's who, let alone 3/4 of the humor.  If you've seen all or most of them, you're probably going to see this one no matter what I say.  I think this is either the best or tied with the best of the other 21 movies.  Like Thor: Ragnarok, it was pure, lighthearted fun.  I laughed enough to feel sore; there were visual gags, there were brilliant gags and there were subtle gags.  For a movie about finding a way to go back in time and save half the population of the universe from being killed off, a very somber subject, it was surprisingly funny. 

One version of the studio poster

Monday, April 29, 2019

Real Hero at Poway Synagogue Shooting Was A Good Guy Without A Gun

According to a story in the Daily Caller, linked at 90 Miles From Tyranny, the person who did the most to end the shooting wasn't the off duty Border Patrol officer who shot at the mass murderer's car, it was a 51 year old combat veteran who heard the shots, ran toward the gunfire and apparently scared the shooter into leaving.
The man who fired a semi-automatic weapon inside the Chabad of Poway synagogue in San Diego on Saturday froze, dropped his gun and sprinted to his car when he saw Oscar Stewart come barreling toward him, yelling so loud the priest at a neighboring church could hear.

“Get down!” Stewart yelled, according to his wife and others who were at the scene. “You motherfucker! I’m going to kill you!”
Stewart, 51, told The Daily Caller on Sunday he doesn’t remember any conscious thought from the moment he heard the gun shots until it was all over — he just acted on instinct to stop the shooter and prevent him from leaving so he couldn’t hurt more people somewhere else. The Iraq combat veteran said his military training kicked in.

“I knew I had to be within five feet of this guy so his rifle couldn’t get to me,” Stewart said. “So I ran immediately toward him, and I yelled as loud as I could. And he was scared. I scared the hell out of him.”

“Looking back, it was kind of a crazy idea to do, but I did it.”
The DC goes on to describe Stewart's military service.  He was EOD - Explosive Ordinance Disposal - in the Navy from 1990 to 1994, then enlisted in the Army after the 9/11 attacks.  He was in Iraq from 2003 to 2004, leaving as a Master Sargeant.  Today, he works in construction.

After Stewart rushed the shooter while screaming he was going to kill him the shooter decided he needed to run for his car.  Stewart ran after him.  When he got to the car he started pounding on it and kicking it, trying to do something to get in and drag the killer out.  That's when the off-duty Border Patrol agent, who attends that synagogue, yelled at Stewart to get out of the way to give the agent clean shots at the car.
Stewart says this man may have saved his life and pointed to his use of a civilian’s gun as evidence that gun control isn’t the answer to these kinds of tragedies. Stewart was off-duty and was apparently handed the weapon by someone else on the scene.

“It takes a good guy with a gun to stop a bad guy with a gun,” he told the Caller.
Although he helped cause the shooter to call off the attack, Stewart will be the first guy to tell you he's not a hero.  The hero would be a woman he knew from the synagogue and had spent some time talking with.  Eyewitnesses say she jumped in front of the rabbi, taking a bullet to protect him.
After he sped off, Stewart ran back into the synagogue and found a woman he knew, 60-year-old Lori Gilbert Kaye, unresponsive on the floor in the lobby. He began CPR and continued trying to bring her back to life as a couple of doctors arrived and began to assist him. She didn’t make it. The two had talked occasionally, and he remembers her as a passionate and kind woman.

“She had different political views, so we had interesting discussions when we talked,” he said. “We didn’t just talk about the weather. It was kind of cool. She was a very loving woman.”
If you don't read anything else today, read this story on the DC.  I'll add a couple of more quotes.
“I don’t know if I consciously made the choice to potentially sacrifice myself,” he added. “But I did. And this lady, she stood and she jumped in front of the shooter and she saved the rabbi’s life. When somebody said I was a hero, I’m like, she was a hero. I just did it instinctively, like an animal. There was no conscious decision. I just did it.”
For his part, Stewart doesn’t attribute the shooter’s actions to a larger agenda and was reluctant to connect him to a larger political context. He doesn’t blame President Donald Trump and expressed hope that people don’t try to blame anyone else for the man’s actions. “He was an individual acting alone,” he said.

“If you’re ignorant and you don’t know what people are like, you don’t know that I’m a person just like you. I go to work every day in a manual labor job. I’m not some, you know – supposedly he said in his manifesto that the Jews control this and that — I don’t control anything. I go to work just like you every day. He didn’t know that.”

(Oscar Stewart - Getty Images)

Oscar Stewart is a gem.  On day when he was suddenly thrown into the worst day of his life, he rose to the occasion on pure instinct.  It's hard to imagine doing better than that.  His appearance and shouting was enough to make this shooter drop his gun and run.  Stewart doesn't believe news reports saying the gun jammed.  The shooter may have suddenly noticed that he didn't have the time to reload he thought he did. 

Funny thing, though.  There was a report from other worshipers that the shouting was exceptionally loud.  Too loud for one man.  Remember "yelling so loud the priest at a neighboring church could hear"?  To quote the article directly:
Others who were there later told him it sounded like four or five people were shouting. He thinks maybe an angel was standing behind him and speaking through his voice.
I'm sure it was just odd acoustics.  Yeah, that's the ticket.  Odd acoustics.  No such thing as an angel army, nothing to see.  Move along.  Move along.

Sunday, April 28, 2019

Radio Sunday #5 – A Little Radio Hacking

Now that we have a little background, let's look at the problem that started this: how big a problem is someone monitoring the local oscillator in your handheld?  How far away can they be.  We're going to draw on the architecture of the superheterodyne and decibel relationships to show you how it's done in real life. 

I'm going to start with my VHF/UHF handie talkie, a Yaesu VX-6R.  This is a recent production multiband VHF/UHF HT that is “high end” compared to the cheap Chinesium HTs or Family Radio Service (FRS) radios out there.  I'm not sure if they're still in production, but they're still widely available (for example).  It essentially receives from 500 kHz (0.500 MHz) up to 1.000 GHz and transmits on amateur bands at 2m, 220 MHz and 440 MHz.  Let's take a quick look at the specifications.

At the top, it says the architecture is dual conversion for AM or Narrow FM no matter what frequency you're tuned to.  For AM and NBFM, it converts to 47.25 MHz, then down to 450 kHz.  The first LO is likely to be a phase-locked loop frequency synthesizer with ways to switch the frequency (there are several), and the second LO is a fixed oscillator 450 kHz above or below 47.25 to mix 47.25 down to 450 kHz.  I think about the tuning range required of their synthesizer and see it could tune on high side or the low side (of 47.25 MHz), but high side is going to be easier, so I predict that the radio will have it's LO at the tuned frequency + 47.25 MHz. 

That's easy to test.  I happen to have the 2m frequency of 146.925 MHz programmed in, so I tune the VX-6R there and tune a second receiver (a long obsolete Icom R-10, 500 kHz to 1300 MHz, all-mode receiver) to 146.925 + 47.250 or 194.175 MHz. Sure enough, it's there.   

The question about this LO “leakage” is how strong it is, and over what sort of distances is it detectable.

Here's some rough numbers to guesstimate what that level should be.  Consider our block diagram of a receiver: everything we want to think about is on the left end with reddish or pink background.

This assumes typical performances, not excellent, high end military or best performances.  That local oscillator, the source we're listening to, is running at roughly +7 dB, 5 milliwatts.  The mixer will suppress that LO signal coming out of it's RF input pin on the left, and that amount is usually specified for the mixer.  This is a wideband application, and those are usually not the best.  Usually around 20 dB.  That puts the LO at the output of the RF amplifier at  7 – 20 = -13 dBm.  The amplifier will provide attenuation of signals on its output going “backwards” toward the input, usually called reverse isolation.  That depends strongly on the amplifier design and, again, I'm assuming this isn't a very high reverse isolation design, and call it 25 dB isolation.  Now were' at -13 – 25 = -38 dBm.  Finally there will be some filtering.  This is where a single purpose, ham band only (or whatever other band you're using) receiver has the advantage, in that they can design a better filter here.  During filter design, it's possible to decide you want better rejection of undesired signals above or below where the radio is receiving.  It's reasonable to get another 30 or 40 dB isolation from the filter.  That says the signal at the antenna connector would be -68 to -78 dBm, as a back of the envelope guesstimate.  Could be worse or could be better. 

