Notebook of Time and Frequency Experiments
A lot of us use Anderson PowerPole connectors for DC power distribution. There's a nearly universal standard to use red and black housings for 12 volt-ish (e.g., 13.8) lines, with the housings arranged per the "Orange County RACES Standard" like…
One of my Gnuradio projects is a tool that records IQ data covering 375 kHz -- which is enough to capture an entire HF ham band (except for 80/75M). A neat trick is to retransmit such a recording to allow…
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…
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…
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%…