Notebook of Time, Frequency,and Ham Radio Experiments
I've noticed that my SDR setup, an Apache Labs Anan-7000DLE transceiver used with the PowerSDR software, seems to rest the S-Meter at a quite high level when there is no signal present. This is unnerving when I try to compare…
Since my updated post on building a P25 trunking scanner with a Raspberry Pi and an RTL-SDR dongle, I've created a copy-and-play image file that gets you up and running in minutes. I've put it (along with a couple of…
I'm using several USB "dongle" SDR sticks from RTL-SDR.com. These nifty $20 devices can receive from 100 kHz to above 1700 MHz. They have a low noise amplifier in the front end that is adjustable from 0 to about 50…
Since I posted my original articles on configuring the Gnuradio-based op25 P25 trunking scanner, there's been a lot of progress in the code. In particular, there is a new fork that changes the program to a command-line version, which saves…
I've continued processing the data generated from software-defined-radio recordings I made during the 2017 solar eclipse at my fairly isolated and low-RF-noise location on Beaver Island, Michigan (45 38 38 N, 85 29 24 W, grid square EN75gp). The nearest…
I set up a smaller version of my mad-scientist stuff at our cottage on Beaver Island, Michigan (45 38 38 N, 85 29 24 W, grid square EN75gp), to record the RF spectrum before, during, and after the eclipse on…
I was fussing about signal generator output accuracy because I wanted to calibrate my HPSDR Hermes software defined radio ("SDR") so that I could calculate the absolute power input in dBm, assuming a 50 ohm load impedance) based on the…
With op25 successfully decoding the control channel, now you just need to set up the trunking configuration. To do this, you'll probably need to set up three files: 1. trunk.tsv defines the sites to be monitored. 2. site_name.tsv provides a…
The info in this and in part 4 was aided tremendously by several folks on the "op25-dev" mailing list. Without their help, I would not have even known where to start in getting my system running. I hope that what…
Here's how to install the OP25 scanning software. If you don't already have Gnuradio installed on a Linux system, do those two things first. Any current Linux distribution works. I use Linux Mint which is very similar to Ubuntu. The…