Specifications

ETSI

Final draft ETSI EN 300 328 V1.8.1 (2012

04)

B.4.1 Power supplies for the battery powered UUT

All tests should be performed using power supplies wherever possible, including tests on UUT designed for battery-

only use. For battery powered equipment, power leads should be connected to the UUT's supply terminals (and

monitored with a digital voltmeter) but the battery should remain present, electrically isolated from the rest of the

equipment, possibly by putting tape over its contacts.

The presence of these power cables can, however, affect the measured performance of the UUT. For this reason, they

should be made to be "transparent" as far as the testing is concerned. This can be achieved by routing them away from

the UUT and down to the either the screen, ground plane or facility wall (as appropriate) by the shortest possible paths.

Precautions should be taken to minimize pick-up on these leads (e.g. the leads could be twisted together, loaded with

ferrite beads at 0,15 m spacing or otherwise loaded).

B.4.2 Site preparation

The cables to the measuring and substitution antenna should be routed horizontally away from the testing area for a

minimum of 2 m (unless, in the case both types of anechoic chamber, a back wall is reached) and then allowed to drop

vertically and out through either the ground plane or screen (as appropriate) to the test equipment. Precautions should be

taken to minimize pick up on these leads (e.g. dressing with ferrite beads, or other loading). The cables, their routing

and dressing should be identical to the verification set-up.

NOTE: For ground reflection test sites (i.e. anechoic chambers with ground planes and Open Area Test Sites)

which incorporate a cable drum with the antenna mast, the 2 m requirement may be impossible to comply

with.

Calibration data for all items of test equipment should be available and valid. For test, substitution and measuring

antennas, the data should include gain relative to an isotropic radiator (or antenna factor) for the frequency of test. Also,

the VSWR of the substitution and measuring antennas should be known.

The calibration data on all cables and attenuators should include insertion loss and VSWR throughout the entire

frequency range of the tests. All VSWR and insertion loss figures should be recorded in the log book results sheet for

the specific test.

Where correction factors/tables are required, these should be immediately available.

For all items of test equipment, the maximum errors they exhibit should be known along with the distribution of the

error e.g.:

• cable loss: ±0,5 dB with a rectangular distribution;

• measuring receiver: 1,0 dB (standard deviation) signal level accuracy with a Gaussian error distribution.

At the start of measurements, system checks should be made on the items of test equipment used on the test site.

B.5 Coupling of signals

B.5.1 General

The presence of leads in the radiated field may cause a disturbance of that field and lead to additional measurement

uncertainty. These disturbances can be minimized by using suitable coupling methods, offering signal isolation and

minimum field disturbance (e.g. optical coupling).

B.5.2 Data Signals

Isolation can be provided by the use of optical, ultrasonic or infra-red means. Field disturbance can be minimized by

using a suitable fibre optic connection. ultrasonic or infra-red radiated connections require suitable measures for the

minimization of ambient noise.