How strong is mine?  This is a tricky measurement because the second receiver doesn't have a calibrated signal strength meter, but I can tell it's fairly weak.  I can connect the VX-6R directly to the receiver (and making sure my transmitter can't transmit into my receiver!), note its level on the radio's "S-meter" and set a signal generator to same level as the signal I get from the VX-6R.  That tells me roughly -75 dBm.  I can directly measure it by putting it on my (also ancient, long obsolete) spectrum analyzer and directly measure what's coming out of the antenna port.  That tells me around -82 dBm.  Those numbers agree pretty well, considering the crudity and lack of “real” amplitude calibrations anywhere. 

You can see in this photograph that I set the radio to 150.000 MHz (sideways, on top of the spectrum analyzer); first so that it can't transmit into the analyzer and second so that I could add 47.25 MHz easily in my head.  There might be whole dB of loss in the cable and adapters between the radio and the analyzer, but I doubt that.

How detectable is -82 dBm?  At what kind of range?  We have to set a sensitivity level to compare to, and here I'm going to say a reasonably good receiver will detect a signal at about -135 dBm (for those who understand, I'm assuming 500 Hz “CW” bandwidth -147 dBm noise floor - and adding 12 dB to split between NF and SNR; that is, say a 6 dB NF and 6 dB SNR, or a 3 and 9)  this isn't precise, but we just don't know enough about what the other side could be using.  That says my signal (at -82) is 53 dB stronger than needed to detect it.  How far away does the bad guy need to be for that signal to fade below threshold?  Roughly 180 feet.  I have a file in Mathcad that tells me the path loss for a given distance and frequency that lets me play with numbers to get close to 53 dB path loss. 

When you're trying to derive numbers like this, remember radio (and light, and other electromagnetic radiation) falls in an inverse square law (illustration near bottom).  If the guy trying to monitor you is twice as far away, he'll get 1/4 of the power; 6 dB down.  That means the signal lost 3/4 of its power by doubling distance.  Likewise to double the range you need to add 6dB, 4x more power, or the monitor needs 6dB more signal acquisition. 

This is a weak signal to detect near that distance, and the quality of the operator and their gear matters.  If they have a high gain antenna, they they could double or quadruple the distance they could detect the radio from, but have to point the antenna at you.  Methods of signal intelligence are whole 'nother set of questions.

Because I've been a ham since I was 22 and have been experimenting with radios since I was 13, I've accumulated some radios and test equipment over time.  I talked about using my old radio, a particularly old example of the Icom R10, because I wanted to point out that a wideband radio is a cheap spectrum analyzer and I found the signal there first.  I'm not up to date on how their current offerings compare but what sets the R10 apart from some radios - and what you should look for - is that at any frequency you can dial up any mode.  For listening for LOs, which aren't modulated, you need to listen in CW or SSB modes.  I'm sure there are other radios out there that would fit the bill as well as the old R10s, I just don't have a rehearsed answer for what to get.

EDIT 4/29/2019 at 1050 EDT: Improved paragraph about power loss with distance (third from last) and corrected error pointed out by drjim in the first comment. 

Saturday, April 27, 2019

College Student: My Generation Is Blind to the Prosperity Around Us

The title describes the author, Alyssa Ahlgren, who's in grad school for her MBA.  It's a short article but definitely worth a read.
I’m sitting in a small coffee shop near Nokomis trying to think of what to write about. I scroll through my newsfeed on my phone looking at the latest headlines of Democratic candidates calling for policies to “fix” the so-called injustices of capitalism. I put my phone down and continue to look around. I see people talking freely, working on their MacBook’s, ordering food they get in an instant, seeing cars go by outside, and it dawned on me. We live in the most privileged time in the most prosperous nation and we’ve become completely blind to it. Vehicles, food, technology, freedom to associate with whom we choose. These things are so ingrained in our American way of life we don’t give them a second thought.
Democratic Congresswoman Alexandria Ocasio-Cortez recently said to Newsweek talking about the millennial generation, “An entire generation, which is now becoming one of the largest electorates in America, came of age and never saw American prosperity.”

Never saw American prosperity. Let that sink in. When I first read that statement, I thought to myself, that was quite literally the most entitled and factually illiterate thing I’ve ever heard in my 26 years on this earth. Now, I’m not attributing Miss Ocasio-Cortez’s words to outright dishonesty. I do think she whole-heartedly believes the words she said to be true. Many young people agree with her, which is entirely misguided. My generation is being indoctrinated by a mainstream narrative to actually believe we have never seen prosperity. I know this first hand, I went to college, let’s just say I didn’t have the popular opinion, but I digress.
"Never saw American Prosperity".  It's stunning when you think of it in those terms, but the attitude that AOC voices is obvious all around us.  The US has roughly 5% of the world's population but contributes about 25% of world GDP; global prosperity, if you will.  Producing that quarter of the world's GDP gets us derided by those same college students for using more than 5% of the world's energy to generate that outsize contribution!  Instead, they should be asking why the other major economic powers aren't contributing as much.  The US has lifted more people out of abject poverty, spread more freedom and democracy, and has created more innovation in technology and medicine than any other nation in human history. When a disaster happens somewhere in the world, US citizens routinely donate more out of their own pockets than any other country's citizens, and generally giving more than entire nations do with tax money (that is, not voluntary charity). 
Why then, with all of the overwhelming evidence around us, evidence that I can even see sitting at a coffee shop, do we not view this as prosperity? We have people who are dying to get into our country. People around the world destitute and truly impoverished. Yet, we have a young generation convinced they’ve never seen prosperity, and as a result, elect politicians dead set on taking steps towards abolishing capitalism. Why? The answer is this, my generation has only seen prosperity. We have no contrast. We didn’t live in the great depression, or live through two world wars, or see the rise and fall of socialism and communism. We don’t know what it’s like not to live without the internet, without cars, without smartphones. We don’t have a lack of prosperity problem. We have an entitlement problem, an ungratefulness problem, and it’s spreading like a plague. 
Churchill spoke of socialism as the "Gospel of Envy" and the daily media spew reeks of that envy taken all the way to resentment.  In the US we have people living in the top 10% of incomes in the country resenting the small percentage making more than they do.  Society stratified so that everyone resents the next higher level of income, with most of those people thinking how bad they have it instead of how good. 

(generic hipster-looking coffee shop image) 

Friday, April 26, 2019

On Letting Felons Vote From Prison

Short version - aw hell no.

Longer version, I assume everyone with a pulse heard Crazy Bernie say felons should be able to vote while they're still incarcerated during a CNN Town Hall Monday night.  Sanders is quoted as saying,
“If somebody commits a serious crime, sexual assault, murder, they're going to be punished. … But I think the right to vote is inherent to our democracy. Yes, even for terrible people.”
This actually stunned the CNN talking heads, with this exchange captured by Steve Guest making the rounds on Twitter:
While discussing Bernie Sanders and Kamala Harris' comments on felons & terrorists voting from prison, Don Lemon says he was “stunned” Democrats are ok with terrorists voting from prison, & Chris Cuomo said it shows that “these people are way out there.” pic.twitter.com/LkyKnPQ6e2 
It shouldn't be extremely surprising because Bernie's from Vermont.  Vermont allows felons to vote while still incarcerated and has for the entire history of the state.  Felons may even run for office while incarcerated in the Green Mountain State. 

Still, Cuomo and Lemon are right: proposing this is going to have most of America thinking the party has slipped too far.  It's interesting that another presidential candidate, South Bend, Indiana, Mayor Pete Buttigieg, (I believe that's pronounced "booty judge" - at least, that's how I pronounce it) countered Sanders, saying, “When you’re convicted of a crime and you’re incarcerated … you lose certain rights.”

