This is a series on the basic problems with privacy in radio communications.
In the event of social unrest, you may want a secure means to communicate with your family, to minimize the chance of opportunists taking advantage of you because of something you say on the radio. This series talks about securing your communications.
Part 1. An overall look at privacy and radio, with concepts from the military (LPI/LPD/LPE), encryption and encoding.
Part 2. Some basic ideas. Keep your transmitter power low - just enough to communicate - keep your transmissions brief - turn off the radio when you're not using it. A basic link budget for analog FM.
Part 3. More advanced ideas. Communicating with low or negative SNR. Information theory. What is spread spectrum? FHSS, DSSS.
Part 4. "Off the shelf" digital communications for hams to experiment with. Low speed because they're audio bandwidth, but with varying degrees of sophistication. MFSK modes.
Part 5. A little information on jamming.
Part 6. Some conclusions. Software Defined Radios you can play with. Some legalities to keep in mind.
More will very likely follow and will be added here when they do follow.
As this is a permanent page, comments to this page are disabled. Comments to the referenced pages are live, but I always must approve comments on posts older than 2 weeks. My purpose is to ensure I see comments that get posted, since I don't go looking for them.