Data transmission system including an RF transponder for generating a broad spectrum of intelligence bearing sidebands

• US 3,967,202 A
• Filed: 07/25/1974
• Issued: 06/29/1976
• Est. Priority Date: 07/25/1974
• Status: Expired due to Term

• Current Assignee: Northern Illinois Gas Company (Southern Company)
• Original Assignee: Northern Illinois Gas Company (Southern Company)
• Inventors: Batz, James E.
• Primary Examiner(s): Griffin, Robert L.
• Assistant Examiner(s): Bookbinder, Marc E.
• Application Number:
  US05/491,829
• Time in Patent Office: 705 Days
• Field of Search: 325/15, 325/17, 325/31, 325/8, 325/1, 325/2, 325/3, 325/64, 325/131, 325/145, 325/147, 325/163, 325/65, 343/6.5 R, 343/6.5 LC, 343/6.5 SS, 343/6.8 R, 343/6.8 LC, 343/225, 343/227, 340/152 T, 340/151, 178/66 R, 178/66 A
• US Class Current: 342/42
• CPC Class Codes: G01S 13/78 discriminating between different kinds of targets, e.g. IFF-radar, i.e. identification of friend or foe G01S13/75, G01S13/79 take precedence
• CPC Class Codes: H04L 1/04 using frequency diversity
• CPC Class Codes: H04L 27/12 Modulator circuits; Transmitter circuits
• CPC Class Codes: H04L 27/152 using controlled oscillators, e.g. PLL arrangements

Abstract

A data transmission system for obtaining information from a plurality of data sources includes an interrogate source for transmitting RF interrogate signals to the locations of the data sources and a transponder associated with each data source for receiving the interrogate signals and for generating RF reply signals representing the information. The transponder includes a transmitter having a voltage controlled oscillator responsive to data signals at first and second levels to generate sinusoidal output signals at first and second frequencies, respectively, a wave shaping circuit which converts the output signals to sawtooth wave signals at the corresponding frequencies and an FM oscillator for providing a carrier signal which is modulated by the sawtooth signals to produce a broad spectrum of sideband signals of approximately equal amplitude.

Claims

1. In a data transmission system for obtaining information from at least one data source, said system including an interrogate source means having first transmitter means and first receiver means, said first transmitter means being operable to generate interrogate signals for transmission to the location of said data source, and transponder means associated with said data source, said transponder means comprising second receiver means for receiving said interrogate signals, data means connected to said data source and controlled by said second receiver means to provide data signals representing the information provided by said data source, and second transmitter means including first oscillator means for generating a carrier signal at a predetermined frequency and drive means responsive to said data signals to provide linearly varying drive signals having unequal rise and fall times for said first oscillator means to effect the generation of a plurality of sets of sideband signals representing said information, wherein the sideband signals of each set are approximately equal in amplitude over a predetermined spectrum to thereby enable the simultaneous reception of at least two adjacent sidebands by said first receiver means.

2. A data transmission system as set forth in claim 1 wherein said data means includes means operable to provide logic level data signals at first and second levels in a sequence coded to represent said information, and wherein said drive means includes first means responsive to data signals at said first level to provide output signals at a first frequency for effecting the generation of a first set of sideband signals differing in frequency in correspondence with said first frequency, said first means being responsive to data signals at a second frequency for effecting the generation of a second set of sideband signals differing in frequency in correspondence with said second frequency.

