Linx Technologies TRM-xxx-NT - Manual (Page 13)

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European Transmission Rules
While the FCC does not have any requirements other than power
and harmonic levels for the 900MHz band, European rules are more
complicated. The 863 to 870MHz band is subdivided into other bands that
are designated for specific applications. These sub bands can be used for
generic devices provided they meet one of two requirements.
The first requirement is duty cycle, which is defined as the amount of time
the transmitter is on per hour. The duty cycle is different for the different
bands and ranges from 0.1% to 10%.
The other option is that the transmitter implement Listen-Before-Talk (LBT)
optionally combined with Adaptive Frequency Agility (AFA). This basically
means that the transmitter will listen to a channel to be sure that it is clear
before transmitting (LBT). If the channel is occupied by another transmitter,
then it will wait until the channel is clear or change to another channel to
transmit its data (AFA).
The NT Series does not implement LBT or AFA, but these features can
be added to a microcontroller outside the module. Implementing these
eliminates the need to track the transmit time to ensure compliance with
the duty cycle limits.
Figure 27 lists the 868MHz channels and their duty cycle requirements if
LBT is not implemented. It is recommended that the designer review ETSI
EN 300 220-1 for the full requirements.
900MHz Channel Selection
CHN_SEL2 CHN_SEL1 CHN_SEL0 CHANNEL FREQUENCY
0 0 0 3 903.37
0 0 1 15 906.37
0 1 0 21 907.87
0 1 1 27 909.37
1 0 0 39 912.37
1 0 1 51 915.37
1 1 0 69 919.87
1 1 1 75 921.37
Figure 26: NT Series Transceiver 900MHz Channel Selection
868MHz Channel Selection
Channel Frequency D.C. Channel Frequency D.C.
0 863.15 0.10% 34 866.55 0.10%
1 863.25 0.10% 35 866.65 0.10%
2 863.35 0.10% 36 866.75 0.10%
3 863.45 0.10% 37 866.85 0.10%
4 863.55 0.10% 38 866.95 0.10%
5 863.65 0.10% 39 867.05 0.10%
6 863.75 0.10% 40 867.15 0.10%
7 863.85 0.10% 41 867.25 0.10%
8 863.95 0.10% 42 867.35 0.10%
9 864.05 0.10% 43 867.45 0.10%
10 864.15 0.10% 44 867.55 0.10%
11 864.25 0.10% 45 867.65 0.10%
12 864.35 0.10% 46 867.75 0.10%
13 864.45 0.10% 47 867.85 0.10%
14 864.55 0.10% 48 867.95 0.10%
15 864.65 0.10% 49 868.05 1%
16 864.75 0.10% 50 868.15 1%
17 864.85 0.10% 51 868.25 1%
18 864.95 0.10% 52 868.35 1%
19 865.05 0.10% 53 868.45 1%
20 865.15 0.10% 54 868.55 1%
21 865.25 0.10% 55 868.65 0.10%
22 865.35 0.10% 56 868.75 0.10%
23 865.45 0.10% 57 868.85 0.10%
24 865.55 0.10% 58 868.95 0.10%
25 865.65 0.10% 59 869.05 0.10%
26 865.75 0.10% 60 869.15 0.10%
27 865.85 0.10% 61 869.25 0.10%
28 865.95 0.10% 62 869.35 0.10%
29 866.05 0.10% 63 869.45 10%
30 866.15 0.10% 64 869.55 10%
31 866.25 0.10% 66 869.75 None/ 1%*
32 866.35 0.10% 67 869.85 None/ 1%*
33 866.45 0.10% 68 869.95 None / 1%*
Figure 27: NT Series Transceiver 868MHz Serial Channels and Duty Cycle Requirements
* No duty cycle limit at 5mW max power, 1% limit at 25mW max power.
Dark Gray = Hardware Selectable Channels