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What can I transmit?

Posted: Tue Apr 16, 2019 2:53 pm
by 2i0jmt
Hi Folks,

As a UK Intermediate License holding, what content am I allowed to transmit using DATV? Is it literally just the same rules as said audio (e.g. literally speaking to one other person, or within a net), or am I allowed to send something that's not me talking, e.g. test signals, picture of scenery, etc?

How do these rules differ between simple, DATV repeaters, and DATV satellites? For example, i see that some conferences and events are being uploaded to repeaters.

I don't intent to start a TV station, but ideally it would be nice to experiment with something that isn't literally just me talking.


Jonny 2I0JMT

Re: What can I transmit?

Posted: Tue Apr 16, 2019 9:25 pm
by G8GKQ
Hi Jonny

The rules are basically the same as for voice. You can send test transmissions (using any respectable picture or moving image as a test card), or you can transmit images to another station or a net.

Within normal decency and copyright, there is no limit on what images you can transmit, although clearly the station you are transmitting them to might get bored....

UK amateur transmissions of conferences and events would normally be transmitted to another amateur and incidentally viewed by a larger audience; the normal rules on not broadcasting apply. Special permission has been granted by OFCOM for the GB2RS news broadcasts, and we might consider applying for similar exemptions for televised technical conferences with a large potential audience. The rules for repeater and satellite transmissions are just the same, although you may see transmissions on the satellite from other countries operating under different rules.

Please note that this is only my interpretation of the licence, and I am prepared to be corrected.

Dave, G8GKQ

Re: What can I transmit?

Posted: Wed Apr 17, 2019 3:30 pm
by 2i0jmt
Hi Dave

Thanks for the reply. It is very helpful!

So essentially, the recent coverage on Es'hail 2 of some of the UK technical conferences, has simply been a transmission to another amateur (and only incidentally picked up by others) ?

Also, if I were to put out a test card, does this have to be aimed at another licensee also? Or is a general (not to anyone in particular) test card ok?

I'm also curious to learn about how some repeaters have like videos of the street etc :)

Sorry for asking so many questions. I'm just really keen to start playing with DATV, but don't want to do anything wrong.


Re: What can I transmit?

Posted: Wed Apr 17, 2019 6:53 pm
by G8GKQ
Hi Jonny

You can put out a test transmission "for testing" or as a CQ. You do not need to be in contact with another amateur for that. However, the moment you start putting content on it, you would need to be in contact.

Repeater street views are essentially moving test cards....

My view is that the important thing is getting on the air. Once you can transmit pictures, there are few restrictions other than those that already apply for voice or CW operation.


Dave, G8GKQ

Re: What can I transmit?

Posted: Wed Apr 17, 2019 8:48 pm
by 2i0jmt
Thanks Dave

Essentially, I would like to transmit some moving images of beautiful scenery of my region, with perhaps some music from a piano that I've played myself, as a test transmission to experiment with getting on the air. Something like Pachelbel's Canon, or even cooler, some tune to the rhythm of some CW.

I would have a caption on the screen that says something like "Please send signal reports to <my email>"

Does that sounds reasonable to you from an Amateur license perspective? Would something like that have to have "CQ" in the caption also? (Of course, I would ensure that I am not breaking copyright law)



Re: What can I transmit?

Posted: Sat Jun 22, 2019 11:12 am
by M0IVJ
I cant find any clear guidance, so the list below are the rules as I see them and are sourced from the UK Amateur Radio License, Ofcom Broadcast Code and guidelines and from primary streaming services. Most of it is common sense.

