System and method for reduced deviation time domain FM/PM discriminator to achieve a reduced bandwidth frequency or phase modulation communications channels
First Claim
Patent Images
1. A receiver for receiving a narrow frequency deviation frequency modulated or phase modulated base band signal comprising:
- a mixer for mixing the received narrow frequency deviation signal to generate an intermediate frequency signal;
a band pass filter for filtering the intermediate frequency signal;
a narrow band discriminator circuit that performs a time domain expansion of the modulation deviation of the intermediate frequency signal and discriminates the base band signal comprising;
an analog to logic level converter for receiving a reduced deviation modulated signal;
a pulse generator that generates pulses with a fixed duration of one half the center frequency period of the intermediate frequency signal;
an exclusive-OR gate that receives an output of the logic level converter and the pulse generator;
an AND gate that receives an output of the exclusive-OR gate and a clock signal on each of its inputs;
a counter comprising an up/down input for indicating whether the counter counts up or down and is attached to the analog to logic level converter output, a clock input attached to the AND gate output, and a clear input attached to a control circuit, the counter further comprising N parallel outputs;
a latch comprising N parallel inputs and connected to the N parallel outputs of the counter and further comprising a clock input attached to an output of the control circuit and N parallel outputs; and
wherein the control circuit clocks the data from the counter to the latch on the positive transition of the intermediate frequency signal, and sequentially clears the counter.
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Abstract
The present disclosure provides a receiver for receiving a narrow frequency deviation frequency modulated or phase modulated base band signal including a mixer for mixing the received narrow frequency deviation signal to generate an intermediate frequency signal, a band pass filter for filtering the intermediate frequency signal, and a narrow band discriminator circuit that performs a time domain expansion of the modulation deviation of the intermediate frequency signal and discriminates the base band signal.
20 Citations
21 Claims
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1. A receiver for receiving a narrow frequency deviation frequency modulated or phase modulated base band signal comprising:
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a mixer for mixing the received narrow frequency deviation signal to generate an intermediate frequency signal; a band pass filter for filtering the intermediate frequency signal; a narrow band discriminator circuit that performs a time domain expansion of the modulation deviation of the intermediate frequency signal and discriminates the base band signal comprising; an analog to logic level converter for receiving a reduced deviation modulated signal; a pulse generator that generates pulses with a fixed duration of one half the center frequency period of the intermediate frequency signal; an exclusive-OR gate that receives an output of the logic level converter and the pulse generator; an AND gate that receives an output of the exclusive-OR gate and a clock signal on each of its inputs; a counter comprising an up/down input for indicating whether the counter counts up or down and is attached to the analog to logic level converter output, a clock input attached to the AND gate output, and a clear input attached to a control circuit, the counter further comprising N parallel outputs; a latch comprising N parallel inputs and connected to the N parallel outputs of the counter and further comprising a clock input attached to an output of the control circuit and N parallel outputs; and wherein the control circuit clocks the data from the counter to the latch on the positive transition of the intermediate frequency signal, and sequentially clears the counter. - View Dependent Claims (2, 3, 4)
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5. A receiver for receiving a narrow frequency deviation frequency modulated or phase modulated base band signal comprising:
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a mixer for mixing the received narrow frequency deviation signal to generate an intermediate frequency signal; a band pass filter for filtering the intermediate frequency signal; a narrow band discriminator circuit that performs a time domain expansion of the modulation deviation of the intermediate frequency signal and discriminates the base band signal comprising; an analog to logic level converter for receiving a reduced deviation modulated signal; a pulse generator that generates pulses with a fixed duration of one half the center frequency period of the intermediate frequency signal; an exclusive-OR gate that receives an output of the logic level converter and the pulse generator; a pulse stretcher that receives an output of the exclusive-OR gate; an AND gate that receives an output of the pulse stretcher and a clock signal on each of its inputs; a flip-flop that receives the output of the pulse generator on an input and the output of the exclusive-OR gate on its clock input; a counter comprising an up/down input for indicating whether the counter counts up or down and is attached to an output of the flip-flop, a clock input attached to the AND gate output, and a clear input attached to a control circuit, the counter further comprising N parallel outputs; a latch comprising N parallel input and connected to the N parallel outputs of the counter and further comprising a clock input attached to an output of the control circuit and N parallel outputs; and wherein the control circuit clocks the data from the counter to the latch on the positive transition of the intermediate frequency signal, and sequentially clears the counter. - View Dependent Claims (6, 7, 8, 9)
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10. A receiver for receiving a narrow frequency deviation frequency modulated or phase modulated base band signal comprising:
