AN4103 Datasheet, PDF (8/20 Pages) STMicroelectronics – Using the SPIRIT1 transceiver under EN 300 220 at 169 MHz

Transmitter parameters
AN4103
2.2
Modulation bandwidth
The range of the modulation bandwidth includes all associated side bands above the
appropriate emissions level and the frequency error or drift under extreme test conditions.
The frequency drift in extreme test conditions primarily depends on the crystal quality, which
is not included in this report.
This measurement applies to equipment not covered by adjacent channel power
measurement for the narrowband systems. In the 169.400 MHz to 169.475 MHz band it is
possible to works with a band ≤ 50 kHz (the narrowband system has a band ≤ 25 kHz), so
standard conformity with a bandwidth ≥ 25 kHz is necessary.
Figure 6 illustrates the ETSI spectral mask with which the radio must comply at the sub-
band edges. Basically, there are only two limit thresholds, what changes is the bandwidth of
integration at the different offset regions.
The same spectral mask is shown in Figure 7 as well. The device center frequency is 169.4
MHz, the data rate is set to 20 kbps, the frequency deviation is set to 10 kHz, the modulation
is set to Gaussian FSK (GFSK) with a BT = 0.5. The applied output power is set to 11 dBm.
With these parameters, the spectral mask of SPIRIT1 complies with ETSI [2] subclause 7.7.
Figure 6.
ETSI spectral mask measurement limits and sub-band edges
NOTE:
- fc is the emission center frequency
AM16349v1
- fe is the sub-band edge frequency
- Only the upper half of the emission is shown. The lower half is a mirror image.
-30dBm/1kHz
-36dBm/1kHz
-36dBm/10kHz
-36dBm/100kHz
fc
fe
fe+200 kHz
fe+400 kHz
fe+1 MHz
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Doc ID 023130 Rev 1