227
µ
PD17062
Fig. 18-6 Relationship among fr, fN, UP, and DW Signals
(1) When fN is lagging behind fr
(2) When fN is leading fr
(3) When fN is in phase with fr
(4) When fN is lower than fr
fr
fN
UP
DW
“H”
fr
fN
UP
DW
“H”
fr
fN
UP
DW
“H”
“H”
fr
fN
UP
DW
“H”
