High frequency multichannel diversity differential phase shift (DPSK) communications system
First Claim
1. A high frequency multichannel communications system having at least a transmitter and a receiver:
- said transmitter comprising;
a) input means for receiving digital signal data for transmission of transmitted data bits;
b) the input means, connected to a plurality of separate diversity frequency channels distributed over a broad spectral region of a high frequency band, each channel including a differential phase shift key (DPSK) modulator, for modulating a channel frequency by successive bits of the digital signal data at a low data rate to produce a DPSK channel signal; and
c) means for combining the DPSK channel signals from each of the plurality of separate diversity frequency channels for transmission; and
wherein said receiver comprising;
a) receiver means for receiving and demodulating the transmitted signals to form baseband signals;
b) said baseband signals from the receiver means being connected to a plurality of narrowband receiver frequency channels, each receiver frequency channel including a DPSK detector responsive to a respective one of the transmitted DPSK channel frequency signals;
c) means for identifying any of said receiver frequency channels corrupted by noise; and
d) semi-coherent processing means, responsive to each transmitted data bit, for vectorially adding DPSK detector output signals, excluding said channels corrupted by noise and for producing a resultant vector signal phase for determining polarity of each transmitted data bit as a data output signal.
1 Assignment
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Accused Products
Abstract
A high frequency transmitter comprises a large number of narrowband channels spaced over a broad bandwidth transmission. In one arrangement input data to be transmitted is demultiplexed (1101) so that sections of data are transmitted in groups of channels at 50 baud (say), each 50 baud channel produces a number of diversity channels modulated using difference phase shift key (DPSK) (103) and then added (105) for transmission. In the receiver, coherent summation (803) of close-bunched channels can be used and semi-coherent channel addition (805) can be used across the complete bandwidth. The received signal is convened to digital form then processed by an FFT circuit to produce frequency bins corresponding to the transmitted diversity channel frequencies. DPSK demodulation is carried out and running averages are carried out in each channel to determine the proportion of times that the phase difference falls within allowed limits (907). A discrimination level (908) determines whether individual channels should be excised (914) because of noise corruption. The remaining channels in groups are then added together to determine each data bit received, in semi-coherent addition (905), the measured phase vectors are added vectorially and the vector sum is used to determine the data bit. In a second arrangement the channels of any one group are arranged in bunches of about 10 spread over a bandwidth of about 2 kHz (the experimentally determined coherence bandwidth) with the bunches spread over the whole transmission bandwidth. The bunch channels are added coherently and the resultants are added semi-coherently as before to determine the group data. The group data is then multiplexed to reproduce the high data rate input data. The arrangement allows high data rates to be transmitted with each of the diversity channels carrying only 50 baud.
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Citations
24 Claims
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1. A high frequency multichannel communications system having at least a transmitter and a receiver:
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said transmitter comprising; a) input means for receiving digital signal data for transmission of transmitted data bits; b) the input means, connected to a plurality of separate diversity frequency channels distributed over a broad spectral region of a high frequency band, each channel including a differential phase shift key (DPSK) modulator, for modulating a channel frequency by successive bits of the digital signal data at a low data rate to produce a DPSK channel signal; and c) means for combining the DPSK channel signals from each of the plurality of separate diversity frequency channels for transmission; and wherein said receiver comprising; a) receiver means for receiving and demodulating the transmitted signals to form baseband signals; b) said baseband signals from the receiver means being connected to a plurality of narrowband receiver frequency channels, each receiver frequency channel including a DPSK detector responsive to a respective one of the transmitted DPSK channel frequency signals; c) means for identifying any of said receiver frequency channels corrupted by noise; and d) semi-coherent processing means, responsive to each transmitted data bit, for vectorially adding DPSK detector output signals, excluding said channels corrupted by noise and for producing a resultant vector signal phase for determining polarity of each transmitted data bit as a data output signal. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A high frequency multichannel communications system having at least a transmitter and a receiver:
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said transmitter comprising; a) input means for receiving digital signal data for transmission of transmitted data bits; b) the input means, connected to a plurality of separate diversity frequency channels distributed over a broad spectral region of a high frequency band, each channel including a differential phase shift key (DPSK) modulator, for modulating a channel frequency by successive bits of the digital signal data at a low data rate to produce a DPSK channel signal; and c) means for combining the DPSK channel signals from each of the plurality of separate diversity frequency channels for transmission; and wherein said receiver comprising; a) receiver means for receiving and demodulating the transmitted signals to form baseband signals; b) said baseband signals from the receiver means being connected to a plurality of narrowband receiver frequency channels, each receiver frequency channel including a DPSK detector responsive to a respective one of the transmitted DPSK channel frequency signals; c) means for identifying any of said receiver frequency channels corrupted by noise; and d) semi-coherent processing means, responsive to each transmitted data bit, for vectorially adding DPSK detector output signals, excluding said channels corrupted by noise and for producing a combined vector signal phase for determining polarity of each transmitted data bit as a data output signal, wherein there is included a channel exciser for excising channels identified as noise corrupted channels.
