US 4,538,280 A · Coherent spread spectrum pseudonoise tracking loop

Abstract

A detector (20) is provided for use in a communication receiver where a received spread spectrum data signal is detected using a locally generated reference signal to decode the data signal. The detector (20) includes first (22) and second channels (24) and circuitry (90) for applying the received encoded data signal to the first (22) and second channels (24). A local generator (50) is provided for generating the reference signal wherein the reference signal has polarity transitions. A demodulator (40) is included in the first channel (22) for generating a detected recovered data signal from the received data signal in response to the reference signal. Circuitry (52) is provided for detecting the polarity transitions in the reference signal and for generating a differential PN signal. Circuitry (42) is further provided in the second channel (24) for correlating the received data signal and the differential PN signal to thereby generate a recovered error signal. The recovered data signal and the recovered error signal are correlated by circuitry (58) to generate a control signal for application to the local generator (50) for locking the reference signal to a component of the received data signal.

Claims35

Dependent claims

A detector for use in a communication receiver where a received data signal is detected using a locally generated reference signal to decode the received data signal comprising:

first channel means;
second channel means;
means for applying the received spread data signal to said first and second channel means;
local generator means for generating the reference signal wherein the reference signal includes polarity transitions;
said first channel means including demodulation means for generating a detected recovered data signal from said received spread data signal in response to the reference signal;
means for detecting said polarity transitions in the reference signal and for generating a differential PN signal;
said second channel means including means for correlating the received spread data signal and said differential PN signal to thereby generate a recovered error signal;
and
means for correlating said recovered data siganl and said recovered error signal to thereby generate a control signal for application to said local generator means for locking the reference signal to a component of the received spread data signal.

6 more elements

In a receiver for a spread specturm encoded signal wherein the received spread spectrum signal includes a carrier signal that has been phase modulated by a data signal and by a pseudonoise signal, a detector comprising:

first channel means;
second channel means;
means for applying the received spread spectrum signal to said first and second channel means;
local generator means for generating a pseudonoise sequence signal having phase transitions which corresponds to the pseudonoise signal component of the received spread spectrum signal;
said first channel means including demodulation means for correlating the pseudonoise signal component of the received spread spectrum signal with said pseudonoise sequence signal generated by said local generator means to thereby generate a detected recovered signal;
means for detecting the polarity of said phase transitions of said pseudonoise reference signal and for generating a differential PN signal;
means for correlating the received spread spectrum encoded signal and said error signal to thereby generate a recovered error signal;
and
means for correlating said detected recovered signal and said recovered error signal to therby generate a control signal for application to said local generator means, wherein said control signal controls the phase of said pseudonoise signal sequence such that said phase of said pseudonoise signal sequence generated by said local generator means is locked to the phase of the pseudonoise signal component of the received spread spectrum signal.

6 more elements

A detector for use in a communication receiver for a spread spectrum signal wherein the signal is modulated by a data signal and by a pseudonoise signal and detected by a locally generated pseudonoise reference signal, comprising:

data channel means;
error channel means;
means for applying the spread spectrum signal to said data channel means and to said error channel means;
voltage controlled oscillator means for generating a local pseudonoise sequence signal having phase transitions which correspond to the pseudonoise signal component of the spread spectrum signal;
said data channel means including demodulation means for removing the pseudonoise signal component of the spread spectrum signal in response to said local pseudonoise sequence signal to thereby generate a partially recovered signal;
filter means for receiving said partially recovered signal and for generating a recovered signal;
differentiating means for determining phase transitions in said local pseudonoise sequence signal and for generating a differential PN signal in response to detected phase transitions;
said error channel means including first mixer means for correlating the spread spectrum signal and said differential PN signal to generate a recovered error signal;
said error channel means including filter means for filtering said recovered error signal;
second mixer means for synchronizing the phase of said recovered error signal with the phase of the recovered signal and for removing the data signal component of said error signal to thereby generate a control signal;
and
means for applying said control signal to said voltage controlled oscillator means for locking said pseudonoise sequence signal generated by said voltage controlled oscillator means to the pseudonoise signal component of the spread spectrum signal.

9 more elements

Dependencies are inferred from the claim text.

Coherent spread spectrum pseudonoise tracking loop

Life of this patent

Coherent spread spectrum pseudonoise tracking loop

Life of this patent

Abstract

Claims35