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4430-V & VN BPSK/QPSK VME Demodulator & Optional Modulator User’s Manual
Doc: 4430_V,VN.fm, © 11 Jul 2005, 14:55
3.5.9
Register 3Dh (7Bh), NCO Strobe
This register is used to load or “strobe” the demodulator and modulator NCO
register settings.
Figure 3.5.9
illustrates the breakout of register bit assignments.
Once the NCO registers have been written and the phase accumulators have
been reset, the appropriate NCO strobes must be set to one then subsequently
written as zeros to complete the NCO load. The load is rising edge triggered.
Figure 3.5.9: Register 3Dh Bit Assignments
Table 3.5.9: NCO Strobe Register Definition
Programming
Example
For the programming example given, the following sequence would be pro-
grammed in this register:
1.
Strobing the NCO clock low: Register 3Dh= 00010000b =10h
2.
Strobing the NCO clock high: Register 3Dh= 01110000b =70h
Bit No.
Bit Name(s)
Functional Description
07
Unused
Set to zero for proper operation
06
Demod NCO
0 - Strobe low
1 - Strobe high
05
Quad NCO
0- Strobe low
1- Strobe high
04
Mod NCO
0- Strobe low
1- Strobe high
00-03
Not used.
7
6
5
4
3
2
1
0
-
-
-
-
0/1
0/1
0/1
-
Unused
Unused
Unused
Unused
Modulator NCO Strobe
Quadrature NCO Strobe
Carrier Frequency NCO Strobe
Unused
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