Moderators: Dave Moll, Steve Anderson
Steve Anderson wrote:So, you're fortunate enough(?) to live in the UK and get your hands on a 405-line TV. Now what? There's been no 405-line TV transmitted since January 1985 for the majority of the UK.
However there are sources available that produce 405 signals, but as ever, I wanted to do it myself. My initial guidance was here...
http://www.thevalvepage.com/projects/te ... stcard.htm
...but things have moved on since then...so here (might be) an updated version...I need the check with the original designer if it's OK to go ahead as I'll be using his video data.
Steve A.
Steve Anderson wrote:Yes generally a VHS VCR (and probably Beta too) will record and playback the old UK 405 standard OK. The 625 and 405 systems both used 50Hz for the the field rate, .i.e 25 frames/sec. The exception would be if the VCR had a timebase corrector, that would need to be switched into bypass. But few machines had that, and those that did were very expensive.
It's a similar concept to the first (that I'm aware of) domestic digital audio recorders that used standard VHS/Beta tapes, made by Sony and encoded the audio into a pseudo-TV waveform. If you viewed the video on a monitor or TV (the encoded audio stream) it looked like a 'rolling barcode'.
I did an item based on the same concept for NBTV. It did appear in the newsletter...which one? No clue! My first attempt at a DC-friendly recoding medium...
Steve A.
Steve Anderson wrote:That e-mail (the Samart one) is well and truly dead now, perhaps around the time the article was published...use the PM function here or my e-mail address on the NBTVA website.
Basically if the video system has an element of 50Hz in the video waveform, then an analogue VCR should record it. There are 'get arounds' for those NBTV systems running a 25/12.5Hz frame-rate too, which are quite simple.
Steve A.
I should have said, "Any European VCR", Unless a US (or other 60Hz machine) is multi standard, it probably wont work...
Steve Anderson wrote:With a 'standard' domestic 625 VCR you need to fool it into thinking it's recording a standard 50Hz field-rate 625 signal when it's actually recording a 12.5Hz NBTV signal. You can basically forget the colour, if there's no colour burst in the input signal, the colour circuits are effectively switched off.
Then it comes down to getting the capstan to lock with the pseudo-TV signal of which it's expecting 50Hz field-rate signal as well as the head drum.
So going back to where this started...405 can be recorded on most 625 VCRs...
Using the analogue (linear) sound track(s) of a VCR doesn't surprise that it wasn't so good. Most TVs can't reproduce 100Hz audio, forget anything lower, likewise the HF end, maybe 10kHz? ...and that's with clean tape-heads! How many people actually cleaned their VCR tape-path? Virtually zero I would say. 'Head-cleaning tapes', OK, let's not bother with them...better to use sandpaper!
Steve A.
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