EV9800 Datasheet, PDF (20/25 Pages) CML Microcircuits – Evaluation Kit

Evaluation Kit User Manual for CMX980A
EV9800
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Destination: At present, receive data may only be output to a file. For file formats see additional
information section.
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Averages: Displays average I and Q values when a receive sequence is completed.
Hints:
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For Rx to work, values must be written to the gain registers.
If one EV9800 which is transmitting, is connected to a second EV9800 which is receiving, using the
single ended connections for I and Q, the transmit ouput must be attenuated by at least 6dB to avoid
over-driving the receiver.
For data recovery at low signal levels it is necessary to null out any system or device offsets. This can
be achieved using the average I and Q values for no signal then adjusting the offset register values
accordingly. It should be noted that for the CMX980A there is a total gain of 1.55 through the 63 tap low
pass and 63 tap RRC filters, therefore any offset adjustment will need to be divided by 1.55. Also, any
subsequent adjustment in the gain registers will require scaling of the offset values.
1.6.4.5 Notes on recovered symbol data
Note that the algorithm used is not a ‘total’ solution. It is designed to show that real data can be
recovered from the Rx data stream but, for a good signal, should give reasonable BER over a dynamic
range of about 60dB on the Rev B printed circuit boards, slightly less on the Rev A boards.
At present there is no adjustment of offsets or of I and Q vernier settings. The Average I and Q can be
used to manually adjust offsets in the I and Q channels. This becomes necessary when receive levels
fall below approximately 25mVrms.
1.6.5 Additional Information
1.6.5.1 Text File Formats
• Tx symbol data
0,000027<CR,LF>
11<CR,LF>
10<CR,LF>
00<CR,LF> ; etc with one symbol in binary format on each line until the last line, line 27
; in this case, with one binary symbol and no carriage return.
01
• Rx segment information
2,024576<CR,LF>
52<CR,LF>
5A<CR,LF>
89<CR,LF> ; etc with one segment value in hex on each line until the last line, line 24576
; in this case, with one segment value and no carriage return.
46
• Tx or Rx symbol data
1,001024<CR,LF>
6D<CR,LF>
AA<CR,LF>
C8<CR,LF> ; etc with four symbols as an 8-bit value in hex on each line until the last line,
; line 1024 in this case, with an 8-bit hex value and no carriage return.
27
• Rx I and Q values.
3,002048<CR,LF>
FFE2<CR,LF> ; First I value.
02D3<CR,LF> ; First Q value.
© 1999 Consumer Microcircuits Limited
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UM9800/3