Sliding scale predictive coding system

Claim 2

A transmission system comprising: a source of an analogue information signal; means for sampling said analogue signal at periodic intervals; means for obtaining an accumulated error signal by comparing the samples of said analogue signal with generated feedback samples; means for sampling said accumulated error signal at periodic intervals; means for quantizing said error samples to produce said feedback samples; means responsive to said accumulated error signal for generating an additional sample of said error signal when said error exceeds a predetermined value; means for subtracting said additional quantized error sample from said accumulated error; and means for encoding and transmitting said additional quantized error samples in succession with said periodic quantized error samples.

Claim 3

Apparatus as defined in claim 1 wherein said means for sampling and quantizing said accumulated error signal comprises first and second sampling means and fine and coarse quantizing means, said first sampling means and said fine quantizing means adapted to produce said periodic quantized samples and said second sampling means and said coarse quantizing means being cooperative with said means responsive to said error signal so that said coarse quantizer circuit produces an additional quantizer sample whenever said accumulated error exceeds said predetermined value.

Claim 4

Apparatus as defined in claim 1 further comprising: means responsive to said additional samples for omitting a preceding periodic sample from the encoded signal; means for interpolating the magnitude of said omitted sample by averaging preceding and succeeding samples; and means for producing a signal representing the error between said interpolated value and said actual value of said omitted sample to adjust said accumulated error signal.

Claim 5

A receiver system in combination with the transmitter of claim 1 comprising: means for detecting said additional transmitted error samples; means cooperative with said detection means for decoding said additional and said periodic encoded samples in succession; and means for filtering said decoded samples to reconstruct said original analogue signal.

Claim 6

In a predictive coding system which transforms an analogue to a digital signal by periodically sampling and quantizing the changes in the analogue signal, apparatus which extends the effective range of the quantizing circuit in said system comprising: means for generating additional quantized samples of the changes in said analogue signal whenever said changes exceed a predetermined threshold; means for coordinating the additional samples with corresponding periodic samples so that their sum represents the change which exceeded said threshold level in said analogue signal; and means for successively encoding said periodic and additional quantized samples.

Claim 7

In a predictive coding system which transforms an analogue to a digital signal by periodically sampling and quantizing the changes in the analogue signal, apparatus which extends the effective range of the quantizing circuit in said system comprising: means for generating additional quantized samples of the changes in said analogue signal whenever said changes exceed a predetermined threshold; means for coordinating the additional samples with corresponding periodic samples so that their sum represents the change which exceeded said threshold level in said analogue signal; and means for successively encoding said periodic and additional quantized samples.

Claim 8

Apparatus as defined in claim 5 further comprising: means responsive to said additional samples for omitting a preceding periodic sample from the encoded signal; means for interpolating the magnitude of said omitted sample by averaging preceding and succeeding samples; and means for producing a signal representing the error between said interpolated value and said actual value of said omitted sample to adjust succeeding samples in compensation for the omission of said interpolated sample.

Claim 9

A receiver system in combination with said coding sysTem in claim 5 comprising: means for decoding the portions of said signal corresponding to the periodic samples; means for detecting and decoding said additional samples as they occur successively in the received signal; means for filtering the decoded signal by summing said additional samples with succeeding periodic samples to reproduce the changes in the original analogue signal.

Claim 10

Receiver apparatus in combination with claim 5 comprising: means for decoding the portions of said encoded signal corresponding to the periodic samples; means for detecting and decoding the portions of said decoded signal corresponding to said additional samples; means responsive to said additional samples for reconstructing said omitted periodic samples by interpolating the value between preceding and succeeding received samples; means for inserting said interpolated samples in time sequence with said periodic and additional received samples; and means for filtering the resultant samples to reconstruct said original analogue signal.

Claim 11

A transmission system comprising: a source of an analogue information signal; filtering means for emphasizing the changes in said signal; first sampling means for sampling the signal at the output of said filtering means; means for obtaining an accumulated error signal, second sampling means for sampling said error signal at periodic intervals and means for quantizing said error samples, said accumulated error signal being formed by subtracting the quantized samples of said error signal from the samples of said first sampling means; means responsive to said accumulated error signal for generating an additional sample of said error signal when said accumulated error exceeds a predetermined threshold; means for subtracting said additional quantized error sample from said accumulated error; means for encoding said additional and periodic quantized error samples; means for storing said additional and periodic encoded samples in succession; and means cooperative with said storage means for transmitting said encoded samples in succession.

Claim 12

A transmission system comprising: a source of an analogue information signal; filtering means for emphasizing the changes in said signal; first sampling means for sampling the signal at the output of said filtering means; means for obtaining an accumulated error signal, second sampling means for sampling said error signal at periodic intervals and means for quantizing said error samples, said accumulated error signal being formed by subtracting the quantized samples of said error signal from the samples of said first sampling means; means responsive to said accumulated error signal for generating an additional sample of said error signal when said accumulated error exceeds a predetermined threshold; means for subtracting said additional quantized error sample from said accumulated error; means for encoding said additional and periodic quantized error samples; means for storing said additional and periodic encoded samples in succession; and means cooperative with said storage means for transmitting said encoded samples in succession.

Claim 13

A receiver system in combination with claim 1 comprising: storage means for storing said transmitted digital signal; means cooperative with said storage means for decoding said periodic encoded samples in succession; means for detecting said additional encoded error samples; means cooperative with said detection means for decoding said additional error samples in succession with said periodic encoded samples; second filtering means having a characteristic the inverse of that of said first filtering means for filtering said decoded error samples; and third filtering means for filtering the output of said second filtering means to reconstruct said original analogue signal.