UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Decca Bradford chassis, help wanted to use in USA

ppppenguin · 20th Jun 2005, 7:48 am

Some clarification:

PAL I (not PAL 1) is the variant used in the UK, Ireland and South Africa. The only significant difference from PAL B/G is that the sound carrier is 6MHz from the vision rather than 5.5MHz.

60Hz PAL is one of those odd hybrid "standards". In the UK we have so-called multistandard VHS machines which can replay NTSC tapes for display on a PAL TV. They convert the colour from NTSC with 3.58MHz subcarrier to PAL with a 4.43MHz subcarrier. The field rate stays at 60Hz so you may need to adjust the field hold on the TV or the picture height may be wrong. Line scan rate is almost the same for PAL and NTSC so there is no problem here. There are other odd hybrid "standards" that exist for similar reasons. Thes include NTSC with a 4.4MHz subcarrier. Don't confuse these "standards" with PAL M and PAL N which are proper standards used in parts of south America.

Part of the reason for having these "standards" is that colour conversion is fairly simple while field rate conversion is much more complex. Simple conversion uses a framestore with field dropping or repeating. This gives odd effects on moving images. The next step up is interpolation between fields which can give very satisfactory results. The most sophisticated converters use motion estimation to give excellent results at a very high price.

You can buy converters at all price points from £200 to £50000.

20th Jun 2005, 7:48 am	#21
ppppenguin Retired Dormant Member Join Date: Dec 2003 Location: North London, UK. Posts: 6,168	Re: Decca Bradford chassis, help wanted Some clarification: PAL I (not PAL 1) is the variant used in the UK, Ireland and South Africa. The only significant difference from PAL B/G is that the sound carrier is 6MHz from the vision rather than 5.5MHz. 60Hz PAL is one of those odd hybrid "standards". In the UK we have so-called multistandard VHS machines which can replay NTSC tapes for display on a PAL TV. They convert the colour from NTSC with 3.58MHz subcarrier to PAL with a 4.43MHz subcarrier. The field rate stays at 60Hz so you may need to adjust the field hold on the TV or the picture height may be wrong. Line scan rate is almost the same for PAL and NTSC so there is no problem here. There are other odd hybrid "standards" that exist for similar reasons. Thes include NTSC with a 4.4MHz subcarrier. Don't confuse these "standards" with PAL M and PAL N which are proper standards used in parts of south America. Part of the reason for having these "standards" is that colour conversion is fairly simple while field rate conversion is much more complex. Simple conversion uses a framestore with field dropping or repeating. This gives odd effects on moving images. The next step up is interpolation between fields which can give very satisfactory results. The most sophisticated converters use motion estimation to give excellent results at a very high price. You can buy converters at all price points from £200 to £50000.