Priority-frequency system for a signal-seeking receiver

Claim 2

In a signal-seeking receiver which automatically scans a plurality of predetermined radio frequencies and tunes to a received signal having a frequency corresponding to one of said predetermined frequencies, a system for selectively designating any particular one of said predetermined frequencies as a priority frequency and tuning said receiver to said priority frequency whenever a signal having the designated priority frequency is received, comprising: variable tuning means adapted to selectively tune said receiver to said predetermined frequencies; scanning means for causing said variable tuning means to sequentially tune said receiver to each of said predetermined frequencies; signal detecting means responsive to the reception of a signal having a frequency corresponding to one of said predetermined frequencies for developing a control signal; means responsive to said control signal for stopping said scanning means to thereby maintain the receiver tuned to the received signal; means for selecting any particular one of said predetermined frequencies as the priority frequency; means for periodically causing said variable tuning means to tune said receiver to said selected priority frequency; priority control means responsive to said control signal for stopping said periodic means to thereby cause said tuning means to maintain the receiver tuned to a received signal having a frequency corresponding to the priority frequency; and means for periodically causing said variable tuning means to tune said receiver to said selected priority frequency, including astable switching means having an asymmetrical switching time and which is switched to the priority-frequency tuning state for a shorter period of time than it is tuned to the non-priority switching state.

Claim 3

In a signal-seeking receiver which automatically scans a plurality of predetermined radio frequencies and tunes to a received signal having a frequency corresponding to one of said predetermined frequencies, a system for selectively designating any particular one of said predetermined frequencies as a priority frequency and tuning said receiver to said priority frequency whenever a signal having the designated priority frequency is received, comprising: variable tuning means adapted to selectively tune said receiver to said predetermined frequencies; scanning means for causing said variable tuning means to sequentially tune said receiver to each of said predetermined frequencies; signal detecting means responsive to the reception of a signal having a frequency corresponding to one of said predetermined frequencies for developing a control signal; means responsive to said control signal for stopping said scanning means to thereby maintain the receiver tuned to the received signal; means for selecting any particular one oF said predetermined frequencies as the priority frequency; means for periodically causing said variable tuning means to tune said receiver to said selected priority frequency; priority control means responsive to said control signal for stopping said periodic means to thereby cause said tuning means to maintain the receiver tuned to a received signal having a frequency corresponding to the priority frequency; and storing means coupled between said signal detecting means and said scanning means for temporarily maintaining said control signal for a predetermined period of time after the termination of the development thereof by said signal detecting means, thereby providing continuous tuning of the receiver to one of the predetermined frequencies during brief interruptions in signal transmission and during the time the receiver is tuned to the priority frequency when no priority-frequency signal is received.

Claim 4

In a signal-seeking receiver which automatically scans a plurality of predetermined radio frequencies and tunes to a received signal having a frequency corresponding to one of said predetermined frequencies, a system for selectively designating any particular one of said predetermined frequencies as a priority frequency and tuning said receiver to said priority frequency whenever a signal having the designated priority frequency is received, comprising: variable tuning means adapted to selectively tune said receiver to said predetermined frequencies; scanning means for causing said variable tuning means to sequentially tune said receiver to each of said predetermined frequencies; signal detecting means responsive to the reception of a signal having a frequency corresponding to one of said predetermined frequencies for developing a control signal; means responsive to said control signal for stopping said scanning means to thereby maintain the receiver tuned to the received signal; means for selecting any particular one oF said predetermined frequencies as the priority frequency; means for periodically causing said variable tuning means to tune said receiver to said selected priority frequency; priority control means responsive to said control signal for stopping said periodic means to thereby cause said tuning means to maintain the receiver tuned to a received signal having a frequency corresponding to the priority frequency; and storing means coupled between said signal detecting means and said scanning means for temporarily maintaining said control signal for a predetermined period of time after the termination of the development thereof by said signal detecting means, thereby providing continuous tuning of the receiver to one of the predetermined frequencies during brief interruptions in signal transmission and during the time the receiver is tuned to the priority frequency when no priority-frequency signal is received.