1. You can transmit anything you like as long as it is of interest to other amateurs and it does not infringe anyone’s copyright or the law in any way.
i) You can stream anything you like as long it does not infringe anyone’s copyright or the law in any way.
ii) Don’t transmit or stream copies of movies, music, television, or any other third party copyrighted material or sexually explicit material or pornography
iii) Don’t transmit or stream hateful videos, harass others, violate someone's privacy, or include defamatory or discriminatory speech or that depict or promote violent activity, extreme or real-life violence, self-harm, or cruelty toward animals.
2. Your intent must be, to only transmitted to other amateurs. Bearing in mind that none amateurs, including children, may be able to see or hear the content.
3. You must not Broadcast (Transmit without an arranged audience) unless you are testing or calling CQ.
4. You should only transmit to another amateur or group of amateurs that you are currently in contact with, and you should always display your call sign.

Section 1 covers both transmitted content and streaming. 2,3 and four are mostly applicable to transmitting.

If anyone would like to add or change anything, please do.
It would be good to have some guidance for us newbies.

John M0IVJ

Re: What can I transmit?

Posted: Tue Jul 16, 2019 7:00 pm
by g4gir
Hi Jonny

Sorry I can't add any further help to your request, I was wondering, after our QO-100 QSO, do you QSL contacts? I can't see any QSL method or info on QRZ.

Thanks in advance


Re: What can I transmit?

Posted: Thu Jul 25, 2019 8:42 am
by g8lce
When you start transmitting moving pictures rather than testcards you find the limits of encoding the source into DATV. If we just transmitted static testcards life would be easy. Changing scenes and various subjects can cause all sorts of effects. Then there is the audio.
I shoot video from 360 degree to 4k and also 3D but getting any of that onto DATV would only be possible with lots of power, a big dish and high sample rates ( just like a satellite broadcaster! ). So we come back down to earth and start with 300 * 200 resolution and work up.
Even with a testcard it is best to have some movement as DATV can store the last received picture. You could think you are receiving a signal when infact you are looking at a memory.
When you start making a video to transmit as a testcard you can have various scenes, test signals and captions which can then be used as a source in vMix and transmitted as a loop. You can then use this as you try different encoding and equipment setups. Use different audio at each scene and include your callsign and location. Don't use shots of people unless they agree in writing and no advertising.
That is my thoughts on the subject of test transmissions.
When you have a QSO with someone then you usually have a camera looking at you and that can be another topic! - how many wires!

Martin - G8LCE

Re: What can I transmit?

Posted: Thu Jul 25, 2019 11:18 am
by g0mjw
Quality at 333k H264 is surprisingly good even for moving pictures. Go to 8PSK and is looking fairly decent. That's possible with a 1.2m dish and 50W on QO100. At the other end of the scale, 33ks DVB-S2 1/4 rate FEC gives poor pictures with no audio that are nevertheless good enough for contest exchanges making best use of power and bandwidth.

H265 can deliver really good pictures but the coding is hard to get right, especially in real time with low latency. Pre-encoded may be interesting. Other codecs can be used and there is no reason to stick with the standard codecs unless you want others to be able to receive you.

I have noticed many people starting out make the mistake of trying to send too high resolution for the available data bandwidth. It would be worth putting together some guidelines.

Keeping to common video resolutions will help those using satellite TV equipment like the Octagon SF8008 which otherwise doesn't display properly on standard monitors. For example, experimentally I have found the following 16x9 resolutions in H264 work well and keep the Octagon happy.

125ks and below: 128x72, 256x144, 384x216
125ks to 333 ks: 512x288, 640x360, 768x432,
500ks to 2 Ms: 896x504, 1024x576, 1152x648, 1280x720
> 2Ms: 1408x792, 1536x864, 1664x936, 1792x1008, 1920x1080

Outside these resolutions usually results in a zoomed in picture at the next lowest 'standard' resolution. Life is too broad an experience for 4x3, its 2019.

At low bandwidth, the audio bitrate needs to be sensible. 64kb/s audio is too much for 125ks QPSK because with the transport stream and FEC overheads there is no space left for the video. FEC is wonderful, but costs data bandwidth in short supply at lower symbol rates. For 125ks and up 10ks AAC seems to work well. Below 125ks it's often better to disable the audio.