RF42/43
3.6.5. Frequency Offset Adjustment
A frequency offset can be adjusted manually by fo[9:0] in registers 73h and 74h. The frequency offset adjustment is
implemented by shifting the Synthesizer Local Oscillator frequency. This register is a signed register so in order to get
a negative offset you will need to take the twos complement of the positive offset number. The offset can be calculated
by the following:
DesiredOffset = 156.25Hz x (hbsel + 1) x fo[9 : 0]
DesiredOffset
156.25Hz x (hbsel + 1)
fo[9 : 0] =
The adjustment range in high band is: ±160 kHz, and adjustment range in low band is: ±80 kHz. For example to
compute an offset of +50 kHz in high band mode fo[9:0] should be set to 0A0h. For an offset of –50 kHz in high band
mode the fo[9:0] register should be set to 360h.
Notes
Function/Descri
ption
D7
D6
D5
D4
D3
D2
D1
D0
POR Def.
Add R/W
R/W
00h
43h
73
Frequency Offset
Frequency Offset
fo[7] fo[6]
fo[5]
fo[4]
fo[3]
fo[2]
fo[1]
fo[9]
fo[1]
fo[8]
73
R/W
74
3.6.6. TX Data Rate Generator
The data rate is configurable between 1–128 kbps. For data rates below 30 kbps the‖txdtrtscale‖ bit in register
70hshould be set to 1. When higher data rates are used this bit should be set to 0.
The TX date rate is determined by the following formula:
txdr[15:0] x1MHz
DR_ TX =
16+5*xdtrtscale
2
DR_ TX X 2 16+5*xdtrtscale
txdr[15:0] =
1MHz
The txdr register may be found in the following registers.
Function/Des
D7
D6
D5
D4
D3
D2
D1
D0
POR Def.
Add R/W
cription
TX Data Rate 1 txdr[15] txdr[14] txdr[13] txdr[12] txdr[11] txdr[10] txdr[9]
TX Data Rate 0 txdr[7] txdr[6] txdr[5] txdr[4] txdr[3] txdr[2] txdr[1]
R/W
txdr[8]
txdr[0]
0Ah
AAh
6E
R/W
6F
24
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