Rev. 1.0, 02/00, page 566 of 1141
26.3
Reference Signal Generators
26.3.1
Overview
The reference signal generators consist of a REF30 signal generator and a CREF signal generator
and create the reference signals (REF30 and CREF signals) used in phase comparison, etc. The
REF30 signal is used to control the phase of the drum and capstan. The CREF signal is used if
REF30 signal cannot be used as the reference signal to control the phase of the capstan in REC
mode. Each signal generator consists of a 16-bit counter which uses the servo clock
φ
s/2 (or
φ
s/4) as its clock source, a reference period register, and a comparator.
The value set in the reference period register should be 1/2 of the desired reference signal period.
26.3.2
Block Diagram
Figure 26.6 shows the block diagram of REF30 signal generator. Figure 26.7 shows that of CREF
signal generator.