Method of and apparatus for channel scanning

Claim 1

A method of scanning for a plurality of reception channels in an automatic channel program of video tape recorders and television is a homodyne detector circuit in which frequency data of a specific channel in said plurality of reception channels is transmitted from a microprocessor to a demodulator circuit via a tuner for producing video signals to be delivered to said homodyne detector circuit where a synchronizing signal is detected within a predetermined time period, and applied to a memory of said microprocessor, said method comprising the step of: receiving frequency data of a first channel for detecting said synchronizing signal from said frequency data for said first channel using a synchronous detection process, said synchronous detection process being performed by: scanning the first frequency data of said first channel, in a first scanning step for a first predetermined time interval, for detecting said synchronizing signal; storing information representative of said first channel in said memory if said synchronizing signal is detected during said first scanning step; decreasing the frequency of said frequency data by a first frequency differential, for scanning, in a second scanning step for a second predetermined time interval, for detecting said synchronizing signal if said synchronizing signal is not detected in said first scanning step; storing information representative of said first channel in said memory if said synchronizing signal is detected during said second scanning step; decreasing the frequency of said frequency data by a second frequency differential, for scanning in a third scanning step for a third predetermined time interval, for detecting said synchronizing signal if said synchronizing signal is not detected in said second scanning step; storing said information representative of said first channel in said memory if said synchronizing signal is detected during said third scanning step; and scanning for a next channel of said plurality of reception channels to receive frequency data of said next channel for repeating said synchronous detection process until a last channel of said plurality of reception channels is scanned.

Claim 2

A method of scanning for a plurality of reception channels in an automatic channel program of video tape recorders and television is a homodyne detector circuit in which frequency data of a specific channel in said plurality of reception channels is transmitted from a microprocessor to a demodulator circuit via a tuner for producing video signals to be delivered to said homodyne detector circuit where a synchronizing signal is detected within a predetermined time period, and applied to a memory of said microprocessor, said method comprising the step of: receiving frequency data of a first channel for detecting said synchronizing signal from said frequency data for said first channel using a synchronous detection process, said synchronous detection process being performed by: scanning the first frequency data of said first channel, in a first scanning step for a first predetermined time interval, for detecting said synchronizing signal; storing information representative of said first channel in said memory if said synchronizing signal is detected during said first scanning step; decreasing the frequency of said frequency data by a first frequency differential, for scanning, in a second scanning step for a second predetermined time interval, for detecting said synchronizing signal if said synchronizing signal is not detected in said first scanning step; storing information representative of said first channel in said memory if said synchronizing signal is detected during said second scanning step; decreasing the frequency of said frequency data by a second frequency differential, for scanning in a third scanning step for a third predetermined time interval, for detecting said synchronizing signal if said synchronizing signal is not detected in said second scanning step; storing said information representative of said first channel in said memory if said synchronizing signal is detected during said third scanning step; and scanning for a next channel of said plurality of reception channels to receive frequency data of said next channel for repeating said synchronous detection process until a last channel of said plurality of reception channels is scanned.

Claim 5

A method of scanning for a plurality of reception channels in an automatic program of a television and video cassette recorder, comprising the steps of: receiving frequency data of a first channel; scanning, in a first scanning step, at a selected frequency for detecting a synchronizing signal of said frequency data, for a first predetermined time period; memorizing said first channel of the detected synchronizing signal, if said synchronizing signal is detected; decreasing said selected frequency in two equal steps, and scanning, in a second scanning step, for said synchronizing signal at each of said two equal steps for a second predetermined time period if said synchronizing signal is not detected in said first scanning step, and memorizing said first channel if said synchronizing signal is detected in said second scanning step; and changing said first channel to a next channel in said plurality of reception channels for receiving frequency data of said next channel to repeat said first and second scanning steps with said first and second predetermined time periods for detecting said synchronizing signal of said next channel, said step for changing channels being repeated until frequency data of a last channel of said plurality of reception channels is received.

Claim 6

A method of scanning for a plurality of reception channels in an automatic program of a television and video cassette recorder, comprising the steps of: receiving frequency data of a first channel; scanning, in a first scanning step, at a selected frequency for detecting a synchronizing signal of said frequency data, for a first predetermined time period; memorizing said first channel of the detected synchronizing signal, if said synchronizing signal is detected; decreasing said selected frequency in two equal steps, and scanning, in a second scanning step, for said synchronizing signal at each of said two equal steps for a second predetermined time period if said synchronizing signal is not detected in said first scanning step, and memorizing said first channel if said synchronizing signal is detected in said second scanning step; and changing said first channel to a next channel in said plurality of reception channels for receiving frequency data of said next channel to repeat said first and second scanning steps with said first and second predetermined time periods for detecting said synchronizing signal of said next channel, said step for changing channels being repeated until frequency data of a last channel of said plurality of reception channels is received.

Claim 10

A method of scanning for synchronizing signals in a plurality of reception channels in an automatic program a television and video cassette recorders, comprising the steps of: scanning, for a first predetermined time period, at a selected frequency to detect a synchronizing signal with frequency data of a channel; obtaining decremented frequencies by decreasing said selected frequency in two steps, and scanning the decremented frequencies for said synchronizing signal for each step of said two steps for a second predetermined time period, if said synchronizing signal is not detected during said first predetermined time period; and memorizing frequency data for said channel if said synchronizing signal is detected.

Claim 11

A method of scanning for synchronizing signals in a plurality of reception channels in an automatic program a television and video cassette recorders, comprising the steps of: scanning, for a first predetermined time period, at a selected frequency to detect a synchronizing signal with frequency data of a channel; obtaining decremented frequencies by decreasing said selected frequency in two steps, and scanning the decremented frequencies for said synchronizing signal for each step of said two steps for a second predetermined time period, if said synchronizing signal is not detected during said first predetermined time period; and memorizing frequency data for said channel if said synchronizing signal is detected.

Claim 16

A device for channel scanning in an automatic channel program, comprising: controller means for memorizing a channel based upon a detection signal; tuner means for tuning to obtain a selected channel from among a plurality of channels and for converting the tuned frequency data into an intermediate-frequency signal; means for demodulating said intermediate-frequency signal received from said tuning means to generate a demodulated signal; and homodyne detection means for enabling detection of a synchronizing signal of said demodulated signal and delivering the detection signal to said controller means upon detection of said synchronizing signal, said homodyne detection means enabling detection of said synchronizing signal by scanning for said synchronizing signal for a first time period, enabling said controller means to sequentially decrease said frequency data of said selected channel two times for second and third time periods if said synchronizing signal is not detected within said first time period, and enabling said controller means to memorize frequency data of said selected channel if said synchronizing signal is detected during one of said first, second and third time periods.

Claim 17

A device for channel scanning in an automatic channel program, comprising: controller means for memorizing a channel based upon a detection signal; tuner means for tuning to obtain a selected channel from among a plurality of channels and for converting the tuned frequency data into an intermediate-frequency signal; means for demodulating said intermediate-frequency signal received from said tuning means to generate a demodulated signal; and homodyne detection means for enabling detection of a synchronizing signal of said demodulated signal and delivering the detection signal to said controller means upon detection of said synchronizing signal, said homodyne detection means enabling detection of said synchronizing signal by scanning for said synchronizing signal for a first time period, enabling said controller means to sequentially decrease said frequency data of said selected channel two times for second and third time periods if said synchronizing signal is not detected within said first time period, and enabling said controller means to memorize frequency data of said selected channel if said synchronizing signal is detected during one of said first, second and third time periods.