Audio frequency indicator for scan tuned radio receiver

Claim 2

In a radio receiver including an automatic frequency scan system and tuning circuitry coupled to said scan system and responsive to a variable scan control signal of said system for scanning through a frequency band; a. generating means for generating an audible signal having a variable characteristic, b. means for coupling said scan system to said generating means for varying said characteristic in response to variations in said scan control signal, said audible signal thereby being indicative of the location of the scan within the frequency band, and c. said scan system including means for providing a disabling signal in response to a cessation in variation of said scan control signal, and d. means for supplying said disabling signal to said generating means when a station is tuned in so as to terminate said audible Signal.

Claim 3

A radio receiver as recited in claim 1 wherein said generating means comprises an oscillator whose output frequency is varied in response to variations in said variable scan control signal.

Claim 4

In a radio receiver including an automatic frequency scan system and tuning circuitry coupled to said scan system and responsive to a variable scan control signal of said system for scanning through a frequency band; a. said scan system including a scan capacitor whose voltage provides said variable scan control signal and means for varying the voltage across said scan capacitor for effecting scan through the frequency band, b. an oscillator for generating an audible signal whose frequency can be varied, and c. means for coupling said scan capacitor to said oscillator for applying a voltage obtained from said capacitor to an input of said oscillator to cause variation in the frequency of said oscillator in response to variation in the voltage across said capacitor, whereby an audible signal is produced having a pitch varying with the voltage across said capacitor to indicate the location of said scan within the frequency band.

Claim 5

In a radio receiver including an automatic frequency scan system and tuning circuitry coupled to said scan system and responsive to a variable scan control signal of said system for scanning through a frequency band; a. said scan system including a scan capacitor whose voltage provides said variable scan control signal and means for varying the voltage across said scan capacitor for effecting scan through the frequency band, b. an oscillator for generating an audible signal whose frequency can be varied, and c. means for coupling said scan capacitor to said oscillator for applying a voltage obtained from said capacitor to an input of said oscillator to cause variation in the frequency of said oscillator in response to variation in the voltage across said capacitor, whereby an audible signal is produced having a pitch varying with the voltage across said capacitor to indicate the location of said scan within the frequency band.

Claim 6

In a radio receiver as recited in claim 3 and furthermore including means coupled to said scan capacitor and responsive to a cessation of current through said scan capacitor for applying a disabling signal to said generating means when a station is tuned in so as to terminate said audible signal.

Claim 7

In a radio receiver having tuning circuitry including variable reactance tuning means; a. automatic frequency scan circuitry coupled to said tuning circuitry to provide a variable scan control signal to said tuning circuitry for scanning through a frequency band, said scan circuitry comprising: i. a scan capacitor coupled to said variable reactance tuning means for supplying said variable scan control signal, ii. variable conductivity control means coupled to said scan capacitor for controlling the charge on said scan capacitor, and iii. threshold means coupled to said control means and coupled to and responsive to an output from said tuning circuitry for determining the conductivity of said variable conductivity control means, b. disabling means coupled to said scan capacitor for providing a disabling signal in response to the cessation of current through said scan capacitor; and c. audible signal generating means, having a signal input and a disabling input; i. said signal input coupled to said scan capacitor whereby said audible signal generating means is responsive to said scan control signal for generating an audible signal whose frequency varies with said scan control signal, and ii. said disabling input coupled to said disabling means to terminate said audible signal in response to the disabling signal.

Claim 8

In a radio receiver having tuning circuitry including variable reactance tuning means; a. automatic frequency scan circuitry coupled to said tuning circuitry to provide a variable scan control signal to said tuning circuitry for scanning through a frequency band, said scan circuitry comprising: i. a scan capacitor coupled to said variable reactance tuning means for supplying said variable scan control signal, ii. variable conductivity control means coupled to said scan capacitor for controlling the charge on said scan capacitor, and iii. threshold means coupled to said control means and coupled to and responsive to an output from said tuning circuitry for determining the conductivity of said variable conductivity control means, b. disabling means coupled to said scan capacitor for providing a disabling signal in response to the cessation of current through said scan capacitor; and c. audible signal generating means, having a signal input and a disabling input; i. said signal input coupled to said scan capacitor whereby said audible signal generating means is responsive to said scan control signal for generating an audible signal whose frequency varies with said scan control signal, and ii. said disabling input coupled to said disabling means to terminate said audible signal in response to the disabling signal.