US5588022A — Method and apparatus for AM compatible digital br…

Claim 1

Independent Claim 149 words

A radio frequency broadcasting method, said method comprising the steps of: amplitude modulating a first carrier signal by an analog signal to generate a first radio frequency signal having a first frequency spectrum, generating a plurality of digitally modulated carrier signals for broadcast, said signals being within a frequency range which encompasses the frequency spectrum of the first radio frequency signal, each of said digitally modulated carrier signals being digitally modulated by a portion of a digital signal, wherein a first group of said digitally modulated carrier signals overlap said first frequency spectrum and are modulated in-quadrature with said first carrier signal, and wherein second and third groups of said digitally modulated carrier signals lie outside of said first frequency spectrum and are modulated both in-phase and in-quadrature with said first carrier signal; and simultaneously broadcasting said first radio frequency signal and said plurality of digitally modulated carrier signals.

Claim 2

Dependent Claim 149 words

A radio frequency broadcasting method, said method comprising the steps of: amplitude modulating a first carrier signal by an analog signal to generate a first radio frequency signal having a first frequency spectrum, generating a plurality of digitally modulated carrier signals for broadcast, said signals being within a frequency range which encompasses the frequency spectrum of the first radio frequency signal, each of said digitally modulated carrier signals being digitally modulated by a portion of a digital signal, wherein a first group of said digitally modulated carrier signals overlap said first frequency spectrum and are modulated in-quadrature with said first carrier signal, and wherein second and third groups of said digitally modulated carrier signals lie outside of said first frequency spectrum and are modulated both in-phase and in-quadrature with said first carrier signal; and simultaneously broadcasting said first radio frequency signal and said plurality of digitally modulated carrier signals.

Claim 3

Dependent Claim 27 words

A radio frequency broadcasting method according to claim 1, wherein: said digitally modulated carrier signals are separated in frequency by a sub-multiple of an allocated channel spacing.

Claim 4

Dependent Claim 26 words

A radio frequency broadcasting method according to claim 1, wherein: no energy is transmitted at digitally modulated carrier signal positions located at centers of adjacent channels.

Claim 5

Dependent Claim 37 words

A radio frequency broadcasting method according to claim 1, wherein: the digitally modulated carrier signals in said first group of said digitally modulated carrier signals have amplitudes which are less than the unmodulated first carrier signal amplitude.

Claim 6

Dependent Claim 41 words

A radio frequency broadcasting method according to claim 4, wherein: the digitally modulated carrier signals in said second and third groups of said digitally modulated carrier signals have amplitudes which are less than the amplitude of the unmodulated first carrier signal.

Claim 7

Dependent Claim 36 words

A radio frequency broadcasting method according to claim 1, wherein: selected ones of said digitally modulated carrier signals lying closest in frequency to the frequency of said first carrier are modulated in a complementary BPSK format.

Claim 8

Dependent Claim 32 words

A radio frequency broadcasting method according to claim 6, wherein: said selected ones of said digitally modulated carrier signals serve as a reference level for other ones of said digital carrier signals.

Claim 9

Dependent Claim 25 words

A radio frequency broadcasting method according to claim 1, wherein said analog signal and said digital signal are different representations of the same program material.

Claim 10

Dependent Claim 27 words

A radio frequency broadcasting method according to claim 1, wherein said second and third groups of said digitally modulated carrier signals are modulated in a 32-QAM constellation.

Claim 11

Dependent Claim 27 words

A radio frequency broadcasting method according to claim 1, wherein said digitally modulated carrier signals lie within a second frequency spectrum occupying a bandwidth of 40 kHz.

Claim 12

Dependent Claim 20 words

A radio frequency broadcasting method according to claim 1, wherein said digitally modulated carrier signals are equally spaced in frequency.

Claim 13

Dependent Claim 27 words

A radio frequency broadcasting method according to claim 11, wherein said digitally modulated carrier signals are spaced in frequency by a sub-multiple of an allocated channel spacing.

