Technique to facilitate the independent bi-directional data transmission on a single amplitude modulated carrier

• US 6,148,182 A
• Filed: 10/22/1997
• Issued: 11/14/2000
• Est. Priority Date: 10/28/1996
• Status: Expired due to Term

• Current Assignee: ClearCube Technology Incorporated
• Original Assignee: INT Labs Incorporated
• Inventors: Thornton, Barry
• Primary Examiner(s): Trost, William G.
• Assistant Examiner(s): GELIN, JEAN ALLAND
• Application Number:
  US08/955,532
• Time in Patent Office: 1,119 Days
• Field of Search: 375/276, 375/277, 375/281, 375/295, 375/326, 375/259, 375/316, 375/329, 375/332, 455/86, 455/526, 455/7, 455/24, 455/47, 455/502, 455/507, 455/557, 455/88, 455/44, 455/108, 455/203, 455/210, 455/500, 455/39, 370/295, 370/485, 370/480, 340/825.05, 340/825.18, 340/870.31
• US Class Current: 455/88
• CPC Class Codes: H04B 1/40 Circuits
• CPC Class Codes: H04B 1/68 for wholly or partially suppressing the carrier or one side band

Abstract

Method and apparatus for facilitating the simultaneous bi-directional transmission of data on a single AM carrier is described. In particular, the process is implemented using two or more transceivers, each comprising a modulator, a demodulator, and an oscillator operating at the same frequency and in locked phase. One of the oscillators functions as a master, to which all other oscillators ("slaves") are locked. Each of the transceivers also includes means for recovering the appropriate signal to be demodulated by the particular transceiver.

Claims

1. A transmission system for enabling simultaneous bi-directional transmission of radio frequency ("RF") signals using a single carrier frequency the transmission system comprising:

a master transceiver comprising;

a local oscillator for generating a master carrier at said carrier frequency; and

a modulator connected to receive said master carrier from said local oscillator, said master transceiver modulator modulating said master carrier using a first data signal input to said master transceiver to create a first modulated data signal and outputting said first modulated data signal to a transmission medium; and

at least one slave transceiver connected to said master transceiver via said transmission medium and comprising;

a carrier recovery device electrically connected to said transmission medium for recovering said carrier from said first modulated data signal on a cycle-by-cycle basis;

a modulator connected to receive said first recovered carrier from said slave transceiver carrier recovery device, said slave transceiver modulator modulating said recovered carrier using a second data signal input to said slave transceiver to create a second modulated data signal and outputting said second modulated data signal to said transmission medium; and

a demodulator connected to receive said first recovered carrier from said slave transceiver carrier recovery device, said slave transceiver demodulator using said first recovered carrier to demodulate signals input thereto from said transmission medium;

wherein said master transceiver further comprises;

a carrier recovery device electrically connected to said transmission medium for recovering said carrier from said second modulated data signal on a cycle-by-cycle basis; and

a demodulator connected to receive said second recovered carrier from said master transceiver carrier recovery device, said master transceiver demodulator using said second recovered carrier to demodulate signals input thereto from said transmission medium;

wherein said master transceiver comprises first means for separating said first and second modulated data signals such that only said second data signal is output from said master transceiver and wherein said slave transceiver comprises second means for separating said first and second modulated data signals such that only said first data signal is output from said slave transceiver.

2. The transmission system of claim 1 wherein each of said first and second means for separating comprises a bi-directional coupler connected to said transmission medium.

3. The transmission system of claim 1 wherein:

said first means for separating comprises a summer having a first input connected to receive signals from said transmission medium, a second input connected to an output of said master transceiver modulator, and an output connected to an input of said master transceiver demodulator for subtracting said first modulated data signal from a sum of said first and second modulated data signals on said transmission medium such that only said second modulated data signal is input to said master transceiver demodulator; and

said second means for separating comprises a summer having a first input connected to receive signals from said transmission medium, a second input connected to an output of said slave transceiver modulator, and an output connected to an input of said slave transceiver demodulator for subtracting said second modulated data signal from a sum of said first and second modulated data signals on said transmission medium such that only said first modulated data signal is input to said slave transceiver demodulator.

4. The transmission system of claim 1 wherein:

said first means for separating comprises a summer having a first input connected to an output of said master transceiver demodulator and a second input connected to receive said first data signal for subtracting said first input data signal from a sum of said first and second data signals subsequent to demodulation of said first and second modulated data signals such that only said second data signal is output from said master transceiver; and

said second means for separating comprises a summer having a first input connected to an output of said slave transceiver demodulator and a second input connected to receive said second data signal for subtracting said second input data signal from a sum of said first and second data signals subsequent to demodulation of said first and second modulated data signals such that only said first data signal is output from said slave transceiver.

5. The transmission system of claim 1 wherein each of said first and second modulated data signals are modulated using a modulation technique selected from the group consisting of amplitude modulation, quadrature amplitude modulation, single side-band modulation, and double side-band modulation.

6. The transmission system of claim 1 wherein said transmission medium is selected from the group consisting of wire, fiber optic cable, and air.

7. The transmission system of claim 1 wherein each of said master transceiver and slave transceiver carrier recovery devices is an electronic wave interferometric filter.

