Pilot signal transmission system

Claim 2

A transmission system utilizing a pilot signal comprising: a. transmission means for transmitting a multilevel amplitude digital signal with a pilot signal imposed thereon to receiving means; b. said transmission means including means for providing a clocking signal establishing a symbol rate fs, means receiving a binary input information signal and responsive to the clocking signal for producing a multilevel amplitude digital signal output, and means responsive to the symbol rate fs of the clocking signal for producing the pilot signal at a frequency rate fs/N (where N = 2, 3, 4, . . . ) and for coupling the pilot signal to the multilevel amplitude signal in in-phase relationship thereto for developing the multilevel digital signal to be transmitted; and c. said receiving means comprising filter means for extracting the frequency components of the transmitted signal in a range above and below the frequency rate fs/N of the pilot signal, and multilevel decoding means responsive to the pilot signal frequency as derived from the frequency components extracted by said filter means, and to the said transmitted signal as received by said receiving means, for providing a decoded signal.

Claim 3

The transmission system as claimed in claim 1, wherein said receiving means includes means responsive to the said pilot signal derived from said extracted frequency components for erasing the pilot signal component of the received multilevel amplitude signal, at each time of multilevel decoding.

Claim 4

The transmission system as claimed in claim 2, wherein said erasing means provides a signal having a period corresponding to that of the pilot signal and an amplitude constant for a predetermined time interval encompassing each time of multilevel decoding.

Claim 5

The transmission system as claimed in claim 3, wherein said erasing means provides a signal of a rectangular waveform.

Claim 6

The transmission system as claimed in claim 3, wherein said erasing means provides a signal of trapezoidal waveform.

Claim 7

The transmission system as claimed in claim 3, wherein said erasing means produces an erasing signal in response to the said derived pilot signal and applies the said erasing signal to the input of said sample-hold circuit to effect the removal of the pilot signal component of the transmitted multilevel amplitude digital signal.

Claim 8

The transmission system as claimed in claim 3, wherein said erasing means applies said erasing signal to the output of said sample-hold circuit to thereby effect the erasing of the pilot signal component of the transmitted multilevel amplitude digital signal.

Claim 9

The transmission system as claimed in claim 2, wherein the output of said filter means is applied to said erasing means for providing the erasing signal and to clock means for providing in response thereto a clock signal, said multilevel decoder means comprising a sample-hold circuit for receiving the transmitted multilevel amplitude digital signal and responsive to the clock signal for sampling the received signal, a comparator circuit for receiving and comparing the received and sampled multilevel amplitude signal with a reference signal to provide a corresponding binary output signal, and a local decoder circuit responsive to the binary output signal and the clock signal for generating the reference signal applied to said comparator circuit.

Claim 10

The transmission system as claimed in claim 8, wherein said erasing means applies said erasing signal to said local decoder and said local decoder coincides the amplitude of the erasing signal with two preselected amplitude levels of the multilevel signal to form a composite signal thereof, said composite signal being supplied as the erasing signal to said comparator circuit to effect the erasing of the pilot signal component from the transmitted and received, multilevel amplitude digital signal.

Claim 11

A transmission system as recited in claim 1 wherein said transmission means further includes an input half adding circuit including cascade-connected half adders receiving corresponding ones of a succession of binary information bits, a plurality of storage means including storage means for receiving the outputs of corresponding ones of said half adders, and a further such storage means, converter means for receiving the outputs of said storage means for converting the binary values thereof to a multilevel output signal, and said clocking means includes first clocking means producing said pilot signal at the frequency rate of fs/N where N = 2 and means connecting the said pilot signal to said cascaded half adder circuits and to said further storage means, and further clocking means producing a closking signal at the symbol rate of fs and means for supplying the storage binary bit values thereof in parallel to said converter means.

Claim 12

A transmission system for transmitting an information signal upon which a pilot signal is imposed, comprising: a. transmitting means for transmitting the information signal with a pilot signal imposed thereon to receiving means; and b. said transmitting means comprises: first storage means for receiving and storing corresponding successive bits of a binary input signal, second storage means for receiving and storing binary bits corresponding to a digital pilot signal, first and second clock circuits for providing first and second clock signals, the first clock signal being at a desired symbol rate fs of the multilevel digital output signal and said second clock signal being at a rate fs/N where = 2, 3, 4, . . . , said second clock signal being supplied to said first storage means as the binary input signal thereto, converting means for converting the binary input signals of said first and second storage means to a corresponding multilevel amplitude digital output signal at the said symbol rate fs, said first and second clock circuits providing said first and second clock signals to said first and second storage means for supply of the binary bits stored therein to said converting means for coupling the binary information bit signals and binary pilot signal bits in a predetermined phase relationship in accordance with the phase difference between the first and second clock signals to produce a corresponding multilevel digital output signal at the said symbol rate fs.

Claim 13

A transmission system for transmitting an information signal upon which a pilot signal is imposed, comprising: a. transmitting means for transmitting the information signal with a pilot signal imposed thereon to receiving means; and b. said transmitting means comprises: first storage means for receiving and storing corresponding successive bits of a binary input signal, second storage means for receiving and storing binary bits corresponding to a digital pilot signal, first and second clock circuits for providing first and second clock signals, the first clock signal being at a desired symbol rate fs of the multilevel digital output signal and said second clock signal being at a rate fs/N where = 2, 3, 4, . . . , said second clock signal being supplied to said first storage means as the binary input signal thereto, converting means for converting the binary input signals of said first and second storage means to a corresponding multilevel amplitude digital output signal at the said symbol rate fs, said first and second clock circuits providing said first and second clock signals to said first and second storage means for supply of the binary bits stored therein to said converting means for coupling the binary information bit signals and binary pilot signal bits in a predetermined phase relationship in accordance with the phase difference between the first and second clock signals to produce a corresponding multilevel digital output signal at the said symbol rate fs.