Claim 14

Independent Claim 73 words

A method of modulating electrical signals, said method comprising the steps of: providing an amplitude modulated signal in a first frequency band; providing a first plurality of orthogonal quadrature amplitude modulated carriers in said first frequency band; and providing second and third groups of quadrature amplitude modulated carriers in second and third frequency bands, said second and third frequency bands encompassing frequencies above and below frequencies encompassed by said first frequency band, respectively.

Claim 15

Independent Claim 73 words

A method of modulating electrical signals, said method comprising the steps of: providing an amplitude modulated signal in a first frequency band; providing a first plurality of orthogonal quadrature amplitude modulated carriers in said first frequency band; and providing second and third groups of quadrature amplitude modulated carriers in second and third frequency bands, said second and third frequency bands encompassing frequencies above and below frequencies encompassed by said first frequency band, respectively.

Claim 16

Dependent Claim 30 words

A method of modulating electrical signals according to claim 13, wherein: said orthogonal quadrature modulated carriers have amplitudes which are less than the unmodulated amplitude of said amplitude modulated signal.

Claim 17

Dependent Claim 36 words

A method of modulating electrical signals according to claim 13, wherein: said second and third groups of said quadrature amplitude modulated carriers have amplitudes which are less than the unmodulated amplitude of said amplitude modulated signal.

Claim 18

Dependent Claim 142 words

A signal transmission method, said method comprising the steps of: amplitude modulating a first carrier signal by an analog signal to generate a first signal having a first frequency spectrum; generating a plurality of digitally modulated carrier signals for transmission, said signals being within a frequency range which encompasses the frequency spectrum of the first signal, each of said digitally modulated carrier signals being digitally modulated by a portion of a digital signal, wherein a first group of said digitally modulated carrier signals overlap said first frequency spectrum and are modulated in-quadrature with said first carrier signal, and wherein second and third groups of said digitally modulated carrier signals lie outside of said first frequency spectrum and are modulated both in-phase and in-quadrature with said first carrier signal; and simultaneously transmitting said first signal and said plurality of digitally modulated carrier signals.

Claim 19

Dependent Claim 142 words

A signal transmission method, said method comprising the steps of: amplitude modulating a first carrier signal by an analog signal to generate a first signal having a first frequency spectrum; generating a plurality of digitally modulated carrier signals for transmission, said signals being within a frequency range which encompasses the frequency spectrum of the first signal, each of said digitally modulated carrier signals being digitally modulated by a portion of a digital signal, wherein a first group of said digitally modulated carrier signals overlap said first frequency spectrum and are modulated in-quadrature with said first carrier signal, and wherein second and third groups of said digitally modulated carrier signals lie outside of said first frequency spectrum and are modulated both in-phase and in-quadrature with said first carrier signal; and simultaneously transmitting said first signal and said plurality of digitally modulated carrier signals.

Claim 20

Dependent Claim 34 words

A signal transmission method according to claim 16, wherein: said carrier signals in said first group of said digitally modulated carrier signals have amplitudes which are less than the unmodulated first carrier signal amplitude.

Claim 21

Dependent Claim 38 words

A signal transmission method according to claim 17, wherein: said carrier signals in said second and third groups of said digitally modulated carrier signals have amplitudes which are less than the amplitude of the unmodulated first carrier signal.

Claim 22

Dependent Claim 23 words

A signal transmission method according to claim 16, wherein said analog signal and said digital signal are different representations of the same information.

Claim 23

Dependent Claim 23 words

A signal transmission method according to claim 16, wherein said second and third groups of carrier signals are modulated in a 32-QAM constellation.

Claim 24

Dependent Claim 19 words

A signal transmission method according to claim 16, wherein said digitally modulated carrier signals are equally spaced in frequency.

