Telefonaktiebolaget Lm Ericsson (publ)

Walter Herbert Widl

Juho Arras

Mats Orjan Mattsson

Orjan Mats Mattsson

A system for phase division multiplex duplex communication over a two-wire circuit has a master terminal and a slave terminal. The master terminal comprises a modulator and a demodulator jointly connected to a first end of the two-wire circuit and arranged to transmit an outgoing AM-signal with an essentially non-suppressed carrier component constituting a pilot signal and to receive an incoming AM-signal with a considerably suppressed carrier component having a frequency identical to the frequency of the pilot signal. An oscillator circuit is arranged to supply the modulator and the demodulator with a first and secnd, respectively, oscillator signal having a respective frequency identical to the frequency of the pilot signal and having such a relative phasing that at the demodulator the phase of the second oscillator signal is phase displaced 90.degree. relative to the phase of the pilot signal. The slave terminal comprises a demodulator and a modulator jointly connected to a second end of the two-wire circuit and arranged to receive the AM-signal with the pilot signal and to transmit the AM-signal with the suppressed carrier component. An oscillator circuit is arranged to supply the demodulator and the modulator with a third and fourth, respectively, oscillator signal having a respective frequency identical to the frequency of the pilot signal and having such a phasing relative so that at the demodulator the phase of the third oscillator signal coincides with the phase of the pilot signal while the phase of the suppressed carrier component is phase displaced 90.degree. relative to the latter.

System for phase division multiplex duplex communication over a two-wire

A method and apparatus for generating a number of weakly correlated pseudorandom pulse trains which is especially useful for generation of noise signals utilized for measurements on telephone cables carrying PCM traffic The apparatus generates a number of mutually phase shifted versions of a binary pulse train which are sampled with individual sampling signals of the same nominal frequency.

Method and apparatus for generating a number of weakly correlated

A method and an apparatus for measuring the bit error frequency in a cable caused by crosstalk from at least one disturbing pair to a disturbed pair at transmission of a 3-level coded PCM signal utilizes the fact that a PCM signal transferred on a pair and the disturbances superimposed on this signal by crosstalk from other pairs are mathematically uncorrelated. The amplitudes of the disturbances measured on the disturbed pair are sampled after equalization in a regenerator with a sampling frequency which equals the bit time frequency of the PCM signal intended for transmission on the pair. The number of detected sampling values whose magnitude exceeds a certain threshold value is a function of the estimated bit error frequency.

Growing community of inventors

Bandhagen, Sweden

Walter Herbert Widl