LDI Intellectual Property.
Not for secondary distribution or replication, in part or entirety.
DIGISONDE-4D
SYSTEM MANUAL
VERSION 1.2.11
4-16 SECTION 4 – HARDWARE DESCRIPTION
Figure 4-12: Tracking Bandpass Filter PCB
PREPROCESSOR CARD
4:28. The Preprocessor card has been developed for the DPS4D as a part of our strategic use of dedicated
digital signal processing (DSP) hardware to build low-power, light-weight instrumentation. The pre-
processor performs all data formatting, routing, buffering, and output function selections, along with Radio
Frequency Interference Mitigation (RFIM) processing.
Functional Description
4:29. Figure 4-13 shows the block diagram of the Preprocessor card assuming twin frequency operation.
The gray blocks represent functions that are implemented inside FPGA. Since the Graychips each output 16-
bit samples as a sequence of four 4-bit nibbles, the first Preprocessor operation assembles the nibbles into
16-bit words. Next, the two simultaneous receiver sample streams are interleaved with receiver 1 samples
followed by receiver 2 samples. Then the interleaved samples are written to memory 1 sorted by receiv-
er/antenna. At the end of the first sample record, the Preprocessor switches to copying mode and simply cop-
ies memory 1 into memory 2. After the copy, the Preprocessor switches back to sampling mode. During the
next sampling interval, the second sample record is stored in memory 1 while the previous sample record is
read from memory 2 to the control computer
To Next Page
Loading...
General