Tuning method

Claim 1

A method for selecting one of a plurality of television channels of different frequencies by a channel switch and adjusting the frequency of the channel selected by a shift switch, comprising the steps of: (a) generating and coupling a first signal from the channel switch to a microcomputer in a tuning apparatus employing a frequency synthesizer system having a phase-locked loop circuit means including a programmable frequency divider; (b) setting-up a division ratio of the programmable frequency divider in response to the first signal by said microcomputer; (c) generating and coupling a second signal from the shift switch to the microcomputer; (d) varying the division ratio of the programmable divider in response to the second signal by said microcomputer; (e) cyclically monitoring the presence or absence of the first and second signal by said microcomputer; (f) repeating said setting-up step (b) when the first signal is detected as a result of said monitoring step (e) and repeating said varying step (d) when the second signal is detected as a result of said monitoring step (e); and wherein said setting-up step (b) further comprises, a first step of calculating the division ratio in accordance with the first signal, a second step of programming the calculated division ratio into the programmable frequency divider, a third step of comparing a voltage corresponding to the frequency of the received channel with a predetermined level, a fourth step of increasing the division ratio when the compared voltage is higher than the predetermined level, and a fifth step of decreasing the division ratio when the compared voltage is lower than the predetermined value.

Claim 2

A method for selecting one of a plurality of television channels of different frequencies by a channel switch and adjusting the frequency of the channel selected by a shift switch, comprising the steps of: (a) generating and coupling a first signal from the channel switch to a microcomputer in a tuning apparatus employing a frequency synthesizer system having a phase-locked loop circuit means including a programmable frequency divider; (b) setting-up a division ratio of the programmable frequency divider in response to the first signal by said microcomputer; (c) generating and coupling a second signal from the shift switch to the microcomputer; (d) varying the division ratio of the programmable divider in response to the second signal by said microcomputer; (e) cyclically monitoring the presence or absence of the first and second signal by said microcomputer; (f) repeating said setting-up step (b) when the first signal is detected as a result of said monitoring step (e) and repeating said varying step (d) when the second signal is detected as a result of said monitoring step (e); and wherein said setting-up step (b) further comprises, a first step of calculating the division ratio in accordance with the first signal, a second step of programming the calculated division ratio into the programmable frequency divider, a third step of comparing a voltage corresponding to the frequency of the received channel with a predetermined level, a fourth step of increasing the division ratio when the compared voltage is higher than the predetermined level, and a fifth step of decreasing the division ratio when the compared voltage is lower than the predetermined value.

Claim 3

A method for selecting one of a plurality of television channels of different frequencies by a channel switch and adjusting the frequency of the channel selected by a shift switch, comprising the steps of: (a) generating and coupling a first signal from the channel switch to a microcomputer in a tuning apparatus employing a frequency synthesizer system having a phase-locked loop circuit means including a programmable frequency divider; (b) setting up a division ratio of the programmable frequency divider in response to the first signal by said microcomputer; (c) generating and coupling a second signal from the shift switch to the microcomputer; (d) varying the division ratio of the programmable divider in response to the second signal by said microcomputer; (e) cyclically monitoring the presence or absence of the first and second signal by said microcomputer; (f) repeating said setting up step (b) when the first signal is detected as a result of said monitoring step (e) and repeating said varying step (d) when the second signal is detected as a result of said monitoring step (e); and wherein said repeating step (f) further comprises, a first step of cyclically monitoring the second signal while the tuning apparatus is in a channel receiving condition as a result of the setting-up step (b), and again performing the varying step (d) when the second signal is detected, and performing a second step in the event the second signal is not detected, said second step comprising monitoring the first signal and performing said setting-up of step (b) when the first signal is detected, but repeating said first step while the above-mentioned condition is maintained in the event that the first signal is not detected.

Claim 4

A method for selecting one of a plurality of television channels of different frequencies by a channel switch and adjusting the frequency of the channel selected by a shift switch, comprising the steps of: (a) generating and coupling a first signal from the channel switch to a microcomputer in a tuning apparatus employing a frequency synthesizer system having a phase-locked loop circuit means including a programmable frequency divider; (b) setting up a division ratio of the programmable frequency divider in response to the first signal by said microcomputer; (c) generating and coupling a second signal from the shift switch to the microcomputer; (d) varying the division ratio of the programmable divider in response to the second signal by said microcomputer; (e) cyclically monitoring the presence or absence of the first and second signal by said microcomputer; (f) repeating said setting up step (b) when the first signal is detected as a result of said monitoring step (e) and repeating said varying step (d) when the second signal is detected as a result of said monitoring step (e); and wherein said repeating step (f) further comprises, a first step of cyclically monitoring the second signal while the tuning apparatus is in a channel receiving condition as a result of the setting-up step (b), and again performing the varying step (d) when the second signal is detected, and performing a second step in the event the second signal is not detected, said second step comprising monitoring the first signal and performing said setting-up of step (b) when the first signal is detected, but repeating said first step while the above-mentioned condition is maintained in the event that the first signal is not detected.