 Distributed clocking system |
| OF THE DRAWINGS An example of a distributed switching network is illustrated in FIG. 1 for ... |
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| Distributed clocking system |
| OF THE DRAWINGS An example of a distributed switching network is illustrated in FIG. 1 for ... |
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| Integrated processor system adapted for portable personal information devices |
| The problems outlined above are in large part solved by a highly integrated, low-power integrated ... |
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| Method of synchronization status message processing in transmission apparatus |
| Accordingly, an object of the present invention is to lighten the load on the master shelf by ... |
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| Docking station |
| What is claimed is: 1. A docking station, comprising: a platform; a motion control mechanism ... |
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| Network clock synchronization |
| According to the present invention, there is provided a network comprising an exchange having a ... |
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| Digital delay system and method for digital cross connect telecommunication systems |
| The present invention provides a digital delay system and method for a digital cross connect system ... |
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| Apparatus for an improved ISDN terminal adapter having baud rate unblocking and methods for use therein |
| The present invention overcomes the deficiencies in the art and satisfies this need by providing an ... |
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| A/D, D/A Converter for PCM transmission system |
| It is, therefore, an object of the present invention to provdide a codec which can be commonly ... |
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| Start-stop synchronous communication speed detecting apparatus |
| It is an object of the present invention to provide a start-stop synchronous communication speed ... |
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Single-sideband radiotelephone system
| Details |
Inventors: Frank, Varn Richard; Wysong, Ronald Eugene; Valentine, Michael David;
Assignee: R. L. Drake Company (Miamisburg, OH)
Primary Examiner: Safourek; Benedict V.
Assistant Examiner: Hearn; Robert
Attorney, Agent or Firm: Biebel, French & Nauman
A single-sideband radiotelephone system includes a single-sideband transmitter which initially broadcasts two frequency-spaced tones simultaneously for a predetermined time interval, and thereafter broadcasts the two tones alternately in a unique code pattern to access a predetermined receiver. Each single-sideband receiver in the system includes a pair of detectors each having a narrow bandpass, the center frequencies of which are spaced apart by the difference in frequency of the transmitted tones. The center frequencies of the detectors are simultaneously varied relative to the initial two-tone broadcast while maintaining the frequency differential therebetween; and simultaneous detection of both tones will terminate the frequency varying mode of operation. The subsequently transmitted unique code pattern is then sensed by the detectors, the code pattern decoded, and the selected receiver is enabled to receive any subsequently broadcasted information. |
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DETAILED DESCRIPTION The present invention relates to a single-sideband radio system which may be used for radiotelephone, radioteletype or for other uses in which at least two audio detectors or filters are employed, the center frequencies of which are varied relative to at least two frequency-spaced tones transmitted simultaneously for a predetermined interval in order to place the transmitted frequency-spaced tones within a band-pass of the detectors or filters.
A single-sideband transmitter includes means for broadcasting initially at least two frequency-spaced tones simultaneously for a predetermined time interval.
Thereafter, these same frequency-spaced tones are broadcast alternately in a unique code pattern to access a predetermined receiver, in the case of a radiotelephone system, or to convey information, in the case of a radioteletype system.
Each single-sideband receiver in the system includes at least two detectors or filters, the center frequencies of which are frequency-spaced the same as the frequency-spaced transmitted tones.
Scanning or sweep control means are included to vary the center frequencies of the detectors or filters relative to the two frequency-spaced tones while maintaining the difference in frequency between the filters.
In a preferred embodiment of the invention, frequency adjustable detectors or filters are used.
The outputs of the detectors or filters are connected to a gate which senses when the two frequency-spaced signals are detected simultaneously, and an output from the gate will terminate the operation of the scanning means.
Other circuit means are provided to decode the subsequently broadcasted unique code patterns.
The receiver means may comprise two adjustable filters, each capable of providing an output in response to an input audio tone within its respective frequency band.
These filters may be of the phase locked loop type, responsive to a frequency band determined by the values of impedances connected thereto.
The sweep control means comprises means for varying the bandpass center frequency of each of the two adjustable filters in a predetermined number of steps, the bandpass at each step overlapping that of the previous step and next succeeding step
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Multiplexer-related 
