Transmitter parameter

AN4126

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Doc ID 023299 Rev 1

Figure 19.

Peak output power at -1 dBm measurement

3.3.2

Conducted harmonics and other harmonics emissions

The maximum permitted field strength of harmonic components for the device working on

the 902 - 928 MHz band is 500 µV/m at 3 m distance: this equates to a conducted power

level of about -41 dBm.

Emissions radiated outside the specified frequency band, except for harmonics, must be

attenuated by at least 50 dB below the level of the fundamental or to the general radiated

emission limits in part 15.209, whichever has the lesser attenuation. According to part

15.33, for an intentional radiator operating below 10 GHz, the frequency range of

measurements must be until the tenth harmonic of the highest fundamental or to 40 GHz,

whichever is lower. The SPIRIT1’s highest fundamental frequency is 928 MHz, so the tenth

harmonic is 9.28 GHz which is the frequency range of measurement.

In

Figure 20 and 21 the harmonics and other harmonics conducted emissions are shown.

The FCC emission mask in accordance with part 15.249 and 15.209 requirements is also

reported. The carrier is modulated with a 2-FSK modulation with a data rate of 500 kbps and

a frequency deviation of 250 kHz. The SPIRIT1 fully complies with the conducted spurious

emission requirements. Pay attention to

Figure 21 as it may seem that the 2nd harmonics

doesn't meet the specification. The requirement for this spurious level is -41 dBm as the

maximum level, the spurious level is -43 dBm, so the specification is met.

AM13163v1

-16

-14

-12

-10

-8

-6

-4

-2

0

2

4

6

9.140E+08

9.145E+08

9.150E+08

9.155E+08

9.160E+08

Frequency [Hz]

2-FSK, 500 kbps, 250 kHz