Tuning apparatus
First Claim
1. Tuning apparatus for a radio receiver, comprising an adjustable tuning section having a tuning condition which is adjustable over a frequency range to be tuned to selected broadcast frequencies;
- an IF section coupled to said tuning section to produce an IF signal;
IF detecting means for detecting whether said IF signal corresponds to a signal received on a broadcast frequency to which said tuning section is tuned, said detecting means producing a tune indicating signal when said tuning section is tuned to a broadcast frequency and said received signal is either a relatively high or a relatively low level signal and said detecting means producing said tune indicating signal when said tuning section is tuned to a frequency within a predetermined amount of said broadcast frequency and said received signal is a relatively high level signal;
adjusting means for changing the tuning condition of said tuning section in predetermined frequency steps selectively in an upward or downward direction; and
sensing means for sensing that said tune indicating signal has been produced to enable said adjusting means to change the tuning condition of said tuning section by predetermined frequency step and then to (a) disable said adjusting means if said tune indicating signal is sensed following the change by said predetermined frequency step of said tuning condition so as to maintain the last-attained tuning condition thereof, or (b) return the tuning condition of said tuning section by said predetermined frequency step if said tune indicating signal is not sensed following said change by said predetermined frequency step of said tuning condition.
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Accused Products
Abstract
In tuning apparatus, a sensor senses when a tune indicating signal has been produced by the IF section so as to enable an adjusting circuit to change the tuning condition of the apparatus by a predetermined frequency step and then to disable the adjusting circuit if the tune indicating signal still is sensed following this frequency change so as to maintain the last-attained tuning condition. Alternatively, if the tune indicating signal no longer is sensed after the tuning condition has been changed by the predetermined frequency step, the tuning section is returned to its preceding tuning condition by this predetermined frequency step. Consequently, if the received signal is a high level signal at a frequency within a predetermined range from a broadcast frequency, the tune indicating signal is produced when the tuning condition of the tuning section differs from the broadcast frequency by this predetermined frequency step; and the tuning condition then is changed by this step so as to arrive at the desired broadcast frequency. If, however, the received signal is a low level signal, the tune indicating signal is produced only when the tuning condition of the tuning section coincides with a desired broadcast frequency, and then this tuning condition is changed by one step followed by a return of one step to the proper condition.
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Citations
18 Claims
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1. Tuning apparatus for a radio receiver, comprising an adjustable tuning section having a tuning condition which is adjustable over a frequency range to be tuned to selected broadcast frequencies;
- an IF section coupled to said tuning section to produce an IF signal;
IF detecting means for detecting whether said IF signal corresponds to a signal received on a broadcast frequency to which said tuning section is tuned, said detecting means producing a tune indicating signal when said tuning section is tuned to a broadcast frequency and said received signal is either a relatively high or a relatively low level signal and said detecting means producing said tune indicating signal when said tuning section is tuned to a frequency within a predetermined amount of said broadcast frequency and said received signal is a relatively high level signal;
adjusting means for changing the tuning condition of said tuning section in predetermined frequency steps selectively in an upward or downward direction; and
sensing means for sensing that said tune indicating signal has been produced to enable said adjusting means to change the tuning condition of said tuning section by predetermined frequency step and then to (a) disable said adjusting means if said tune indicating signal is sensed following the change by said predetermined frequency step of said tuning condition so as to maintain the last-attained tuning condition thereof, or (b) return the tuning condition of said tuning section by said predetermined frequency step if said tune indicating signal is not sensed following said change by said predetermined frequency step of said tuning condition. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
- an IF section coupled to said tuning section to produce an IF signal;
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12. Tuning apparatus for a radio receiver adapted to receive broadcast channels, each broadcast channel having a broadcast frequency and a predetermined bandwidth with adjacent broadcast channels being frequency-separated from each other by a multiple of a basic frequency step, said apparatus comprising an adjustable tuning section having a tuning condition which is adjustable to be tuned to selected ones of said broadcast channels, said adjustable tuning section including frequency synthesizing means for synthesizing a local variable frequency oscillating signal for determining said tuning condition;
- and IF section coupled to said tuning section to produce an IF signal;
IF detecting means for detecting whether said IF signal is produced in response to the tuning of said tuning section to a broadcast channel, said IF detecting means producing a tune indicating signal of predetermined state when said tuning section is tuned to a broadcast channel or is within said basic frequency step of a broadcast channel;
UP/DOWN counting means responsive to counting pulses and an UP/DOWN control signal supplied thereto for counting said counting pulses in an upward or downward direction as a function of the state of said UP/DOWN control signal, the count of said UP/DOWN counting means establishing the frequency of the local oscillating signal synthesized by said frequency synthesizing means;
a source of said counting pulses;
means for supplying said counting pulses from said source to said UP/DOWN counting means;
shift register means for receiving said tune indicating signal and having at least first and second outputs, said tune indicating signal being shifted to said first output in synchronism with a change in the count of said UP/DOWN counting means corresponding to a change in the frequency of said local oscillating signal equal to said basic frequency step and said tune indicating signal being shifted to said second output in synchronism with another change in the count of said UP/DOWN counting means corresponding to a change in the frequency of said local oscillating signal equal to another basic frequency step;
a source of said UP/DOWN control signal, said UP/DOWN control signal exhibiting a count-up state and a count-down state;
means for changing over the state of said UP/DOWN control signal when said tune indicating signal is shifted to said first output of said shift register means;
first count inhibit signal generating means for generating a first inhibit signal when said tune indicating signal is shifted to said first output of said shift register means and said IF detecting means continues to produce a tune indicating signal;
second count inhibit signal generating means for generating a second inhibit signal when said tune indicating signal is shifted to said second output of said shift register means; and
means for inhibiting the supply of said counting pulses to said UP/DOWN counting means in response to said first or second inhibit signal. - View Dependent Claims (13, 14, 15, 16, 17, 18)
- and IF section coupled to said tuning section to produce an IF signal;
Specification