Moderators: Dave Moll, Andrew Davie, Steve Anderson
Harry Dalek wrote:BTW when does NBTV stop and MBTV start ? 100 line ?
Steve Anderson wrote:Jeremy Jago takes the attitude that anything less than 405 is suitable for the newsletter, which would include 240-lines. There was a short 240-line item a few years ago. Even SSTV is OK in small doses, again a SSTV item was in a recent newsletter.
Otherwise it's an individuals perception I guess. Some might say less than 10kHz bandwidth, others might say that it can be contained in a wave file (96kHz bandwidth, 192kHz sample rate), others possibly more.
Steve A.
Klaas Robers wrote:I think Steve is right. Narrow Band will say narrow bandwidth. That is the bandwidth of the video signal.
625 lines 25 Hz = 5 MHz
525 lines 30 Hz = 4 MHz
405 lines 25 Hz = 3 MHz
120 lines 25 Hz = 275 kHz
60 lines 12,5 Hz = 34 kHz
32 lines 12,5 Hz = 10 kHz (NBTVA-standard)
120 lines 1/7.2 Hz = 1 kHz (SSTV-standard)
Now is the question: What is narrow bandwidth?
Steve Anderson wrote:Of note is the fact that with a standard VHS/Betamax VCR if the field or frame rate is 50Hz (60Hz US or a multi-standard machine) any analogue format can be recorded. 405 monochrome recordings on a VCR are very good as the 405 sinal only requires 3MHz and the VCR delivers around 2MHz, 66%. For 625 that drops to 40% of the luminance signal, we'll ignore colour here.
So MDTV (whatever standard), 120/50 or any not far from those sort of bandwidths will be fine. You don't need the complex vertical sync signal, a single broad pulse of around 160us per frame/field will do.
The question is - who still has an operational VHS/Betamax VCR? Are the tapes you still have any good?
[/quote]I have a VHS machine wrapped up in a plastic bag that hasn't been switched on in a decade at least. I can imagine perished belts, pinch-rollers and dry electrolytics etc.
Steve A.
Harry Dalek wrote:Its a wonder it has not been really worked out yet i was thinking at first what ever is recordable in the audio range of a analog or digital recording device .
Perhaps it should just be looked at as its analog original signal unchanged in any way .
Medium bandwidth Television i would think is out of Audio recording range and up to 1 MHZ we need a judge ! Judge Andrew ~!
Steve Anderson wrote:The question is - who still has an operational VHS/Betamax VCR? Are the tapes you still have any good?
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