Transmitter parameter

AN4147

10/14

Doc ID 023516 Rev 1

3.1

Spurious RF conducted emission

According to FCC section 15.231, the field strength of all emissions from intentional

radiators outside the fundamental and the band defined in section 15.205 must be lower

than the values defined in

Table 1. The field strength limits are specified at a distance of 3

meters. The limits on the field strength of the spurious emissions in the

Table 1 are based on

the fundamental frequency of the intentional radiator. Spurious emissions shall be

attenuated to the average limits shown in this table or to the general limits shown in section

15.209, whichever limit permits higher field strength.

According to section 15.33, for an intentional radiator operating below 10 GHz, the

frequency range of measurements must be up to the tenth harmonic of the highest

fundamental or to 40 GHz, whichever is lower. The SPIRIT1 highest fundamental frequency

is 315 MHz, so the tenth harmonic is 3.15 GHz. The measurements are performed up to 5

GHz.

In

Figure 4 and 5 the spurious conducted emissions and the FCC emission mask are

shown. The carrier is unmodulated. The SPIRIT1 is fully compliant with the conducted

spurious emission requirements.

Figure 4.

TX spurious emission below 1 GHz

-90

-80

-70

-60

-50

-40

-30

-20

-10

0.0E+00

1.0E+08

2.0E+083.0E+08

4.0E+08

5.0E+08

6.0E+08

7.0E+088.0E+08

9.0E+08

1.0E+09

Frequency [Hz]

Output power

FCC mask

AM13274v1