More information about the proposed Amateur TV experiments at 29.250 MHz & 51.7 MHz

In a previous post in August of 2021, I outlined how some radio amateurs in Europe plan to experiment with digital ATV (Amateur TV) on the 10-metre band in the Summer of 2022. That post generated quite a bit of interest.

On Monday the 6th of December 2021, the BATC streamed a YouTube presentation about current Amateur TV techniques and activity as part of the RSGB Tonight at 8 series.

While the video is about 75 minutes in length, the piece I found really interesting was about the proposed ATV experiments at 29.250 MHz and 51.7 MHz. They refer to these as the 'lower ATV bands'.

Amateur TV up to now has normally been used on the UHF and microwave bands. This new development at 29 MHz and 51 MHz will potentially allow ATV signals to be sent on frequencies which will achieve much greater distances via the ionosphere - i.e Sporadic-E and F2 layer.

I find it amazing that there is the potential of sending amateur TV signals between say Europe and  North America on the 10-metre band.

 The presentation with time guides are shown below...

Video guide...
03:35: Introduction starts
05:15: G8GTZ begins his presentation
06:55: What is ATV - Amateur TeleVision / Why amateur television? / ATV is going digital

12:00: Analogue V Digital ATV / Reduced bandwidth (RB-TV) / 80 kHz RBTV

16:30: UK ATV activity and repeaters
20:45: ATV on the air - 1 The lower ATV bands

22:45: ATV on the air - 2 Low cost 5.6 GHz FM ATV with example contact

29:45: ATV on the air 3 - DATV on QO100 (Geostationary satellite)

38:20 - DATV equipment / Getting started / Ryde DATV receiver / Portsdown DATV transceiver / DATV receive system / DATV transmit system / 

57:55: Info about British Amateur Television Club (BATC)

1:01:00 Q &A session

I am told that the numbers involved are likely to be small with perhaps something like 20-30 stations taking part. Special boards are being developed at present and no doubt, these will be be got ready for the Sporadic-E season next May.

It would be very interesting if some radio amateurs in North America got interested in this project.

Links...
1) BATC website... https://batc.org.uk/

New Amateur TV activity proposed for the 10m band in 2022

I was informed recently that some radio amateurs in Europe will be experimenting with ATV on the 10-metre band in the Summer of 2022. It is likely to be mostly confined mainly to stations in England, the Netherlands and Germany.

While ATV (Amateur TV) is normally associated with the 70cms and 23 cms bands, there have been experiments in recent years on 146 MHz, 71 MHz and 51.7 MHz. This new experiment on 29 MHz will allow much more use of Sporadic-E propagation for contacts.

From what I understand, it will be DVB-T digital TV operating on 29.250 MHz with a 300 kHz bandwidth. This is below the input frequencies of the various FM repeaters around Europe.

I am told that the numbers involved are likely to be small with perhaps something like 20-30 stations taking part. Special boards are being developed at present and no doubt, these will be be got ready for the Sporadic-E season next May.

The photo at the top of the post is of an ATV signal on 10m that was upconverted to 149.250 MHz.

Successful 5.6 GHz ATV test in Cork Harbour

As part of the ongoing Cork VHF Group nets on Tuesday evenings, we hold an experimental night whenever there is a fifth Tuesday in the month. On a previous evening, we experimented with sending and receiving Slow-Scan TV pictures on 2-metres FM using apps on Smartphones. For the fifth Tuesday of September 2020, the group experimented with Amateur TV signals at 5.6 GHz.

For the experiment, Jim, EI8GS went portable to the town of Cobh and set up his ATV gear to point at Don, EI8DJ in Crosshaven. After discovering that there was no reception through a glass patio window, Don took his gear outside and successfully received an ATV signal from Jim at 5.6 GHz. The distance of the path across Cork Harbour was 4.7 kms.

The photo above looks a bit crude but it's a screenshot from my PC from a Zoom meeting of a phone pointing at another screen! What it shows are the lights from the oil refinery at Whitegate in Cork Harbour and the small string of lights to the left is the village of Whitegate itself. The tests were done when it was dark so the picture would be more relevant and clearer if it was in daylight.

The lines in the foreground are in fact superimposed by the camera. The unit is supposed to be used as an aid for vehicles reversing and the lines show the 'safe' distance areas. In this case, it was used for sending an ATV signal across Cork Harbour!

The photo above shows what Jim, EI8GS was using in Cobh. He was located at a well known viewing point high above the town allowing a good line of sight path across to EI8DJ in Crosshaven.

Jim was using 0.6 watts output power into a 40cm dish with a dipole at the feed point. 

Next it was Jim's turn to try and receive an ATV signal from Don. The receiver module is shown above and a photo of the signal received by Jim in Cobh is shown below.

Don sent a number of different test cards and this is another screen shot...

The photo below shows the set-up as used by EI8DJ...

The grey box (top left) contained a Raspberry Pi Zero which generated the sequence of test cards. 

The module in the centre with the display is a portable screen that is used by drone pilots. It has its own 5.6 GHz receiver built in.

The top right box contains the 5.6 GHz transmitter module and the antenna mounted on the outside of the box is a 4 element Bi-Square with a reflective plate behind.

The photo above shows the box containing the transmitter module with a microwave relay on the left for switching from receive to transmit. The PCB in the background with the toroid is a voltage upconverter to generate 28 volts for the coil of the changeover relay.

The FM ATV signal from the transmitter has a measured output of 0.6 watts.

In conclusion... The purpose of this initial experiment was more of a proof of concept than anything else - i.e. could an ATV signal at 5.6 GHz be sent over a line of sight path and over a modest distance of about 5 kms. The answer was a conclusive yes!

The next steps the group are looking at is maybe to look at increasing the distance and exploring more paths.

About 20 years ago, there was a small but active group on 23cms (1.2 GHz) using ATV in the Cork area. Hopefully these new experiments might reignite some interest in the mode.