Relay and exchange system for time division multiplex data

A relay and exchange system for time division multiplex data, comprising:

• a plurality of exchanges each performing relay and exchange operations of transmission information such as a voice signal or a facsimile signal;
• a plurality of transmission lines for connecting the plurality of exchanges in tandem;
• a plurality of output side multiplexing apparatuses, each connected to each of said plurality of exchanges at an output side thereof and connected to each of said transmission lines at one end, and including a coder for performing a code conversion from m bits or (m-1) bits to n (m>n) bits or (n-1) bits, respectively;
• and
• a plurality of input side multiplexing apparatuses, each connected to each of said plurality of exchanges at an input side thereof and connected to each of said transmission lines at the other end, and including a decoder for performing a code conversion from n bits or (n-1) bits to m bits or (m-1) bits, respectively,
• said transmission information being transmitted in a usual mode in a multiframe in which each frame is transmitted on each of said plurality of transmission lines, with n bits, while each frame is transmitted at the input side and the output side of each of said plurality of exchanges, with m bits,
• said transmission information being transmitted in a signaling mode where signaling information used for controlling an exchange processing of said transmission information is inserted cyclicly in one frame in said multiframe and is transmitted by frames each composed of (n-1) bits on each of said plurality of transmission lines, and said signaling information of one bit is transmitted by the related frame in an in-slot form, while the transmission information is transmitted, at the input side and the output side of each of said exchanges, by (m-1) bits and the signaling information is transmitted in an out-slot form, said relay and exchange system further comprising:
• operational mode determining means coupled to each coder, for making the coder operate in the signaling mode if the signaling information is detected, and for making the coder operate in the usual mode if the signaling information is not detected;
• and
• signaling information inserting means coupled to each decoder, for making the decoder operate in the signaling mode if the signaling information is received and detected and for inserting new signaling information, to be given to a following one of the plurality of exchanges, in a LSB of the related frame of m bits and for sending the related frame of m bits.

A relay and exchange system for time division multiplex data, supplied with a first ADPCM signal, comprising:

• a first multiplexing apparatus for receiving the first ADPCM signal, for detecting first signaling information included within the first ADPCM signal, and for converting the first ADPCM signal of n bits or less than n bits into a first PCM signal of m (m>n) or less than m bits, respectively, the first ADPCM signal and the first PCM signal being less than n bits and less than m bits, respectively, when the first signaling information is present, and for inserting second signaling information into the first PCM signal;
• an exchange coupled to said first multiplexing apparatus, for exchanging the first PCM signal based on the first signaling information to generate a second PCM signal;
• and
• a second multiplexing apparatus coupled to said exchange, for receiving the second PCM signal, for detecting second signaling information included within the second PCM signal, and for converting the second PCM signal of m or less than m bits into a second ADPCM signal of n bits or less than n bits, respectively, the second PCM signal being less than m bits and the second ADPCM signal being less than n bits when the second signaling information is detected.

A method for relaying and exchanging a first ADPCM signal, comprising the steps of:

• a) detecting whether first signaling information is included within the first ADPCM signal;
• b) converting the first ADPCM signal of n bits or less than n bits into a first PCM signal of m(m>n) or less than m bits, respectively, the first ADPCM signal being less than n bits and the first PCM signal being less than m bits when the first signaling information is detected in said step (a);
• c) inserting second signaling information into the first PCM signal;
• d) exchanging the first PCM signal based on the second signaling information;
• e) detecting the second signaling information included within the second PCM signal;
• and
• f) converting the second PCM signal of m or less than m bits to a second ADPCM signal of n bits or less than n bits, the second PCM signal being less than m bits and the second ADPCM signal being less than n bits when the second signaling information is detected in said step (e).