I think that's the starting point.  The example of capital crimes, like the Boston Marathon Bomber that Sanders was questioned about, is particularly egregious.  This guy deprived other people of all of their rights by killing them, and I don't think it's appropriate to talk about giving the murderer more rights than his victims.  By that standard, no felon who commits murder should ever get any of their rights back.

Longtime readers will know that one of the drums I beat regularly is the Over Regulated State, including how everything is becoming a felony, and how the average American now commits three felonies a day.  I should point out that lawyer Harvey Silvergate wrote that book back in 2011; I wouldn't be surprised if one could argue that it's up to four or five felonies a day by now.  Central to this story is that there are felonies which are minor crimes compared to the Boston bombing, murder, rape or other capital crimes.  Do you remember the story of inventor Krister Evertson?
Consider small-time inventor and entrepreneur Krister Evertson, who will testify at today's hearing. Krister never had so much as a traffic ticket before he was run off the road near his mother's home in Wasilla, Alaska, by SWAT-armored federal agents in large black SUVs training automatic weapons on him.

Evertson, who had been working on clean-energy fuel cells since he was in high school, had no idea what he'd done wrong. It turned out that when he legally sold some sodium (part of his fuel-cell materials) to raise cash, he forgot to put a federally mandated safety sticker on the UPS package he sent to the lawful purchaser.
Pulled over by SWAT team in full gear, pointing guns at him, because he forgot a sticker?   The story gets a bit worse because while the jury for this trial sided with Evertson, the prosecutor was not going to let a small time mistake dangerous thug like this embarrass him, nosiree.  He came up with another crime to charge Evertson with: "abandoning" his "dangerous" fuel cell materials while he was in jail for the label incident.  Although they were stored as the valuable materials they were, and not abandoned in some sort of dangerous state, he was convicted and spent a couple of years in Federal prison because of running afoul of this prosecutor, backed by the infinite checkbook of the Fed.gov.

Where am I going with this?  I think of someone like Evertson when I hear about felons in Federal prison, not the Boston Bomber (yeah, I know: really "terrible people" - as Bernie said - are there, too).  I think of some ordinary working guy who committed one of the countless felonies that happen everyday, but caught the attention of a zealous prosecutor.  When you're in prison, you lose many of your rights, and the right to vote doesn't seem like a major loss to me.  I lean to saying that while someone is in prison, they don't get normal citizen's rights.  Once they're released, and their "debt to society" is considered paid, they should get those rights back, including the right to legally buy a firearm, vote and all the rest.  The reality is that if someone is not in prison they can get a gun.  If the purpose is to keep them from hurting someone, and there's a genuine concern they will, keep them in prison!  Once they're out, once they've been declared ready to go back into society, they should get their rights back.

If everything is becoming a felony such that we're all committing three felonies a day, then we're all one random encounter with a zealous prosecutor from being a prohibited person and we all lose our 2nd amendment rights. This would allow us to get them back. 

(From the Daily Caller

Thursday, April 25, 2019

Wednesday, April 24, 2019

Four Days After Pad "Anomaly", No Clear Details on SpaceX Crew Dragon

On Sunday, YouTube offered me a video by space enthusiast Scott Manley "SpaceX's Crew Dragon Capsule Destroyed In Engine Test".  He used photographs from the local newspaper, Florida Today, showing clouds of orange smoke coming from the test.  The problem is that his video is pretty much Fact Free due to how quickly he put it out; none of the facts he claims are substantiated by SpaceX or backed up by anybody.  Florida Today is still calling it an accident or anomaly with no details on exactly what happened.  Space.com is the same.  In short, nobody is saying exactly what went wrong.  Quite possibly, nobody knows. 

(Florida Today photo)

The test was an unmanned test of their Crew Dragon capsule, but nobody will say for certain whether or not it was the same capsule used in their test flight early last month (as is widely reported) or a second crew dragon capsule.  Nobody is saying for certain that the failure involved the capsule's launch abort system, which is based on the hypergolic-fueled SuperDraco engine, but the orange clouds are characteristic of the Nitrogen Tetroxide (NTO) oxidizer the SuperDraco uses (and some nasty shit you don't want to be exposed to!)  That might mean the engine exploded and it might mean something else blew up the NTO tank.

Aside - Hypergolic fuel systems explode on contact, removing the need for ignition systems.  These aren't new, the Titan II ICBM (also used during the Gemini program) used hypergolic propellants.  The idea is almost as old as rocketry.  Likewise the SuperDraco engine isn't new, and has been tested numerous times in the past.

I've been holding off on this story waiting for more details to pass along, but none have been released.  The speculation is that this will push the first SpaceX manned flight into next year and allow Boeing to catch up or pass SpaceX in their competition to be the contractor for manned flights to the Space Station.  It's reasonable to speculate, but without harder facts that strikes me as pointless.  All we have is some generic, vanilla statements.
"Earlier today, SpaceX conducted a series of engine tests on a Crew Dragon test vehicle on our test stand at Landing Zone 1 in Cape Canaveral, Florida," a company spokesperson told Space.com in a statement. "The initial tests completed successfully but the final test resulted in an anomaly on the test stand."
"Ensuring that our systems meet rigorous safety standards and detecting anomalies like this prior to flight are the main reasons why we test," SpaceX said in the same statement. "Our teams are investigating and working closely with our NASA partners."
"The NASA and SpaceX teams are assessing the anomaly that occurred today during a part of the Dragon Super Draco Static Fire Test at SpaceX Landing Zone 1 in Florida," NASA administrator Jim Bridenstine said via Twitter Saturday night. "This is why we test. We will learn, make the necessary adjustments and safely move forward with our Commercial Crew Program."
Uncharacteristically, Elon Musk has been silent.  He regularly tweets matter-of-factly when they screw up something, like crashing a booster into a recovery drone or dropping one in the ocean.  Maybe he was too busy hyping his self-driving cars.

Tuesday, April 23, 2019

What if Democrats Understood Economics?

The last few days have been full or statements of idiocy from the 623 announced Democratic presidential candidates, and made me think of how even an undergrad econ student should understand where they're wrong.

Since I only have time to focus on one, Elizabeth Warren, Fauxcahontas, proposed to pay off $1.25 trillion in total student debt over ten years, and also called for a $100 billion increase in federal student aid that does not have to be paid back.  She also proposed that public two and four-year universities be completely tuition-free by way of a "state/Federal partnership".  And a new, super duper, ultra tax for billionaires that I need better numbers on to see if that's remotely realistic. 

This article will emphasize the free college.  I feel bad about writing about stuff that's so blatantly obvious - you, dear Reader, are far too smart to believe Democratic primary promises - but I hope I can add a piece of information or two that might be helpful for you.

First off what's wrong with higher education in one word?  Government.  Too short?  How about this?
  1. Colleges and well meaning parents have created the narrative that the only way to get a good job is college.  That creates an almost total demand - virtually every child in that generation thinks they need college.
  2. The number of real seats in classrooms to put equally real student butts into is far smaller than the number of said butts.  There's no quick fix for this imbalance because the number of qualified teachers is too small to embark on a grand plan to add thousands of other colleges to drive prices down.  This means demand is far beyond supply and is going to stay that way.
  3. When demand vastly outpaces supply, prices go up.  In a free market, with people spending their own money, some percentage would say, "that's too expensive" and find a way around the problem.  But it doesn't matter what the price is, because government has guaranteed that grants, scholarships, and loans are available to pay for those seats regardless of the costs.  
  4. The politicians can't ration or cut money for college loans and grants because they would be called mean, haters, or the old standby, racist.  Not providing infinite student loans would deprive some poor underprivileged student of their chance - their chance to take out an enormous loan while betting they'll be able to pay it back and not go bankrupt.
  5. In order to appear "concerned about rising costs", government imposes more costs for more administrators and more hoops for the colleges to jump through.  The colleges couldn't care less because the cost just raises tuition so it gets stuck onto the student's loan.  But the politicians can say they're doing financial oversight of the colleges.
Everything wrong with education comes from government screwing it up by supplying lots of money.  Warren's answer?  "Let's do it again, only harder!!"

