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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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
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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
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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 August 21, 2017. The recordings were successful, and I captured
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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
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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
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Just when you thought it couldn’t get more boring (reference my last post about signal generator calibration…
I did all these careful calibrations of my signal generator to check its accuracy and linearity. Everything looked good, except that the signal reading was about 1 dB low.
HP power meters
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UPDATE: it turns out that my “best” power meter was actually about 0.5 dB off. See my later post for further details.
I want to calibrate my software defined radio receiver prior to doing a bunch of recordings of the ham bands for the upcoming solar eclipse (check out the
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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 table of talkgroup numbers and names for that site.
3.
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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 I’m documenting here will be helpful for others going down
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