Claim 5

In a signal-seeking receiver which automatically scans a plurality of predetermined radio frequencies and tunes to a received signal having a frequency corresponding to one of said predetermined frequencies, a system for selecting any particular one of said predetermined frequencies as a priority frequency and tuning said receiver to said priority frequency whenever a signal having the selected priority frequency is received, comprising: variable tuning means having a local oscillator circuit operable to selectively oscillate at each of a corresponding plurality of local oscillator frequencies, said local oscillator including a corresponding plurality of tuning elements adapted to be operatively connected into said local oscillator individually; clock means for generating a timing signal; digital logic sequential switching means responsive to said timing signal for operatively connecting each of said tuning elements into said local oscillator circuit individually to thereby cause said local oscillator circuit to selectively oscillate at each of said local oscillator frequencies; signal detecting means responsive to the reception of a signal having a frequency corresponding to one of said predetermined frequencies for developing a control signal; a threshold switching circuit responsive to said control signal for stopping the generation of said timing signal by said clock means; a selector switch coupled to said local oscillator circuit and having a corresponding plurality of switch positions for selecting any particular one of said predetermined frequencies as the priority frequency; a priority control circuit responsive to said control signal for developing a priority control signal; an astable switching circuit coupled between said priority control circuit and said selector switch for periodically switching said local oscillator circuit between the state in which the local-oscillator frequency corresponds to the non-priority frequency to which the receiver is then tuned and the state in which the local-oscillator frequency corresponds to said selected priority frequency, said astable switching circuit being responsive to said priority control signal for remaining in the priority-frequency switching state; and said astable switching circuit including an astable multivibrator having an asymmetrical switching time, a first switching transistor responsive to said multivibrator switching to said priority-frequency switching state for operatively connecting into said local oscillator the tuning element corresponding to the local-oscillator frequency corresponding to said selected priority frequency, and a second switching transistor responsive to said multivibrator being switched to said priority-frequency switching state for operatively disconnecting from said local oscillator circuit the tuning elements corresponding to the local-oscillator frequencies corresponding to the non-priority frequencies.

Claim 6

In a signal-seeking receiver which automatically scans a plurality of predetermined radio frequencies and tunes to a received signal having a frequency corresponding to one of said predetermined frequencies, a system for selecting any particular one of said predetermined frequencies as a priority frequency and tuning said receiver to said priority frequency whenever a signal having the selected priority frequency is received, comprising: variable tuning means having a local oscillator circuit operable to selectively oscillate at each of a corresponding plurality of local oscillator frequencies, said local oscillator including a corresponding plurality of tuning elements adapted to be operatively connected into said local oscillator individually; clock means for generating a timing signal; digital logic sequential switching means responsive to said timing signal for operatively connecting each of said tuning elements into said local oscillator circuit individually to thereby cause said local oscillator circuit to selectively oscillate at each of said local oscillator frequencies; signal detecting means responsive to the reception of a signal having a frequency corresponding to one of said predetermined frequencies for developing a control signal; a threshold switching circuit responsive to said control signal for stopping the generation of said timing signal by said clock means; a selector switch coupled to said local oscillator circuit and having a corresponding plurality of switch positions for selecting any particular one of said predetermined frequencies as the priority frequency; a priority control circuit responsive to said control signal for developing a priority control signal; an astable switching circuit coupled between said priority control circuit and said selector switch for periodically switching said local oscillator circuit between the state in which the local-oscillator frequency corresponds to the non-priority frequency to which the receiver is then tuned and the state in which the local-oscillator frequency corresponds to said selected priority frequency, said astable switching circuit being responsive to said priority control signal for remaining in the priority-frequency switching state; and said astable switching circuit including an astable multivibrator having an asymmetrical switching time, a first switching transistor responsive to said multivibrator switching to said priority-frequency switching state for operatively connecting into said local oscillator the tuning element corresponding to the local-oscillator frequency corresponding to said selected priority frequency, and a second switching transistor responsive to said multivibrator being switched to said priority-frequency switching state for operatively disconnecting from said local oscillator circuit the tuning elements corresponding to the local-oscillator frequencies corresponding to the non-priority frequencies.

