AMATEUR RADIO AND OTHER STUFF !

PSAT APRS Contact

I was disappointed to find that the SSTV 20 year Anniversary transmissions from the ISS weren't running on time.

Was all ready to go for a capture .... and nothing heard so I decided to console myself and try again for a PSAT APRS contact.

This time it worked!! 🚀

SatGate update - from Nov 2020

After some additional tweaking and, most recently, using my mobile phone as a hotspot and hoping to benefit from a faster upload link; I have managed to get another ISS packet I-gated/SatGated successfully.

Unfortunately, the bulk of the packets are seen as duplicates and although I can see inherently why they are ... although I've asked questions in a number of places, so far I am not sure as to how I can improve the speed/reliability of the I-gating process.

Here's my second, out of many attempts, at relaying an ISS packet to the Internet. This particular pass elicited 12 successfully received and I-gated packets of which 11 were discarded.

I think location and compromised antenna conditions mean that this is not quite ready to be set-up on a permanent basis.
😖

2020-11-26 18:49:10 GMT: F4FEB>TWRSR6,NA1SS*,PCSAT-1,APRSAT,qAR,G8VVY-6:'|=Xl `/]73 de JEROME via Sat JN37GJ

Setting up a Satellite I-gate - SatGate 😉

This was a project to try establish an I-gate - more specifically, a SatGate - to gate APRS packets from stations working the ISS.

I have now succesfully achieved that, and with about the most basic set-up possible!

I made a simple 120 degree dipole - cut for 145.825 MHz - and mounted it as high as possible inside my flat. It's not in the roof space, as I didn't want it to interfere with my wire dipoles, but it does give a 1.07:1 SWR and so I did hope for some positive results.

I used an RTL-SDR USB receiver, UISS and Dany/LU4EG's UISS-SatGate2 module. You additionally require a "validation number" to allow you to both send data to APRS2 servers and let it to pass through to the I-gates, including your own!

The station I-gated, (SatGated), was the 3rd packet down on the following UISS main screen screenshot.

and here is the ARISS.NET entry.

2020-10-29 06:33:17 GMT:
ON4BN>CQ,NA1SS*,RS0ISS,qAR,G8VVY-6:=5104.08N/00522.49E-73' Via Satellite frm Belgium, op:Jurgen

I'd tried using a handheld yagi uda but, although the gain is much better, it was virtually impossible to 'point' the antenna and adjust manually for Doppler at the same time!

The 120 degree dipole should give positive results for high passes.

Dr. Tony England/W0ORE on board Challenger!

I've managed to bring back to life an historic recording of the one of the first space to Earth SSTV transmissions from 1985.

My equipment was:

The ubiquitous Robot 400 SSTV decoder/encoder
Icom IC251E 2m all modes transceiver
9 element horizontally polarised Tonna beam
BBC Micro Model 'B' - for titling
Grundig CR455A - which I still have and is still in mint condition
😉

I played back the recording and decoded it using an Android mobile phone app. then tidied up the image in Paint Shop Pro.

The date was Saturday 3rd August 1985 and the transmission started at approximately 19:10 GMT.

The recording link has all the comments from Dr. Tony England/W0ORE on board the shuttle and - I think - is well worth listening to! You could even try decoding it the same way as I did!
😃

Here's the link ....

● SSTV recording using Robot 400 ●

Before and after tidying up and enhancing the scanned image.

B/W image received at GB3RS.

Colour image received at GB3RS.

The equipment used at GB3RS:

Yaesu FT726R transceiver

Two Jaybeam 10 XY Yagis with switchable polarization

Robot 1200C colour SSTV converter

Part of the transcript from September 1985's RadCom:

"The Society had been advised that Dr England would attempt to have a contact with GB3RS during Orbit 79.

Equipment was checked and re-checked and a simple picture, consisting of a short greetings message to Dr England and a drawing of the spacecraft, was hastily prepared in case it proved possible to transmit it to the Shuttle.

As 1909 GMT approached, three pairs of ears were listening down into the noise. At 1910 GMT the voice of Dr England was heard, in contact with the Scout station EI3ISJ at the Irish Scout Jamboree

At that stage the signal was quite noisy but as W0ORE had a brief contact with the Denbigh School Radio Society station G1GJY at Bletchley he rapidly became fully quieting in the GB3RS receiver.

And then the magic words "GB3RS, this is W0ORE on board Challenger" were heard and a historic contact began.

Dr England said that they had "....a kind of a rocky start" but that they were now "doing great" and indeed were to remain in orbit for another day.

Asked about the progress of the British experiments, Dr England said that both the X-ray telescope and the CHASE experiment to measure the amount of helium on the sun were working very well and that, all in all, "....your British experiments are getting along famously".

He then sent the complete sequence of slow-scan television pictures, which were almost perfectly resolved, and GB3RS transmitted its reply. By then, however, the spacecraft was rapidly disappearing over the horizon and it was not known for some time whether Dr England had received TV pictures from GB3RS.

Happily, NASA was able to confirm later that the pictures had been "perfect copy" aboard Challenger.

GB3RS was therefore the first (and, as it later turned out, the only) station outside the United States to have two-way voice and television contact with the spacecraft, although by no means the first to have two-way voice contact."