Apparatus and method for detecting tone signals occuring within a predetermined frequency range

Claim 2

Apparatus operative to detect a recorded tone signal within a predetermined playback frequency range, comprising: means responsive to playback of a recording medium bearing at least one recorded tone signal of predetermined frequency to provide an output signal comprising repetitive pulses at a playback frequency determined by said predetermined recording frequency and by the relationship between the recording speed and the playback speed within a predetermined range of playback speeds of the recording medium; first timing means operative in response to an output signal pulse to produce a first timing signal for a first period of time having a duration no less than the period of the lowest frequency in said predetermined range of playback frequencies; coincidence means responsive to said first timing signal and to said repetitive pulse output signals to produce a first control signal when the next pulse of said output signal occurs coincident with said first time signal; and first control means responsive to said first control signal to produce a control output signal only in response to the consecutive occurrence of at least a predetermined plurality of said control signals coincident with a corresponding plurality of consecutive first periods of time.

Claim 3

Apparatus as in claim 1, further comprising: means for providing relative movement of the recording medium and a transducing means at said predetermined recording speed to selectively record at least said one tone signal at a certain recorded frequency; and said movement means being operative to provide relative movement of the recording medium and a transducing means at a second speed which is variable over said predetermined range of playback speeds to reproduce said at least one recorded tone signal at said playback frequency within said range of playback frequencies.

Claim 4

Apparatus as in claim 1, wherein said first control means includes: charge storage means operative to receive a substantially uniform charge current in response to each of said control signals; and switch means operatively responsive to the accumulated charge on said charge storage means to produce said control signal when a predetermined charge is present on said charge storage means.

Claim 5

Apparatus as in claim 1, wherein said first control means includes: constant current means responsive to each said control signal to provide a counting pulse having substantially certain pulse current amplitude; charge storage means connected to receive each of said counting pulses and operative to assume a quantity of electrical charge therefrom; bleed means operatively connected with said charge storage means to bleed said electrical charge from said charge storage means at a predetermined rate, and switch means operatively responsive to said charge storage means to produce said control signal when a predetermined accumulated electrical charge is present on said charge storage means.

Claim 6

Apparatus operative to detect either of two tone signals of different frequencies recorded on a recording medium and reproduced within certain ranges of playback frequencies; comprising: means responsive to playback of the recording medium to provide an output signal comprising repetitive pulses at a first playback frequency within a certain first range of playback frequencies determined by one of said predetermined recording frequency and by the relationship between the recording speed and the playback speed within a predetermined range of playback speeds of the recording medium, and further providing repetitive signal pulses at a second playback frequency within a certain second range of playback frequencies determined by the other of said predetermined recording frequencies and by said relationship between recording speed and playback speeds; said ranges of playback frequencies being mutually exclusive, and said second range of playback frequencies being lower in frequency than said first range of playback frequencies; first timing means operative in response to an output signal pulse to establish a first timing signal for a first period of time having a dUration no less than the period of the lowest frequency in said first range of playback frequencies; second timing means operative in response to said output signal pulse to establish a second timing signal for a period second of time having a duration no less than the period of the lowest frequency in said second range of playback frequencies; first coincidence means responsive to said first timing signal and to said repetitive pulse output signals to produce a first control signal when the next pulse of said output signal occurs coincident with said first time signal; and second coincidence means responsive to said first and second timing signals and to said repetitive pulse output signals to produce a second control signal when the next pulse of said output signal occurs after said first period of time and during said second period of time.

Claim 7

Apparatus operative to detect either of two tone signals of different frequencies recorded on a recording medium and reproduced within certain ranges of playback frequencies; comprising: means responsive to playback of the recording medium to provide an output signal comprising repetitive pulses at a first playback frequency within a certain first range of playback frequencies determined by one of said predetermined recording frequency and by the relationship between the recording speed and the playback speed within a predetermined range of playback speeds of the recording medium, and further providing repetitive signal pulses at a second playback frequency within a certain second range of playback frequencies determined by the other of said predetermined recording frequencies and by said relationship between recording speed and playback speeds; said ranges of playback frequencies being mutually exclusive, and said second range of playback frequencies being lower in frequency than said first range of playback frequencies; first timing means operative in response to an output signal pulse to establish a first timing signal for a first period of time having a dUration no less than the period of the lowest frequency in said first range of playback frequencies; second timing means operative in response to said output signal pulse to establish a second timing signal for a period second of time having a duration no less than the period of the lowest frequency in said second range of playback frequencies; first coincidence means responsive to said first timing signal and to said repetitive pulse output signals to produce a first control signal when the next pulse of said output signal occurs coincident with said first time signal; and second coincidence means responsive to said first and second timing signals and to said repetitive pulse output signals to produce a second control signal when the next pulse of said output signal occurs after said first period of time and during said second period of time.

