I plan to build an ADS-B tracker. However, I live in an RF noisy urban neighborhood, and all that noise can desense an RF receiver, so I bought this FlightAware Dual UAT+ADS-B filter. I put it on the spectrum analyzer and I measured a passband from ~930Mhz to ~1.2Ghz with ~1.5dB of insertion loss. Since this is all up in the gighertz range, my plan is to keep the antenna feedlines short by mounting a raspberry pi 4 in a weather-rated enclosure close to the antenna. I’ll power all of it by running a network cable with POE to the raspberry pi with a POE hat.
You’re about ready to get your radio geek on and you get a PortAudio Error -9999 Unanticipated host error, followed by a PortAudio Error -9988 Invalid stream pointer. WTF since everything was working fine on Windows XP/Windows 7/Windows 10. Well, the mighty fine folks at Microsoft decided to tighten up security with applications (“apps” if you’re cool) permissions to access the microphone.
The fix is straight-forward: On Windows 10, you go to settings->privacy->microphone and enable it. If you are privacy concerned like me, you can then go through the “Choose which apps can access your microphone” and turn them all off.
For you new software engineers – this is a great example of a shitty error message. If the message said “Access denied while trying to open your microphone or input device. Please make sure this device is enabled and the access permissions are correct” that would make it much easier to diagnose the issue.
The HF Voyager is an autonomous Wave Glider (drone) traveling from Hawaii to California. What’s fascinating is the JRFARC club has included a low power HF radio as part of the payload. The Elecraft KX3 radio only puts out a max of 10 watts (and they’re probably running lower power than that) and I was able to receive the FT8 mode transmission with a simple magnetic loop antenna connected to my Anan 200D HF radio 1600 miles away.
The openspot by SharkRF is a digital radio gateway that allows you to use your d-star, dmr, or c4fm radio worldwide. What I liked about it the most is it is simple – plug it in, do some simple configuration via your browser, and you can start talking around the world on a little portable handheld radio. Afterward the success of that excitement, I decided to tear it down to see what it was using under the hood.