3. In a data transmission system for obtaining information from at least one data source, said system including an interrogate source means having first transmitter means and first receiver means, said first transmitter means being operable to generate interrogate signals for transmission to the location of said data source, and transponder means associated with said data source, said transponder means comprising second receiver means for receiving said interrogate signals, data means connected to said data source and controlled by said second receiver means to provide logic level data signals at first and second levels in a sequence representing the information provided by said data sourcee, and second transmitter means including first oscillator means for generating a carrier signal at a predetermined frequency and drive means including second oscillator means responsive to said logic level data signals at said first and second levels to provide sinusoidal output signals at respective first and second frequencies, and wave shaping means responsive to the sinusoidal output signals provided by said second oscillator means to provide sawtooth waveform drive signals at said first and second frequencies for said first oscillator means to effect the generation of first and second sets of sideband signals representing said information, the sideband signals of said first and second sets differing in frequency in correspondence with said first and second frequencies respectively, and the sideband signals of each set being approximately equal in amplitude over a predetermined spectrum to enable the simultaneous reception of at least two adjacent sidebands by said first receiver means.

4. In a data transmission system including a mobile interrogate source including means for generating interrogate signals for transmission to the location of a data source to effect the generation of reply data signals representing information provided by said data source, said interrogate source including first receiver means for receiving said reply data signals, and transponder means associated with said data source, said transponder means comprising second receiver means for receiving the interrogate signals, data means connected to said data source and controlled by said second receiver means to provide bilevel data signals in a sequence representing said information, and transmitter means including oscillator means for generating a carrier signal and drive means responsive to said data signals to provide linearly varying drive signals at first and second frequencies for said oscillator means to effect the generation of first and second sets of sideband signals representing said information wherein the sideband signals of each set are approximately equal in amplitude over a predetermined portion of an output spectrum for said transmitter means, said first receiver means being tuned to simultaneously receive at least two adjacent sideband signals in a preselected portion of the output spectrum, and said first receiver means being operable to recover the information from said two sideband signals.

5. A data transmission system as set forth in claim 4 wherein the sideband signals of said first and second sets differ in frequency by said first and second frequencies, respectively, and wherein said first receiver means includes first means responsive to at least two adjacent sideband signals to produce a signal corresponding to the difference in frequency between said two sideband signals.

6. A data transmission system as set forth in claim 4 wherein each set of sideband signals includes at least three sideband signals which are approximately equal in amplitude and wherein said first receiver means is tuned to receive said three sideband signals, said first receiver means including means responsive to first and second ones of said three sideband signals to produce a signal corresponding to the difference in frequency between said first and second sideband signals.

7. In an RF transmitter circuit responsive to information signals to provide RF data signals representing information to be transmitted, the improvement comprising first oscillator means for generating a carrier signal, second oscillator means controlled by said information signals to provide sinusoidal output signals at first and second frequencies, and wave shaping means responsive to said output signals to provide linear drive signals at said first and second frequencies for said first oscillator means for modulating said carrier signal thereby effecting the generation of sideband signals of said carrier signal representing said information, the sideband signals being approximately equal in amplitude over a predetermined output spectrum.

8. A transmitter circuit as set forth in claim 7 wherein said wave shaping means includes control means responsive to said sinusoidal output signals to provide a control pulse for each cycle of the sinusoidal output signals, and output means responsive to each control pulse to provide a sawtooth waveform output.

9. A data transmitter circuit as set forth in claim 8 wherein said output means includes means for establishing the amplitude of said drive signals and therefore the width of the output spectrum provided by said first oscillator means.

10. A transmitter circuit as set forth in claim 8 wherein the ratio of the rise time to the fall time of each sawtooth output signal is determined by the width of said control pulse and wherein said control means includes means for establishing the pulse width for said control pulse to provide a risetime to falltime ratio in the range of 10 to 20.

11. A transmitter circuit as set forth in claim 8 wherein said first oscillator means comprises semiconductor means having at least a control electrode and an output electrode, resonant circuit means connected to said output electrode to establish the carrier frequency for said first oscillator means, said control electrode being connected to an output of said wave shaping means to receive said sawtooth output signals.

12. A transmitter circuit as set forth in claim 8 wherein said first oscillator means comprises semiconductor means having at least a control electrode and an output electorde, bias means connected to said control electrode for establishing a fixed bias for said semiconductor means, resonant circuit means including variable reactance means connected to said output electrode to establish the carrier frequency for said first oscillator means, and circuit means for extending said sawtooth output signals to said variable reactance means.

