Signal-seeking radio receiver

Claim 2

In a superheterodyne radio receiver for receiving RF signals each having a nominal amplitude in excess of a minimum reception level and each having a carrier frequency within a given reception band, the combination comprising: input means for receiving RF signals at a reception frequency; tuner means connected to the input means for varying the reception frequency in a particular tuning direction over the reception band, the tuner means responsive to the application of a start signal to initiate variation of the reception frequency and responsive to the application of a stop signal to terminate variation of the reception frequency, the tuner means exhibiting an inertia such that the reception frequency of the input means is varied over a stopping frequency range after the application of the stop signal; heterodyne means for producing an IF signal having a nominal amplitude determined by the nominal amplitude of each received RF signal and having a carrier frequency determined by the difference between the reception frequency of the input means and the carrier frequency of each received RF signal as the reception frequency of the input means is varied in the tuning direction toward the carrier frequency of the received RF signal; trigger means connected to the heterodyne means for producing different IF response curves each corresponding to a different amplitude of the IF signal, the trigger means including amplitude responsive means for compressing the IF response curves with respect to overall magnitude and including frequency-responsive means for skewing the IF response curves with respect to peak frequency in the tuning direction, the compressed and skewed IF response curves constraining the amplitude of the IF signal to exceed a trigger level only if the nominal amplitude of the IF signal corresponds to a received RF signal having a nominal amplitude in excess of the minimum reception level and only when the carrier frequency of the IF signal corresponds to a received RF signal having a carrier frequency which differs from the reception frequency of the input means by an amount approximately equal to the stopping frequency range of the tuner means; tuning initiation means connected with the tuner means for applying a start signal to the tuner means when manually activated; and tuning termination means connected between the trigger means and the tuner means for applying a stop signal to the tuner means when the amplitude of the IF signal exceeds the trigger level; whereby the reception frequency of the input means is tunable to the carrier frequency of each received RF signal within the reception band having a nominal amplitude iN excess of the minimum reception level.

Claim 3

In a superheterodyne radio receiver for receiving RF signals each having a nominal amplitude in excess of a minimum reception level and each having a carrier frequency within a given reception band, the combination comprising: an RF stage having an RF response exhibiting an RF peak frequency for receiving RF signals; tuner means connected with the RF stage for varying the RF peak frequency in a particular tuning direction over the reception band, the tuner means responsive to the application of a start signal to initiate variation of the RF peak frequency and responsive to the application of a stop signal to terminate variation of the RF peak frequency, the tuner means having an inertia such that the RF peak frequency of the RF stage is varied over a stopping frequency range after the application of a stop signal; an IF stage having an IF response curve exhibiting an IF peak frequency for processing IF signals; a converter stage connected between the RF stage and the IF stage for producing an IF signal having a nominal amplitude proportional to the nominal amplitude of each received RF signal and having a carrier frequency differing from the IF peak frequency by an amount equal to the amount by which the RF peak frequency differs from the carrier frequency of each received RF signal so that the carrier frequency of the IF signal approaches the IF peak frequency in the tuning direction as the RF peak frequency approaches the carrier frequency of the received RF signal in the tuning direction; and trigger means for providing different IF response curves each corresponding to a different amplitude of the IF signal, the trigger means including a limiter for clipping the amplitude of the IF signal to produce an IF limited signal, and a pair of inductively coupled LC tank circuits responsive to the introduction of the IF limited signal into one of the tank circuits having a resonant frequency approximately equal to the IF peak frequency to develop an IF control signal in the other of the tank circuits having a resonant frequency slightly offset from the IF peak frequency in the tuning direction, the combination of the limiter and the LC tank circuits compressing the IF response curves with respect to overall magnitude and skewing the IF response curves with respect to peak frequency thereby to constrain the amplitude of the IF control signal to exceed a trigger level only if the nominal amplitude of the IF signal corresponds to a received RF signal having a nominal amplitude in excess of the minimum reception level and only when the frequency of the IF signal corresponds to a received RF signal having a carrier frequency which differs from the RF peak frequency by an amount approximately equal to the stopping frequency range; tuning initiation means connected with the tuner means for applying a start signal to the tuner means when manually activated; and tuning termination means connected between the trigger means and the tuner means for applying a stop signal to the tuner means when the amplitude of the IF control signal exceeds the trigger level, whereby the RF peak frequency is tunable to the carrier frequency of each received RF signal within the reception band having a nominal amplitude in excess of the minimum reception level.