Let's be honest here.  There's more evidence of simply stunning economic idiocy.  A college degree is valuable - to the extent that it still is valuable - because not everyone has one.  Not everyone can master the work.  If everyone has an Associates or Bachelor's degree (depending on which candidate is promising), it will become equivalent to today's High School diploma.  You can actually see this already happening in that the only degrees that help graduates to get hired are the ones with strong skills imparted.  There simply aren't many jobs for holders of degrees in Philosophy, Literature, or Offended Minority Studies.  Any 12th grader wanting to major in those things needs to know they're going to go deeply in debt and have a meager life when they graduate. 

If college becomes "14th grade", the perks and higher pay will go to the Master's Degree holders, the Ph.D.s or some degree that doesn't exist yet.

But you don't have to take my word for it.  What we predict with simple application of econ 101, "Supply and Demand" is already true in South Korea where college attendance is almost 100%.
Seongho Lee, a professor of education at Chung-Ang University, criticizes what he calls "college education inflation." Not all students are suited for college, he says, and across institutions, their experience can be inconsistent. "It’s not higher education anymore," he says. "It’s just an extension of high school." And subpar institutions leave graduates ill prepared for the job market.

A 2013 McKinsey study found that lifetime earnings for graduates of Korean private colleges were less than for workers with just a high-school diploma. The unemployment rate for new graduates has topped 30 percent.
I've used the following graph several times.  As I said the last time, it's kind of old but searching for updates wasn't fruitful.  It shows the inflation of college tuition (top) vs. medical care (mid) and the official cost of living (bottom).  This is the effect of the unlimited loans and other free money. 

From John Uebersax on Creative Commons (Wikimedia).

Here's the hard question.  Does Warren actually know this?  Does she actually know her ideas can't work and will just destroy colleges and force more people into the pursuit of higher degrees?  Back during the Obamanation, Bamster did an end run around the law and appointed her to "staff up" the just-created Consumer Financial Protection Bureau, which she did and that apparently involved economics.  But I also found some criticism of her work by one of her professors back at Rutgers, before she did the affirmative action gig at Harvard.  He didn't think too much of her intellectual prowess. 

It could be that she just thinks Democrat primary voters are complete idiots and will vote for her because of this idea. Or it could be she's a big enough idiot to believe it herself. 

Monday, April 22, 2019

Happy Erf Day!

It's time for our annual bacchanalia of the made-up holiday they call Earth Day.

Earth Day, as most of you know, was made up in the late 1960s at the start of the national environmental movement.  Ira Einhorn is one of the main founders of Earth Day, if not the guy who started it.  Ira practiced what he preached: he murdered his girlfriend (less stress on the planet, ya know) and composted her body in his closet.  (Hey - reduce, re-use, recycle!)  And that was before people started worrying about their carbon footprints.  What a leader!
You won't find Ira Einhorn's name listed in any of the Earth Day promotional literature, as the organizers have taken great pains to distance themselves from this man, at least since he became better known for composting his girlfriend in a trunk in his closet for a couple of years in the late 1970s.
The movement led to the creation of the Environmental Protection Agency, the High Priests of Junk Science, probably the single best example of an agency that has outlived its usefulness. 

Over the years, I've wasted far too many minutes writing about Earth Day.  It's too long to sort through and pretty much all curmudgeonly, so I'll just say I hope you had a nice day.  Still, there are a a couple of good things to remember about the modern environmental movement.  If you'll just remember that nature wants you dead and most environmentalists prefer the wild animals over you (look at how they respond to wolf attacks on cattle or people), you'll have a pretty good start.  In fact, it's probably easier just to say that mainstream environmentalists want you dead. 
  • CNN Founder Ted Turner: "A total population of 250-300 million people, a 95% decline from present levels, would be ideal."
  • Dave Foreman, Earth First Co-Founder: "My three main goals would be to reduce human population to about 100 million worldwide, destroy the industrial infrastructure and see wilderness, with it’s full complement of species, returning throughout the world."
  • Maurice Strong: "Isn’t the only hope for the planet that the industrialized civilizations collapse? Isn’t it our responsibility to bring that about?"
Gee, the moderate guy only wants to kill off more than 95% of the human race.  See the current world population is around 7 .7 billion people.  For Dave Foreman, 100 million out of 7 billion is 100 out of 7700 or 1.3 %.  At 300 million, Ted Turner would generously let 3.9 % live.

Unfortunately, between Erf Day and Easter falling so closely together this year, plus spending lots of time helping the still-on-a-cane Mrs. Graybeard, I forgot to get the tires for my celebratory tire fire.  I'll have to turn on all the lights in the house and both air conditioners to make up for it.  If you have your tires, just remember your tire fire should be visible from Proxima Centauri; and if you don't have tires to burn, your house should be visible from that star system.

More seriously, the environmentalist predictions have been so consistently wrong, Borepatch has a few (and only a few), if you could find a place that takes bets, bet against the greens every time.  If they think I shouldn't be having a tire fire, it's a safe bet I should.

Sunday, April 21, 2019

Happy Easter!

I thought it was time to re-dress my annual Easter post and drop some of the links that are over five years old.  Part of my usual posting is hard to drop, because it's part of my personal conversion story, so parts of that will still be here.

Coming from my background, it was a large change.  I had studied biochemistry and microbiology in college through my third year before life imposed some detours, eventually getting my degree and starting to ply my trade as an engineer.  I had been an amateur astronomer, so between them I was deeply marinated in the standard model of Cosmology as well as conventional biological evolutionary theory.  Frankly, I wasn't giving it much thought any longer, but my wife had re-affirmed her faith (she had first accepted Christ as child) and I was having all of my mental models disrupted.  She had started a subscription to Bibical Archaeology Review and the constant refrain from archaeologists, not religiously motivated, along the lines of "we thought this was old Jewish folklore, but here it is" got me thinking "if that's true, maybe there's more that's true."  Strobel's The Case for Christ, played a role in filling in the gaps in my historical knowledge. 

Easter is the most important day in Christianity and far more important than Christmas because of the resurrection.  Everyone has a birthday, but only one man in history has been resurrected.  So since virtually everyone, including honest atheists, agrees Jesus was a real man in history (Jesus' existence is better attested in ancient sources than that of Julius Caesar - but no one claims Julius was not a real person) and died on the cross, the question becomes whether or not it can be verified that Christ was seen after the resurrection by someone other than the closest circle of disciples. Strobel says:
Did anyone see Jesus alive again? I have identified at least eight ancient sources, both inside and outside the New Testament, that in my view confirm the apostles’ conviction that they encountered the resurrected Christ. Repeatedly, these sources stood strong when I tried to discredit them.

Could these encounters have been hallucinations? No way, experts told me. Hallucinations occur in individual brains, like dreams, yet, according to the Bible, Jesus appeared to groups of people on three different occasions – including 500 at once!

In the end, after I had thoroughly investigated the matter, I reached an unexpected conclusion: it would actually take more faith to maintain my atheism than to become a follower of Jesus.
For a great examination of this, see the 2016 post "Five Confounding Facts About Jesus' Resurrection" at Sense of Events. Donald Sensing put together an excellent piece; simply put, it's preposterous to reconcile the events of that time without saying Jesus rose from the dead that Sunday.  This year, Sensing has outdone himself with several days worth of posts on the historical Jesus, including a rather long piece on exactly why Pontius Pilate executed Jesus.  This is followed by articles put together by working scientists, "Can A Scientist Believe in the Resurrection?" and "Is Belief in the Resurrection Unscientific?"

