Detection and bypass of tandem vocoding using detection codes
First Claim
1. A method for avoiding tandem vocoding in a communications system wherein speech data vocoded according to a predetermined vocoding format is transmitted over a pulse code modulated (PCM) system having a PCM communications link, comprising the steps of:
- converting, at a first vocoder, vocoded data from a first remote source into a first PCM encoded signal for transmission over said PCM communications link;
including in said first PCM encoded signal a transmitted detection code;
receiving at said first vocoder a second PCM encoded signal over said PCM communications link;
converting, at said first vocoder, said second PCM encoded signal into vocoded data for transmission to said first remote source;
monitoring at said first vocoder said second PCM encoded signal to discern whether said second PCM encoded signal comprises a received detection code;
including directly in said first PCM encoded signal said vocoded data from said first remote source if said second PCM encoded signal comprises said received detection code;
monitoring at said first vocoder said second PCM encoded signal to discern whether said second PCM encoded signal comprises vocoded data from a second remote source; and
passing by said first vocoder said vocoded data from said second remote source as said vocoded data for transmission to said first remote source if said second PCM encoded signal comprises vocoded data from said second remote source.
1 Assignment
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Accused Products
Abstract
A first remote vocoder receives analog voice and produces packetized vocoder data which is transmitted over a wireless link. A first local vocoder receives the packetized vocoder data from the wireless link. The first local vocoder converts the packetized data to a multibit PCM output. The first local vocoder also adds a detection code to one of the least significant bits (LSB) of the PCM output. The first local vocoder passes the PCM signal to the PSTN from the second end user. The first local vocoder also receives PCM input over the PSTN. The first local vocoder constantly monitors the least significant bit of the PCM input for a detection code indicating that a second local vocoder is connected at the receiving end. If the first local vocoder detects the detection code from the second local vocoder, it begins to substitute packetized data and a redundancy check for a second one of the LSB'"'"'s of the outgoing PCM. The first local vocoder also begins to monitor the second one of the LSB'"'"'s of the incoming PCM. If the redundancy check indicates that valid packetized data has been received, the first local vocoder stops converting the PCM output into packetized data and simply passes the packetized data on the second one of the LSB'"'"'s to the first remote vocoder. If at any time the redundancy check fails and the detection code is not detected, the first local vocoder returns to converting the incoming PCM to packetized data. In this way, the tandem vocoding arrangement is avoided.
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Citations
36 Claims
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1. A method for avoiding tandem vocoding in a communications system wherein speech data vocoded according to a predetermined vocoding format is transmitted over a pulse code modulated (PCM) system having a PCM communications link, comprising the steps of:
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converting, at a first vocoder, vocoded data from a first remote source into a first PCM encoded signal for transmission over said PCM communications link; including in said first PCM encoded signal a transmitted detection code; receiving at said first vocoder a second PCM encoded signal over said PCM communications link; converting, at said first vocoder, said second PCM encoded signal into vocoded data for transmission to said first remote source; monitoring at said first vocoder said second PCM encoded signal to discern whether said second PCM encoded signal comprises a received detection code; including directly in said first PCM encoded signal said vocoded data from said first remote source if said second PCM encoded signal comprises said received detection code; monitoring at said first vocoder said second PCM encoded signal to discern whether said second PCM encoded signal comprises vocoded data from a second remote source; and passing by said first vocoder said vocoded data from said second remote source as said vocoded data for transmission to said first remote source if said second PCM encoded signal comprises vocoded data from said second remote source. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A system for providing direct transmission of vocoded voice signals over a public telephone system, said vocoded voice signals produced using a predetermined vocoding format, comprising:
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a first remote vocoder for receiving a first sampled voice signal, encoding said first sampled voice signal to produce a first vocoded data signal, and transmitting a first wireless link signal comprising said first vocoded data signal, and for receiving a second wireless link signal comprising a second vocoded data signal and decoding said second vocoded data signal to produce a second sampled voice signal; a first wireless link for conveying said first and second wireless link signals; a first local vocoder for receiving said first wireless link signal from said first wireless link, encoding a first PCM encoded signal in response to said first vocoded data signal, and passing said first vocoded data signal and a detection code directly within said first PCM encoded signal, and for receiving a second PCM encoded signal, extracting said second vocoded data signal from said second PCM encoded signal, and providing said second wireless link signal comprising said second vocoded data signal to said first wireless link; a public switch telephone network for conveying said first and said second PCM encoded signals; a second local vocoder receiving said first PCM encoded signal from said public switch telephone network, extracting said first vocoded data signal from said first PCM encoded signal, and transmitting a third wireless link signal comprising said first vocoded data signal, and for receiving a fourth wireless link signal comprising said second vocoded data signal, encoding said second PCM encoded signal in response to said second vocoded data signal, and passing said second vocoded data signal directly within said second PCM encoded signal; a second wireless link for conveying said third and said fourth wireless link signals; and a second remote vocoder for receiving said third wireless link signal from said second wireless link and decoding said first vocoded data signal to produce a third sampled voice signal, and for receiving a fourth sampled voice signal, encoding said fourth sampled voice signal to produce said second vocoded data signal, and transmitting said fourth wireless link signal comprising said second vocoded data signal on said second wireless link. - View Dependent Claims (13)
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14. A method of communicating digital data having a predetermined encoded format over a pulse code modulated (PCM) system comprising the steps of:
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encoding an incoming digital signal to produce an outgoing PCM signal; decoding an incoming PCM signal to produce an outgoing digital signal; implanting within said outgoing PCM signal an outgoing detection code;
monitoring said incoming PCM signal to determine if said incoming PCM signal comprises an incoming detection code;implanting on said outgoing PCM signal an outgoing confirmation code if said incoming PCM code comprises said incoming detection signal; monitoring said incoming PCM signal to determine if said incoming PCM signal comprises an incoming confirmation code; implanting on said outgoing PCM signal said incoming digital signal if said incoming PCM signal comprises said incoming confirmation code; extracting said outgoing digital signal from said incoming PCM signal; and monitoring a quality index of said outgoing digital signal. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. In a base station vocoder, a method for detection and bypass of tandem vocoding in a communications system having a pulse code modulated (PCM) communications link, comprising the steps of:
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receiving a first vocoded data signal from a remote source; converting said first vocoded data signal into a first PCM signal; including in said first PCM signal a transmitted detection code signifying that said first PCM signal is originating from said base station vocoder; transmitting said first PCM signal over said PCM communications link; receiving a second PCM signal from said PCM communications link; monitoring said second PCM signal for inclusion of a received detection code signifying that said second PCM signal originated from another base station vocoder; and including said first vocoded data within said first PCM signal if said second PCM signal includes said received detection code. - View Dependent Claims (27, 28, 29, 30, 31, 32)
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33. In a vocoder, an apparatus for detection and bypass of tandem vocoding in a communications system having a pulse code modulated (PCM) communications link, comprising:
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means for converting incoming vocoded packets from a first remote source into an outgoing PCM signal for transmission over said PCM communications link, said incoming vocoded packets generated according to a predetermined vocoding format; means for converting an incoming PCM signal from said PCM communications link into outgoing vocoded packets for transmission to said remote source; means for implanting within said outgoing PCM signal an outgoing detection code to signify that said outgoing PCM signal is originating from a vocoder; and means for monitoring said incoming PCM signal to determine if said incoming PCM signal comprises an incoming detection code. - View Dependent Claims (34, 35, 36)
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Specification