Method for reducing the bandwidth of communication signals

Claim 1

A method for reducing data signals, particularly picture signals, for adaptation to the limited capacity of a transmission channel, comprising the steps of: forming a transformed signal of the input data signals by forming the differences between adjacent scanning values of the input data signals; determining the frequency distribution of the amplitudes of the transformed signal in a given time interval, by detecting the frequency with which the amplitudes of the transformed signal exceed individual thresholds within said time interval; forming a control signal whose value depends on the determined frequency distribution; delaying the input data signals for the duration of said time interval; forming a predicted value signal for the scanning values of the delayed input data signal; selecting the relevant scanning values out of the delayed input data signal by comparing said control signal with the difference between the scanning values of the delayed input data signal and the respective predicted values and producing an output signal to gate the delayed input data signal whenever the control value is exceeded; counting nonrelevant successive scanning values to provide the location signals for the relevant scanning values; and feeding the relevant scanning values and the location signals to at least one buffer store, from where they are transmitted to the transmission channel in equidistance sequences.

Claim 2

A method for reducing data signals, particularly picture signals, for adaptation to the limited capacity of a transmission channel, comprising the steps of: forming a transformed signal of the input data signals by forming the differences between adjacent scanning values of the input data signals; determining the frequency distribution of the amplitudes of the transformed signal in a given time interval, by detecting the frequency with which the amplitudes of the transformed signal exceed individual thresholds within said time interval; forming a control signal whose value depends on the determined frequency distribution; delaying the input data signals for the duration of said time interval; forming a predicted value signal for the scanning values of the delayed input data signal; selecting the relevant scanning values out of the delayed input data signal by comparing said control signal with the difference between the scanning values of the delayed input data signal and the respective predicted values and producing an output signal to gate the delayed input data signal whenever the control value is exceeded; counting nonrelevant successive scanning values to provide the location signals for the relevant scanning values; and feeding the relevant scanning values and the location signals to at least one buffer store, from where they are transmitted to the transmission channel in equidistance sequences.

Claim 7

A method for reducing digital data signals, particularly quantized picture signals, which are in a digital form, for adaptation to the limited capacity of a transmission channel, comprising the steps of: comparing adjacent sample values of the input data signals to provide comparison signals; determining the frequency distribution of the amplitudes of the comparison signals in a given time interval, by means of counters for individual thresholds, by counting sample clock pulses during the time during which the comparison signal exceeds the respective thresholds; deriving control signals from the determined frequency distribution to control the selection and the quantization of relevant sample values; delaying the input sample values by said given time interval; selecting the relevant sample values from the input data signals by forming the difference between the delayed input sample values and a predicted value which is stored in a memory, comparing this difference value to a threshold value set by said control signals, and initiating a relevance signal to gate the delayed input sample values whenever the threshold value is exceeded; counting the nonrelevant successive sample values to provide location signals for the relevant values with the count constituting the code word for the address when a relevant sample value is present; quantizing the relevant sample values; feeding the quantized relative simple values and the code words for the address to at least one buffer store for transmission to a transmission channel; and controlling the quantization of the relevant sample values and the maximum sequence of nonrelevant sample values counted so that the quantity of data bits transmitted during each transmission time interval remains constant.

Claim 8

A method for reducing digital data signals, particularly quantized picture signals, which are in a digital form, for adaptation to the limited capacity of a transmission channel, comprising the steps of: comparing adjacent sample values of the input data signals to provide comparison signals; determining the frequency distribution of the amplitudes of the comparison signals in a given time interval, by means of counters for individual thresholds, by counting sample clock pulses during the time during which the comparison signal exceeds the respective thresholds; deriving control signals from the determined frequency distribution to control the selection and the quantization of relevant sample values; delaying the input sample values by said given time interval; selecting the relevant sample values from the input data signals by forming the difference between the delayed input sample values and a predicted value which is stored in a memory, comparing this difference value to a threshold value set by said control signals, and initiating a relevance signal to gate the delayed input sample values whenever the threshold value is exceeded; counting the nonrelevant successive sample values to provide location signals for the relevant values with the count constituting the code word for the address when a relevant sample value is present; quantizing the relevant sample values; feeding the quantized relative simple values and the code words for the address to at least one buffer store for transmission to a transmission channel; and controlling the quantization of the relevant sample values and the maximum sequence of nonrelevant sample values counted so that the quantity of data bits transmitted during each transmission time interval remains constant.