Claim 25

Dependent Claim 151 words

A radio frequency transmitter comprising: means for amplitude modulating a first carrier signal by an analog signal to generate a first radio frequency signal having a frequency spectrum; means for generating a plurality of digitally modulated carrier signals within a frequency range which encompasses the frequency spectrum of the first radio frequency signal, each of said digitally modulated carrier signals being digitally modulated by a portion of a digital signal, wherein a first group of said digitally modulated carrier signals overlap the frequency spectrum of the first radio frequency signal and are modulated in-quadrature with said first carrier signal, and wherein second and third groups of said digitally modulated carrier signals lie outside of the frequency spectrum of said first signal and are modulated both in-phase and in-quadrature with said first carrier signal; and means for simultaneously transmitting said first radio frequency signal and said plurality of digitally modulated carrier signals.

Claim 26

Dependent Claim 151 words

A radio frequency transmitter comprising: means for amplitude modulating a first carrier signal by an analog signal to generate a first radio frequency signal having a frequency spectrum; means for generating a plurality of digitally modulated carrier signals within a frequency range which encompasses the frequency spectrum of the first radio frequency signal, each of said digitally modulated carrier signals being digitally modulated by a portion of a digital signal, wherein a first group of said digitally modulated carrier signals overlap the frequency spectrum of the first radio frequency signal and are modulated in-quadrature with said first carrier signal, and wherein second and third groups of said digitally modulated carrier signals lie outside of the frequency spectrum of said first signal and are modulated both in-phase and in-quadrature with said first carrier signal; and means for simultaneously transmitting said first radio frequency signal and said plurality of digitally modulated carrier signals.

Claim 27

Dependent Claim 158 words

A radio frequency receiver comprising: means for receiving both analog and digital portions of a composite radio frequency waveform, wherein the waveform includes a first signal having a first carrier amplitude modulated by an analog signal, and a plurality of digitally modulated carrier signals within a frequency range which encompasses the frequency spectrum of the first signal, each of said digitally modulated carrier signals being amplitude modulated by a portion of a digital signal, wherein a first group of said digitally modulated carrier signals overlapping the frequency spectrum of the first signal are modulated in-quadrature with said first carrier signal, and wherein second and third groups of said digitally modulated carrier signals lie outside of the frequency spectrum of the first signal and are modulated both in-phase and in-quadrature with said first carrier signal; means for detecting said analog signal on said first amplitude modulated carrier; and means for detecting said digital signal on said digitally modulated carriers.

Claim 28

Dependent Claim 158 words

A radio frequency receiver comprising: means for receiving both analog and digital portions of a composite radio frequency waveform, wherein the waveform includes a first signal having a first carrier amplitude modulated by an analog signal, and a plurality of digitally modulated carrier signals within a frequency range which encompasses the frequency spectrum of the first signal, each of said digitally modulated carrier signals being amplitude modulated by a portion of a digital signal, wherein a first group of said digitally modulated carrier signals overlapping the frequency spectrum of the first signal are modulated in-quadrature with said first carrier signal, and wherein second and third groups of said digitally modulated carrier signals lie outside of the frequency spectrum of the first signal and are modulated both in-phase and in-quadrature with said first carrier signal; means for detecting said analog signal on said first amplitude modulated carrier; and means for detecting said digital signal on said digitally modulated carriers.

Claim 29

Dependent Claim 34 words

A radio frequency receiver according to claim 23, wherein said means for detecting said digital signal uses the phase of said first carrier signal as a phase reference to demodulate said digitally modulated carriers.

Claim 30

Dependent Claim 29 words

A radio frequency receiver according to claim 23, further comprising: a filter for extracting said analog signal from an in-phase channel of said means for detecting said analog signal.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1999-12-24	2000-06-24	2000-12-24	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2003-12-24	2004-06-24	2004-12-24	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2007-12-24	2008-06-24	2008-12-24	$7700.00	Window Closed / Lapsed

Method and apparatus for AM compatible digital broadcasting

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