Nicam or “German” stereo?

[nhope]

Dumb question and not really relevant to this forum, but you lot should know. I’m in Thailand and I need to buy a new TV. Does anyone know what the difference between Nicam and German (AV?) stereo is? The sales people here can’t explain.

[hakko504]

Quick explanation:
Nicam is digital stereo.
"German" or A2 is AM stereo
In the US NTSC have FM stereo.

Long explanation:
First: most PAL standard mono sound uses Amplitude Modulation (AM) sound. This provides a reasonable quality sound and a very easy transmitter/reciever solution.
A2 is an addition to the normal PAL mono sound. It transmits an extra channel containing the left stereo channel. This means that the right channel must be calculated from the transmitted ones. R=L-2*C
Nicam on the other hand is a digital stream that can include 1 high quality mono, 2 standard mono channels or 1 stereo sound. It uses a total bitrate of ~700kbps. Each sample is 10 bits but it is a float, not integer, with 7 bits for base and 3 bits for exponent. So it really has 7 bits resolution but 14 bits dynamics, i.e. largest value is 2^14 times bigger than the smallest but when the values grow bigger the step size between two samplevalues also increases. I don't remember the exact sampling frequency, but I think it is 22050Hz. I do remember that the high quality mono setting doubles the samplerate. It can also be used for transmitting data to the TV, but I doubt that anyone actually does so.
US NTSC on the other hand uses frequency modulated sound, originally one channel mono. Now they too uses FM stereo, with two distinct channels transmitted side by side, just like FM radio. This can explain why most US TV-cards also have FM-radio reception whereas the same card in Europe doesn't - they would need two audio recievers.