RFM92 Datasheet, PDF (44/126 Pages) List of Unclassifed Manufacturers – Low Power Long Range Transceiver Module

RFM92W/93W V3.0
Type
Round bit rates
(multiples of 12.5, 25 and
50 kbps)
Watch Xtal frequency
BitRate
(15:8)
0x0A
0x05
0x80
0x01
0x00
0x00
0x00
0x00
0x03
BitRate
(7:0)
0x00
0x00
0x00
0x40
0xD5
0xA0
0x80
0x6B
0xD1
(G)FSK
(G)MSK
12.5 kbps
25 kbps
50 kbps
100 kbps
150 kbps
200 kbps
250 kbps
300 kbps
32.768 kbps
OOK
12.5 kbps
25 kbps
32.768 kbps
Actual BR
(b/s)
12500.00
25000.00
50000.00
100000.0
150234.7
200000.0
250000.0
299065.4
32753.32
4.2.2. FSK/OOK Transmission
4.2.2.1. FSK Modulation
FSK modulation is performed inside the PLL bandwidth by changing the fractional divider ratio in the feedback loop of the
PLL. The high resolution of the sigma-delta modulator allows for very narrow frequency deviation. The frequency deviation
F_DEV is given by:
F_DEV = F_STEP × Fdev(13,0)
To ensure correct modulation the following limit applies:
F_{DE V}
+
-----^R--
2
≤
( 250 ) k H z
Note No constraint applies to the modulation index of the transmitter, but the frequency deviation must be set between
600 Hz and 200 kHz.
4.2.2.2. OOK Modulation
OOK modulation is applied by switching on and off the power amplifier. Digital control and ramping are available to improve
the transient power response of the OOK transmitter.
4.2.2.3. Modulation Shaping
Modulation shaping can be applied in both OOK and FSK modulation modes to improve the narrowband response of the
transmitter. Both shaping features are controlled with PaRamp bits in RegPaRamp.
Š In FSK mode, a Gaussian filter with BT = 0.5 or 1 can be used to filter the modulation stream, at the input of the sigma-
delta modulator. If the Gaussian filter is enabled when the RFM92W/93W is in Continuous mode, DCLK signal on pin
10 (DIO1/DCLK) will trigger an interrupt on the uC each time a new bit has to be transmitted. Please refer to section
5.4.2 for details.
Š When OOK modulation is used the PA bias voltages are ramped up and down smoothly when the PA is turned on and
off to reduce spectral splatter.
Page 44
Tel: [phone] Fax: [phone] E-mail: [e-mail] http://www.hoperf.com