RFM92 Datasheet, PDF (43/126 Pages) List of Unclassifed Manufacturers – Low Power Long Range Transceiver Module

RFM92W/93W V3.0
4.2. FSK/OOK Modem
4.2.1. Bit Rate Setting
The bit rate setting is referenced to the crystal oscillator and provides a precise means of setting the bit rate (or equivalently
chip) rate of the radio. In continuous transmit mode (Section 3.2.2) the data stream to be transmitted can be input directly
to the modulator via pin 9 (DIO2/DATA) asynchronously, unless Gaussian filtering is used, in which case the DCLK signal
on pin 10 (DIO1/DCLK) is used to clock-in the data stream. See section 4.2.2.3 for details of the Gaussian filter.
In Packet mode or in Continuous mode with Gaussian filtering enabled, the Bit Rate (BR) is controlled by bits BitRate in
RegBitrateMsb and RegBitrateLsb
BitRate = ---------------------------^F----^X----^O-----^S---^C-----------------------------
Bi
tR at
e(15,0)
+
-----ⁱ--^t--^r--^a----^t--^e---^F----^r--^a----^c-
16
Note: BitrateFrac bits have no effect (i.e may be considered equal to 0) in OOK modulation mode.
The quantity BitrateFrac is hence designed to allow very high precision (max. 250 ppm programing resolution) for any
bitrate in the programmable range. Table 18 below shows a range of standard bitrates and the accuracy to within which
they may be attained.
Table 18 Bit Rate Examples
Type
Classical modem baud rates
(multiples of 1.2 kbps)
Classical modem baud rates
(multiples of 0.9 kbps)
BitRate
(15:8)
0x68
0x34
0x1A
0x0D
0x06
0x03
0x01
0x00
0x02
0x01
BitRate
(7:0)
0x2B
0x15
0x0B
0x05
0x83
0x41
0xA1
0xD0
0x2C
0x16
(G)FSK
(G)MSK
1.2 kbps
2.4 kbps
4.8 kbps
9.6 kbps
19.2 kbps
38.4 kbps
76.8 kbps
153.6 kbps
57.6 kbps
115.2 kbps
OOK
1.2 kbps
2.4 kbps
4.8 kbps
9.6 kbps
19.2 kbps
Actual BR
(b/s)
1200.015
2400.060
4799.760
9600.960
19196.16
38415.36
76738.60
153846.1
57553.95
115107.9
Page 43
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