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a mixer for mixing the received narrow frequency deviation signal to generate an intermediate frequency signal; a band pass filter for filtering the intermediate freciuency signal; a narrow band discriminator circuit that performs a time domain expansion of the modulation deviation of the intermediate frequency signal and discriminates the base band signal comprising; an analog to logic level converter for receiving a reduced deviation modulated signal; a pulse generator that generates pulses with a fixed duration of one half the center frequency period of the intermediate frequency signal; an exclusive-OR gate that receives an output of the logic level converter and the pulse generator; a pulse stretcher that receives an output of the exclusive-OR gate; an AND gate that receives an output of the pulse stretcher and a clock signal on each of its inputs; a flip-flop that receives the output of the pulse generator on an input and the output of the exclusive-OR gate on its clock input; a counter comprising a clock input attached to the AND gate output and a clear input attached to a control circuit, the counter further comprising N parallel outputs; an accumulator and an accumulator latch interposed between the counter and the latch for receiving the N parallel outputs of the counter, adding or subtracting the N parallel outputs of the counter based upon the output of the flip-flop received on the accumulator'"'"'s plus/minus input to generate N parallel outputs to the accumulator latch; a latch comprising N parallel inputs and connected to the N parallel outputs of the accumulator latch and further comprising a clock input attached to an output of the control circuit and N parallel outputs; and wherein the control circuit clocks the data from the counter to the latch on the positive transition of the intermediate frequency signal, and sequentially clears the counter. - View Dependent Claims (11, 12, 13)
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14. A receiver for receiving a narrow frequency deviation frequency modulated or chase modulated base band signal comprising:
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a mixer for mixing the received narrow frequency deviation signal to generate an intermediate frequency signal; a band pass filter for filtering the intermediate frequency signal; a narrow band discriminator circuit that performs a time domain expansion of the modulation deviation of the intermediate frequency signal and discriminates the base band signal comprising; an analog to logic level converter for receiving a reduced deviation modulated signal; a pulse generator that generates pulses with a fixed duration of one half the center frequency period of the intermediate frequency signal minus the time delay of the maximum frequency deviation; an exclusive-OR gate that receives an output of the logic level converter and the pulse generator; an AND gate that receives an output of the exclusive-OR gate and a clock signal on each of its inputs; a counter comprising a clock input attached to the AND gate output and a clear input attached to a control circuit, the counter further comprising N parallel outputs; a latch comprising N parallel input and connected to the N parallel outputs of the counter and further comprising a clock input attached to an output of the control circuit and N parallel outputs; and wherein the control circuit clocks the data from the counter to the latch on the positive transition of the intermediate frequency signal. - View Dependent Claims (15, 16, 17)
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18. A receiver for receiving a narrow frequency deviation frequency modulated or phase modulated base band signal comprising:
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a mixer for mixing the received narrow frequency deviation signal to generate an intermediate frequency signal; a band pass filter for filtering the intermediate frequency signal a narrow band discriminator circuit that performs a time domain expansion of the modulation deviation of the intermediate frequency signal and discriminates the base band signal comprising; an analog to logic level converter for receiving a reduced deviation modulated signal; a pulse generator that generates pulses with a fixed duration of one half the center frequency period of the intermediate frequency signal; an exclusive-OR gate that receives an output of the logic level converter and the pulse generator; a flip-flop having an input connected to the pulse generator, a clock input connected to the output of the exclusive-OR gate, an output and a NOT output; a first switch for receiving the output of the exclusive-OR gate and the output of the flip-flop and passing the flip-flop output when the output of the exclusive-OR gate is positive; a second switch for receiving the output of the exclusive-OR gate and the NOT output of the flip-flop and passing the flip-flop output when the output of the exclusive-OR gate is negative; an integrator having a positive input connected to the first switch and a negative input connected to the second switch; and a low pass filter connected to the output of the integrator. - View Dependent Claims (19)
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20. A receiver for receiving a narrow frequency deviation frequency modulated or phase modulated base band signal comprising:
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a mixer for mixing the received narrow frequency deviation signal to generate an intermediate frequency signal; a band pass filter for filtering the intermediate frequency signal; a narrow band discriminator circuit that performs a time domain expansion of the modulation deviation of the intermediate frequency signal and discriminates the base band signal comprising; an analog to logic level converter for receiving a reduced deviation modulated signal; a pulse generator that generates pulses with a fixed duration of one half the center frequency period of the intermediate frequency signal minus the time delay of the maximum frequency deviation; an exclusive-OR gate having an input attached to the output of the analog to logic level converter and an input attached to the output of the pulse generator; and a low pass filter attached to the output of the exclusive-OR gate. - View Dependent Claims (21)
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Specification