Thursday 18 September 2014

Listening for VC1T, was there any chance of hearing them?

How I listened for VC1T the recent Two Metre Trans-Atlantic attempt which took place 4-11 July 2014.

I have a very modest station but could I ever hear a transatlantic signal? Well maybe, after all I've heard tropospheric signals from the Azores, Madeira and the Canaries on 144MHz and UA3 via sporadic E. Distances in the order of 2500km. The distance between me and VC1T was 3600km. Yes, eleven hundred kilometres more but nevertheless I thought I should at least try and their signal could arrive via the ionosphere! So here's what I did.

To make the best of the opportunity I realised that I needed to monitor continuously and not just when in the shack. VC1T were going to be using WSJT9 modes FSK441 and JT65B.

My setup, no large antenna here


Beside the radio, the computer is a vital part of attempts like these. On mine it would be necessary to run three programs WSJT9, Radio-sky Pipe and PowerSDR-IQ. So a day or so before VC1T went on air I started up the three programs to see if there were any conflicts. None, all worked first time, WSJT and Radio-sky Pipe sharing Virtual Audio Cable. WSJT was set to record any decodes and Radio-sky Pipe set to record any signal just above the noise. PowerSDR-IQ set to 144.155MHz.

Test JT65B using GB3NGI


        I have used Radio-sky Pipe, in the past, to monitor beacons and calling frequencies when not in the shack. It can be set to record audio files to a signal level trigger point. It also draws a strip chart that helps to identify short lived signals.

So, from the first day of transmission from VC1T I was ready to monitor. FSK441 was the first mode in their schedule so WSJT9 was set to that mode, monitor only, save any decodes and the station left running.


Monitoring FSK441 for any MS from VC1T
Nothing of any interest was received on the first day, the 4th July, just one or two EU stations on tropospheric and some backscatter MS. The next day the mode would change to JT65B but that was at 0100z, so I changed mode as late as  possible but before VC1T. WSJT would not be able to decode but Radio-sky Pipe would still record any signals.

On Saturday the 5th July there seemed to be many more EU station around but nothing from VC1T.

Part call sign decode but in the wrong period so not VC1T

Sunday the 6th back to FSK441. I was in the shack all morning, lots of EU stations calling, and some very nice backscatter pings. I don't know about anyone else but that morning I had a feeling that something was different propagation wise compared to the previous two days. There was a contest in EU and I heard many pings from contest stations  on VC1T's frequency, CW and phone. Then came the exciting news. And exciting it was. And congratulations to them but I was not surprised that VC1T's signals had been decoded. It just seemed as if things were going to happen. But I heard nothing from outside EU.


A Meteor scatter ping as recorded using RadioSky Pipe but was it VC1T

The news of the decode was very encouraging and so my equipment was left running, recording away. I saved all the audio files from WSJT and Radio-sky Pipe to a memory stick and transferred them daily to another computer searching them for anything interesting. It was possible to run them all through WSJT and look for decodes.  I spend a lot of time searching the Radio-sky Pipe recordings using a spectrogram.

In the end I found just one file that I think I can say, maybe, just maybe, could have come from VC1T.  Timing seems crucial here.  The ping came just inside VC1T's transmit period but perhaps my timing was out or an EI station's timing was out or both. You can see it was recorded Sunday 6th July at 1021 and 30seconds, 0.7 of a second into VC1T's transmit period.

Could this be VC1T?


Whether I heard any thing of VC1T or not I had a great time trying. I only hope there's another attempt soon, I would certainly monitor again, you just never know your luck.

UPDATE:

A year after I made this post the saved files of the 6th July 1021:30sec  ping were sent to JT himself for analysis.  I was happy with the message back,  "it could have been VC1T but there's no way to prove it".  Better I think "than it couldn't have been because ......".