Transmitter parameters

AN4103

8/20

Doc ID 023130 Rev 1

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

standard conformity with a bandwidth

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

- fc is the emission center frequency

- fe is the sub-band edge frequency

- Only the upper half of the emission is shown. The lower half is a mirror image.

NOTE:

fc

fe

fe+200 kHz

fe+400 kHz

fe+1 MHz

-30dBm/1kHz

-36dBm/1kHz

-36dBm/10kHz

-36dBm/100kHz

AM16349v1