Claim 4

In a superheterodyne radio receiver for receiving RF signals each having a nominal amplitude in excess of a minimum reception level and each having a carrier frequency within a given reception band, the combination comprising: an RF stage having an RF response exhibiting an RF peak frequency for receiving RF signals; tuner means connected with the RF stage for varying the RF peak frequency in a particular tuning direction over the reception band, the tuner means responsive to the application of a start signal to initiate variation of the RF peak frequency and responsive to the application of a stop signal to terminate variation of the RF peak frequency, the tuner means having an inertia such that the RF peak frequency of the RF stage is varied over a stopping frequency range after the application of a stop signal; an IF stage having an IF response curve exhibiting an IF peak frequency for processing IF signals; a converter stage connected between the RF stage and the IF stage for producing an IF signal having a nominal amplitude proportional to the nominal amplitude of each received RF signal and having a carrier frequency differing from the IF peak frequency by an amount equal to the amount by which the RF peak frequency differs from the carrier frequency of each received RF signal so that the carrier frequency of the IF signal approaches the IF peak frequency in the tuning direction as the RF peak frequency approaches the carrier frequency of the received RF signal in the tuning direction; and trigger means for providing different IF response curves each corresponding to a different amplitude of the IF signal, the trigger means including a limiter for clipping the amplitude of the IF signal to produce an IF limited signal, and a pair of inductively coupled LC tank circuits responsive to the introduction of the IF limited signal into one of the tank circuits having a resonant frequency approximately equal to the IF peak frequency to develop an IF control signal in the other of the tank circuits having a resonant frequency slightly offset from the IF peak frequency in the tuning direction, the combination of the limiter and the LC tank circuits compressing the IF response curves with respect to overall magnitude and skewing the IF response curves with respect to peak frequency thereby to constrain the amplitude of the IF control signal to exceed a trigger level only if the nominal amplitude of the IF signal corresponds to a received RF signal having a nominal amplitude in excess of the minimum reception level and only when the frequency of the IF signal corresponds to a received RF signal having a carrier frequency which differs from the RF peak frequency by an amount approximately equal to the stopping frequency range; tuning initiation means connected with the tuner means for applying a start signal to the tuner means when manually activated; and tuning termination means connected between the trigger means and the tuner means for applying a stop signal to the tuner means when the amplitude of the IF control signal exceeds the trigger level, whereby the RF peak frequency is tunable to the carrier frequency of each received RF signal within the reception band having a nominal amplitude in excess of the minimum reception level.

Claim 5

In a superheterodyne radio receiver for receiving RF signals each having a carrier frequency within a given reception band and each having a nominal amplitude in excess of a minimum reception level, the combination comprising: an RF stage having an RF response curve centered about an RF peak frequency for receiving an RF signal; tuner means connected with the RF stage and including a drive mechanism for defining the RF peak frequency of the RF stage as a function of the position of the drive mechanism so that the RF peak frequency is varied across the reception band in a particular tuning directioN in response to movement of the drive mechanism, the tuner means responsive to the application of a start signal to initiate movement of the drive mechanism to begin variation of the RF peak frequency and responsive to the application of a stop signal to terminate movement of the drive mechanism to end variation of the RF peak frequency, the RF peak frequency varying over an additional stopping frequency range after the application of the stop signal to the tuner means as the drive mechanism gradually coasts to a stop due to the inherent inertia of the drive mechanism; an IF stage having an IF response curve centered about an IF peak frequency for processing IF signals; a converter stage connected between the RF stage and the IF stage for producing an IF signal having a nominal amplitude proportional to the nominal amplitude of each received RF signal and having a carrier frequency differing from the IF peak frequency by an amount equal to the amount by which the RF peak frequency differs from the carrier frequency of each received RF signal so that the carrier frequency of the IF signal approaches the IF peak frequency in the tuning direction as the RF peak frequency approaches the carrier frequency of the received RF signal in the tuning direction; and trigger means for providing different IF response curves each corresponding to a different amplitude of the IF signal, the trigger means including a limiter for clipping the amplitude of the IF signal to provide an IF limited signal, a transformer for developing an IF control signal in a secondary winding in response to the application of the IF limited signal to a primary winding, the combination of the limiter and the transformer acting to compress the IF response curves with respect to overall magnitude, and a pair of capacitors each connected across a different one of the primary and secondary windings to form a primary tuned circuit having a resonant frequency equal to the IF peak frequency and a secondary tuned circuit having a resonant frequency slightly offset from the IF peak frequency in the tuning direction, the combination of the transformer and the pair of capacitors acting to skew the IF response curves with respect to peak frequency, the compressed and skewed IF response curves constraining the amplitude of the IF control signal to exceed a trigger level only if the nominal amplitude IF signal corresponds to a received RF signal having a nominal amplitude in excess of the minimum reception level and only when the carrier frequency of the IF signal corresponds to a received RF signal having a carrier frequency which differs from the RF peak frequency by an amount equal to the stopping frequency range of the drive mechanism; tuning initiation means connected with the tuner means for applying a start signal to the tuner means when manually activated; and tuning termination means connected between the control means and the tuner means for applying a stop signal to the tuner means when the amplitude of the IF control signal exceeds the trigger level; whereby the drive mechanism of the tuner means coasts to a stop at a position corresponding to the carrier frequency of each received RF signal within the reception band having a nominal magnitude in excess of the minimum reception level.

