58
4430-V & VN BPSK/QPSK VME Demodulator & Optional Modulator User’s Manual
Doc: 4430_V,VN.fm, © 11 Jul 2005, 14:55
4.
Write the value to the register.
Programming
Example
For the programming example given, the following steps apply:
1.
Calculating the value for R
in
:
For the 4430-VN
R
in
= ((2.55 x 10
-5
) x (Demod f
C
))/(LBW
2
x C)
R
in
= ((2.55 x 10
-5
) x (8000))/(4
2
x 6.8 x 10
-7
)
R
in
= 18750
2.
Calculating the value for R3 and rounding:
R
3
= 1 x 10
6
/R
in
R
3
= 1 x 10
6
/18750 = 53.4 = 53
3.
Using
Figure 3.5.18
Register 33h Bit Assignments on page 57
the bit values are
determined as follows:
a. 53 - 27 = 26 (Bit 3 is set to a “1”)
b. 26 - 9 = 17 (Bit 2 is set to a “1”)
c. 17 - 3 = 14 (Bit 1 is set to a “1”)
d. 14 - 1 = 13 (Bit 0 is set to a “1”)
e. 81 - 53 = 28
f. Since the results of Step d. are less than that of Step e., the addition of the
bit weights of bits 0 through 4 are a closer approximation to the value of R
3
than the value of 81.
4.
Set bits 0 through 6 according to Step 3 results and write the following value
to register 33h:
Register 33h = 00001111b = 0Fh
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