Si1000/1/2/3/4/5
Table 23.3. Frequency Band Selection (Continued)
9
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
330–339.9 MHz
340–349.9 MHz
350–359.9 MHz
360–369.9 MHz
370–379.9 MHz
380–389.9 MHz
390–399.9 MHz
400–409.9 MHz
410–419.9 MHz
420–429.9 MHz
430–439.9 MHz
440–449.9 MHz
450–459.9 MHz
460–469.9 MHz
470–479.9 MHz
660–679.9 MHz
680–699.9 MHz
700–719.9 MHz
720–739.9 MHz
740–759.9 MHz
760–779.9 MHz
780–799.9 MHz
800–819.9 MHz
820–839.9 MHz
840–859.9 MHz
860–879.9 MHz
880–899.9 MHz
900–919.9 MHz
920–939.9 MHz
940–960 MHz
10
11
12
13
14
15
16
17
18
19
20
21
22
23
The chip will automatically shift the frequency of the Synthesizer down by 937.5 kHz (30 MHz ÷ 32) to
achieve the correct Intermediate Frequency (IF) when RX mode is entered. Low-side injection is used in
the RX Mixing architecture; therefore, no frequency reprogramming is required when using the same TX
frequency and switching between RX/TX modes.
23.3.3. Easy Frequency Programming for FHSS
While Registers 73h–77h may be used to program the carrier frequency of the transceiver, it is often easier
to think in terms of “channels” or “channel numbers” rather than an absolute frequency value in Hz. Also,
there may be some timing-critical applications (such as for Frequency Hopping Systems) in which it is
desirable to change frequency by programming a single register. Once the channel step size is set, the fre-
quency may be changed by a single register corresponding to the channel number. A nominal frequency is
first set using Registers 73h–77h, as described above. Registers 79h and 7Ah are then used to set a chan-
nel step size and channel number, relative to the nominal setting. The Frequency Hopping Step Size
(fhs[7:0]) is set in increments of 10 kHz with a maximum channel step size of 2.56 MHz. The Frequency
Hopping Channel Select Register then selects channels based on multiples of the step size.
Fcarrier Fnom fhs[7 :0]( fhch[7 :0]10kHz)
For example: if the nominal frequency is set to 900 MHz using Registers 73h–77h and the channel step
size is set to 1 MHz using "Register 7Ah. Frequency Hopping Step Size". For example, if the "Register
79h. Frequency Hopping Channel Select" is set to 5d, the resulting carrier frequency would be 905 MHz.
Once the nominal frequency and channel step size are programmed in the registers, it is only necessary to
program the fhch[7:0] register in order to change the frequency.
Rev. 1.0
247
SILICON [ SILICON ]