Claim 6

In a superheterodyne radio receiver for receiving RF signals each having a carrier frequency within a given reception band and each having a nominal amplitude in excess of a minimum reception level, the combination comprising: an RF stage having an RF response curve centered about an RF peak frequency for receiving an RF signal; tuner means connected with the RF stage and including a drive mechanism for defining the RF peak frequency of the RF stage as a function of the position of the drive mechanism so that the RF peak frequency is varied across the reception band in a particular tuning directioN in response to movement of the drive mechanism, the tuner means responsive to the application of a start signal to initiate movement of the drive mechanism to begin variation of the RF peak frequency and responsive to the application of a stop signal to terminate movement of the drive mechanism to end variation of the RF peak frequency, the RF peak frequency varying over an additional stopping frequency range after the application of the stop signal to the tuner means as the drive mechanism gradually coasts to a stop due to the inherent inertia of the drive mechanism; an IF stage having an IF response curve centered about an IF peak frequency for processing IF signals; a converter stage connected between the RF stage and the IF stage for producing an IF signal having a nominal amplitude proportional to the nominal amplitude of each received RF signal and having a carrier frequency differing from the IF peak frequency by an amount equal to the amount by which the RF peak frequency differs from the carrier frequency of each received RF signal so that the carrier frequency of the IF signal approaches the IF peak frequency in the tuning direction as the RF peak frequency approaches the carrier frequency of the received RF signal in the tuning direction; and trigger means for providing different IF response curves each corresponding to a different amplitude of the IF signal, the trigger means including a limiter for clipping the amplitude of the IF signal to provide an IF limited signal, a transformer for developing an IF control signal in a secondary winding in response to the application of the IF limited signal to a primary winding, the combination of the limiter and the transformer acting to compress the IF response curves with respect to overall magnitude, and a pair of capacitors each connected across a different one of the primary and secondary windings to form a primary tuned circuit having a resonant frequency equal to the IF peak frequency and a secondary tuned circuit having a resonant frequency slightly offset from the IF peak frequency in the tuning direction, the combination of the transformer and the pair of capacitors acting to skew the IF response curves with respect to peak frequency, the compressed and skewed IF response curves constraining the amplitude of the IF control signal to exceed a trigger level only if the nominal amplitude IF signal corresponds to a received RF signal having a nominal amplitude in excess of the minimum reception level and only when the carrier frequency of the IF signal corresponds to a received RF signal having a carrier frequency which differs from the RF peak frequency by an amount equal to the stopping frequency range of the drive mechanism; tuning initiation means connected with the tuner means for applying a start signal to the tuner means when manually activated; and tuning termination means connected between the control means and the tuner means for applying a stop signal to the tuner means when the amplitude of the IF control signal exceeds the trigger level; whereby the drive mechanism of the tuner means coasts to a stop at a position corresponding to the carrier frequency of each received RF signal within the reception band having a nominal magnitude in excess of the minimum reception level.