Lindos LA100 - Test Level Segments (T,V)

Sequence 18 makes use of this facility to define a sequence compatible with German
standards which specify distortion measured at +6dBu, sweep 20dB below +6dBu, noise
referred to +6dBu, crosstalk at +6dBu, W&F at 0dBu and phase at 10dB below +6dBu.
The definition is:
T+6 U-14 C+6 D+6 N W Z-4
It could have been be defined as:
T U-20 C D0 N W-6 Z-10
and run with a Test Level of +6dBu set but this would generate the FSK at +6dBu instead
of 0dBu since the FSK is always generated at the Test Level. Note that no level is given
for crosstalk as segment C runs at 0dB anyway (‘C0’ would have the same effect), but 0 is
given for segment D which would otherwise run at +8dB. No measurement level is
specified for noise which is always relative to the measured test level segment (segment T
in this case), and similarly, the crosstalk segments should normally be run at the same
level as the test level segment, since the measured crosstalk is always referred to the
measured TL OUT result.
The Test Level segments (T and V) are not normally given a measurement level, as they
are normally run at the Test Level so that the result (TL OUT) shows the true test level
which was in use for the sequence.
All segments except noise segments can be given a measurement level. Multi-level
distortion segments (E and I) can be given a measurement level but this is not
recommended as the displayed and printed levels will not be changed. For example, I+4
will measure distortion at +4dB and at -14dB and will display +4dB in the heading but
will still display +8 and -10dB which are the default levels. The FSK header is always
transmitted at 0dB (relative to Test Level).
4.6 Test Level Segments (T,V) Test level segment 400Hz test level4
Segment T generates a 1kHz reference tone at 0dB for 1s. Segment V is similar, but uses
a 400Hz tone, and is intended for use with FM transmitter systems. The level is measured
by the LA102 and displayed under the heading ‘
TL OUT’, and gives an indication of the
gain of the system.
These segments are called Test Level segments because they normally run at the Test
Level (which is set globally for the whole sequence, as described in sections 3.7 and
4.21). Although it is possible to give these segments a measurement level to make them
run at a level different from the test level, this would not normally be done as it makes
more sense to adjust the level for the whole sequence by setting the global test level.
A test level segment should usually be the first segment of a sequence as it is used to
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4. User Defined Sequences