Bluetooth testing | Bluetooth test tools | RF,PHY,Tx,Rx
This page covers Bluetooth testing. It describes bluetooth device transmitter and receiver testing including RF and baseband(PHY) conformance cases. Bluetooth test tools from leading vendors or manufacturers are also mentioned.
As we know bluetooth is a wireless technology which has become popular in various applications such as bluetooth headsets to receive calls on mobile phones, bluetooth data and file transfer and so on. There are different versions of bluetooth which include V1.0, V1.2, V2.0, V2.1, V3.0, V4.0 etc. These different versions support different modulation schemes (e.g. GFSK, DQPSK, DPSK), packet formats and data rates.
All the bluetooth packets are categorized into basic rate type amd enhanced dara rate type. Bluetooth basic rate packet consists of access code, header and payload. Bluetooth EDR (Enhanced Data Rate) consists of access code, header, guard, sync, enhanced data rate payload and trailer.
Bluetooth standard defines different power classes to be used by bluetooth devices viz. class-1, class-2 and class-3. Hence bluetooth devices will have different transmit power profile including power range, minimum and maximum power limits.
In general Bluetooth devices support two test modes in order to simply testing process of mass number of bluetooth devices under production. They are loopback test mode and transmit test mode. The figure-1 depicts bluetooth testing modes.
In loopback test mode, bluetooth device transmits the packet received from bluetooth tester back with the same payload as received from tester. In this test, tester compares the payload transmitted with the one received from bluetooth device in order to declare the pass/fail verdict.
In transmit test mode, bluetooth device receiver the instruction from the bluetooth tester which packet to transmit. It transmits the packet accordingly and tester does comparison with what has been instructed.
Other than the above mentioned test modes, bluetooth device need to be evaluated as per protocol stack. There are two main standard technologies based on which bluetooth devices are being developed viz. standard legacy bluetooth (before V4.0) and bluetooth low energy (version 4.0 and after).
Various bluetooth conformance test tools are available as outlined below for bluetooth testing as Physical layer, RF layer and upper layer specifications.
The major criteria in Bluetooth RF testing is to test modulation characteristics and RF channel frequency of bluetooth device. Bluetooth standard device uses 79 channels from 2.4GHz to 2.4835GHz with the spacing of 1MHz between them. Bluetooth low energy device (BLE) uses 40 channels from 2.402GHz to 2.480GHz which includes 3 advertising and 37 data channels.
Transmitter part of bluetooth testing
Following are the transmitter tests performed during bluetooth device testing:
• Transmit power measurements including maximum output power, maximum power density, power control range, EDR relative transmit power.
• Transmit spectral measurements including frequency range, 20 dB BW, adjacent channel power, in-band spurious, out-band spurious etc.
• Transmit modulation measurements including modulation characteristics e.g. frequency deviation, carrier frequency drift, carrier frequency error, EDR-carrier frequency stability, EDR-differential phase encoding, EDR-differential error vector magnitude (EVM) or modulation accuracy etc.
Receiver part of bluetooth testing
Following are the receiver tests performed during bluetooth testing:
• C/I performance
• Maximum usable receiver level
• EDR- BER performance characteristics
Bluetooth test tools
Following table mentions various bluetooth test tools from reputed vendors/manufactures for various needs as per conformance requirements of RF, PHYSICAL (i.e. baseband) and upper layers including MAC layer.
|Vendor or Manufacturer||Bluetooth test tool with features|
|Anritsu||MT8852B, Bluetooth test set|
|Intertek||Bluetooth compatibility testing covering various test cases as per different versions|
|NTS ( National Technical System Inc. )||Bluetooth Testing and Certification Provider|
|Litepoint||IQ2010, IQxel-80, IQxel-160|
|Rohde & Schwarz||R&S® CBT/CBT32 Bluetooth testing tool for RF and audio measurements|
|Keysight Technologies|| Following keysight tools are useful for bluetooth device testing:
• N7606B-Bluetooth signal studio
• N9081A,W9081A-Bluetooth measurement applications
• N4010A-Bluetooth headset testing tool
• T1111S,T1212S-Bluetooth protocol conformance test system
• E1852B-Bluetooth test set