8. A transmission system for enabling simultaneous bi-directional transmission of radio frequency ("RF") signals using a single carrier frequency, the transmission system comprising:

a master transceiver comprising;

means for generating a master carrier at said carrier frequency; and

modulating means connected to receive said master carrier from said master transceiver generating means, said master transceiver modulating means for modulating said master carrier using a first data signal input to said master transceiver to create a first modulated data signal and outputting said first modulated data signal to a transmission medium; and

at least one slave transceiver connected to said master transceiver via said transmission medium and comprising;

carrier recovery means electrically connected to said transmission medium for recovering said carrier from said first modulated data signal on a cycle-by-cycle basis;

modulating means connected to receive said first recovered carrier from said slave transceiver carrier recovery means, said slave transceiver modulating means for modulating said recovered carrier using a second data signal input to said slave transceiver to create a second modulated data signal and outputting said second modulated data signal to said transmission medium; and

demodulating means connected to receive said first recovered carrier from said slave transceiver carrier recovery means, said slave transceiver demodulating means using said first recovered carrier to demodulate signals input thereto from said transmission medium;

wherein said master transceiver further comprises;

carrier recovery means electrically connected to said transmission medium for recovering said carrier from said second modulated data signal on a cycle-by-cycle basis;

demodulating means connected to receive said second recovered carrier from said master transceiver carrier recovery means, said master transceiver demodulating means using said second recovered carrier to demodulate signals input thereto from said transmission medium; and

means for separating said first and second modulated data signals such that only said second data signal is output from said master transceiver; and

wherein said slave transceiver further comprises;

means for separating said first and second modulated data signals such that only said first data signal is output from said slave transceiver.

9. The transmission system of claim 8 wherein each of said separating means comprises a bidirectional coupler connected to said transmission medium.

10. The transmission system of claim 8 wherein:

said master transceiver separating means comprises summing means having a first input connected to receive signals from said transmission medium, a second input connected to an output of said master transceiver modulating means, and an output connected to an input of said master transceiver demodulating means, said master transceiver summing means for subtracting said first modulated data signal from a sum of said first and second modulated data signals on said transmission medium such that only said second modulated data signal is input to said master transceiver demodulating means; and

said slave transceiver separating means comprises summing means having a first input connected to receive signals from said transmission medium, a second input connected to an output of said slave transceiver modulating means, and an output connected to an input of said slave transceiver demodulating means, said slave transceiver summing means for subtracting said second modulated data signal from a sum of said first and second modulated data signals on said transmission medium such that only said first modulated data signal is input to said slave transceiver demodulating means.

11. The transmission system of claim 8 wherein:

said master transceiver separating means comprises summing means having a first input connected to an output of said master transceiver demodulating means and a second input connected to receive said first data signal, said master transceiver summing means for subtracting said first input data signal from a sum of said first and second data signals subsequent to demodulation of said first and second modulated data signals such that only said second data signal is output from said master transceiver; and

said slave transceiver separating means comprises summing means having a first input connected to an output of said slave transceiver demodulating means and a second input connected to receive said second data signal, said slave transceiver summing means for subtracting said second input data signal from a sum of said first and second data signals subsequent to demodulation of said first and second modulated data signals such that only said first data signal is output from said slave transceiver.

12. The transmission system of claim 8 wherein each of said first and second modulated data signals are modulated using a modulation technique selected from the group consisting of amplitude modulation, quadrature amplitude modulation, single side-band modulation, and double side-band modulation.

13. The transmission system of claim 8 wherein said transmission medium is selected from the group consisting of wire, fiber optic cable, and air.

14. The transmission system of claim 8 wherein each of said master transceiver and slave transceiver carrier recovery means is an electronic wave interferometric filter.

15. A method of enabling simultaneous bi-directional transmission of radio frequency ("RF") signals on a single carrier frequency via a transmission medium, the transmission system comprising a master transceiver connected to at least one slave transceiver via the transmission medium, the method comprising steps of:

(a) generating a master carrier at said carrier frequency;

(b) modulating said master carrier using a first data signal input to said master transceiver to create a first modulated data signal;

(c) outputting said first modulated data signal from said master transceiver onto said transmission medium;

(d) recovering said carrier from said transmitted first modulated data signal on a cycle-by-cycle basis;

(e) modulating said recovered carrier using a second data signal input to said slave transceiver to create a second modulated data signal;

(f) outputting said second modulated data signal from said slave transceiver onto said transmission medium;

(g) using said first recovered carrier to demodulate signals input to said slave transceiver from said transmission medium;

(h) recovering said carrier from said second modulated data signal on a cycle-by-cycle basis; and

(i) using said second recovered carrier to demodulate signals input to said master transceiver from said transmission medium;

wherein steps a, b, c, h, and i are performed at said master transceiver and steps d, e, f, and g are performed at said slave transceiver;

the method further comprising the steps of, at each of said master transceiver and said slave transceiver, separating said first and second modulated data signals such that only said second data signal is output from said master transceiver and only said first data signal is output from said slave transceiver.

16. The method of claim 15 wherein said separating comprises:

at said master transceiver, prior to execution of step i, subtracting said first modulated data signal from a sum of said first and second modulated data signals on said transmission medium; and

at said slave transceiver, prior to execution of step g, subtracting said second modulated data signal from a sum of said first and second modulated data signals on said transmission medium.

17. The method of claim 15 further comprising:

at said master transceiver, subsequent to execution of step i, subtracting said first input data signal from a sum of said first and second data signals; and

at said slave transceiver, subsequent to execution of step g, subtracting said second input data signal from a sum of said first and second data signals.

18. The method of claim 17 further comprising:

at said master transceiver, subsequent to said subtracting, filtering said second data input signal; and

at said slave transceiver, subsequent to said subtracting, filtering said first data input signal.

19. The method of claim 15 wherein steps b and e are performed using a modulation technique selected from the group consisting of amplitude modulation, quadrature amplitude modulation, single side-band modulation, and double side-band modulation.

20. The method of claim 15 wherein said transmission medium is selected from the group consisting of wire, fiber optic cable, and air.

21. The method of claim 15 wherein steps d and h are performed using an electronic wave interferometric filter.