START CODE IN-TAKING CIRCUIT FOR MAGNETIC DISK DEVICE

Japanese Patent JPH01169780

A

PURPOSE:To make an uptaking start code accurate by providing a shift register and shifting a PDM signal only when the PDM signal is obtained continuously. CONSTITUTION:The clocks of a P phase and a Q phase, which the phase inverses each other at a reference clock transmitter 10, are outputted to a selecting circuit 12. The circuit 12 detects the startup of a head reproducing signal, and sends the P or the Q phase clock to a gate pulse selecting circuit 14. The circuit 14 counts the selected reference clock, measures the time from a startup edge of the reproducing signal, and outputs PDM signals phi1 and phi2, a non-PDM signal phi3 and a clear signal phi4. The signals phi1-phi3 are inputted through two pair of gate circuits G1-G4, which are decoding means, an AND circuit and an OR circuit to a shift register 22. Then, when the signal phi3 exists, the gate signal G3 is not set and the register 22 is cleared with the timing of the signal phi4. Thus, the continuous PDM signals can be obtained and an accurate start code can be uptaken.

JPH0936756	RECORDING CODING AND REPRODUCING DEVICE
JPS6061959	CLOCK SYNCHRONIZING CIRCUIT OF MULTI-TRACK TYPE MAGNETIC RECORDING AND REPRODUCING DEVICE

TAKESHITA KENICHIRO

JP32576387A

July 05, 1989

December 23, 1987

Click for automatic bibliography generation  

YAMAHA CORP

G11B20/14; G11B27/10; (IPC1-7): G11B20/14; G11B27/10

Kunihiko Kato

Previous Patent: RESYNCHRONIZING CIRCUIT FOR MAGNETIC DISK DEVICE

Next Patent: PULSE-WIDTH MODULATION CIRCUIT AND COMPARATOR USED FOR IT