Joint setting of demodulating carrier phase, sampling time and equalizer gain parameters in synchronous data transmission systems

Claim 2

In combination with a receiver for a synchronous data transmission system provided with a transversal equalizer in which attenuators connected to spaced taps thereon are adjusted in accordance with the correlation of received samples of test signals appearing at such taps with an error signal obtained from the difference between the summed equalizer output and locally generated reference waves: sampling time recovery means, means jointly responsive to the time derivative of said reference waves and said equalizer output for controlling the phase of said sampling time recovery means in a direction to minimize said error signal, local oscillator means for generating a demodulating carrier wave, and means jointly responsive to said reference waves and said equalizer output for adjusting the phase of said demodulating carrier wave in a direction to minimize said error signal.

Claim 3

The combination defined in claim 1 in which said test signals are modulated onto a single-sideband of the carrier wave and said means for adjusting the phase of the demodulating carrier wave correlates said equalizer output with said shaped reference waves shifted into relative phase quadrature with those generating said error signals.

Claim 4

The combination defined in claim 1 in which said test signals are modulated onto a single sideband of the carrier wave and said means for adjusting the phase of the demodulating carrier wave correlates said shaped reference waves with said equalizer output shifted in phase by 90 degrees.

Claim 5

The combination defined in claim 1 in which said test signals are modulated into a frequency bandwidth exceeding that occupied by a single sideband of the carrier wave and said means for controlling the phase of the demodulating carrier wave correlates the stored difference between a first equalizer output derived from the demodulating carrier wave in normal phase and said shaped reference waves and a second equalizer output derived from the quadrature phase of said demodulating carrier wave.

Claim 6

The combination defined in claim 4 in which said test signals are modulated onto double sidebands about said carrier wave.

Claim 7

The combination defined in claim 4 in which said test signals are modulated onto a vestigial sideband of said carrier wave.

Claim 8

Apparatus for concurrent adjustment of critical parameters in a receiver for a synchronous data transmission system in accordance with a single performance criterion comprising in combination: a transmitting terminal, a transmission channel and a receiving terminal, means at said transmitting terminal for applying a first train of test pulses at a subsynchronous rate to said channel, and said receiving terminal comprises: means for generating a second train of test pulses matching said first train; a shaping filter responsive to said second train of pulses for generating reference waves having a predetermined impulse response; a transversal equalizer having an output formed from a summation of the attenuated individual contributions of a plurality of spaced taps thereon, each provided with an adjustable attenuator; timing means controlling said generating means and including phase adjusting means; subtracting means jointly responsive to said equalizer output and to said reference waves to form an error difference signal; means for correlating said error difference signal with signals at each tap of said equalizer to form first control signals for the attenuators associated with such taps, said attenuators being adjusted in accordance with said control signals to reduce said difference signal; means for differentiating said reference wave; means jointly responsive to said equalizer output and to said differentiating means for furnishing a second control signal to said timing means for control of the phase adjusting means therein; a demoduLating carrier-wave source also including phase adjusting means; and means jointly responsive to the quadrature component of one and the direct component of the other of said reference wave and said equalizer output for controlling the phase adjusting means in said carrier-wave source.

Claim 9

Apparatus for concurrent adjustment of critical parameters in a receiver for a synchronous data transmission system in accordance with a single performance criterion comprising in combination: a transmitting terminal, a transmission channel and a receiving terminal, means at said transmitting terminal for applying a first train of test pulses at a subsynchronous rate to said channel, and said receiving terminal comprises: means for generating a second train of test pulses matching said first train; a shaping filter responsive to said second train of pulses for generating reference waves having a predetermined impulse response; a transversal equalizer having an output formed from a summation of the attenuated individual contributions of a plurality of spaced taps thereon, each provided with an adjustable attenuator; timing means controlling said generating means and including phase adjusting means; subtracting means jointly responsive to said equalizer output and to said reference waves to form an error difference signal; means for correlating said error difference signal with signals at each tap of said equalizer to form first control signals for the attenuators associated with such taps, said attenuators being adjusted in accordance with said control signals to reduce said difference signal; means for differentiating said reference wave; means jointly responsive to said equalizer output and to said differentiating means for furnishing a second control signal to said timing means for control of the phase adjusting means therein; a demoduLating carrier-wave source also including phase adjusting means; and means jointly responsive to the quadrature component of one and the direct component of the other of said reference wave and said equalizer output for controlling the phase adjusting means in said carrier-wave source.

Claim 12

The method of claim 8 in which said first plurality of pulses are modulated onto a single sideband of the carrier wave and the correlation forming said third control signal is between a direct component of one and a quadrature component of the other of said first plurality of pulses as shaped by said equalizer and of said second plurality of pulses as shaped into the desired system response.

Claim 13

The method of claim 9 in which the frequency components of said first plurality of pulses are modulated onto more than one sideband of the carrier wave and the correlation forming said third control signal is between said error difference signal derived from normally demodulated odd-ordered members of said first plurality of pulses and the following even-ordered members of said first plurality of pulses demodulated by a quadrature carrier-wave component and shaped by said equalizer.