Measurement of Bluetooth low energy signal with real-time spectrum analyzer

With the real-time mode of the signal analyzer MSA500 series, the intermittent signal and frequency hopping signal of Bluetooth Low Energy (BLE) can be acquired.

Application

Bluetooth Low Energy (BLE), which is added with Bluetooth 4.0 or later, has been adopted for many small wireless devices with the recent spread of IoT (Internet of Things) technology. BLE has the specifications specialized for IoT by drastically reducing power consumption and simplifying device connection from conventional communication methods of Bluetooth 3.0 or earlier. So, it is desirable to use a real-time spectrum analyzer to accurately acquire the radio wave of the BLE signal in communication that connects and disconnects the device frequently and repeatedly as in the sensor network field.

Our handheld signal analyzer (real-time spectrum analyzer) MSA500 series has the spectrogram analysis and powerful trigger function. With these functions, it is possible to accurately acquire the intermittent signals of the advertising channels (CH37 to 39) and the frequency hopping signals of the data channels (CH 0 to 36) used for BLE device detection. Also, with the time domain analysis, the modulation signal of BLE can be analyzed with time axis waveform.

Solution

[Time domain analysis]

By displaying Frequency vs. time (left fig.) and IQ vs. time (right fig.), it’s possible to observe the frequency deviation and the baseband signal of GFSK which is the modulation method of BLE.

MAIN screen (top) [FREQ-T] SUB screen (bottom) [SPECTROGRAM]
MAIN screen (top) [IQ-T] SUB screen (bottom) [SPECTROGRAM]

System configuration

Handheld signal analyzer ［MSA538］

Lithium-ion Battery ［MB400］

Portable antenna 2.4GHz band [M304]

Shield box [MY3710]
Handheld signal analyzer MSA538
– Measurement Frequency : 20kHz to 3.3GHz
– Maximum span : 20kHz

*For 5 GHz band measurement, MSA 558 is also available.
– Measurement Frequency : 20kHz to 8.5GHz