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Transmission signal processing circuit which can determine an optimum stuff threshold value corresponding to a sort of a tributary unit of an input signal

  • US 5,642,357 A
  • Filed: 12/27/1995
  • Issued: 06/24/1997
  • Est. Priority Date: 12/27/1994
  • Status: Expired due to Term
First Claim
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1. A transmission signal processing circuit supplied with an input transmission signal synchronized with input clock pulses, said input transmission signal having an input frame which is synchronized with an input frame pulse and which includes a tributary unit, said transmission signal processing circuit being further supplied with output clock pulses and an output frame pulse for processing said input transmission signal into an output transmission signal having an output frame including said tributary unit by transferring said tributary unit from said input frame onto said output frame of the output transmission signal with said output transmission signal synchronized with said output clock pulses and with said output frame synchronized with said output frame pulse, said transmission signal processing circuit comprising:

  • a deriving circuit for deriving said input clock pulses and said input frame pulse from said input transmission signal;

    a memory supplied with said input transmission signal;

    a recognition circuit supplied with said input transmission signal and connected to said deriving circuit for recognizing the tributary unit of said input frame in response to said input clock pulses and said input frame pulse to produce a location signal representative of a location of said tributary unit in said input frame;

    a write controller connected to said deriving circuit and said recognition circuit for controlling writing of the tributary unit of said input frame in said memory in response to said input clock pulses, said input frame pulse, and said location signal by supplying a write address signal to said memory;

    a read controller supplied with said output clock pulses and said output frame pulse for controlling reading of said tributary unit out of said memory in response to a stuff request signal by supplying a read address signal to said memory;

    a stuff execution judgement circuit given an input stuff threshold value and connected to said write controller and said read controller for judging whether or not a stuff operation should be executed by comparing a difference between said write address signal and said read address signal with said input stuff threshold value, said stuff execution judgement circuit producing said stuff request signal when said stuff execution judgement circuit judges that said stuff operation should be executed; and

    an output transmission signal producing circuit supplied with said output clock pulses and said output frame pulse and connected to said memory for producing said output transmission signal;

    said recognition circuit further produces a type signal representative of a type of the tributary unit in said input frame;

    said transmission signal processing circuit further including;

    a threshold determining circuit connected to said recognition circuit for determining an optimum stuff threshold value in response to said type signal to produce said optimum stuff threshold value as said input stuff threshold value.

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