Notebook of Time and Frequency Experiments
Thanks to Graham Norbury, here is how to set up a Raspberry Pi OP25 scanner to stream audio to an icecast or other streaming server. I have updated my plug-and-play op25-rpi.img image at http://febo.com/os_images/ to include this capability (look for…
As part of the HamSci Solar Eclipse experiment, I recorded wideband data from my SDRs on the theory that capturing the data for later study might be more productive (and less stressful) than trying to do measurements in real time.…
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…
This post documents a few tricks I found useful when making SD card images for Raspberry Pi projects, to minimize file size and download times while making full use of the SD card space. These instructions work for Raspbian Stretch…
In Part 1 I described some background about SDR dynamic range as an introduction to the measurements I did on a RTL-SDR.com v3 USB "dongle" SDR. Now for the results. I wrote a Gnu Radio program to help measure the…
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…
Here's a waterfall showing the 80M CW band from a bit after 1600 UTC (noon) and 2000 UTC (4:00PM EDT) on eclipse day. There was clearly enhanced propagation for about an hour, starting ~15 minutes before the local maximum (73%…
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…