User manual

7-6 Section 7: System Description
Moseley SL9003Q 602-12016 Revision G
The resultant carrier is translated up to 70 MHz by the IF Upconverter daughter card (located in
the same module). This is accomplished by a standard mixing of the carrier with a phase-
locked LO. A 70 MHz SAW filter provides an exceptional, spectrally-clean output signal.
7.6.4. Transmit Module (Upconverter)
12.8 MHz Ref Osc
BPF
950 MHz
70 MHz IF
Input
uP
RFA Fw d Pw r Level
IPA Level
Synth Level
Temp Sense
Synth Lock
RF Output
944-952 MHz
TX A LC
BPF
70 MHz
BPF
950 MHz
Diple xe r
NMS
Synth Data
Synth Enbl
PLL
Loop
Filter
VCO
880 MHz PLL
Synth Lock
Synth Level
Data
Clk
Enbl
Ref
RFA Rev Pw r Level
Synth Clk
Figure 7-4 Transmit Module (Upconverter) Block Diagram
The RF output carrier of the IF Upconverter is fed to the Upconverter via an external (rear
panel) semi-rigid SMA cable. This module performs the necessary conversion to the carrier
frequency. There is an on-board CPU for independent control of the critical RF parameters of
the system.
Since this is a linear RF processing chain, an automatic leveling control loop (ALC) is
implemented here to maintain maximum available power output (and therefore maximum
system gain). The ALC monitors the PA forward power (FWD) output sample, and controls the
Upconverter gain per an algorithm programmed in the CPU. The ALC also controls the power-
up RF conditions of the transmitter output.