Sailor RE2100, Technical Manual

Page: 116 / 186

5 CIRCUIT DESCRIPTION AND SCHEMATIC DIAGRAMS RE2100
PAGE 5-16 9406
PHASE LOCKED LOOP 2
The change between transmitted and received upper and lower sideband is generated by a frequency
change in PLL2 as illustrated below.
USB Receiver
IF1 - Filter
70 MHz 10,7 MHz
LSB - Filter
f
+
-
LO2
59,3 MHz
IF2
f
70-100 MHz
LO1
+
f
0-30 MHz
f - f
RF m
-
25741
f
m
= Modulation frequency
f
IF2
= f
LO1
- f
LO2
- f
RF
- f
m
.
The modulation frequency f
m
changes sign meaning that a received upper sideband signal will pass
through the 10.7 MHz lower sideband IF-filter.
LSB Receiver
IF1 - Filter
70 MHz 10,7 MHz
LSB - Filter
f
-
LO2
80,7 MHz
IF2
f
70-100 MHz
LO1
+
f
0-30 MHz
f - f
RF m
-
25742A
-
+
f
m
= Modulation frequency
f
IF2
= f
LO2
- f
LO1
+ (f
RF
- f
m
)
The modulation frequency f
m
does not change sign meaning that a received lower sideband signal will
pass through the 10.7 MHz lower sideband IF filter.