Full duplex FSK system
First Claim
1. A wideband single sideband FSK transmitter comprising:
- a. a clock for providing a desired R.F. carrier frequency, fc and a peak deviation frequency, Δ
fb. means for generating baseband FSK data representing a mark or a space state, andc. a single sideband modulator coupled to the clock and the FSK data generating means for producing quadrature components of the carrier frequency, fc, and the deviation frequency, Δ
f, and generating a single sideband output R.F. carrier signal, fc, having a peak deviation frequency of Δ
f and directly modulated with the baseband FSK data.
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Accused Products
Abstract
A frequency agile homodyne full duplex FSK system having a receiver section using an image-cancellation mixer wherein sum and difference signals generated by a pair of double-balanced mixers are added together with proper phase to cancel out the image response normally associated with heterodyne receivers and directly down-convert the carrier frequency to the baseband frequency. The transmitter section of the FSK system consists of an FSK modulator whose peak deviation is controlled by an active derivative of a crystal clock. The FSK modulator functions in the manner of a phasing single sideband (SSB) mixer with upper or lower sideband signals generated by the proper phasing of quadrature components of the carrier frequency and the peak deviation signal derived from a crystal clock.
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Citations
29 Claims
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1. A wideband single sideband FSK transmitter comprising:
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a. a clock for providing a desired R.F. carrier frequency, fc and a peak deviation frequency, Δ
fb. means for generating baseband FSK data representing a mark or a space state, and c. a single sideband modulator coupled to the clock and the FSK data generating means for producing quadrature components of the carrier frequency, fc, and the deviation frequency, Δ
f, and generating a single sideband output R.F. carrier signal, fc, having a peak deviation frequency of Δ
f and directly modulated with the baseband FSK data. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A wideband single sideband FSK receiver comprising:
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a. an input R.F. amplifier for receiving and amplifying a single sideband carrier signal, fc, FSK-modulated with baseband mark and space data and generating an output, b. a local oscillator for generating a signal output at a frequency substantially equal to the frequency of the carrier signal, fc, c. a demodulator for receiving the output of the R.F. amplifier and the output of the local oscillator, and recovering the FSK data representing the baseband mark and space data directly at baseband frequency, said demodulator comprising; a phase splitter for receiving said FSK-modulated carrier, fc, and generating quadrature component signals, a first balanced mixer receiving a respective one of the quadrature component signals and the local oscillator output generating a first demodulated output signal at baseband frequency, a second balanced mixer receiving a respective one of the quadrature component signals and the local oscillator output generating a second demodulated output signal at baseband frequency, and a second phase splitter having separate output channels and input channels coupled to the balanced mixers for receiving the first and second demodulated output signals and adding the first and second signals phase adjusted to minimize any adverse image response and generate baseband mark and space data signals at baseband frequency on separate output channels, and d. means coupled to the demodulator for recovering signals representing the baseband mark and space data. - View Dependent Claims (10, 11)
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12. A full duplex FSK transmitting and receiving system comprising:
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a. a clock circuit including a single frequency synthesizer for generating an R.F. carrier signal having a center frequency, fc, for both the transmitter and the receiver, b. a transmitter having a modulator for frequency-shift-keying the R.F. carrier with mark and space data directly at baseband frequency, said modulator comprising; means for generating FSK data representing a mark or a space state, and a single sideband modulator coupled to said clock circuit and the FSK data generating means for generating a single sideband output R.F. carrier signal, fc, having a peak deviation frequency of Δ
F and modulated with the baseband frequency FSK data, andc. a receiver for translating an input FSK-modulated carrier directly to baseband frequency for recovering the mark and space data. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A method of generating a single sideband FSK-modulated output R.F. carrier signal comprising the steps of:
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a. generating a desired R.F. carrier frequency, fc, and a baseband peak deviation frequency, Δ
fb. generating baseband FSK data representing a mark or a space state, and c. directly modulating quadrature components of the R.F. carrier frequency, fc, with quadrature components of the baseband deviation frequency, Δ
f, and generating the single sideband output R.F. carrier, fc, having a peak deviation frequency of Δ
f. - View Dependent Claims (24)
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25. A method of recovering FSK data from a single sideband R.F. carrier signal, fc, FSK modulated with baseband mark and space data comprising the steps of:
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a. amplifying the single sideband R.F. carrier signal, fc, FSK-modulated with the baseband mark and space data, b. generating a local oscillator frequency of fc, c. generating quadrature component signals from the amplified FSK-modulated single sideband R.F. carrier signal, fc, d. double-balanced mixing each of the quadrature components and the local oscillator frequency, fc, e. generating a demodulated signal at baseband frequency in response to the double-balanced mixing of the quadrature components, the demodulated signal having a sum and a difference signal, f. adding the sum and difference signals phase adjusted to minimize image response and generate the baseband mark and space data signals at baseband frequency on separate channels, and g. recovering the FSK data represented by the generated baseband mark and space data signals in each channel.
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26. A method of providing a full duplex FSK transmitting and receiving system comprising the steps of:
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a. generating a R.F. carrier signal having a center frequency, fc, for both a transmitter and a receiver by a common center frequency synthesizer, b. frequency-shift-keying the R.F. carrier signal, said frequency-shift-keying comprising the steps of; generating a baseband frequency FSK data signal representing a mark or space state, and modulating the R.F. carrier signal with the baseband frequency FSK data to generate a single sideband output R.F. carrier signal, fc, having a peak deviation frequency of Δ
f, andc. translating an input FSK-modulated carrier directly to baseband frequency in a receiver for recovering the mark and space data.
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27. A wideband single sideband FSK transmitter comprising:
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a clock means for providing a desired R.F. carrier frequency signal, fc, and a peak deviation frequency signal, Δ
f;means for generating a baseband FSK data signal representing a baseband mark of a space state; means for generating quadrature components of the R.F. carrier frequency signal fc ; means for generating quadrature components of the deviation frequency signal Δ
f from the FSK baseband signal wherein the quadrature components comprise a deviation frequency Δ
f reference signal and a 90°
shifted deviation frequency Δ
f signal such that there is a +90°
phase shift for a first baseband mark or space state and a -90°
phase shift for a second baseband mark or space state in the shifted deviation frequency Δ
f signal;a single sideband modulator for receiving the quadrature R.F. carrier frequency signals, fc and the shifted and reference deviation frequency Δ
f signals and generating direct FSK modulated R.F. single sideband output. - View Dependent Claims (28)
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29. A method of generating a single sideband FSK-modulated output R.F. carrier signal comprising the steps of:
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generating an R.F. carrier signal at a frequency fc ; generating a peak deviation signal deviating by a frequency Δ
f from the R.F. carrier signal;generating baseband FSK data representing a mark or a space state; shifting the deviation frequency Δ
f signal ±
90°
according to the mark or space state of the FSK baseband data to generate quadrature deviation frequency Δ
f signal components;shifting the R.F. carrier frequency fc signal to generate quadrature carrier frequency fc components; mixing a fist quadrature deviation frequency Δ
f signal component with a first quadrature carrier frequency fc component to generate a first FSK-modulated signal;mixing a second quadrature deviation frequency Δ
f signal component with a second quadrature carrier frequency fc component to generate a second FSK-modulated signal; andadding the first and second FSK-modulated output signals to output a direct FSK modulated R.F. carrier signal.
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Specification