Claim 7

In a signal-seeking receiver which automatically scans a plurality of predetermined radio frequencies and tunes tO a received signal having a frequency corresponding to one of said predetermined frequencies, a system for selecting any particular one of said predetermined frequencies as a priority frequency and tuning said receiver to said priority frequency whenever a signal having the selected priority frequency is received, comprising: variable tuning means having a local oscillator circuit operable to selectively oscillate at each of a corresponding plurality of local oscillator frequencies, said local oscillator including a corresponding plurality of tuning elements adapted to be operatively connected into said local oscillator individually; clock means for generating a timing signal; digital logic sequential switching means responsive to said timing signal for operatively connecting each of said tuning elements into said local oscillator circuit individually to thereby cause said local oscillator circuit to selectively oscillate at each of said local oscillator frequencies; signal detecting means responsive to the reception of a signal having a frequency corresponding to one of said predetermined frequencies for developing a control signal; a threshold switching circuit responsive to said control signal for stopping the generation of said timing signal by said clock means; a selector switch coupled to said local oscillator circuit and having a corresponding plurality of switch positions for selecting any particular one of said predetermined frequencies as the priority frequency; a priority control circuit responsive to said control signal for developing a priority control signal; an astable switching circuit coupled between said priority control circuit and said selector switch for periodically switching said local oscillator circuit between the state in which the local-oscillator frequency corresponds to the non-priority frequency to which the receiver is then tuned and the state in which the local-oscillator frequency corresponds to said selected priority frequency, said astable switching circuit being responsive to said priority control signal for remaining in the priority-frequency switching state; and said priority control circuit including a storing circuit for temporarily maintaining said priority control signal for a predetermined period of time after the termination of the development of the signal-detector control signal, thereby providing continuous tuning of the receiver to one of the predetermined frequencies during brief interruptions in priority-frequency signal transmission.

Claim 8

In a signal-seeking receiver which automatically scans a plurality of predetermined radio frequencies and tunes tO a received signal having a frequency corresponding to one of said predetermined frequencies, a system for selecting any particular one of said predetermined frequencies as a priority frequency and tuning said receiver to said priority frequency whenever a signal having the selected priority frequency is received, comprising: variable tuning means having a local oscillator circuit operable to selectively oscillate at each of a corresponding plurality of local oscillator frequencies, said local oscillator including a corresponding plurality of tuning elements adapted to be operatively connected into said local oscillator individually; clock means for generating a timing signal; digital logic sequential switching means responsive to said timing signal for operatively connecting each of said tuning elements into said local oscillator circuit individually to thereby cause said local oscillator circuit to selectively oscillate at each of said local oscillator frequencies; signal detecting means responsive to the reception of a signal having a frequency corresponding to one of said predetermined frequencies for developing a control signal; a threshold switching circuit responsive to said control signal for stopping the generation of said timing signal by said clock means; a selector switch coupled to said local oscillator circuit and having a corresponding plurality of switch positions for selecting any particular one of said predetermined frequencies as the priority frequency; a priority control circuit responsive to said control signal for developing a priority control signal; an astable switching circuit coupled between said priority control circuit and said selector switch for periodically switching said local oscillator circuit between the state in which the local-oscillator frequency corresponds to the non-priority frequency to which the receiver is then tuned and the state in which the local-oscillator frequency corresponds to said selected priority frequency, said astable switching circuit being responsive to said priority control signal for remaining in the priority-frequency switching state; and said priority control circuit including a storing circuit for temporarily maintaining said priority control signal for a predetermined period of time after the termination of the development of the signal-detector control signal, thereby providing continuous tuning of the receiver to one of the predetermined frequencies during brief interruptions in priority-frequency signal transmission.