DocID025421 Rev 1

9/19

AN4378

Transmitter parameter

19

3.3

Maximum power spectral density level in the fundamental

emission

The power spectral density conducted from the intentional radiator to the antenna shall not

be greater than 8 dBm in any 3 kHz band during any time interval of continuous

transmission. By rule, the same method as used to determine the conducted output power

shall be used to determine the power spectral density, i.e. if maximum peak conducted

output power was measured, then the peak PSD procedure shall be used; and if maximum

conducted output power was measured, then the average PSD procedure shall be used.

In this document, the maximum peak conducted output power is measured, so the peak

power spectral density measurement method is applied.

To perform this measurement, center the spectrum analyzer center frequency on the

desired channel. Set the span to 1.5 times the BlueNRG channel bandwidth. Set the RBW

greater than or equal to 3 kHz. Set the VBW greater than or equal to 3 times the RBW. The

detector must be set to peak and the trace set to max hold. Use the peak marker function to

determine the maximum amplitude level. If the measured value exceeds the limit, reduce

RBW (not less than 3 kHz) and repeat.

The measurement result is shown in Figure 6. The BlueNRG meets the power spectral

density requirement by a large margin.

Figure 6. Power spectral density measurement

AM17621v1

-60

-50

-40

-30

-20

-10

0

2.4005E+09

2.4010E+09

2.4015E+09

2.4020E+09

2.4025E+09

2.4030E+09

2.4035E+09

Frequency [Hz]