KG-STV experimental Slow Scan from ISS - Feb 2022

On the 20th of February 2022 the ISS cross-band repeater rig - Kenwood D710GA - was 're-assigned' to run a digital Slow Scan TV experiment.

ARISS Europe - using the callsign ON4ISS - was uplinking the images from the amateur radio telebridge groundstation in Belgium.

A 1 minute and 40 second transmission was followed by a 1 minute and 20 second break.

KG-STV - a Minimum Shift Keying application designed by JJ0OBZ - was used to transmit a number of images over 5 passes  between 05:10 and 12:00 UTC whilst the ISS was over Europe.

KG-STV sends a 320 x 240 compressed JPEG in 15 lines of 20-off 16 x 16 pixel blocks. 2 frequencies are used ... 1800Hz for the ones and 1200Hz for the zeros. The signal only occupies 600Hz and so is very efficent.

It is possible for the receiving station to send a block repeat request to the transmitting station in order to have it resend missing, or corruped, blocks to produce a 100% image but unfortunately this would not be possible with this test.

My images were from the 08:31Z and 10:08Z - the two highest altitude passes. The 87 degree pass produced the better of the 2 images, but both are marred by missing and corrupted data.

 

  

 

 Passion SSTV - an amateur radio group in France - kindly created a certificate for the occasion!

 

 

 Click on the image to see it full size! 😉

 

Hopefully there will be more tests in the future!

Zachtek 80To10 200mW WSPR transmitter

After having a play with WSPR using WSJT-X, and after reading a glowing review of Zachtek's 80To10 model WSPR transmitter, I decided to break the bank and purchase one for myself! 😊

It is basically a 200mW, multi band hopping, standalone WSPR beacon transmitter .. that also doubles as a precision signal generator.

I thought it would be ideal to run through my fan dipoles - 40, 20, 15 and 10m - and give me a great picture of conditions across these bands during the course of a day.

A PC is only required for the initial set-up, which is very straightforward. A supplied active GPS antenna picks up a signal for positional and timing purposes and once it has a lock, the transmitter gets on with the business of beaconing on the selected bands.

Current draw is around 100mA at idle and 250mA whilst transmitting, and a phone charger makes a suitable power source, when not running from a PC USB port.

I did have some 'teething troubles' because I was having a combination of low GPS satellite signal strength and potential RFI blocking .. made worse by the poor signal level. After a re-positioning of the antenna puck, all was working absolutely fine!

All in all, an excellent piece of equipment for accurate and informative propagation studies!

And my thanks to Harry for quickly guiding me to relocate the GPS antenna when I was convinced it was something more serious! 🙂

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Please look at the updates further down the page to follow my progress
with 'fine tuning' and getting things working satisfactorily.

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I now have the Zachtek transmitter working, and beaconing on the 40, 20, 15 and 10m bands.

It cycles from one band to the next and I have a 120 second break after the 4 band cycle before the process starts again.

I'm achieving some astonishing distances, bearing in mind the output power is only 200mW, or 23dBm.

When I've accrued more data, I want to try and see how each of these bands varies, propagation wise, throughout the day.

Here are some 2D plots for each of the bands.

Click on the images to see them full size! 😉

10m

15m

20m

40m

UPDATE! - 4th February 2022

I now have the Zachtek transmitter working standalone and have collected - at the time of writing - around 6 hours of continuous data.

Here is a map - with band key - showing just where I am reaching.

Click on the image to see it full size! 😉

UPDATE! - 8th February 2022

After running in to some issues regarding the transmitter 'freezing' after some 8 to 10 hours of operation, all appears to now be resolved.

I contacted Harry Zachrisson at Zachtek and appraised him of what was occurring.

After a protracted period of running the transmitter, it would just cease beaconing. The first time it happened I was able to get it to restart by removing the charger connection, plugging it back into my laptop and running the configuration software. I could see it polling the ‘visible’ satellites and then getting a positional lock.

To me, it seemed as if the device was perhaps drifting and losing the GPS position/timing signal. Harry suggested it was far more likely that the GPS antenna was picking up RFI and that, combined with the fact that I was receiving only a very weak satellite signal anyway, was the cause of the failed beaconing.

I relocated the GPS head and used double sided tape to secure it to the window glass. Then I powered up the transmitter and monitored it during a 12 hour plus period; it worked fine! 

Panic over.  😃

The following screen shot shows reporters that have picked up my transmissions during the course of 12 hours over the 8th February 2022.

Click on the image to see it full size! 😉

WSPR - Weak Signal Propagation Reporter

Joe Taylor - the Nobel Prize winning amateur radio enthusiast who developed WSJT-x - devised WSPR in 2008.

It is another machine to machine application that uses low power transmissions to determine propagation paths.

It uses a 6Hz wide FSK signal to send callsign, grid locator and signal strength (dBm).

Each frame is 120 seconds long, of which 110.6 seconds is transmission.

There is nominally a 5:1 receive:transmit ratio.

I have been using the built-in WSPR transmitter/receiver in WSJT-X.

The best reception to date on 20m was a 10mW signal from Italy! 😊

I've included a map of WSPR reporters picking up my 20m band signals where I've been using my FT817ND, running 500mW.

The longest distance reports were in Queensland and New South Wales - 10,372 miles and 10,696 miles respectively.

Click on the images to see them full size!  😉

UPDATE! - 8th February 2022

After running in to some issues regarding the transmitter 'freezing' after some 8 to 10 hours of operation, all appears to now be resolved.

I contacted Harry Zachrisson at Zachtek and appraised him of what was occurring.

After a protracted period of running the transmitter, it would just cease beaconing. The first time it happened I was able to get it to restart by removing the charger connection, plugging it back into my laptop and running the configuration software. I could see it polling the ‘visible’ satellites and then getting a positional lock.

To me, it seemed as if the device was perhaps drifting and losing the GPS position/timing signal. Harry suggested it was far more likely that the GPS antenna was picking up RFI and that, combined with the fact that I was receiving only a very weak satellite signal anyway, was the cause of the failed beaconing.

I relocated the GPS head and used double sided tape to secure it to the window glass. Then I powered up the transmitter and monitored it during a 12 hour plus period; it worked fine! 

Panic over.  😃

UPDATE! - 4th February 2022

I now have the Zachtek transmitter working standalone and have collected - at the time of writing - around 6 hours of continuous data.

Here is a map - with band key - showing just where I am reaching.

Click on the image to see it full size! 😉

UPDATE! - 3rd February 2022

I now have the Zachtek transmitter working, and beaconing on the 40, 20, 15 and 10m bands.

It cycles from one band to the next and I have a 120 second break after the 4 band cycle before the process starts again.

I'm achieving some astonishing distances, bearing in mind the output power is only 200mW, or 23dBm.

When I've accrued more data, I want to try and see how each of these bands varies, propagation wise, throughout the day.

Here are some 2D plots for each of the bands.

Click on the images to see them full size! 😉

10m

15m

20m

40m