RF31 Hope Microelectronics co., Ltd, RF31 Datasheet - Page 37

• Manufacturer Part Number: RF31
• Description: Rf31 Ism Receiver
• Manufacturer: Hope Microelectronics co., Ltd

7. RX Modem Configuration
7.1. Modem Settings for FSK and GFSK
The modem performs channel selection and demodulation in the digital domain. The channel filter bandwidth is
configurable from 620 to 2.6 kHz. The data-rate, modulation index, and bandwidth are set via registers 1C–25. The
modulation index is equal to 2 times the peak deviation divided by the data rate (Rb).
Table 15 gives the modem register settings for various common data-rates. Select the desired data-rate (Rb), and
Deviation (Fd) to determine the proper register settings. For data-rates and modulation types not listed in the table
a calculator tool within EXCEL can be used.
When Manchester coding is disabled, the required channel filter bandwidth is calculated as BW = 2 x (Fd + 0.25Rb)
where Fd is the frequency deviation and Rb is the data rate. For modulation indices below 1 the required channel
filter bandwidth is calculated as BW = Fd + Rb. The channel filter needs to be increased when the frequency offset
between transmitter and receiver is more than half the channel filter bandwidth. In this case it is recommended to
enable the AFC and choose the IF bandwidth equal to 2 x frequency offset.
kbps
19.2
38.4
57.6
100
100
125
2.4
2.4
4.8
4.8
9.6
9.6
Rb
10
10
20
20
40
40
50
2
Application parameters
19.6
28.8
300
125
kHz
4.8
4.8
4.8
9.6
Fd
36
45
45
40
10
40
20
40
25
50
5
5
Tel: [phone]
mod index
30.00
18.75
5.00
4.00
2.00
1.00
9.38
1.00
8.00
1.00
1.00
4.00
1.02
1.00
2.00
1.00
1.00
1.00
6.00
2.00
Table 15. RX Modem Configurations for FSK and GFSK
BW -3dB
112.1
191.5
620.7
335.5
11.5
11.5
75.2
12.1
95.3
18.9
95.3
18.9
37.7
37.7
95.3
75.2
75.2
75.2
kHz
90
90
Fax: [phone]
RX Modem setting examples for GFSK and FSK
dwn3_bypass
1Ch
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
ndec_exp[2:0]
E-mail: [e-mail]
1Ch
3
3
0
3
0
2
0
2
0
1
1
0
0
0
0
0
0
0
0
0
Register values (hex)
filset[3:0]
1Ch
E
3
3
1
4
4
1
4
1
3
1
1
4
1
1
5
1
3
F
8
rxosr[10:0]
20,21h
0FA
0D0
1A1
0C8
http://www.hoperf.com
683
068
341
068
064
190
068
064
068
064
064
050
045
078
078
060
R F 3 1
ncoff[19:0]
21,22,23h
1D7DC
09D49
04EA5
147AE
051EC
147AE
0A3D7
147AE
147AE
013A9
13A93
13A93
13A93
13A93
1999A
08312
02752
11111
11111
15555
crgain[10:0]
24,25h
4EE
4EE
2AD
06B
0A0
00A
02B
0A6
4D5
76E
0B8
005
278
024
521
521
521
291
668
446
37