CMX7163 QAM Modem
CMX7163
Only if P4.8 b1=0 then this controls the delay in indicating Tx Done and Tx Last Tail indications, in units of
1.2 symbol times. The default value makes Tx Done indication coincide with when the end of the last data
field symbol analog signal is produced at the CMX7164 IOUTPUT and QOUTPUT pins when the default
Tx pulse shaping filter is engaged. The user may adjust this parameter value to suit the different delay of
any other different pulse shaping filter used.
P4.10: Offset tx end sequence start time
Adjusts the tx end sequence start time to be earlier than the default time. Adjustment is in symbols.
Program Block 5 – Burst Tx Sequence. To reduce calibration time a calibration sequence may be
configured that omits some stages of the calibration process. However there must always be a Setup and
TidyUp stage, and if ErrorQHi and ErrorIHi are included then the High gain stage must be included as well.
The registers used during Tx dc offset calibration are:
10.1.18 Modem Mode and Control - $6B write
0
P4.8: Set legacy timing mode
b0
b1
ADC Sample
Delay
0 - minimal delay mode (gives a delay of 1.2 symbol times)
1 - legacy delay mode (gives a delay of 8.2 symbol times)
Tx Done and
Tx Last Tail
indication
timing
0-Selects minimal jitter of +/-0.6 symbol times for Tx Done and Tx Last Tail
indication timing.
Enables the use of the P4.9 delay adjustment control for Tx Done and Tx
Last Tail indication timing. Adjusting these delays enables indication timing to
be changed to better match any changes in Tx pulse shaping filter delay or
for other user purposes.
1-legacy timing delay mode (delay not specified; delay and jitter behaviours will
be consistent so long as the number of data field symbols, number of tail
symbols, and other factors are not changed)
b2-15
Reserved
Reserved – set to 1
P4.9: Set Tx Done delay
Only if P4.8 b1=0 then this controls the delay in indicating Tx Done and Tx Last Tail indications, in units of
1.2 symbol times. The default value makes Tx Done indication coincide with when the end of the last data
field symbol analog signal is produced at the CMX7164 IOUTPUT and QOUTPUT pins when the default
Tx pulse shaping filter is engaged. The user may adjust this parameter value to suit the different delay of
any other different pulse shaping filter used.
P4.10: Offset tx end sequence start time
Adjusts the tx end sequence start time to be earlier than the default time. Adjustment is in symbols.
Program Block 5 – Burst Tx Sequence
10.1.30 I/Q Offset - $75, $76 read
10.1.8 I/Q Output Control - $5D, $5E write
7.4.12 Other Modem Modes
Tx Preamble
In Tx mode a transmit preamble feature is provided to aid setup – the preamble may be programmed to
any useful repeating 8-bit pattern.
2014 CML Microsystems Plc
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CMLMICRO [ CML MICROCIRCUITS ]
