Service manual

Chapter 4: System Overview 29
CW Doppler Processing
CW Doppler data will be presented to the signal processor as complex (I/Q) data from the analog front end of the
external DSP. The 16-bit data will be presented as consecutive samples at a data rate varying from 1.5 kHz to 64
kHz for the complex pair. Most of CW processing is similar to that of PW except for the QBP function. In place of
QBP will be a low pass decimating filter that operates on incoming I/Q data.
The Doppler Processing block must allow storage of 128 undetected I/Q pairs in to allow the system to measure
and correct for phase mismatch. Measuring and correcting will need to be accomplished in system software.
Figure 4.4 CW Doppler Processing Function Block Diagram
Wall Filter/
I-V
I
Q
Q
I
I Sum
QSum
A/D Filter
Q
I
Q
I
Q
I
Sample Clock
A/D
A/D
Complex
BP PRF
Filter
Q
I
To Doppler
Processing
Amplifier
Other Channel with
same Delay
LO Gen
Freq
Delay
Master Clk
LO I
LO Q
Amplifier
Other Channel with
same Delay
LO Gen
Freq
Delay
Master Clk
LO I
LO Q
Mux
Mux
CW Asic PCB DSP
Wall Filter/
I-V
I
Q
Q
I
I Sum
QSum
A/D Filter
Q
I
Q
I
Q
I
Sample Clock
A/D
A/D
Complex
BP PRF
Filter
Q
I
To Doppler
Processing
Amplifier
Other Channel with
same Delay
LO Gen
Freq
Delay
Master Clk
LO I
LO Q
Amplifier
Other Channel with
same Delay
LO Gen
Freq
Delay
Master Clk
LO I
LO Q
Mux
Mux
CW Asic
PCB
DSP