Title: Full duplex data transmission system using two speeds of diphase signal for simplified sync

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1. A method for exchanging data between local and remote terminals, via a two wire transmission line, the method comprising the steps of:

a. in the local terminal, transmitting a coded diphase signal having first and second portions, respectively representing data bits of first and second states, the first portions having two transitions per data bit and the second portion having four transitions per data bit; and

b. in the remote terminal, receiving the coded diphase signal,

c. generating, from the received coded diphase signal, first signals at the baud rate of the coded diphase signal and synchronized therewith and second signals at half of said baud rate and in phase with said first portions,

d. decoding the received coded diphase signal in synchronism with the first and second signals, to derive the data bits,

e. transmitting a diphase signal, at half the baud rate of the coded diphase signal, synchronized with said second signal and representing other data bits; and

f. in the local terminal receiving the diphase signal delayed by less than half the period of the baud rate of the coded diphase signal,

g. decoding the diphase signal in synchronism with a signal in phase with said first portions, to derive the other data bits.

2. An apparatus for exchanging data between a local terminal and a remote telephone terminal, via a two wire transmission line terminated with hybrid circuit means, the apparatus comprising:

in the local terminal, means for transmitting, via said hybrid circuit means and said transmission line, a coded diphase signal, having first and second portions, respectively representing data bits of first and second states, the first portion having two transitions per data bit and the second portion having four transitions per data bit; and

in the remote terminal, means for receiving the coded diphase signal,

means, responsive to the received coded diphase signal, for generating first signals at the baud rate of the coded diphase signal and synchronized therewith, and for generating second signals at half of said baud rate and in phase with said first portions,

means for decoding the received coded diphase signal in synchronism with the first and second signals, to derive the data bits,

means for transmitting, via said hybrid circuit means and said two wire transmission line, a diphase signal, at half the baud rate of the coded diphase signal, synchronized with said second signal and representing other data bits; and

in the local terminal, means for receiving said diphase signal, delayed by less than half the baud rate of the coded diphase signal,

means, synchronized with a signal in phase with said first portion in the local terminal, for decoding the diphase signal to derive the other data bits.

3. A method for exchanging data between a local terminal and a remote telephone terminal, the local and remote terminals each coupled via hybrid circuit means to a two wire transmission line, the local terminal also coupled to a first source of clock pulses and second source of clock pulses occurring at half the rate and synchronized with the first source of clock pulses, the method comprising the steps of:

a. in the local terminal, generating a coded diphase binary signal, in which the bits of the diphase binary signal representing first binary data bits, from the local terminal, of one of two states, correspond to the first clock pulses and the bits of the diphase binary signal representing the first binary data bits, from the local terminal, of the other of the two states, correspond to the second clock pulses, and applying the first diphase binary signal to one of the hybrid circuit means to facilitate transmission of a coded diphase signal over the transmission line,

b. in the remote telephone terminal, receiving the coded diphase signal from the other hybrid circuit means delayed by less than half the period of the rate of the first clock pulse signals, in transmission from the local terminal, and regenerating the coded diphase binary signal therefrom,

c. regenerating clock pulse signals from the signal regenerated in step (b),

d. generating half rate clock pulse signals in response to the regenerated clock pulse signals and in synchronism with the bits of the signal regenerated in step (b) which represent said other of the two states,

e. decoding the signal regenerated in step (b), in synchronism with the regenerated clock pulse signals and the generated half rate clock pulse signals to derive the first binary data bits,

f. generating a diphase binary signal representing second binary data bits, in synchronism with the generated half rate clock pulse signals and applying the diphase binary signal to the other of the hybrid circuit means to facilitate transmission of a diphase signal over the transmission line; and

g. in the local terminal, receiving the diphase signal from the one hybrid circuit means delayed by less than half the period of the rate of the first clock pulses, in transmission from the remote telephone terminal, and regenerating therefrom a diphase binary signal,

h. decoding the diphase binary signal in synchronism with the second clock pulse signals, to derive the second binary data bits.

4. An apparatus, for facilitating an exchange of data between a local terminal and a remote telephone terminal via a two wire transmission line, in the local terminal the apparatus comprising:

means, responsive to first clock pulses and second clock pulses occurring at half the rate of the first clock pulses and synchronized therewith, for generating a coded diphase binary signal, in which bits of the coded diphase binary signal representing first binary data bits of one of two states, from the local terminal, correspond to the first clock pulses and bits of the coded diphase binary signal representing the first binary data bits of the other of the two states correspond to the second clock pulses;

first hybrid circuit means having an output port, an input port for the application of the coded diphase binary signal thereto, and a transmission line port connected to the transmission line, for the transmission of coded diphase signals and for the reception of diphase signals;

means, responsive to the second clock signals, for decoding the second diphase signals appearing at the output port of the first hybrid circuit means and delayed in transmission from the remote telephone terminal by less than half the period of the rate of said first clock pulses, to derive second binary data bits therefrom; and in the remote telephone terminal the apparatus comprising:

means, responsive to binary data bits in the remote telephone terminal and to regenerated half rate clock pulse signals, for generating a diphase binary signal;

second hybrid circuit means having an output port, an input port for the application of the diphase binary signals thereto, and a transmission line port, for the transmission of the diphase signals and the reception of the coded diphase signals;

means, responsive to the coded diphase signals, appearing at the output port of the second hybrid circuit means, for regenerating clock pulses;

means, responsive to the regenerated clock pulse signals and to the coded diphase signal, delayed in transmission by less than half the period of the rate of the first clock pulse signals, for regenerating the half rate clock pulse signals;

means, responsive to the regenerated clock pulse signals, and the regenerated half rate clock pulse signals, for decoding the first diphase signal, appearing at the output port of the second hybrid circuit means, to derive the first binary data bits therefrom.

Other info:

Inventors: Korver, Klaas (Ottawa, CA, US)

Application Number: 517218
Filing Date: 1974-10-23
Publication_date: 1976-02-03
Assignee: Northern Electric Company Limited (Montreal, CA)
Primary Class(es): 370/284 370/518, 375/258, 375/283, 375/371
Other Classes:
US Patent Ref:

3519743	Jul, 1970	Herzer	178/58.
3618025	Nov, 1971	Tomozawa	178/58.

Other Refs:
Primary Examiner: Claffy, Kathleen H.
Assistant Examiner: KEMENY, E. S.
Attorney: Mowle; J. E.