The other religions of the world are about ritual and ultimately about self, about proving yourself worthy; Christianity is about grace.  You're not worthy on your best day; you're saved by Grace.  No other religion teaches Grace.  Islam teaches that Allah is unknowable.  Christianity teaches that not only is God knowable, he wants us to know him.  Islam doesn't teach salvation, it teaches servitude to a fickle, arbitrary, distant Allah.  Christianity teaches forgiveness by Grace; that you're given a gift you don't deserve by a God who wants a close personal relationship with us.  I like the way the Message translation talks about being saved by Grace (Ephesians 2: 8)
It's God's gift from start to finish! We don't play the major role. If we did, we'd probably go around bragging that we'd done the whole thing! No, we neither make nor save ourselves. God does both the making and saving. 
Evolution vs. creation? I believe people pay way too much attention to this.  There's no mention of evolution in the bible, but there's no mention of the laws of thermodynamics, Avogadro's number,  relativity or thousands of other such things.  The bible isn't a science book.  Look at it this way: the creation story, how we got here, takes up a page.  The next thousand pages (or more, depending on font size, paper size, and so on) are concerned with how we treat each other while we're here; how we create and maintain a civil society.  Creation is clearly not the emphasis of the book, the other 99.999% is. 

Saying a fluctuation in the quantum vacuum exploded creating everything sounds remarkably like "Let there be light", especially if someone were trying to explain the standard model of cosmology to people who were mathematically at the level of today's preschoolers.  You got a better way to explain modern physics to kindergartners? 

Enjoy your day.  Enjoy your families. As usual there's a pork butt in the smoker but with the added experiment of seeing how doing most of it in the ultra-controlled sous vide cooker does.  Pulled pork tonight.

Saturday, April 20, 2019

Radio Sunday #4 - Modulation Basics

This post will be Saturday instead of Sunday - because Easter, of course. 

We've covered the development of radio receivers up until the end of the 19-teens, but have never talked about what the receivers are actually receiving.  That requires a side track into transmitters that had to wait for us to get past the development of the triode and superheterodyne because modern transmitters use the same basic superheterodyne approach.  Suffice it to say that radios were being used for communications long before the advent of modern architecture (superheterodyne) transmitters and receivers.

Single radio frequency generation would rely on the development of the vacuum tube triode oscillator, a circuit that deliberately creates that “microphone in front of the speaker”, positive feedback effect by tapping some of the output and sending it through a circuit back to the input, which tunes the frequency of oscillation.  The invention of the oscillator is another of those things credited to Edwin Armstrong.  These circuits are most often an inductor/capacitor from output to input.  (Since the schematic symbol for an inductor is usually called “L” and a capacitor is called “C”, these are referred to as LC oscillators)  All that is needed is a gain of 1 and this positive feedback to ensure the generation of an output at the frequency of the LC circuit.  By varying either component, a Variable Frequency Oscillator or VFO could be obtained, and that allowed tuning many frequencies, not just one. 

Modulation is the process of adding intelligence to a signal, called the carrier, to communicate over a distance.  In its simplest form, a transmitter's output can be keyed on and off, giving the Morse code we hear today (called Continuous Wave modulation or CW), but the goal was to transmit sound – voice and music.  Turning the signal on and off is the most extreme form of changing its amplitude, but what if we could vary the amplitude of the transmitter signal with the amplitude of the speech?  Of course, this is Amplitude Modulation or AM (and sometimes referred to as “Ancient Modulation” by hams).  I'm going to spend a bit of time here on AM and then FM because they're the modes people are most familiar with. 

AM modulation can be done at low power levels in the transmitter, but was typically done in the final amplifier stage.  Why?  If the modulation is done at a low power level, the amplifiers that produce the transmit power can distort the modulation, unless they're run to be “linear”, so that the output signal is an enlarged version of the input.  This is an inefficient mode, or "class"  – the tube has to run considerably more power than if it's just setup to amplify as much as it can – so designers typically run everything as “wide open” (highest gain) as they can and modulate the output.

A generic low level modulated versus high level (plate modulated) AM transmitter.  The block diagrams are very sparse on details; that box labeled “VFO & LO” can be several pages of schematics.  In older models, that might be a VFO tuning half or one MHz in the low HF spectrum, say from 5.00 to 6.00 MHz, and a host of crystals to mix with that to generate the desired HF bands.  Today, that box might be a single chip Direct Digital Synthesizer for casual use, or a complex Phase Locked Loop synthesizer for the highest performance.  On the left, those two RF amplifiers might be four or more stages, all “Class A”, high linearity stages.  On the right, there might be more than two stages, but they all would be higher gain, “Class C” stages.

AM as seen on an oscilloscope. The carrier is so much higher in frequency than the audio that we see what looks like an audio frequency envelope filled with lighter color that's the many cycles of the carrier.  The amount of AM is measured in percentage and that can be calculated by measuring the amplitude of the peaks and valleys of the signal, my rough guess is this is about 80% modulated.

Any portion of the transmitter's power amplifier circuit can be used to modulate the output amplifier: the cathode, grid or the output (plate); modulators are referred to by what they modulate. I don't follow AM enough to say what the most common mode is, but since plate modulation is running the RF circuits in the most efficient mode possible (class C), I always thought the industry would have used that. A high voltage transformer is used to apply the modulation to the plate circuitry.

Mathematically, AM modulation is mixing: multiplying the carrier times the audio frequency.  If the audio includes a DC value of the proper voltage, the output of the circuit is the carrier (the DC term) along with the sum and difference frequencies – the carrier plus the audio and the carrier minus the audio.  The sum is referred to as the upper sideband and the difference as the lower sideband.  If you think about it a minute, if all the information is in the sidebands, and the same information is in either sideband, the logical conclusion is if you only transmit one sideband you transmit 100% of the information, at a tremendous saving in power.  The only thing sending full AM does is make the receiver easier.  Bell Labs was researching this in the early 1920s.

As anyone who has listened to an AM radio can tell you, AM is prone to noise pickup.  This is because static, electrical sparks, and so much more, cause noise spikes of high amplitude at the receiver frequency and this unwanted AM gets “stuck onto” the desired signal.  While Frequency Modulation was experimented with for noise improvement before Armstrong's work, this was work done on narrowband FM and that legitimately doesn't provide as much immunity to noise as the wideband FM that Armstrong patented in 1933.  Wideband FM (WBFM) hadn't been properly analyzed by others and they hadn't foreseen some of the benefits of WBFM.  Today's Broadcast FM stations are the WBFM that Armstrong originally developed (with the addition of stereo).  Because FM detectors are designed to detect changes in frequency rather than amplitude, they are much less affected by AM noise like lightning static, powerline noise and so on.  Part of the protection is the use of VHF frequencies for FM broadcast – the sources I just mentioned are naturally reduced in amplitude as the radio frequency goes up.

The amount of modulation in an FM signal is referred to as deviation, expressed as how far the carrier deviates during use.  NBFM is used in amateur handheld radios, with a typical deviation of 5kHz peak; the WBFM which broadcasters use is 75 kHz peak, 15 times greater. 

In practice, it's impossible to distinguish Frequency Modulation from Phase Modulation, and many typical FM radios are actually phase modulated.  If the audio goes through an RC integrator before being modulated, the result is FM (pdf warning).  Often, the amount of modulation is calculated to be a fraction of the desired and frequency multiplication increases the deviation.

Frequency multiplication increases the amount of deviation by the multiplication ratio.

Dispensing with more of the details of the historical steps, it is possible to put intelligence on a radio signal by modulating amplitude, frequency, carrier phase or any combination of those.  We can control every characteristic of a radio frequency signal and every characteristic can be used to get information from one person to another. 

Today, we've developed general purpose modulators that can produce whatever form of modulation is required.  These require signals with a 90 degree phase difference between them, referred to as I and Q signals for In-phase and Quadrature-phase signals.  Any form of modulation (pdf warning) can be created with the right waveforms on those two signals.  Virtually all of these transmitters are done with the low level modulation scheme used on the left in the figure comparing AM transmitters above.

The most common forms of modulation used commercially are probably Bi-Phase Shift Keying and Quad-Phase Shift Keying, BPSK and QPSK respectively, but higher number of phase shifts like 8PSK are common in places.   When you hear of a mode like 64 QAM – quadrature AM – this is combination of both phase and amplitude modulation. 

If there are general purpose modulators, there are general purpose demodulators.