Claim 8

Apparatus as in claim 5, wherein: said second coincidence means is inoperative to produce said second control signal during said first period of time.

Claim 9

Apparatus as in claim 6, wherein: said second timing means and said second coincidence means are operatively connected to commence said second period of time in response to the termination of said first timing signal condition and the continuation of said second timing signal condition.

Claim 10

Apparatus as in claim 5, wherein: said first timing means comprises a first timing circuit operative to produce a first enabling signal for said first period of time in response to a timing pulse derived from a pulse of said output signal; said second timing means comprises a second timing circuit operative to produce a second enabling signal for a period of time equal to the sum of said first and second time periods and also commencing in response to said timing pulse; said first coincidence means is operative in response to the occurrence of a pulse of said output signal coincident with said first enabling signal to produce said first control signal; and said second coincidence means is operative in response to the occurrence of a pulse of said output signal coincident with the presence of said second enabling signal and the absence of said first enabling signal to produce said second control signal.

Claim 11

Apparatus as in claim 8, wherein: said second timing circuit is operative in response to the occurrence of said first control signal during the first period of time to terminate said second enabling signal and thus to prevent said second coincidence means from producing a second control signal during the second period of time immediately following said first period of time.

Claim 12

Apparatus as in claim 8, further comprising: circuit means operatively connected between said reproducing means and said first and second timing circuits to supply said timing circuits with timing pulses to commence producing said respective periods of time; said circuit means including gate means connected to be responsive to said first and second timing circuits to enable a timing pulse to be supplied to said first and second timing circuits only when neither of said timing circuits is producing said corresponding enabling signals.

Claim 13

Apparatus as in claim 10, wherein: said circuit means additionally includes pulse shaping means operative in response to each of said pulses of said output signal to produce a said timing pulse having a leading edge and a trailing edge; and each of said timing circuits is operative to commence producing the respective enabling signals in response to the trailing edge of a timing pulse supplied through said gate means.

Claim 14

Apparatus for detecting at least two predetermined frequency tones occurring within two mutually exclusive frequency ranges, comprising: means for generating a series of repetitive pulses in response to an input frequency tone, the repetition rate of said pulses being a function of the frequency of said frequency tone; first timing means responsive to a first pulse of a series of said repetitive pulses to establish a first period of time having a minimum duration sufficient to include the expected occurrence of the next repetitive pulse of the highest frequency in a higher one of said frequency ranges, and having a maximum duration sufficient to include the expected occurrence of the next repetitive pulse of the lowest frequency in said higher range of frequencies; second timing means responsive to said first pulse to establish a second period of time commencing at a time sufficient to include the expected occurrence of the next repetitive pulse of the highest frequency in the lower one of said frequency ranges and terminating at a later time sufficient to include the expected occurrence of the next repetitive pulse of the lowest frequency in said lower range of frequencies; first coincidence means responsive to said first timing means and to said repetitive pulses to produce a first control signal when said next-occurring one of said repetitive pulses occurs during said first period of time; and second coincidence means responsive to said first and second timing means and to said repetitive pulses to produce a second control signal when said next-occurring one of said repetitive pulses occurs after said first period of time and during said second period of time.

Claim 15

Apparatus for detecting at least two predetermined frequency tones occurring within two mutually exclusive frequency ranges, comprising: means for generating a series of repetitive pulses in response to an input frequency tone, the repetition rate of said pulses being a function of the frequency of said frequency tone; first timing means responsive to a first pulse of a series of said repetitive pulses to establish a first period of time having a minimum duration sufficient to include the expected occurrence of the next repetitive pulse of the highest frequency in a higher one of said frequency ranges, and having a maximum duration sufficient to include the expected occurrence of the next repetitive pulse of the lowest frequency in said higher range of frequencies; second timing means responsive to said first pulse to establish a second period of time commencing at a time sufficient to include the expected occurrence of the next repetitive pulse of the highest frequency in the lower one of said frequency ranges and terminating at a later time sufficient to include the expected occurrence of the next repetitive pulse of the lowest frequency in said lower range of frequencies; first coincidence means responsive to said first timing means and to said repetitive pulses to produce a first control signal when said next-occurring one of said repetitive pulses occurs during said first period of time; and second coincidence means responsive to said first and second timing means and to said repetitive pulses to produce a second control signal when said next-occurring one of said repetitive pulses occurs after said first period of time and during said second period of time.