Thoughts on a Wideband SDR Recording Tool

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 used a simple Gnu Radio flowgraph to do the recording from an HPSDR Hermes receiver. When I say simple, I mean simple. Here’s the whole thing, which records four 384 kHz […]

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RTL-SDR.com Dongle Measurements (Part 2 — Results)

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, shows a spectrum display, and also shows the power in a 500 Hz bandwidth around the tuned frequency. That power reading is what I used for these measurements. The flowgraph is […]

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RTL-SDR.com Dongle Measurements (Part 1 — background)

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 the gain setting on receiver performance, and the results are below. First, some introduction. The dongles use an 8 bit analog-to-digital converter (“ADC”). The number of bits sets the dynamic range, […]

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Eclipse — 80M Waterfall

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% obscuration) at 1819 UTC. There aren’t many signals shown at any time, but that’s to be expected at mid-day in this frequency range. In order to show this long time period, the waterfall only updated every 60 seconds and I […]

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More Solar Eclipse Analysis (HF Propagation)

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 AM station is about 28 miles away, so it’s a pretty good site for monitoring the high frequency bands. The data was recorded over the eight hours from 1400 – 2200 UTC (10AM to 6PM EDT) on Monday, August 21, […]

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FTS-4100 Cesium Standard tests

It wasn’t too hard for the HamSci guys to convince me to bring a Cesium frequency standard to my portable location in Michigan to drive the HPSDR receiver that will do band recordings for the 2017 Total Solar Eclipse HF Wideband Recording Experiment. I had been planning to use a GPSDO, but that would be too simple. My “sort-of-portable” Cesium is an old FTS-4100 that came out of military service. It was designed for shipboard use (I think as part […]

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Hermes SDR as spectrum analyzer

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 dBFS (db full scale of the ADC chip) output from the radio. This is in preparation for the upcoming solar eclipse, where as part of the HamSci 2017 Total Solar Eclipse HF Wideband Recording Experiment I’m planning to use the […]

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An interface from Hermes/ANAN to the TASS relay board

I didn’t even think of it when I was designing the TASS-R relay switch system, but the relay board can be used with an HPSDR Hermes, ANAN-10, or ANAN-100/200 radio without requiring use of an Arduino or other controller.  These radios provide 7 open collector outputs that can be programmed from within the PowerSDR software.  A simple interface board allows the TASS-R to be controlled by these outputs. The idea is that two of the outputs can be used as […]

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TASS Switching System announced, and fun with enclosures

Today TAPR announced availability of a project I’ve been working on for a while, a computer-controlled switch system called the TASS.  It consists of an 8-port relay bank that handles from DC to 150 MHz, a shield for an Arduino, and open source software for the Arduino. You can order the boards from http://tapr.org/kits_tass.html. I also designed an enclosure for a TASS board plus touchscreen controller, and had that built by Front Panel Express.  Here are some pictures of the […]

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