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8. A high frequency multichannel communications system having at least a transmitter and a receiver:
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said transmitter comprising; a) input means for receiving digital signal data for transmission of transmitted data bits; b) the input means, connected to a plurality of separate diversity frequency channels distributed over a broad spectral region of a high frequency band, each channel including a differential phase shift key (DPSK) modulator, for modulating a channel frequency by successive bits of the digital signal data at a low data rate to produce a DPSK channel signal; and c) means for combining the DPSK channel signals from each of the plurality of separate diversity frequency channels for transmission; and wherein said receiver comprising; a) receiver means for receiving and demodulating the transmitted signals to form baseband signals; b) said baseband signals from the receiver means being connected to a plurality of narrowband receiver frequency channels, each receiver frequency channel including a DPSK detector responsive to a respective one of the transmitted DPSK channel frequency signals; c) means for identifying any of said receiver frequency channels corrupted by noise; and d) semi-coherent processing means, responsive to each transmitted data bit, for vectorially adding DPSK detector output signals, excluding said channels corrupted by noise and for producing a combined vector signal phase for determining polarity of each transmitted data bit as a data output signal wherein said DPSK modulator is an M phase DPSK modulator which produces an M phase DPSK channel signal where M is an integer and the means for identifying noise-corrupted channels includes a phase window detector having M phase windows of width <
360/M deg centered on M phase states. - View Dependent Claims (9, 10, 11, 12)
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13. A high frequency multichannel communications system having at least a transmitter and a receipt;
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said transmitter comprising; a) input means for receiving digital signal data for transmission Of transmitted data bits; b) the input means, connected to a plurality of Separate diversity frequency channels distributed over a broad spectral region of a high frequency band, each channel including a differential phase shift key (DPSK) modulator, for modulating a channel frequency by successive bits Of the digital signal data at a low data rate to produce a DPSK channel signal; and c) means for combining the DPSK channel signals from each of the plurality of separate diversity frequency channels for transmission; and wherein said receiver comprising; a) receiver means for receiving and demodulating the transmitted signals to form baseband signals; b) said baseband signals from the receiver means being connected to a plurality of narrowband receiver frequency channels, each receiver frequency channel including a DPSK detector responsive to a respective one of the transmitted DPSK channel frequency signals; c) means for identifying any of said receiver frequency channels corrupted by noise; and d) semi-coherent processing means, responsive to each transmitted data bit, for vectorially adding DPSK detector output signals, excluding said channels corrupted by noise and for producing a combined vector signal phase for determining polarity of each transmitted data bit as a data output signal wherein the plurality of narrowband channels in the receiver are arranged into contiguous broader bandwidth groups where the channels of each group are connected to a respective coherent adder for coherently adding uncorrupted channel signals and the adder outputs are connected to the semi-coherent processing means for vectorially adding the adder outputs. - View Dependent Claims (14, 15, 16)
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17. A high frequency multichannel communications system having at least a transmitter and a receiver:
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said transmitter comprising; a) input means for receiving digital signal data for transmission of transmitted data bits; b) the input means, connected to a plurality of separate diversity frequency channels distributed over a broad spectral region of a high frequency band, each channel including a differential phase shift key (DPSK) modulator, for modulating a channel frequency by successive bits of the digital signal data at a low data rate to produce a DPSK channel signal; and c) means for combining the DPSK channel signals from each of the plurality of separate diversity frequency channels for transmission; and wherein said receiver comprising; a) receiver means for receiving and demodulating the transmitted signals to form baseband signals; b) said baseband signals from the receiver means being connected to a plurality of narrowband receiver frequency channels, each receiver frequency channel including a DPSK detector responsive to a respective one of the transmitted DPSK channel frequency signals; c) means for identifying and of said receiver frequency channels corrupted by noise; and d) semi-coherent processing means, responsive to each transmitted data bit, for vectorially adding DPSK detector output signals, excluding said channels corrupted by noise and for producing a combined vector signal phase for determining polarity of each transmitted data bit as a data output signal wherein said vectorially added DPSK detector output signals are connected to each means for identifying channels corrupted by noise. - View Dependent Claims (18, 19)
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20. A high frequency multichannel communications system having at least a transmitter and a receiver:
