The use of primary level PCM systems on junction cable routes is one method of increasing the capacity of these routes. To efficiently plan the installation of such systems, information is required on how they interac...
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The use of primary level PCM systems on junction cable routes is one method of increasing the capacity of these routes. To efficiently plan the installation of such systems, information is required on how they interact with each other and with other services in the junction cable. One important parameter that determines this interaction is the power spectral density of the PCM signal. In this paper an idealized model of the idling condition of a 24-channel PCM system is presented and from this model the power spectral density of the line signal is derived. The results indicate that when idling the power spectrum of the PCM signal is significantly more concentrated near its maximum value (which occurs close to half the line rate) than when carrying random digital signals. Graphs of power spectral density are included.
A PCM section with simplified regenerators is considered, which digitally regenerate receiving pulses only with respect to their shape (but not in their phase position). The accumulation of the stochastic jitter by me...
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A PCM section with simplified regenerators is considered, which digitally regenerate receiving pulses only with respect to their shape (but not in their phase position). The accumulation of the stochastic jitter by means of such simplified regenerators is described, using a method which makes it possible to treat jitter disturbances as stochastic processes separated from the useful signal. delta -functions used to eliminate disturbing amplitudes at discrete times make it possible to give a closed form of fade-out processes.
A more rugged and reliable instrument based on the successful PCM Multiplex Tester type TF 2807 has been developed. The new model TF 2807A incorporates the specification changes and improvements required to meet curre...
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A more rugged and reliable instrument based on the successful PCM Multiplex Tester type TF 2807 has been developed. The new model TF 2807A incorporates the specification changes and improvements required to meet current international specifications evolved for testing pulse code modulation (p. c. m. ) systems. All the measurement facilities of the previous model are retained with the addition of quantizing distortion measurement using an 850 Hz sinusoidal stimulus. Crosstalk measurement is normally at 850 Hz also, but simple factory incorporated alternative frequency modifications are available.
Since the high-speed PCM system is constructed by hierarchical multiplexing using pulse stuffing synchronization, hierarchical restoration of synchronization is required for restoration of the synchronization of the w...
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Since the high-speed PCM system is constructed by hierarchical multiplexing using pulse stuffing synchronization, hierarchical restoration of synchronization is required for restoration of the synchronization of the whole system when a group frame becomes desynchronized. A method of improving the system resynchronization and a desirable hierarchical structure were proposed.
A modified DPCM system for videophone signals is introduced. Picture elements within the present frame as well as in the previous frame are used for prediction. Moving areas are filtered by a spatial low-pass filter w...
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A modified DPCM system for videophone signals is introduced. Picture elements within the present frame as well as in the previous frame are used for prediction. Moving areas are filtered by a spatial low-pass filter when the amount of activity within the picture scene increases. The amount of this filtering is controlled by the content of the buffer, which is required for statistical coding. Beyond that a subsampling modus is initiated when using the strongest low-pass filtering. Experimental investigations concerning this concept have shown that a good picture quality (nearly independent of motion within the picture scene) is achieved with 1 bit/picture element (2 Mbit/s).
The second-order covariance phi ( tau //1, tau //2) is derived for a pulse series with renewal properties and the pulses being multiplied alternatingly by constants A and B. For A equals minus B and upon integration, ...
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The second-order covariance phi ( tau //1, tau //2) is derived for a pulse series with renewal properties and the pulses being multiplied alternatingly by constants A and B. For A equals minus B and upon integration, phi ( tau //1, tau //2) is obtained for a random telegraph signal when the distribution of upward and downward crossings need not be distributed identically. For A equals B, it is shown that different univalued pulse trains, which possess the same first-order covariance PHI ( tau ), can be distinguished on the basis of PHI ( tau //1, tau //2).
The calculations of Huang and Reiss for the power spectrum of a pulse code modulation message is here extended, corrected, and generalized to include a formalism for an arbitrary Markovian process. The formalism conta...
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The calculations of Huang and Reiss for the power spectrum of a pulse code modulation message is here extended, corrected, and generalized to include a formalism for an arbitrary Markovian process. The formalism contains arbitrary pulse shape and transmission times. For a first-order Markovian message the importance of the quasidiscrete frequencies is emphasized and it is concluded that these frequencies are more significant in defining the necessary bandwidth for transmission than any “optimized” choice of transmission times.
The paper explains the principles of pulse code modulation and also draws attention to the relationship between bit rate and the bandwidth of the signal, as well as to the formation of quantization noise. Examples of ...
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The paper explains the principles of pulse code modulation and also draws attention to the relationship between bit rate and the bandwidth of the signal, as well as to the formation of quantization noise. Examples of the application of PCM are taken from the field of sound transmission and TV transmission.
It is argued that PCM systems will be exclusively employed for some years to set up point-to-point links. Present possibilities of PCM are reviewed and future aspects are considered.
It is argued that PCM systems will be exclusively employed for some years to set up point-to-point links. Present possibilities of PCM are reviewed and future aspects are considered.
Differential pulse code modulation (DPCM) with previous-element prediction is extended to Adaptive Differential pulse code modulation (ADPCM) by a switched quantizer. The ADPCM-coder analyzes the video signal and clas...
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Differential pulse code modulation (DPCM) with previous-element prediction is extended to Adaptive Differential pulse code modulation (ADPCM) by a switched quantizer. The ADPCM-coder analyzes the video signal and classifies the picture elements in sets of various structures (areas, details, etc. ). A different quantization is used for every set. As the adaption depends on the previous code words, ADPCM enables a code with fixed word length and constant bit rate. The properties of this adaptive picture coding process with 3 bit/picture element are experimentally studied and compared with DPCM.
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