This takes in an RF or IF signal and an LO, splits the LO so that one side is 90 degrees behind the phase of the other side.  These are then multiplied by the RF, which is simply equally power split with both legs in phase with each other.  The result is it strips off the I and Q modulations.  If the LO equals the tuned RF, this becomes a Zero IF receiver and in most of what's on the market, the I&Q data streams go into Analog to Digital Converters.

If the input is on the right, as I and Q signals, the radio frequency output is on the left, this circuit becomes your general purpose modulator. These are commodity components made and sold by the tens of thousands - or more.  And that's just one supplier.  They're made in a variety of technologies with the same block diagram. 

It might be helpful for you to know that in receivers this circuit is called an image reject mixer, or image reject front end.  Last week, during the brief introduction to the Direct Conversion (Zero IF) receiver, I mentioned its drawback of hearing anything on the image frequency at the same level as the desired station.  While this won't give unlimited suppression of the image, it can reduce the image 30 to perhaps 45 dB, not shabby at all.

Friday, April 19, 2019

Citibank Questioned at Shareholders' Meeting - Come up BSing

It's almost unfolding as you'd expect.  According to TTAG - The Truth About Guns - at Citicorp's annual shareholder meeting, they had their feet held to the fire for the way they impose on gun businesses.
Justin Danhof, General Counsel for the National Center [for] Public Policy Research and Free Enterprise Project posed a simple question. “Can you tell us – your investors – exactly how much money we stand to lose because of this decision, and explain why you have this right while Warren Buffet has this wrong?”
I say "almost as you'd expect" because Justin Danhof isn't from one of the mutual fund companies who are actively managing money for millions of Americans; his letterhead says, he's the General Counsel and Free Enterprise Project Director for The National Center for Public Policy Research.  He's interested, but it's not his job to be optimizing return on every penny.  Still, he's asking the right question: what makes you think you'll get me better returns on my investments than Warren Buffet and Berkshire Hathaway - who have made lots of millionaires over the years?  Buffet famously said,
“I don’t believe in imposing my political opinions on the activities of our businesses,” he said. It was the second time he stated his position. Earlier in 2018, he stated it just as clearly. “I don’t believe in imposing my views on 370,000 employees and a million shareholders. I’m not their nanny on that.”
Unfortunately, Citibank CEO Michael Corbat is either a moron or liar (not that he can't be both) because he really gave some stupidity for his answers.
Corbat said Citigroup’s policy to discriminate against firearms manufacturers and retailers who refuse to abide by their policy of instituting age-based gun bans – deny a right to keep and bear arms by a legal adult – wasn’t a Second Amendment threat, rather a “good practice.”

Corbat tried to couch it that they would only do business with retailers who conduct full background checks and no financing for companies who use loans to convert legal firearms into illegal firearms.

If it sounds confusing, it’s because Corbat purposefully was aiming to do so.
Since the readership here is generally quite aware of the laws for buying and selling guns, I don't need to quote the next paragraph from TTAG - but I will, with emphasis added.  The important point is that Corbat is either lying about what their practices are or he's too stupid to know he's asking them to do what they already do.  Again, not that he can't be both lying and stupid.
All federally licensed firearms retailers are required by federal law to conduct an FBI background check at the point-of-sale before they can transfer a firearm to a consumer. This is done each and every time. This is not a “best practice,” it’s the law which the industry supports.  Also, no firearms manufacturers use any money – lent, invested or earned – to convert legal firearms into illegal ones. It’s a quick way lose a manufacturing license and head to prison.
In Danhof's letter (pdf warning), he accuses Corbat of not meeting his fiduciary duties to shareholders, but merely following the lead of the liberal media:
The company joins a list of corporations following the liberal whim of the moment and not looking out for the best interests of long-term shareholders. CNBC talking head Andrew Ross Sorkin has been pressuring banks and credit cards to take a stand against gun rights. But you don’t work for the interests of a liberal journalist. 
Corbat wouldn't commit to how much money this policy has cost Citibank, merely saying, it hasn't “cost us a meaningful amount of money.”  This is debatable, and there are details at the original article.  

Like the rest of us, CEOs are never 100% right or wrong.  This is a wrong decision on the part of Corbat, or the Board of Directors.  Is it the only wrong decision?  Doubtful, but I don't know.  Citibank stands out especially because they're only in business today due to taxpayers bailing them out in 2008.  As their way of thanking taxpayers, Citi is making sure to deny 2nd amendment rights to taxpayers that are "too young" in their view.  It's none of their Citi's damned business.  If the gun store is following all applicable state and federal laws, that's all they need to know.  

You know I'm dedicated to free market principles, and the right principle here is for the Mutual Funds and other Citi stockholders to hold Corbat responsible for a stupid decision.  Hopefully, word of this will get around and increase the chance they get rid of Corbat and get a saner CEO in place.  Which is why I'm passing the word around.

Thursday, April 18, 2019

NASA to Open Lunar Samples Untouched Since Collection

Frankly, this article shocked me, but according to a news article from Machine Design, NASA and the Lawrence Livermore National Laboratory will soon be opening some lunar samples that have not been touched since Apollo 17 at the very end of 1972.  The samples were sealed while on the moon to keep them "vacuum packed" and have never been opened.
Nine “special samples” were collected during the Apollo 15, 16, and 17 missions and stored in containers with indium knife-edge seals to maintain a lunar-like vacuum. Apollo mission planners devised these special sample containers to meticulously preserve fragile and transitory sample characteristics (e.g., solar wind volatiles and volatile coatings). Three of these samples have remained sealed in their original Apollo containers until today.

Cosmochemists at Lawrence Livermore National Laboratory will get a chance to analyze these Apollo 17 relics to study the geologic history of the site where the rocks were collected, a geologic cold trap where water may have been able to freeze. This marks the first time a sample will be studied in detail since the end of the Apollo program.
The surface of the moon is covered by a fine, powdery, dust called regolith created by meteoritic bombardment of the Moon’s surface over the past 4.5 billion years.  Volatile elements, such as those from coronal mass ejections from the sun, can get trapped in the powdery regolith and the techniques for finding, identifying, and determining quantities of these volatiles have improved in the intervening 50 years. 

One of the neatest aspects of this new analysis is that the guy who collected some of these samples, Geologist Harrison Schmitt, 83, will be part of the LLNL team doing the studies.

(Harrison Schmitt on the lunar surface during Apollo 17 - his only space flight.  It's only when you look at device in the right foreground that you realize you're looking at a color photograph, the scene is so monochromatic - NASA photo)
A new NASA program, the Apollo Next Generation Sample Analysis, has selected nine teams to extend the science legacy of the Apollo missions by studying pieces of the Moon that have been carefully stored and remained untouched for nearly 50 years. LLNL is part of the University of New Mexico team of scientists that will look at the vacuum-sealed samples to study both the volatile element record and the geologic history of the Apollo 17 site.

The teams were selected by NASA’s Planetary Science Div. and will be funded by the space agency’s Lunar Discovery and Exploration Program. The goal is to get the most data possible from these samples in preparation for future lunar missions anticipated in the 2020s and beyond.

LLNL will conduct the measurement of noble gasses, as well as analyze major and trace elements and chronology on large clasts. Specifically, they will determine how noble gases were modified by meteorite impacts on the regolith, define the source of hydrogen in hydrogen-bearing minerals in the regolith, and investigate the origin of meteorites that hit the Moon through its history. The group will also determine the ages of samples in the regolith using a variety of dating techniques to better understand the timing of crust formation on the Moon.
One would have to consider these specimens to be essentially priceless and irreplaceable, at least for now.  Naturally nobody is just going to pop open the vacuum container and say, "now what?"  That's going to be decided long in advance.  Before that happens, the teams will meet at NASA's Johnson Space Flight Center in Houston for planning sessions to determine the best way to open the samples to avoid contaminating them or destroying opportunities to learn something from them.