Claim 14

A transmission system for transmitting an information signal upon which there is imposed a synchronizing pilot signal, said system comprising: transmitting means for transmitting the information signal to receiving means and including: means for amplitude modulating a carrier signal of a selected frequency with the information signal to be transmitted, to produce a modulated carrier signal, means providing a synchronizing pilot signal at a frequency substantially equal to that of the carrier signal, and means for coupling the synchronizing pilot signal to the modulated carrier signal in an inphase relationship to the composite vector of the information signal modulation components disposed in a range above and below the frequency of the pilot signal, the pilot signal thereby being of a frequency within the bandwidth of the information signal, for transmission to the receiving means; and receiving means for receiving the transmitted signal from said transmitting means and producing a demodulated output signal corresponding to the information signal, said receiving means including: means for dividing the received signal into first and second signals, narrow band filter means for filtering the first signal for extracting the frequency components thereof lying within a narrow range of frequencies extending symmetrically above and below the frequency of the pilot signal thereby to reproduce at said receiving means a pilot signal corresponding in frequency and phase to that of said transmitting means, demodulator means receiving the second signal from said receiving means and responsive to the reproduced pilot signal output of said narrow band filter means for demodulating the said second signal to produce a demodulated output signal, the demodulated output signal having upper and lower sidebands with the lower sideband including an undesired d.c. component, and erasing means for coupling a d.c. signal, of an amplitude and polarity relative to said undesired d.c. component, to the output of said demodulator means thereby to erase the undesired d.c. component therein.

Claim 15

A transmission system for transmitting an information signal upon which there is imposed a synchronizing pilot signal, said system comprising: transmitting means for transmitting the information signal to receiving means and including: means for amplitude modulating a carrier signal of a selected frequency with the information signal to be transmitted, to produce a modulated carrier signal, means providing a synchronizing pilot signal at a frequency substantially equal to that of the carrier signal, and means for coupling the synchronizing pilot signal to the modulated carrier signal in an inphase relationship to the composite vector of the information signal modulation components disposed in a range above and below the frequency of the pilot signal, the pilot signal thereby being of a frequency within the bandwidth of the information signal, for transmission to the receiving means; and receiving means for receiving the transmitted signal from said transmitting means and producing a demodulated output signal corresponding to the information signal, said receiving means including: means for dividing the received signal into first and second signals, narrow band filter means for filtering the first signal for extracting the frequency components thereof lying within a narrow range of frequencies extending symmetrically above and below the frequency of the pilot signal thereby to reproduce at said receiving means a pilot signal corresponding in frequency and phase to that of said transmitting means, demodulator means receiving the second signal from said receiving means and responsive to the reproduced pilot signal output of said narrow band filter means for demodulating the said second signal to produce a demodulated output signal, the demodulated output signal having upper and lower sidebands with the lower sideband including an undesired d.c. component, and erasing means for coupling a d.c. signal, of an amplitude and polarity relative to said undesired d.c. component, to the output of said demodulator means thereby to erase the undesired d.c. component therein.

Claim 16

A transmission system as claimed in claim 12, wherein the information signal is a multilevel digital signal.

Claim 17

The transmission system as claimed in claim 12, wherein said transmitting means includes band filter means for filtering the output signal derived from said coupling means to provide a vestigial side band signal for transmission.

Claim 18

A receiver for use in a transmitting system which transmits an information signal by modulating a carrier signal of a selected frequency with the information signal and furthermore transmits the pilot signal of a frequency equal to the carrier signal within the bandwidth of the information signal modulated on the carrier to produce a demodulated output signal corresponding to the information signal transmitted, comprising: means for dividing the received signal into first and second signals, narrow band filter means for filtering the first signal for extracting the frequency components thereof lying within a narrow range of frequencies extending symmetrically above and below the frequency of the pilot signal thereby to reproduce at said receiving means a pilot signal corresponding in frequency and phase to that of said transmitting means, demodulator means receiving the second signal from said receiving means and responsive to the reproduced pilot signal output of said narrow band filter means for demodulating the said second signal to produce a demodulated output signal, the demodulated output signal having upper and lower sidebands, the lower sideband including an undesired DC component, and said receiving means includes erasing means for coupling a DC signal of an amplitude level and opposite polarity relative to the said undesired DC component signal to the output of said demodulator means thereby to erase the undesired DC component therein.

Claim 19

A receiver for use in a transmitting system which transmits an information signal by modulating a carrier signal of a selected frequency with the information signal and furthermore transmits the pilot signal of a frequency equal to the carrier signal within the bandwidth of the information signal modulated on the carrier to produce a demodulated output signal corresponding to the information signal transmitted, comprising: means for dividing the received signal into first and second signals, narrow band filter means for filtering the first signal for extracting the frequency components thereof lying within a narrow range of frequencies extending symmetrically above and below the frequency of the pilot signal thereby to reproduce at said receiving means a pilot signal corresponding in frequency and phase to that of said transmitting means, demodulator means receiving the second signal from said receiving means and responsive to the reproduced pilot signal output of said narrow band filter means for demodulating the said second signal to produce a demodulated output signal, the demodulated output signal having upper and lower sidebands, the lower sideband including an undesired DC component, and said receiving means includes erasing means for coupling a DC signal of an amplitude level and opposite polarity relative to the said undesired DC component signal to the output of said demodulator means thereby to erase the undesired DC component therein.