NBTV 160 Meter Test, 1855 kHz, 6 June 2009, Melbourne, Australia, by VK3ASE and VK3AML.

32 lines @ 12.5 pictures/second - transmitted by VK3ASE, received by VK3AML over a 15 km range, using a stock standard 100 watt a.m. transmitter and a transistor radio broadcast receiver. The setup was not optimised in any way, but was run purely to see what would happen to pictures using an unmodified audio channel for the video. It was transmitted near midnight on Saturday, 6 June 2009, on 1855 kHz, on the 160 meter amateur band.

We honestly didn't think that the rude finger gesture would be recognisable - ugh - oh well, my bad!

There are obvious phase shifts, overshoot and noise in this - the transistor radio receiver used an internal ferrite rod antenna, and the levels recorded were well below optimum. For a first effort on an unmodified link on 1855 kHz, not too bad. The receiver's AGC is rather too fast to permit the low frequency response necessary for NBTV (ideally 10 Hz - 6 kHz). On our next test, a receiver with a broad, phase-flat I.F. will be used, and an external antenna should produce better signal-to-noise. There is a HUGE amount of room for improvement, obviously.

Nevertheless, this proves that viable moving picture television can be transmitted on the lower h.f. ham bands with simple equipment. My thanks to VK3ASE for providing transmitting facilities.

Video software (32-line NBTVA standard) was designed and provided by Gary Millard of Sydney, refer:
http://users.tpg.com.au/users/gmillard/nbtv.htm
Those interested in television transmitted in a narrow bandwidth should also refer:
http://www.nbtv.wyenet.co.uk/

Category:

Science & Technology

Tags:

• NBTV
• 32-line
• narrow bandwidth TV
• narrow band TV
• NBTVA
• Gary Millard
• VK3AML
• VK3ASE
• Baird television
• mechanical television.

[punishedexistence]

That's actually pretty good for just being transmitted on an audio bandwidth. Oh, and +1 on the "rude finger gesture"! I am rather impressed on the quality though!

[AusRadioHistorian]

@punishedexistence This is nowhere near the quality that is possible. It's streaky and smeary. That's just what you get with an unmodified ham (amplitude modulation) transmitter and a cheap broadcast transistor radio receiver. With a decent phase-shift free modulator and a good communications receiver with a slow AGC and broad IF response, the pictures should be indistinguishable from those on a studio monitor. (The rude gesture was intended as a comment to those using these techniques!)

[AusRadioHistorian]

The system WAS used for long range TV broadcasts before 1936 in Britain - via the medium frequency a.m. broadcast band, from London. However the picture quality was not so great. Today it can be optimised far better. But you can not use single sideband for this - it MUST be either amplitude modulation or vestigial sideband modulation. The carrier is required to provide a phase reference for the video signal.

[punishedexistence]

@AusRadioHistorian Very true! But I have yet to broadcast video, let alone a picture via MF radio...I am not a true expert on radio, but I have an undying passion for all things RF. Just to actually witness your broadcast is pretty cool...it's kinda like the video images that were made on a 78 rpm record...I forget the name of it at the moment, but I love seeing good old school technology doing what these fancy things nowadays do...after all they sent men to the moon on a calculator computer!

[kargaroc386]

why is NBTV only heard on ham radio in the east?

[Richardddoobies]

Impressive! My father is a ham operator, and I was just wondering why the shortwave bands were never used for long distance television broadcast?

It seems like a good idea for areas of low population, to cover a larger audience.

Very interesting!

[MarcusV2]

That's great, Pretty damn clear.

I would've pissed myself if I actually managed to receive that!

I'm on the look out for another radio hopefully I can pick the transmissions up soon.