Wednesday, April 17, 2019

Question for Fellow Google Bloggers

Is anyone else seeing a big increase in Spam comments?  A couple of weeks ago, I woke up to something like 10 comments to 10 different posts - like the last 10 posts I put up.  They all contained links to some commercial site.  Deleting Spam is "all in a day's work" as they say.

This is different.

It may be the way I have things set up that makes them standout to me, but lately I've been getting about a half dozen to a dozen Spam comments every day.  They're always to old posts, and this is the strange part, they will comment repeatedly to the same post over a period of days.  I've had posts from 2010 or 2014 that just get commented to over and over again.  It's like they latch onto that post and keep trying to get through.

The way I have the blog configured is that comments to posts over 14 days old go into moderation.  I do this for a couple of reasons: first, to know that comments to old posts have been made.  The blog displays about the last 30 posts, about a month, and I don't go watch comments on posts more than a few days old.  When they show up in my Gmail inbox, I can go read and react if necessary.  The second main reason is that older posts tend to be found by whatever mechanisms the spammers use and it's best to delete those comments rather than clog up the reading for people who come across the post later.  Occasionally, though, I get comments on old posts that are valid and related to the post.  I approve those and let them post.  My twin posts on getting ripped off by Ian Sinclair Design for their credit card knives are an easy, good, example.  Between the two posts, they got 128 comments over more than two years.   

These latest Spam comments have all sounded like they're either auto generated, or left by non-English speakers.  They alternate between random words, flattering comments on how wonderful the blog looks, or ask questions about things that seem designed to get me to respond.  It might be an AI system learning or just a simple SpamBot. 

My assumption is that if I post them, that will tell the spammers that they can post their ads or other things they're posting.  Or get their credit for whatever they're doing.

Anyone else seeing this?

(Spambot image source)

Tuesday, April 16, 2019

SpaceX's Falcon Heavy Wasn't A Perfect Day After All

News was released yesterday that the center booster of the Falcon Heavy was lost at the drone ship due to sea conditions.
"Over the weekend, due to rough sea conditions, SpaceX's recovery team was unable to secure the center core booster for its return trip to Port Canaveral," SpaceX representatives said in an emailed statement. "As conditions worsened with 8- to 10-foot swells, the booster began to shift and ultimately was unable to remain upright. While we had hoped to bring the booster back intact, the safety of our team always takes precedence. We do not expect future missions to be impacted."
This is the time of year when it's very common for the area around the Cape to get strong winds off the ocean and those winds bring rough seas.  While it's a shame to see them lose the booster, reality is the system has to be designed for these seas.  Balanced all the while against the cost of a ship that much bigger and more stable than the ones they're using.

It's widely reported that the ships are autonomous, and the crews are relocated onto another ship that stands back well away from the drone ship while the landing attempt is made.  The first step is for a crew to return to the ship and secure the booster to the deck by welding hold down brackets to the landing feet on the Falcon 9, according to the Wikipedia entry.  The statement from SpaceX makes it sound as if they viewed it too dangerous to deploy the welders onto the drone - or to leave them there if they were already aboard.

When you look at the feet of the booster, remember these things are a lot bigger than you might think.

The same view with some workers near the legs adds perspective.  Those hold downs aren't standard U-bolts you're going to find at Ace Hardware.  

And the Atlantic off the Florida east coast gains another stretch of artificial reef a bit over 225 feet long and 12 feet across.

Monday, April 15, 2019

Monday Odds and Ends - Peak Florida

Two stories that are short and don't belong together.

Peak Florida

You're probably thinking of more Florida man/woman stories.  This time it's a Florida Reptile.

You may know we have a problem with Burmese Pythons taking over the ecosystem in the Florida Everglades.  I know I've done a few stories on these (cool photo or useful map of python range).  Our local paper carried a story that shows even a bad python may have a silver lining (?)  It seems the pythons are killing off rattlesnakes by carrying a parasite that is decimating the pygmy rattlesnake population.
Now, Burmese pythons are killing — although indirectly — one of their own ilk, the pygmy rattler.

A new study, led by researchers at Stetson University, shows that parasitic worms spread by invasive Burmese pythons are killing native Florida pygmy snakes.

The researchers found the invasive worms in Central Florida, more than 100 miles away from where the Burmese pythons reside in the southern portion of the state. But that doesn't mean the pythons are there. The parasite is getting that far north by other means, hitching rides in reptiles and other host critters that Florida snakes eat, with risk of spreading far beyond the Sunshine State.
Yes, I know that rattlesnakes can be important predators in the ecosystem, but I don't mind a few less pygmy rattlers.  While I know people who have encountered very large eastern diamondback rattlers, pygmy rattlers are more likely to brush up against the people in suburbs and more rural areas.  

OTOH, this being Florida, Australia of the northern hemisphere, the pygmy rattlesnakes are probably keeping something even worse under control.

Back on the first Sunday of March, I posted about Mrs. Graybeard's painful trip over the hose while setting up to wash the cars.  For the rest of March and into last week, she was confined to a walker with instructions to not put any weight on that foot, along with lots of other restrictions.  We did x-rays every week to ensure the part of her thigh bone that broke off didn't displace but started to attach to the rest of her femur.  

Last Monday, week 5, the doctor cleared her to start putting more weight on that, and to get around on a cane instead of the walker.  We have both the cane and the walker from earlier "adventures" so it was easy to transition. She pretty much re-achieves some extra motion and extra ability daily, getting a bit more back to normal a little at a time. 

Today we did what we probably would have done a month ago, and went to our local multi theater to catch Captain Marvel.  Unless you pay no attention to the Marvel Cinematic Universe (MCU) you'll know that calling for Captain Marvel was Nicky Fury's last act at the end of Avengers Infinity War and there are scenes in the trailers showing her working with the remaining Avengers for Endgame.  It was originally rumored she was the only Avenger strong enough to take on Thanos.

Let me start out by saying this is a good movie that belongs in the MCU; it's not stuck on like they didn't know where else to put the character.  Both Mrs. Graybeard and I were dreading that it was going to be too full of "Grrrl Powerrr" stuff and it wasn't.  Captain Marvel is played by Brie Larsen, and back in 2017, when I wrote about Kong: Skull Island, I referred to her as "the designated pretty girl" part.  I didn't think much of her because she was really a background character playing a stereotype role in a comic book movie.  In this movie, she shows quite a bit more acting range and is actually quite good. 

The movie is Captain Marvel's backstory to help setup Avengers Endgame.  I don't really want to do paragraphs explaining the plot - go see it.  In using this movie to do Captain Marvel's story, they devote the full two hours to her story which makes much more sense than a half hour tacked onto Avengers Endgame.  This way, I'll bet Marvel makes both movies more watchable and gives a more complete storytelling than, say, the first half of Wonder Woman doing her backstory.

If Thor Ragnarok is my favorite of the MCU movies, I can't rate this one higher than that, but this was a good, fun movie.  Better than Black Panther, not as funny as Ant Man or Ragnarok, and better than I expected.  Good solid 4 and some change out of 5.  The movie starts with a modified opening that replaces the familiar flipping comic book pages with a tribute to Stan Lee.  Stan appears in this one in a cameo, and I understand he appears in Endgame, too.  The usual Marvel previews during and after the credits are worth waiting for. 

Oh, and watch for the cat, Goose. 

Sunday, April 14, 2019

Radio Sunday #3 - The Birth of the Modern Receiver

The Superheterodyne – Part 1

Now we're back where we started, before the look at earlier architectures for receivers. The most common receiver design is the superheterodyne, developed by Edwin Armstrong in 1918 – during World War I – and just after the Tuned RF design. Undoubtedly both men were working on the same problems and Armstrong found a way to overcome many of the problems of the TRF design along with other competing ideas. The superheterodyne principle of operation is followed in virtually every modern radio; whether or not that design is implemented in hardware or software.

