Rainbow Electronics RF22 - Manual (Page 32)

RF22
Version: 0.1 Date: 12/23/2008
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468.4 1 11
518.8 1 12
577 1 13
620.7 1 14
The proper settings for ndec[2:0] are listed in Table 19 where Rb is the data rate (Rb) which is doubled when
Manchester coding is enabled.
Table19. ndec[2:0] Settings
Rb(1+ enmanch) [kbps]
Min
Max
ndec[2:0]
0 1 5
1 2 4
2 3 3
3 8 2
8 40 1
40 65 0
The clock recovery oversampling rate is set via rxosr[10:0] in "Register 20h. Clock Recovery Oversampling Rate" and
"Register 21h. Clock Recovery Offset 2". ndec_exp and dwn3_bypass together with the receive data rate (Rb) are
used to calculate rxosr:
( )
( )
enmanch Rb
bypass dwn
rxosr
ndec + Ч Ч
Ч + Ч
=
−
1 2
_ 3 2 1 500
3 exp _
Where: Rb is in kbps and enmanch is the Manchester Coding parameter. The resulting rxdr[10:0] value should be
rounded to an integer hexadecimal number.
The clock recovery offset ncoff[19:0] in "Register 21h. Clock Recovery Offset 2", "Register 22h. Clock Recovery Offset
1", and "Register 23h. Clock Recovery Offset 0" is calculated as follows:
( )
( )
bypass dwn
enmanch Rb
ncoff
ndec
_ 3 2 1 500
2 1 exp _ 20
Ч + Ч
Ч + Ч
=
+
Where: Rb is in kbps.
The clock recovery gain crgain[10:0] in "Register 24h. Clock Recovery Timing Loop Gain 1" and "Register 25h. Clock
Recovery Timing Loop Gain 0" is calculated as follows:
rxosr
crgain
16 2
2
+ =
Table20. RX Modem Configuration for OOK with Manchester Disabled
RX Modem Setting Examples for OOK (Manchester Disabled)
Appl Parameters Register Values
Rb RX BW dwn3_bypass ndec_exp[2:0] filset[3:0] rxosr[10:0] ncoff[19:0] crgain[10:0]
[kbps] [kHz] 1Ch 1Ch 1Ch 20,21h 21,22,23h 24,25h
1.2 75 0 4 1 0D0 09D49 13D
1.2 110 0 4 5 0D0 09D49 13D
1.2 335 1 4 8 271 0346E 06B
1.2 420 1 4 A 271 0346E 06B
1.2 620 1 4 E 271 0346E 06B
2.4 335 1 3 8 271 0346E 06B
4.8 335 1 2 8 271 0346E 06B
9.6 335 1 1 8 271 0346E 06B
10 335 1 1 8 258 0369D 06F
15 335 1 1 8 190 051EC 0A6