BATC Forum

Several of us in the US are trying to get our transmitters to output a good ATV signal. Here is what we have discovered.
1. While trying to use the DATV-Express board, going though our repeater, the picture is in black and white and the audio is distorted.
2. With the same setup and using a local STB we receive a nice color picture. While looking at the info page, on the STB we notice the signal is PAL even though NTSC has been select in the Portsdown setup area. The STB can decode the PAl source but our commercial receiver at the repeater can't.

Is the Portsdown system not able to output a NTSC signal? Fred WB6ASU has tried changing PIDs on the Express side but no success there. Since a trip to the "hill" is quite an adventure no one has been able to see if the commercial receiver can be reprogrammed to receive the Portsdown source.

Bob -WB6KWT

Hi Bob

An interesting problem, but not quite as it seems (I think). My initial thoughts, but I'm sure that Charles or another expert will correct me:

1. DVB-S has no concept of PAL or NTSC (although I think that there might be a data field indicating what type of source the video was coded from). It does however have different picture sizes (measured in pixels) and different frame rates.

2. The Portsdown has a pre-determined picture size (depending on video bit rate) and frame rate. The PAL/NTSC selection is related to the EasyCap Video capture device. Some of these (including the Fushicai one I use) need telling whether the input source is PAL or NTSC. The setting has no effect on the transmitter output format.

3. Some early decoders were only able to decode a subset of the allowable DVB-S parameters. My guess is that the decoder at your repeater falls into this category, whilst your local (more modern) STB will accept any signal that meets the DVB-S standard.

Perhaps the place to start is to find what parameters (picture size, frame rate etc) work for your repeater, and then we can look at whether Portsdown can be adjusted to output those?

Hope that helps

Dave, G8GKQ

Thanks Dave, that all makes sense and now we know what the PAL/NTSC menu item is all about. I think that kind of through out thinking off some. We do suspect it's an issue with the commercial receiver on the hill. The next time up there Fred will be taking a STB up and put it in the place of the AM receiver that's there now, leaving the commercial receiver on channel 2 and STB on channel 1. We have 4 channels active now. We don't have anyone using AM.

Bob