So what does superheterodyne mean? It is essentially a buzzword; an advertising line. The best explanation I've read is that super was a big advertising word, hetero came from the word for “different” referring to different frequencies and dyne from power. Heterodyne has come to mean to combine two signals by multiplication, which produces the sum and difference of the two signals. This process is widely used, but it's usually called mixing, so that the components that do this on purpose are called mixers. Multiplication? Like light, if you put two radio signals through a medium like the air, or (for radio) a wire, they stay as their separate frequencies and don't affect each other. Only if you combine them in a circuit that affects their amplitudes nonlinearly will you get the sum and difference frequencies.

Let me present a block diagram of a superheterodyne (superhet) receiver that looks more conventional to hams and others who have studied some electronics than the one I posted in the Receiver Hunting story.

The big X in the mixer is to signify that it's multiplying two signals times each other; due to a property of math, when we multiply two sine waves, we get the sum and difference of the two frequencies.  Real mixer circuits put out four frequencies: the RF, LO, and the sum and difference frequencies.  From a circuit performance standpoint, the best mixers are called double balanced mixers; others exist but thousands or millions of double balanced mixers are sold every year.  The balance refers to electrical currents being balanced in the mixer to help with various performance measures I'll get to later. 

Without the demodulator and audio amplifier, this is a frequency converter.  Back around 1981, I made a shortwave converter for my car.  The local oscillator was two crystals in an oscillator set so one was switched on at a time.  They were set to 9.000 and 14.000 MHz.  The filter took the difference of the input minus the crystal.  That meant that with the 9.000 MHz crystal, 10.000 MHz WWV (time and frequency standard) came out at 1.000 MHz so I could listen to it on my pickup truck's AM radio.  Likewise with the 14.000 MHz crystal, 15.000 MHz WWV came out at 1.000.  I could listen to the “31 meter” and “19 meter” shortwave bands; 9.55 to 9.95 MHz and 15.1 to 15.4 MHz. 

This approach is universally used for frequency converters like this.  Some years later, I designed a two meter transverter for my ham radio station (transverters work for transmitting and receiving).  This took low level transmitter signals and mixed it with a crystal, taking the sum, not the difference.  For the oscillator, I used a 116.000 MHz crystal.  When I set to transmit at 28.000 MHz, the transverter output 144.000.  On the receive side, the system went the other way; it took in 144.000 MHz, subtracted off 116.000 and put 28.000 into the radio. 

There's problem lurking here.  All superheterodyne receivers will receive the undesired mixing product just as strong as the desired.  It's called the Image frequency.  In the case of my shortwave converter, I wanted to receive LO + IF.  My receiver would put out just as strong a response at LO – IF.   That would be at 8.000 or 13.000 MHz depending one which crystal I turned on.  That's why the block diagram has that RF filter at the input – to reduce the strength of anything on the image frequency.

(This image is based on the common IF of 455 kHz, mentioned below)

Mixers can be made in many different ways; Armstrong used vacuum tubes, and as transistors and FETs appeared, those were adopted into service.  The following picture shows what's called a Double Balanced Mixer: a four diode bridge with the Local Oscillator applied on the left, the Radio Frequency applied on the right and the Intermediate Frequency taken out of the tap at the lower right.  These also work “the other way”.  If you apply a low frequency to the IF, perhaps your modulated audio for a transmitter, the RF port becomes an output, not an input.

So why do we do this?  Why do we build an oscillator into the radio, and add the mixer stage?  The architecture buys you some important things
  • It allows you to spread out the gain between RF, IF and audio.  For ordinary use, you might need gain of over a billion.  That would surely oscillate if the radio was all one frequency.  If you spread the gain out intelligently, the chance of a problem goes to zero.  
  • You only tune two circuits: the RF filter and the Local Oscillator.  In practical radios, your RF filter may be switched from a bank of similar circuits as you change bands, and the LO will have components switched so it can tune several bands.  Most of the fussiness of tuning wide frequency ranges in the TRF approach goes away.  
  • You have most of the receiver working on one frequency.  Amplifiers and filters change performance as you tune across your frequencies of interest.  Typically, the higher you tune, the lower the gain goes.  Now you have one stage to be concerned about.  Ordinarily, the IF filter is where the ultimate channel selectivity is obtained; with this approach it stays the same whichever RF band you tune. 
This architecture is universal.  It can mix a low frequency signal up to a higher IF or mix a higher signal down to a lower IF (appropriately called upconversion or downconversion).  Cheap AM radios (remember them?) settled on an IF just below the bottom of the AM broadcast band, 455 kHz, long ago.  Multiband radios with shortwave coverage sometimes upconvert to another IF, usually because there's a filter they want to use first, then downconvert to 455 kHz, in an architecture called dual conversion.  Microwave receivers downconvert, sometimes a dual conversion, to get to a frequency where the signals are processed. 

The block diagram above is single conversion.  High performance receivers in the vacuum tube era went to double and sometimes triple conversion (I haven't personally seen quad conversion, but they might be out there).  Double conversion is still very common.  A very common technique today is to convert the entire receive spectrum, from 0.5 to 30 MHz up to around 70 MHz, filter and amplify, then downconvert to a lower frequency, sometimes in the low kHz.  For example, an Icom 7600, their last superheterodyne HF radio, upconverts to a “roofing filter” (no signal wider than that gets into the rest of the receiver) at 64.455 MHz then downconverts that to 36 kHz where the signal is digitized and all the signal processing is done digitally.

There's an application of the superheterodyne principle that has become widely adopted among hams and is now a frequently used architecture in commercial wireless systems.  Hams call it direct conversion, and the novelty of this architecture is that the IF is 0 Hertz – DC.  The architecture could be the same as previously shown, but in most ham uses, the mixer is the detector. 

In modern radios, the audio filter will usually amplify was well, so it's not a big change.  

So how does this work?  A common example might help: consider you want to make an amateur receiver with minimal power drain, and small enough to fit in a tiny package for backpacking or camping.  You want 40meters (7.0 to 7.35 MHz).  The local oscillator tunes that range (usually called a VFO for Variable Frequency Oscillator).  We know the mixer will give us the sum and difference frequencies, and we want to tune in someone transmitting Morse Code (CW) on 7.025 MHz.  If we tune to exactly 7.025, the receiver would hear nothing.  At this point, you could be using a multi-thousand dollar receiver.  Most of those  receivers offset the display from where you're tuned so that when the display reads 7.025 the LO is really offset from that, and the tone you hear in the speaker is from that offset.  They have a separate product detector, which is a mixer and Beat Frequency Oscillator, BFO.

Instead, we tune the VFO slightly off the exact frequency by tuning it to make a Morse code tone we like.  We've made our demodulator into a product detector and our LO is their BFO.  The problem is that you also hear the image frequency if someone is transmitting on it - the signal that's the same offset as the desired on the other side of the LO.  If your LO is at 7.024, you'll hear someone on 7.023; if your LO is at 7.026, you'll hear someone at 7.027.

In effect, you double the number of potential interfering signals.  This is called the Single Signal problem with direct conversion.  There are ways to reduce it, but it's always there.

The main drawback of the superheterodyne architecture is the complexity of having more parts in more circuits, so cost and complexity.  As a rule, whenever we introduce new circuit blocks and complexity, we have a tendency to fix some problems and introduce others.  In the vacuum tube era, receivers used crystal oscillators and VFOs as their LOs to change bands.  Starting primarily in the 1970s, with digital integrated circuits, those began to be replaced by frequency synthesizers (Phase-locked loops or PLLs).  When those were introduced, problems the existing circuits didn't have started to show up, and radios took a giant leap backwards until that was understood.  Similarly, when transistors replaced vacuum tubes, problems with strong signal handling surfaced that the high standing voltages or currents of vacuum tubes masked, and it took years to understand that, too.

A less obvious problem is that mixers, being the only deliberately nonlinear component in the radio, can introduce problems with hearing signals that aren't really there.  The image is not considered one of these.  The details are probably more of interest to designers than people just trying to learn about how receivers work but makers of mixers sometimes provide charts of all the undesired products their mixers will receive.  Double balanced mixers are better in this regard (better suppression of undesired) than single balanced, or unbalanced mixers, but the "spur table" has to be designed for.   Here's where I get to wave my hands and say, "that's beyond the scope of this article".