Local oscillator phase noise cancelling modulation technique
First Claim
Patent Images
1. A data transmission system, comprising:
- a source of a data signal, said data signal exhibiting first and second levels;
a voltage controlled square wave oscillator, having a frequency control input terminal coupled to said data signal source, said voltage controlled square wave oscillator producing an output signal at a first frequency in response to said first level of said data signal and a second frequency in response to said second level of said data signal;
a modulator, responsive to said output signal, producing a first modulated signal representing said data signal, and a second modulated signal representing a signal 180°
out-of-phase wih said data signal, said first and second modulated signals having the same polarity;
said first modulated signal having frequency deviations in first and second directions in response to said output signal, said second modulated Signal having opposite frequency deviations in response to said output signal;
said modulator including an oscillator subject to undesired phase deviation, said phase deviation affecting said first and second modulated signals by introducing phase error into each of said first and second modulated signals in the same direction;
a transmission channel, transporting said first and second modulated signals;
a first demodulator, coupled to said transmission channel, demodulating said transported first modulated signal and producing said data signal and a noise signal caused by said phase error;
a second demodulator, coupled to said transmission channel, demodulating said transported second modulated signal and producing said data signal 180°
out-of-phase with said data signal and said noise signal caused by said phase error;
a subtractor, coupled to said first and second demodulators, producing a signal representative of said data signal and cancelling said noise signal.
1 Assignment
0 Petitions
Accused Products
Abstract
A data transmission system includes a source of a data signal and a modulator, responsive to the data signal, producing a first modulated signal representing the data signal and a second modulated signal representing a signal 180 out-of-phase with the data signal. The first and second modulated signals are transported via a transmission channel. A first demodulator demodulates the transported first modulated signal and a second demodulator demodulates the transported second modulated signal. A subtractor, responsive to the first and second demodulators, produces a signal representative of the data signal.
120 Citations
14 Claims
-
1. A data transmission system, comprising:
-
a source of a data signal, said data signal exhibiting first and second levels; a voltage controlled square wave oscillator, having a frequency control input terminal coupled to said data signal source, said voltage controlled square wave oscillator producing an output signal at a first frequency in response to said first level of said data signal and a second frequency in response to said second level of said data signal; a modulator, responsive to said output signal, producing a first modulated signal representing said data signal, and a second modulated signal representing a signal 180°
out-of-phase wih said data signal, said first and second modulated signals having the same polarity;said first modulated signal having frequency deviations in first and second directions in response to said output signal, said second modulated Signal having opposite frequency deviations in response to said output signal; said modulator including an oscillator subject to undesired phase deviation, said phase deviation affecting said first and second modulated signals by introducing phase error into each of said first and second modulated signals in the same direction; a transmission channel, transporting said first and second modulated signals; a first demodulator, coupled to said transmission channel, demodulating said transported first modulated signal and producing said data signal and a noise signal caused by said phase error; a second demodulator, coupled to said transmission channel, demodulating said transported second modulated signal and producing said data signal 180°
out-of-phase with said data signal and said noise signal caused by said phase error;a subtractor, coupled to said first and second demodulators, producing a signal representative of said data signal and cancelling said noise signal. - View Dependent Claims (2, 3, 4, 5)
-
-
6. A data transmission system, comprising:
-
a source of a data signal; a modulator, responsive to said data signal, producing a first modulated signal representing said data signal, and a second modulated signal representing a signal 180°
out-of-phase with said data signal;a transmission channel, transporting said first and second modulated signals; a first demodulator, coupled to said transmission channel, demodulating said transported first modulated signal; a second demodulator, coupled to said transmission channel, demodulating said transported second modulated signal; a subtractor, coupled to said first and second demodulators, producing a signal representative of said data signal; and further comprising the serial connection, coupled between said transmission channel and said first and second demodulators, of; a down converter translating said transported first and second modulated signals to respective first and second intermediate frequencies; and a bandpass filter having a passband passing said translated first and second modulated signals; wherein said modulator comprises a voltage controlled square wave oscillator having a frequency control input terminal coupled to said data signal source;
wherein said modulator further comprises an up-converter, coupled to said square wave oscillator.
-
-
7. A data receiver, comprising:
-
a source of a first modulated signal representing a data signal, and a second modulated signal representing a signal 180°
out-of-phase with said data signal, said first and second modulated signals having the same polarity;said first modulated signal having frequency deviations in first and second directions in response to said data signal, said second modulated signal having opposite frequency deviations in response to said data signal; said first and second modulated signals each exhibiting an undesired phase error deviating in the same direction; a first demodulator demodulating said first modulated signal and producing said data signal and a noise signal caused by said phase error; a second demodulator demodulating said second modulated signal and producing said data signal 180°
out-of-phase with said data signal and said noise signal caused by said phase error; anda subtractor, responsive to said first and second demodulators, producing a signal representative of said data signal and cancelling said noise signal. - View Dependent Claims (8, 9)
-
-
10. A data transmitter producing a first modulated signal representing a data signal and a second modulated signal representing a signal 180°
- out-of-phase with said data signal, comprising;
a source of said data signal; and a voltage controlled square wave oscillator, having a frequency control input terminal coupled to said data signal source. - View Dependent Claims (11)
- out-of-phase with said data signal, comprising;
-
12. A dual data signal transmission system, comprising:
-
a source of a first data signal; a source of a second data signal; a modulator, responsive to said first and second data signals, producing a first modulated signal representing a composite of said first and second data signals, and a second modulated signal representing a composite of said second data signal and a signal 180 out-of-phase with said first data signal; a transmission channel, transporting said first and second composite modulated signals; a first demodulator, coupled to said transmission channel, demodulating said transported first composite modulated signal; a second demodulator, coupled to said transmission channel, demodulating said transported second composite modulated signal; a subtractor, coupled to said first and second demodulators, producing a signal representative of said first data signal; and an adder, coupled to said first and second demodulators producing a signal representative of said second data signal.
-
-
13. A data receiver, comprising:
-
a source of a first modulated signal representing a composite of a first and a second data signal, and a second modulated signal representing a composite of said second data signal and a signal 180 out-of-phase with said first data signal; a first demodulator demodulating said first composite modulated signal; a second demodulator demodulating said second composite modulated signal; a subtractor, coupled to said first and second demodulators, producing a signal representative of said first data signal; and an adder, coupled to said first and second demodulators producing a signal representative of said second data signal. - View Dependent Claims (14)
-
Specification