NICAM

NICAM stands for Near Instantaneous companded audio multiplex ( almost immediately compressed sound multiplex ) and describes the digital transmission of two channels of sound in analog TV. The method is specified as ETS EN 300 163.

The sound is bit encoded with 14 at 32 kHz sampling rate PCM.

History

NICAM was developed in the 1980s by the BBC and used since 1986 in the UK for the transmission of stereo broadcasts. The transfer method is used worldwide by many stations with PAL B / G, I, D / K, as in the Nordic countries, Benelux, Spain, Israel, Hong Kong and New Zealand. In Germany, Austria and Switzerland, the two-channel technique (also called A2 ) technique used.

Technology

The NICAM signal is transmitted independently from mono sound carrier signal used as a separate subcarrier (5.85 MHz at system B / G or 6.552 MHz for the system I). This enables up to three completely independent audio signals are transmitted: the conventional mono signal and the two channels of the NICAM signal.

The transmitter is via a control box the contents of the two NICAM channels:

• A stereo audio channel
• Two mono audio channels (eg different languages)
• A mono audio channel and a 352 kbit / s data channel
• A 704 kbit / s data channel

The sound is digitized to 14 bits at 32 kHz and each as a package of 32 samples compressed (corresponding to a millisecond) to 10 bits. So that the frequency range is limited to 15 kHz.

The compiled data are sent as packaged with control and parity information in a 728 bit long frame and QPSK modulated.