Instruction Manual

7.1.2 Conducted Power Measurements with Modulated Carrier
Depending on the applied modulation scheme and the spectrum analyzer settings specified by the relevant EMC regulations, the meas-
ured power levels are usually lower compared to the results with unmodulated carrier. These differences are measured and used as
relaxation factors on the results of the radiated measurement performed with unmodulated carrier. This way, the radiated compliance
with modulated transmission can be evaluated.
In this case, both the ETSI EN 300-328 and the FCC 15.247 regulations define the following spectrum analyzer settings for measuring
the unwanted emissions above 1 GHz:
• Detector: Average
• RBW: 1 MHz
The table below shows the measured differences for the supported modulation schemes.
Table 7.1. Measured Relaxation Factors for the Supported Modulation Schemes
Applied Modulation
(Packet Length:
255 bytes)
BLE Coded PHY:
125 Kb/s (PRBS9) [dB]
BLE Coded PHY:
500 Kb/s (PRBS9) [dB]
BLE 1M PHY: 1 Mb/s
(PRBS9) [dB]
BLE 2M PHY: 2 Mb/s
(PRBS9) [dB]
2nd harmonic -2.7 -3.1 -3.3 -9.1
3rd harmonic -4.8 -5.2 -5.2 -10.7
4th harmonic -5.5 -6.5 -6.7 -11.9
5th harmonic -6.3 -6.5 -6.7 -11.4
As shown, the BLE 125 Kb/s coded modulation scheme has the lowest relaxation factors. These values will be used as the worst case
relaxarion factors for the radiated measurements.
7.2 Radiated Power Measurements
During measurements, the BRD4186C Radio Board was attached to a Wireless Starter Kit Mainboard which was supplied by USB. The
voltage supply for the radio board was 3.3 V, for the power amlifier (PAVDD) it was 1.8 V. The radiated power was measured in an
antenna chamber by rotating the board 360 degrees with horizontal and vertical reference antenna polarizations in the XY, XZ, and YZ
cuts. The measurement planes are illustrated in the figure below.
X
Z
Y
Figure 7.2. Illustration of Reference Planes with a Radio Board
Note: The radiated measurement results presented in this document were recorded in an unlicensed antenna chamber. Also, the radi-
ated power levels may change depending on the actual application (PCB size, used antenna, and so on). Therefore, the absolute levels
and margins of the final application are recommended to be verified in a licensed EMC testhouse.
BRD4186C Reference Manual
RF Performance
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