AN4126 datasheet(13/28 Pages) STMICROELECTRONICS

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AN4126

Transmitter parameter

Doc ID 023299 Rev 1

13/28

Figure 6.

Full band hopping channels measurement

3.1.4

Frequency hopping systems peak output power

To measure the peak output power, center the spectrum analyzer on a hopping channel and

put the SPIRIT1 into modulated mode. Set the span about 5 times the 20 dB bandwidth

measured, the RBW greater than the 20 dB bandwidth and the VBW equal or greater than

the RBW. The maximum permitted output power is 30 dBm (1 W) for the 50 hopping

channels and 24 dBm (0.25 W) for the 25 hopping channels.

To perform this measurement on the SPIRIT1, the cases with 2-FSK modulation, 250 kbps

data rate and 127 kHz frequency deviation are chosen. The span is set to 2 MHz (4 times

the 20 dB measured bandwidth), the RBW is set to 1 MHz (greater than the 20 dB

bandwidth), and the VBW equal to the RBW. The measured SPIRIT1 output power is 10

dBm. This output power is lower than the maximum permitted output power. An external PA

must be used to reach the maximum output power.

AM13149v1

-60

-50

-40

-30

-20

-10

9.00E+08

9.05E+08

9.10E+08

9.15E+08

9.20E+08

9.25E+08

9.30E+08

Frequency [Hz]

500 kHz hopping

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