Apparatus and method for injecting an ancillary signal into a low energy density portion of a color television frequency spectrum
First Claim
1. A method for compatibly transmitting and receiving both a program signal and an ancillary signal within a frequency band normally occupied by the program signal alone, the program signal including a modulated carrier having a carrier frequency and a low energy density portion of the frequency band, the method comprising the following steps:
- receiving the program signal; and
,selectively adding the ancillary signal at an injection frequency within the lower energy density portion of the frequency band so that the injection frequency is locked to the carrier frequency.
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Accused Products
Abstract
An ancillary signal is injected into a program signal within the frequency band normally occupied by the program signal alone. The program signal includes a modulated carrier having a carrier frequency and a low energy density portion of the frequency band. The ancillary signal is selectively added at an injection frequency within the lower energy density portion of the frequency band so that the injection frequency is locked to the carrier frequency and to the frequency of a local oscillator.
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Citations
52 Claims
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1. A method for compatibly transmitting and receiving both a program signal and an ancillary signal within a frequency band normally occupied by the program signal alone, the program signal including a modulated carrier having a carrier frequency and a low energy density portion of the frequency band, the method comprising the following steps:
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receiving the program signal; and
,selectively adding the ancillary signal at an injection frequency within the lower energy density portion of the frequency band so that the injection frequency is locked to the carrier frequency. - View Dependent Claims (2, 3)
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4. A system for compatibly transmitting and receiving both a program signal and an ancillary signal within a frequency band normally occupied by the program signal alone, the program signal including a modulated carrier having a carrier frequency and a low energy density portion of the frequency band, the system comprising:
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a receiver which is arranged to receive the program signal, wherein the receiver has a local oscillator producing a local oscillator frequency; and
,a signal injector which is arranged to selectively add the ancillary signal at an injection frequency within the lower energy density portion of the frequency band so that the injection frequency is locked to the local oscillator frequency. - View Dependent Claims (5, 6, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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7. A system for compatibly transmitting and receiving a television program signal and an RF ancillary signal, wherein the television program signal is in a predetermined RF frequency band, and wherein the television program signal has a modulated video carrier signal and a low energy density portion of the frequency band, the system comprising:
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a tuner arranged to receive the television program signal, the tuner having as outputs a local oscillator signal and a modulated carrier signal; a first mixer arranged to mix an injection signal at a predetermined baseband injection frequency with a signal representative of the modulated carrier signal to produce an intermediate frequency injection signal; a second mixer arranged to mix the local oscillator signal with the intermediate frequency injection signal to produce the RF ancillary signal; and
,a coupler arranged to couple the RF ancillary signal into the received television program signal. - View Dependent Claims (20, 21, 22)
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23. A method of injecting an RF ancillary signal into a low energy density portion of a channel normally occupied by a color television program signal having a modulated video carrier, a chrominance subcarrier, and the low energy density portion, the method comprising the steps of:
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a) tuning the color television program signal so as to produce a local oscillator signal and a modulated carrier signal as outputs; b) mixing an injection signal at a predetermined injection frequency with a signal representative of the modulated carrier signal to produce an output injection signal; c) mixing the local oscillator signal with the output injection signal to produce the RF ancillary signal; and
,d) coupling the RF ancillary signal into the color television program signal. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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38. A broadcast tuning measurement method in which an RF ancillary channel recognition signal is added to a television program signal received at a predetermined channel frequency within a sampled dwelling unit, wherein the RF ancillary channel recognition signal is subsequently read from the television program signal at a viewing site, the method comprising the steps of:
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a) tuning the television program signal so as to produce a local oscillator frequency and a video carrier signal as outputs; b) providing an injection signal at a predetermined frequency which is selected to be in a low energy density part of a channel; c) combining the video carrier signal with the injection signal to form a carrier/injection signal; d) combining the carrier/injection signal with the local oscillator frequency to form the RF ancillary channel recognition signal; and
,e) coupling the RF ancillary channel recognition signal into the television program signal. - View Dependent Claims (39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52)
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Specification