Tracking error detecting circuit

A tracking error detecting circuit for a magnetic reproducing apparatus which reproduces an information signal from tracks formed obliquely on a magnetic tape relative to a longitudinal direction of the magnetic tape, the tracks having selectively recorded thereon a pilot signal multiplexed with the information signal, said tracking error detecting circuit comprising:

• a rotating magnetic head for scanning the tracks and reproducing the information signal on which the pilot signal is selectively multiplexed to obtain a reproduced signal;
• a comparator for comparing a level of the reproduced signal with a specified level and for outputting a binary signal having a pulse width varying according to the level of a pilot signal contained in the reproduced signal;
• a clock generating circuit for generating a clock signal;
• a sampling circuit for sampling the binary signal output by the comparator at a sampling rate set by the clock signal and for outputting a corresponding sampled signal;
• and
• a level detecting circuit for detecting a level of the pilot signal contained in the reproduced signal from the sampled signal output by the sampling circuit.

A tracking error detecting circuit for a magnetic reproducing apparatus which reproduces an information signal from tracks formed obliquely on a magnetic tape relative to a longitudinal direction of the magnetic tape, the tracks having selectively recorded thereon a pilot signal multiplexed with the information signal, said tracking error detecting circuit comprising:

• a rotating magnetic head for scanning the tracks and for reproducing the information signal on which the pilot signal is selectively multiplexed to obtain a reproduced signal;
• a comparator for comparing a level of the reproduced signal with a specified level and for outputting a binary signal having a pulse width varying according to the level of a pilot signal contained in the reproduced signal;
• a clock generating circuit for generating a first clock signal;
• a first sampling circuit for sampling the binary signal output by the comparator at a sampling rate set by the first clock signal and for outputting a corresponding first sampled signal;
• a low-pass filter for passing a low frequency component of the first sampled signal output by the first sampling circuit to obtain a low-pass filtered signal;
• a frequency dividing circuit for frequency-dividing the first clock signal to obtain a second clock signal;
• a second sampling circuit for sampling the low-pass filtered signal obtained by the low-pass filter at a sampling rate set by the second clock signal and for outputting a corresponding second sampled signal;
• and
• a level detecting circuit for detecting a level of the pilot signal contained in the reproduced signal from the second sampled signal output by the second sampling circuit.

A tracking error detecting circuit for a magnetic reproducing apparatus which reproduces an information signal from tracks formed obliquely on a magnetic tape relative to a longitudinal direction of the magnetic tape, the tracks having selectively recorded thereon a pilot signal multiplexed with the information signal, said tracking error detecting circuit comprising:

• a rotating magnetic head for scanning the tracks and reproducing the information signal on which the pilot signal is selectively multiplexed to obtain a reproduced signal;
• a comparator for comparing a level of the reproduced signal with a specified level and for outputting a binary signal having a pulse width varying according to the level of a pilot signal contained in the reproduced signal;
• a clock generating circuit for generating a first clock signal;
• a sampling circuit for sampling the binary signal output by the comparator at a sampling rate set by the first clock signal and for outputting a sampled signal having high and low levels representing a sampled result;
• a counter for counting up or down clock pulses of the first clock signal during a period in which the sampled signal output by the sampling circuit is the high level;
• a frequency dividing circuit for frequency-dividing the first clock signal to obtain a second clock signal;
• a first latch circuit for latching an output of the counter at a timing set by the second clock signal;
• a second latch circuit for latching an output of the first latch circuit at a timing set by the second clock signal;
• a subtractor for producing a difference signal indicative of a difference between the output of the first latch circuit and an output of the second latch circuit;
• and
• a level detecting circuit for detecting a level of the pilot signal contained in the reproduced signal from the difference signal produced by the subtractor.

A tracking control apparatus for a magnetic reproducing apparatus for reproducing an information signal from tracks formed obliquely on a magnetic tape relative to a longitudinal direction of the magnetic tape, the tracks having selectively recorded thereon a pilot signal multiplexed with the information signal, said tracking control apparatus comprising:

• a rotating magnetic head for scanning the tracks and reproducing the information signal on which the pilot signal is selectively multiplexed to obtain a reproduced signal;
• a comparator for comparing a level of the reproduced signal with a specified level and for outputting a binary signal having a pulse width varying according to the level of a pilot signal contained in the reproduced signal;
• a level detecting circuit for detecting a level of the pilot signal contained in the reproduced signal from the binary signal output by the comparator;
• a tracking error detecting circuit for detecting a tracking error from an output of the level detecting circuit;
• and,
• a control means responsive to the tracking error signal for maintaining a predetermined relative position between the magnetic head and the track as the track is scanned by the magnetic head.