Bluetooth 5 Module Performance Measurement and Recommendation for IoT Product Design

BT840F range easurement update, May 2017

We re-measure Bluetooth line of sight range between 2 BT840F in May 2017:

  • using S140 alpha 3 version SoftDevice
  • using BT840F V0 modules on EV BT840F V3 evaluation boards
  • Both antenna on vertical direction, facing each other
  • One antenna is 12 meters above ground, on a bridge over a river. The other antenna is 3 meters above ground.
  • TX power is set to +9 dBm
  • measuring the range for Bluetooth connection.
  • Results: 810 meters at 1Mbps, measured in Shen Zhen, China.

The same pair of modules with the same version firmware are measured in Scottsdale Arizona 

  • Both antenna are 7 feet or 2.1 meters above ground
  • Other test conditions are the same
  • Results: 410 meters at 1Mbps

The same boards are re-program with SoftDevice S140 alpha 1 version.

  • Both antenna are 7 feet or 2.1 meters above ground
  • Other test conditions are the same
  • Results: 620 meters at 1Mbps.

Conclusions:

  • Bluetooth range is longer if one antenna is very high above ground
  • We expect significant improvement in Bluetooth range when Nordic releases production silicon and SoftDevice.
  • The range is much longer when used for drone remote control application than used for lawn sprinkler control application.
  • In a mesh network, we suggest installing the router node high above ground.

Performance of BT840F Bluetooth 5 Module

BT840F is the first module made with Nordic nRF52840 SoC. Before the first shipping on March 10th, 2017, we measured the performance of new Bluetooth 5 transceiver supporting CODED PHY.

Benchmarking BT840F with BT832F, a production module

Nordic nRF52840 module, BT840F uses the same antenna circuit as BT832F, an nRF82832 module. We set BT840F transmission power to +4dBm, the same as maximum transmission power by BT832F. Data rate is set to 1Mbps. 

BT832F range measurements are described in BlueNor Mesh User Manual, available on Download Module Document page. Nordic has not released mesh stacks for S140 SoftDevice. BT840F ranges are measured with connection indication LED lights. One module is rotated by 30 degrees after each measurement. Twelve measurements are taken. 

Comparing Bluetooth line of sight ranges between two BT840F Bluetooth 5 modules and two BT832F

Comparing Bluetooth line of sight ranges between two BT840F Bluetooth 5 modules and two BT832F

  • Average range between 2 BT832F is 273 meters
  • Average range between 2 BT840F is 234 meters.

Average range of BT840F is about 86% of that of BT832F. Given the same +4 dBm TX power, BT840F receiver is 1.3 dB lower than that of BT832F.

Nordic errata 142 states 3 dB lower sensitivity for the engineering chip samples. Our measurement result is 1.3 dB lower sensitivity. Or, nRF52840 receiver sensitivity is -94.7 dBm.

Range measurement for maximum +9 dBm Transmission power

Nordic nRF52840 data sheets specifies maximum TX of +8 dBm. TX can be set to +9 dBm in firmware. On the angle that two BT832Fs have the best range of 330 meters, the range between two BT840Fs is 510 meters. 

BT832F has a link budget of 100 dBm (from +4 dBm to -96 dBm). BT840Fs' range is 1.55 times longer than that of BT832Fs, or 3.8 dB better. Total link budget of BT840F is 103.8 dB. When set to +9 dBm, TX power of nRF52840 is 103.8-94.7=9.1 dBm.

Setting in firmware (+9 dBm) is closer to our measurement result than the value in datasheets (+8 dBm). However, they are within measurement error.

Bluetooth Range measurements for coded phy

On the same best relative angle between 2 BT840F modules, Bluetooth line of sight range is 930 meters when TX is set to +9 dBm with CODED PHY. The range is 1.82 times of that without CODED PHY. Or, the gain for CODED PHY is 5.2 dB.

Receiver sensitivity of nRF52840 is -96 dBm at 1Mbps, -103 dBm at 125 Kbps. The receiver gain for CODED PHY is 7 dB. Or, range is 2.24 times longer.

Bluetooth line of sight range measurements

BLE 4.1 module Bluetooth line of sight range measurement reports. Conclusions of reports: For the best Bluetooth line of sight range performance, antenna shall be mounted on vertical direction and pointing to the sky or ceiling. We recommend this mounting direction when designing your IoT products. Unless stated otherwise, all subsequent range measurements have antenna mounted vertically.