I compared my old HP 5061A cesium standard against a much newer HP 5071A with high performance tube. Cesium standards are tweaked by adjust an electromagnet in the tube; this adjustment is called the “C Field.” In the 5061A you need to set the C Field manually, but the 5071A
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This is the first of several boring posts where I’m documenting the offset of a couple of my frequency standards so that I can come back later and determine aging rate.
This is my Oscilloquartz 8607-008 BVA quartz oscillator. I don’t know the last time it was adjusted, but when
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Many people use HF transceivers in situations where they back the power down significantly from full output. Examples are driving an amplifier that may require 20 or 30 watts for full output, or using a transverter that might want just a few milliwatts.
The method many modern HF transmitters use
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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 the 2018-03-18_op25_rpi.zip or later-dated file).
1. Copy the following
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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. I think that theory played out very well.
I
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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 other RPi image files) at http://febo.com/pages/os_images/. The filenames
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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 images; not sure about older or newer versions.
The first
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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 dongle. It tunes the dongle, sets its front-end gain,
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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 dB gain. I wanted to determine the impact of
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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 a lot of CPU resources and also offers added features.
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