Carrier Sleuth generates very high resolution waterfalls from I/Q recording files made by several SDR (Software Defined Radio) programs. It's a powerful tool for detecting very weak MW stations that you cannot necessarily hear. And it can be used to "fingerprint" station carriers for identification purposes.
More details and downloads here:
https://www.blackcatsystems.com/software/medium_wave_carrier_display_app.htmlI examined 1710 kHz with Carrier Sleuth, using SDR recordings from roughly 1700 UTC 24 December 2019 - 1430 December 25 2019. Here's the high resolution waterfall it produced:
I used my AFE822x SDR to make the recordings, it's A/D clock is not locked to GPS so it can drift and have errors. When I spot checked 10 MHz WWV this morning it was reading 12 Hz high, so at 1710 kHz the frequencies would be 2 Hz high. the antenna was my new 120 ft T2FD.
At the beginning of the waterfall we can see three carriers. I believe the center one (1710.008 kHz) is the Flight 93 TIS (or at least one of them, apparently it has two transmitters).
Just before 2100 UTC we see what I believe to be Radio Corsair's transmitter (1710.0025 or so) appear and disappear a few times. I believe this was him tuning up in preparation for the later show.
At 2142 UTC a transmitter is turned on. You can tell it was turned on and was not fading in due to the frequency drift. This is fairly characteristic of most transmitters when they either turn on or change power levels, due to thermal effects on the oscillator. This settles to 1710.0073 or so, and then goes QRT at 2240 UTC. But it's not Radio Corsair, because they signed on at 2208 UTC, which can be clearly observed. I assume this was another pirate?
Another carrier appears on 1709.991 at 2240 UTC. There is no drift. Same transmitter we observed above, but something changed the frequency. It's weaker also, so maybe lower power? Off at 2300 UTC.
Radio Corsair signs on at 2208 UTC, drifts a little, and ends up on 1709.996 kHz, and goes QRT at 0208 UTC, which matches the audio I heard.
Another transmitter appears at 0144, and drifts down to 1710.007 kHz or so, tough to tell. It sure looks like the one that appeared earlier at 2142 UTC.
There's another transmitter that appears at 0208 UTC around 1709.990 kHz and goes off 0213 UTC. Radio Corsair again? It's weaker than their previous signal, so perhaps someone else.
There's a zoo of other carriers that appeared overnight. The strong signal from Radio Corsair made it difficult to see them when it was on the air, another night's observations might shed some light on them. There are quite a few TIS stations on 1710, plus of course who knows how many pirates.
Many of the 1710 kHz TIS stations (as well as TIS stations on other frequencies) are operated by the Federal government, and do not appear in the FCC database. I filed a FOIA request and obtained information about these stations, which is incorporated into my DX ToolBox program for Windows and macOS (along with lots of other useful information and tools). I believe this is the only public source for these TIS stations. Information and downloads for DX ToolBox are here:
https://www.blackcatsystems.com/software/ham-shortwave-radio-propagation-software.htmlHere's the TIS stations that appear on 1710 kHz. I suspect some of these are the weak carriers observed on the waterfall:
Stations fade out as expected around sunrise, leaving the Flight 93 station(s), as well as probably Hudson County NJ and Springfield MA as the last to go.
Topic: Looking at 1710 kHz with Carrier Sleuth (Read 2035 times)