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said transmitter comprising; a) input means for receiving digital signal data for transmission of transmitted data bits; b) the input means, connected to a plurality Of separate diversity frequency channels distributed over a broad spectral region of a high frequency band, each channel including a differential phase shift key (DPSK) modulator, for modulating a channel frequency by successive bits of the digital signal data at a low data rate to produce a DPSK channel signal; and c) means for combining the DPSK channel signals from each of the plurality of separate diversity frequency channels for transmission; and wherein said receiver comprising.; a) receiver means for receiving and demodulating the transmitted signals to form baseband signals; b) said baseband signals from the receiver means being connected to a plurality of narrowband receiver frequency channels, each receiver frequency channel including a DPSK detector responsive to a respective one of the transmitted DPSK channel frequency signals; c) means for identifying any of said receiver frequency channels corrupted by noise; and d) semi-coherent processing means, responsive to each transmitted dam bit, for vectorially adding DPSK detector output signals, excluding said channels corrupted by noise and for producing a combined vector signal phase for determining polarity of each transmitted data bit as a data output signal wherein the transmitter includes a demultiplexer [(1101)]responsive to the digital signal data for providing at respective outputs demultiplexed portions of said signal data, said plurality of separate frequency channels are divided into groups of different frequency channels, each group connected to a respective demultiplexed portion of said signal data and each channel transmitting at a low data rate between 20-100 bps and the receiver includes a multiplexer to reproduce the transmitted data signal. - View Dependent Claims (21)
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22. A high frequency multichannel communications system having at least a transmitter and a receiver:
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said transmitter comprising; a) input means for receiving digital signal data for transmission of transmitted data bits; b) the input means, connected to a plurality of separate diversity frequency channels distributed over a broad spectral region of a high frequency band, each channel including a differential phase shift key (DPSK) modulator for modulating a channel frequency by successive bits of the digital signal data at a low data rate to produce a DPSK channel signal; and c) means for combining the DPSK channel signals from each of the plurality of separate diversity frequency channels for transmission; and wherein said receiver comprising; a) receiver means for receiving and demodulating the transmitted signals to form baseband signals; b) said baseband signals from the receiver means being connected to a plurality of narrowband receiver frequency channels, each receiver frequency channel including a DPSK detector responsive to a respective one of the transmitted DPSK channel frequency signals; c) means for identifying any of said receiver frequency channels corrupted by noise; and d) semi-coherent processing means, responsive to each transmitted data bit, for vectorially adding DPSK detector output signals, excluding said channels corrupted by noise and for producing a combined vector signal phase for determining polarity of each transmitted data bit as a data output signal wherein the receiver means is connected to the receiver frequency channels via an analogue to digital converter connected to a Fast Fourier Transform (FFT) processor which has a number of frequency channels equal to the number of receiver frequency channels and the signal phase is detected in each receiver frequency channel.
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23. A high frequency multichannel communications system having at least a transmitter and a receiver;
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said transmitter comprising; a) input means for receiving digital signal data for transmission of transmitted data bits; b) the input means, connected to a plurality of Separate diversity frequency channels distributed over a broad spectral region of a high frequency band, each channel including a differential phase shift key (DPSK) modulator, for modulating a channel frequency by successive bits of the digital signal data at a low data rate to produce a DPSK channel signal; and c) means for combining the DPSK channel signals from each of the plurality of separate diversity frequency channels for transmission; and wherein said receiver comprising; a) receiver means for receiving and demodulating the transmitted signals to form baseband signals; b) said baseband signals from the receiver means being connected to a plurality of narrowband receiver frequency channels, each receiver frequency channel including a DPSK detector responsive to a respective one of the transmitted DPSK channel frequency signals; c) means for identifying any of said receiver frequency channels corrupted by noise; and d) semi-coherent processing means, responsive to each transmitted data bit, for vectorially adding DPSK detector output signals, excluding said channels corrupted by noise and for producing a combined vector signal phase for determining polarity of each transmitted data bit as a data output signal wherein the transmitter includes a pseudorandom number generator (PNG) connected to the means for combining the DPSK channel signals for modulating the combined channel signals with a pseudorandom code and said receiver includes a demodulator connected to the same coherent processing means for demodulating the transmitted data signal. - View Dependent Claims (24)
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Specification