13. A transmitter circuit as set forth in claim 7 wherein said information signals comprise bilevel data signals, said second oscillator means being controlled by said bilevel data signals to provide output signals at first and second frequencies and wherein said wave shaping means is responsive to said output signals to provide drive signals at said first and second frequencies to thereby effect the generation of first and second sets of sideband signals.

14. A transmitter circuit as set forth in claim 13 wherein the sideband signals of said first set differ in frequency in correspondence with said first frequency and the sideband signals of said second set differ in frequency in correspondence with said second frequency.

15. In an RF data transmitter circuit responsive to bi-level data signals representing information to be transmitted for providing RF data signals representing said information, the improvement comprising first oscillator means for generating a carrier signal, second oscillator means responsive to a data signal at a first level to provide a sinusoidal output signal at a first frequency and responsive to a data signal at a second level to provide a sinusoidel output signal at a second frequency, and wave shaping means including control means responsive to each cycle of the output signals provided by said second oscillator means to provide a control signal, output means responsive to each control signal to provide a sawtooth waveform output signal, the frequency of the sawtooth output signal being determined by the frequency of the sinusoidal signal supplied to said wave shaping means, said sawtooth waveform signals being supplied to said first oscillator means to effect the generation of a first set of sideband signals whenever sawtooth signals at said first frequency are provided, and to effect the generation of a second set of sideband signals whenever sawtooth signals at said second frequency are provided.

16. In an RF transmitter circuit responsive to information signals to provide RF data signals representing information to be transmitted, the improvement comprising oscillator means for generating a carrier signal at a predetermined frequency, and drive means controlled by said information signals to provide linearly varying amplitude drive signals at first and second frequencies for said oscillator means for modulating said carrier signal to effect the generation of respective first and second sets of sideband signals of said carrier signal representing said information, said drive signals having unequal rise and fall times whereby the sideband signals are approximately equal in amplitude over a predetermined output spectrum.

17. In a data transmission system, transmitter means at a first location for transmitting information provided by a data source means at said first location to a receiver means at a second location, said transmitter means comprising first oscillator means operable to generate a carrier signal, second oscillator means connected to said data source means and controlled by data signals representing said information provided by said data source means to provide sinusoidal output signals at predetermined frequencies, and wave shaping means responsive to said sinusoidal output signals to provide linearly varying drive signals having unequal rise and fall times for said first oscillator means to effect the generation of sets of sidebands of said carrier signal representing said information for transmission to said receiver means.

18. A data transmission system as set forth in claim 17 wherein said first oscillator means comprises semiconductor means having at least a control electrode and an output electrode, resonant circuit means connected to said output electrode to establish the carrier frequency for said first oscillator means, said control electrode being connected to an output of said wave shaping means to receive said drive signals.

19. A data transmission system as set forth in claim 17 wherein said wave shaping means includes means for establishing the amplitude of said varying drive signals at a predetermined value to thereby establish the width of the output spectrum of said transmitter means.

20. A data transmission system as set forth in claim 17 wherein said first oscillator means comprises semi-conductor means having at least a control electrode and an output electrode, bias means connected to said control electrode for establishing a fixed bias for said semiconductor means, resonant circuit means including variable reactance means connected to said output electrode to establish the carrier frequency for said first oscillator means, and circuit means for extending said drive signals to said variable reactance means.

21. A data transmission system as set forth in claim 17 wherein said wave shaping means includes control means responsive to said sinusoidal output signals to provide a control pulse for each cycle of the sinusoidal output signals, and output means responsive to each control pulse to provide a sawtooth waveform output signal.

22. A data transmission system as set forth in claim 21 wherein the ratio of the rise time to the fall time of each sawtooth output signal is determined by the width of said control pulse and wherein said control means includes means for establishing the pulse width for said control pulse to provide a risetime to falltime ratio in the range of 10 to 20.