BT Designer: Bluetooth RF Test Guidance

1 RF Test Case Overview

1.1 RF Test Cases

1.2 Test Cases Performed at Test House

There are 15 RF test cases all are at category A (Spurious emissions has been deleted), and all can be performed at a test house equipped with a TS8960 test system.

2 Conducting RF tests at a Test House

Most test houses will recommend booking a period of a week for conducting all the RF tests cases at all conditions.

There is a separation of roles between the test house staff who make measurements and write test reports, and the BQB who reads the test reports and other Compliance Folder evidence and who has the authority to list Bluetooth technology products and components. Generally test house staff will be aware of what a BQB will allow during testing, but if specific problems occur, it is up to the customer to ask to speak to the BQB. It is important that the BQB is fully aware of the test program for the unit under test, but also whether the unit includes pre-qualified components, or if it is to be a pre-qualified component included in other products.

There are general conventions that apply to testing at test houses under any standard, and many of these apply to Bluetooth technology products, but there also some specific Bluetooth technology requirements:

The purpose of the tests is to prove the design, not a particular unit. Therefore it is permitted to change units or to use multiple units during testing.

• It is allowed for auto-calibration in software to re-trim settings during or between test cases, but it is not allowed to make manual changes to settings.

• For Bluetooth wireless Qualification, great reliance is placed on the Declaration of Compliance signed by the manufacturer. The test evidence for a category B test case is described as a Category B Declaration. This is in recognition of the fact that until validated test equipment is available for category A testing, which takes place at qualified test facilities, the test evidence submitted at category B cannot be validated. Therefore the manufacturer must also declare that the implementation is compliant.

• If tests are performed at a certain power level, and then the power has to be reduced to pass another test, it is usually accepted that the test evidence at the higher level does not have to be repeated

• If some tests performed at an extreme condition of temperature or voltage pass and others do not, all extreme condition tests must be performed at the same conditions even if some tests have already passed at more severe conditions.

• A manufacturer can choose to perform some or all category B test cases at his own test facility without giving any reason until the date that the tests are activated at category A by the Test Case Reference List

• Neither test house staff nor a BQB can require a category B test case to be performed at a test house facility, or on a particular type of test equipment.

• Manufacturers must describe to the BQB’s satisfaction the test method used for any category test cases conducted at the manufacturer’s or other facilities.

• The test report from one test house should be readily accepted by a BQB from any other test house. There should be not disadvantage for using an independent BQB, or one from another test house.

• Test house equipment should be calibrated and serviced regularly, but can fail. If unexpected readings occur during testing the manufacturer can ask for the equipment to be checked at any time.

• Spurious responses, for instance spikes in emission tests caused by mobile phones can be re-measured over a limited range to replace the spurious response.

• It is advised that all test case results should be printed so the manufacture has a hard copy of all test cases before finishing the test session, for two reasons. Electronic test case results have been deleted in error , and it is desirable for the manufacturer to check the results carefully.

3 RF Test Cases

3.1 Introduction

All the test cases in the RF test specification version 0.92 are specified to be performed in loopback mode.

A description of relevant information for each test case based on experience at test houses follows. However, probably the most important factor for passing tests the first time is to have performed extensive pre-testing so the performance of the implementation is known under all planned test conditions

Test times given are approximate, and for a single test case run. For extreme conditions each test is conducted at low and high voltage at both high and low temperature, so each test is conducted 5 times in total. The section below should be read in conjunction with the RF test specification for more detailed information about the test method.

3.2 TRM/CA/01/C Output Power

The first decision required during RF testing is the power level. For Class 2 units this is likely to be full power, but for Class 1 units the power may have to be reduced to pass all tests at all conditions. The tests that actually determine this are TRM/CA/04/C Tx Output Spectrum - Frequency Range, TRM/CA/06/C Tx Output Spectrum - Adjacent Channel Power. Any spikes in the spectrum may cause a failure in one of these three tests. Careful pre-testing can identify the maximum power setting that is likely to pass all tests. The effect of extreme conditions must be taken into account, for instance maximum power will be transmitted at low temperature and high voltage, and spikes will also tend to be higher as output power rises.

3.3 TRM/CA/02/C Power Density

Note that the antenna gain in dBi is added to the measured power density, so the gain must be known at the time of testing and taken into account when choosing the power level for Class 1 units.

3.4 TRM/CA/03/C Power Control (optional)

For this test a power control table must be loaded into the Persistent Store memory.  The power steps are changed automatically by the TS8960 test system.

3.5 TRM/CA/04/C Tx Output Spectrum - Frequency Range

This test may cause problems if the spectral peak is too wide or there are close in spikes. Power may have to be reduced as a result to keep all responses out of band below –30 dBm.

TRM/CA/05/C Tx Output Spectrum - 20 dB BW

FCC required test incorporated into Bluetooth test specification. A separate report will be required for an FCC application. This BW measured is relative to the power peak so is not affected by power changes.

3.6 TRM/CA/06/C Tx Output Spectrum - Adjacent Channel Power

This test will often determine the power level for the unit. Three exceptions above the limit of –40 dBm are allowed, and the worst case occurs at 2441 MHz where spikes on both sides of the wanted signal fall in band.

3.7 TRM/CA/07/C Modulation Characteristics

TRM/CA/08/C Initial Carrier Frequency Tolerance

TRM/CA/09/C Carrier Frequency Drift

3.8 TRC/CA/01/C Out-of-Band Spurious Emissions

This test case has been deleted because the requirements are mirrored by the regulatory approvals requirements that differ between Europe and the USA.

3.9 RCV/CA/01/C Sensitivity - single slot packets

3.10 RCV/CA/02/C Sensitivity - multi slot packets

3.11 RCV/CA/03/C C/I performance

Customers must ensure that the image frequency (as in RF ICS/IXIT) is correctly entered into the test system for this test or erroneous results will be recorded. The test system requests the IF offset, and a box is ticked to indicate whether the image is high or low side. The correct values are 1.5 MHz on low side, giving the image frequency at –3MHz. Customers should carefully check the test listing to ensure the image is correctly indicated.

3.12 RCV/CA/04/C Blocking Performance

3.13 RCV/CA/05/C Intermodulation Performance

Customers must ensure that the value n=5 (as in RF ICS/IXIT) is correctly entered into the test system for this test or erroneous results will be recorded

3.14 RCV/CA/06/C Maximum Input Level

Units with input amplifiers and high sensitivity may need attenuation set by PS settings for this test.

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