RFM67W Datasheet, PDF (12/37 Pages) List of Unclassifed Manufacturers – ISM TRANSMITTER MODULE

ADVANCED COMMUNICATIONS & SENSING
RFM 67W
DATASHEET
5. Operation of the RFM67W
The RFM67W is an integrated ISM band transmitter module and features a fully integrated frequency synthesizer,
modulator and power amplifier. This section describes the operation of the RFM67W and the functionality of these blocks.
5.1. Main Parameters
5.1.1. Center Frequency
The carrier output center frequency, f_RF, of the RFM67W is programmable via the SPI interface. It is determined by
the following equation:
where freq_rf(23:0) is the decimal value of the 24 bit number stored in configuration registers FrfMsb, FrfMid and FrfLsb
and f_XOSC is the frequency of the crystal oscillator. If the optimal value of 32 MHz is selected for the crystal oscillator, then
this results in a programmable frequency resolution of 61.035 Hz.
Note that RF output frequencies are only valid in the bands 290-340 MHz, 431-510 MHz and 862-1020 MHz. Note also,
that for ease of use, the band selection process is performed automatically.
5.1.2. Frequency Deviation
The frequency deviation of the RFM67W in FSK mode is given by the following
equation:
where df_coeff is the decimal value of the 14 bit contents of the FdevLsb and FdevMsb configuration registers.
5.1.3. Bit Rate
The bit rate (or, depending upon coding, the chip rate) of the RFM67W is given by the following equation:
where f_XOSC is the crystal oscillator frequency, br_ratio is the decimal value of the 16 bit contents of registers BrMsb and
BrLsb. Note that for OOK modulation the maximum bit rate is 32.7 kbps which corresponds to a br_ratio(15:0) of 979.
The table below gives examples of some of the standard data rates accessible with RFM67W.
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