Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
278 words
System for phase division multiplex duplex communication over a two-wire circuit comprising: a master terminal and a slave terminal; said master terminal comprising a first modulator and a first demodulator jointly connected to a first end of the two-wire circuit, the first modulator being arranged to transmit an outgoing AM-signal with an essentially non-suppressed carrier forming a pilot signal and the first demodulator being arranged to receive an incoming AM-signal with a considerably suppressed carrier component having a frequency identical to the frequency of the pilot signal, a first oscillator circuit being arranged to supply the first modulator and the first demodulator with a first and a second, respectively, oscillator signal having a frequency identical to the frequency of the pilot signal and with a deviation from a phase relationship of 90° equal to the absolute value of the total phase shift in the transmission path from the first modulator to the first demodulator via the first end of the two-wire circuit; and the slave terminal comprising a second demodulator and a second modulator jointly connected to a second end of the two-wire circuit and arranged to receive the AM-signal with the pilot signal to transmit, respectively, the AM-signal with the suppressed carrier component, a second oscillator circuit being arranged to supply the second demodulator and the second modulator with a third and fourth, respectively, oscillator signals of a frequency identical to the frequency of the pilot signal and with a deviation from a phase relationship of 90° equal to the absolute value of the total phase shift in the transmission path from the second modulator to the second demodulator via the second end of the two-wire circuit.
Claim 2
Dependent Claim
278 words
System for phase division multiplex duplex communication over a two-wire circuit comprising: a master terminal and a slave terminal; said master terminal comprising a first modulator and a first demodulator jointly connected to a first end of the two-wire circuit, the first modulator being arranged to transmit an outgoing AM-signal with an essentially non-suppressed carrier forming a pilot signal and the first demodulator being arranged to receive an incoming AM-signal with a considerably suppressed carrier component having a frequency identical to the frequency of the pilot signal, a first oscillator circuit being arranged to supply the first modulator and the first demodulator with a first and a second, respectively, oscillator signal having a frequency identical to the frequency of the pilot signal and with a deviation from a phase relationship of 90° equal to the absolute value of the total phase shift in the transmission path from the first modulator to the first demodulator via the first end of the two-wire circuit; and the slave terminal comprising a second demodulator and a second modulator jointly connected to a second end of the two-wire circuit and arranged to receive the AM-signal with the pilot signal to transmit, respectively, the AM-signal with the suppressed carrier component, a second oscillator circuit being arranged to supply the second demodulator and the second modulator with a third and fourth, respectively, oscillator signals of a frequency identical to the frequency of the pilot signal and with a deviation from a phase relationship of 90° equal to the absolute value of the total phase shift in the transmission path from the second modulator to the second demodulator via the second end of the two-wire circuit.
Claim 3
Dependent Claim
41 words
System according to claim 1 wherein an adjustable phase shifter is connected in cascade with the two-wire circuit in order to provide, between the ends of thereof, a phase shift for the pilot signal equal to an integer multiple of 90°.
Claim 4
Dependent Claim
30 words
System according to claim 1 wherein the phase of said second oscillator signal is controlled by a phase locked oscillator provided with said pilot signal received at said first demodulator.
Claim 5
Dependent Claim
57 words
System according to claim 1 wherein said second demodulator is supplied with a pilot tone and the phase of said fourth oscillator signal is controlled by a phase locked oscillator having a control input connected to said second demodulator via a band-pass filter tuned to said pilot tone, an envelope detecting circuit and minimum-locked differentiating circuit means.
Claim 6
Dependent Claim
23 words
System according to claim 4 wherein said minimum-locked differentiating circuit means comprises a bistable flip-flop switched by a differentiator via a threshold detector.