Rohde & Schwarz CMU-K20 Operating Manual Download Page 217

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CMU-K20/K21/K22/K23/K24

Signalling: Receiver Quality Measurements

1115.6088.12 4.139

E-12

(automatic gain control). The

AGC Holdoff Time

is also applied

if the RF level changes during the

Receiver Quality

measurement.

Sync Holdoff Time

Delay time after which the signalling unit of the CMU starts

synchronizing to the bit stream. This holdoff time is not applied
in the case of RF level changes during the

Receiver Quality

measurement.

Both holdoff times depend on the performance of the mobile station. A reduction of
the holdoff times towards their mobile-dependent lower limits can accelerate the
measurement.

Remote control

CONFigure:RXQuality:CONTrol:HTIMe <AGCTime>,<SynchTime>

Confidence
Settings

The

Confidence Settings

section sets the parameters for statistical BER tests. For

background information and application examples refer to section

Statistical BER

Tests

on p.

4.125

ff. The settings are available for the

BER

application and valid in

the measurement modes

RBER/FER, BER

and

Burst by Burst.

Note:

In the measurement modes

RBER/FER

and

BER,

the Class II BER

provides the pass/fail criteria. In the measurement modes

Burt by

Burst

and

BER/DBLER

, the

BER

calculated from all bits is used. No

statistical results are provided for AMR full rate tests and for
measurement in GPRS test mode A.

Statistical testing is activated by setting

Stop Condition = Confidence Level;

see

below.

The results

(Early Fail, Early Pass etc.)

are displayed in the measurement

menu. The following confidence settings are provided:

Confidence Fail

Confidence level for early fail decisions: After the

Min. Test Time

the confidence test is stopped with an

”Early Fail”

message as

soon as the probability of the DUT to have a BER above the
specified upper limit (see section

Upper Limits for Bit Error Rate

(Receiver Quality Configuration – Limits)

on p.

4.143

ff.) is larger

than the confidence fail value.

Confidence Pass

Confidence level for early pass decisions: After the

Min. Test

Time

, the confidence test is stopped with an

”Early Pass”

message

as soon as the probability of the DUT to have a BER

below the specified upper limit

times the

Bad DUT

factor

of 1.5

is larger than the confidence pass value.

Note:

The confidence levels are the complement of the

probabilities of

wrong decision F

used in the test specification:

<Confidence Level> = 1 – F.

Bad DUT

Fixed bad DUT factor of 1.5; see section

Statistical BER Tests

on p.

4.125

ff.

Result Window

BER range factor for statistical dual-limit BER tests. A factor of

% means that the BER must be within the range

[<BER Limit> (1 – n %), <BER Limit> (1 + n %)]. The

OFF

setting

corresponds to a single-limit BER test.

Min. Test Time

Minimum test time before a check of the early pass and early fail
limits can stop the measurement. Minimum test times are
necessary in particular if the test conditions introduce some
fluctuations that disturb the statistical independence of the single
bit error events and must be averaged out (e.g. multipath fading,
birth/death propagation, moving propagation).

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