Showing papers on "Frequency-division multiplexing published in 1969"
Patent•
16 Apr 1969TL;DR: In this paper, a binary data multiplexing system is described where data from a binary source is applied to two encoders, one encoder operates to impart a self-clocking coding to the data and to thus cause the data to lie in a frequency band near the upper limits of the baseband frequency spectrum of the system.
Abstract: A binary data multiplexing system is disclosed wherein data from a binary source is applied to two encoders. One encoder operates to impart a self-clocking coding to the data and to thus cause the data to lie in a frequency band near the upper limits of the baseband frequency spectrum of the system. The second encoder operates to impart a low frequency coding to the data and to thus cause the data to lie in a frequency band near the lower limits of the baseband frequency spectrum of the system. In this way the data transmitted by the two encoders is made to lie in different and separated frequency bands.
9 citations
Patent•
09 Oct 1969
TL;DR: In this article, a time division multiplex (TDM) electrical signalling system with a main carrier modulated by a first group of subcarriers to produce signals in higher frequency bands of higher frequency than the main carrier and a second group of SU's arranged to modulate the main SU's signals in frequency bands having lower frequency than that of the main SA's is considered.
Abstract: In a time division multiplex electrical signalling system having a main carrier modulated by a first group of subcarriers to produce signals in frequency bands of higher frequency than the main carrier and a second group of subcarriers arranged to modulate the main carrier to produce signals in frequency bands having lower frequency than that of the main carrier. Each subcarrier of the first group is modulated with respect to the main carrier by a respective information-bearing signal and each subcarrier of the second group is modulated with respect to a respective subcarrier of the first group by an informationbearing signal.
4 citations
Patent•
29 May 1969
TL;DR: In this paper, a ring-signal-to-voice-frequency signal converter is described which is fully transistorized for battery operation from the 48volt battery supply of the telephone system.
Abstract: Improved in-band signalling apparatus useful in the conversion of O-type frequency division multiplexing equipment for the multiplexing of rural subscriber lines is disclosed Specifically, a ring-signal-to-voice-frequency-signal converter is described which is fully transistorized for battery operation from the 48volt battery supply of the telephone system and contains no circuit dependent on external AC power for operation. Furthermore, there is provision for transient-free frequency switching, and the circuit is suitable for use in small fully enclosed spaces. Local generation of the ringing signal is provided to obtain complete separation of the ring detection circuit from the subscriber line.
3 citations
TL;DR: Various synchronization systems which function to multiplex lower speed pulse-code-modulated (PCM) signals into a high-speed signal and to drop each lower signal from the highspeed PCM signal are considered from a practical viewpoint, and a suitable evaluation basis is introduced.
Abstract: Various synchronization systems which function to multiplex lower speed pulse-code-modulated (PCM) signals into a high-speed signal and to drop each lower signal from the highspeed PCM signal, are considered from a practical viewpoint for a useful PCM hierarchial network, and a suitable evaluation basis for such systems is introduced. Three new stuff-synchronization methods are proposed and designed. A severly reliable bit synchronization function necessary for bit multiplexing can be provided by using a quartz crystal resonant circuit. Relations between the system parameters and transmission performance, such as framing time and stuffing error rate, especially stuff-jitter response for coded frequency-division-multiplex (FDM) signal, are analyzed, and the design technique has been established. The test equipments operated perfectly to verify the expected performances. The results suggest these systems are two or four times as advantageous as usual systems on the evaluation basis.
1 citations