Transmission system
First Claim
1. A transmission system for audio signals in which at a transmitter:
- a monphonic signal and a difference signal are derived from multiple input signals, a digital version of the difference signal is bandlimited to a predetermined bandwidth smaller than that of the monophonic signal, the sampling rate of the digital bandlimited difference signal is reduced; and
the monophonic and resulting difference signals are transmitted to a receiver; and
in which at a receiver;
upon reception, the sampling rate of the digital difference signal is increased, frequencies above the predetermined bandwidth in the difference signal are attenuated, and left and right output signals are derived from the monophonic and resultant difference signals; and
in which, either at the transmitter or receiver, compensation for differential delays in the monophonic and difference signals is introduced.
1 Assignment
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Accused Products
Abstract
A stereo coding system is described in which 7 kHZ bandwidth sum (L+R) and difference (L-R) signals are converted to digital form (11 and 12). The difference signal is then bandlimited (13) to 2 kHZ and downsampled (14) to 4K samples/sec prior to being encoded (16), and the sum signal is encoded (15); both are then multiplexed together (17) prior to transmission. After reception, the signal is demultiplexed (19) and the difference signal is decoded (20) upsampled (21) to its original bit rate and filtered to prevent aliasing (22), and the sum signal is delayed in a digital buffer (28) and decoded (24) prior to both being converted back to analogue form (23 and 25). The delay introduced by the digital buffer (28) equalizes the excess delay introduced into the difference signal.
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Citations
17 Claims
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1. A transmission system for audio signals in which at a transmitter:
- a monphonic signal and a difference signal are derived from multiple input signals, a digital version of the difference signal is bandlimited to a predetermined bandwidth smaller than that of the monophonic signal, the sampling rate of the digital bandlimited difference signal is reduced; and
the monophonic and resulting difference signals are transmitted to a receiver; and
in which at a receiver;
upon reception, the sampling rate of the digital difference signal is increased, frequencies above the predetermined bandwidth in the difference signal are attenuated, and left and right output signals are derived from the monophonic and resultant difference signals; and
in which, either at the transmitter or receiver, compensation for differential delays in the monophonic and difference signals is introduced. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
- a monphonic signal and a difference signal are derived from multiple input signals, a digital version of the difference signal is bandlimited to a predetermined bandwidth smaller than that of the monophonic signal, the sampling rate of the digital bandlimited difference signal is reduced; and
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17. A transmission apparatus for stereophonic audio signals comprising:
- means for forming monophonic and difference signals from left and right input signals;
means for bandlimiting the difference signal to substantially 2 kHz; and
means for transmitting the monophonic and difference signals.
- means for forming monophonic and difference signals from left and right input signals;
Specification