Transmitter parameter

AN4126

14/28

Doc ID 023299 Rev 1

Figure 7.

Peak output power measurement

3.1.5

Frequency hopping systems 100 kHz bandwidth of band edges

conducted emission

According to part 15.247, in any 100 kHz bandwidth outside the frequency bands in which

the spread spectrum intentional radiator is operating, the radio frequency power that is

produced by the intentional radiator must be at least 20 dB below that in the 100 kHz

bandwidth within the band that contains the highest level of the desired power. In addition,

radiated emissions which fall in the restricted bands, as defined in part 15.205, must also

comply with the radiated emission limits specified in part 15.209.

To perform these measurements, select the channels closest to the frequency band edges

at 902 MHz and 928 MHz. Set the span to be wide enough to observe the peak level of the

emission on the channel closest to the band edge as well as any modulation products that

fall outside the authorized band of operation. The RBW (resolution bandwidth) is set to 100

kHz, and the VBW is set to 100 kHz or greater. The measurements are performed at 902

and 928 MHz with a data rate of 250 kbps, a frequency deviation of 127 kHz and a 2-FSK

modulation. In

Figure 8 and 9 the measured spectrums are shown. The conducted

emissions in the band edges are lower than 20 dB integrated in 100 kHz bandwidth, making

the SPIRIT1 usable for FCC part 15.247.

AM13151v1

-10

-5

0

5

10

15

20

9.140E+08

9.145E+08

9.150E+08

9.155E+08

9.160E+08

Frequency [Hz]

2-FSK, 250 kbps, 127 kHz