4.21 Sequence Level Segment (/) Sequence level segment / segment (set sequence level) FSK level
Test level can be set within a sequence using /n before any test segments, where n is the
level in dB (with 0.01dB resolution). This is equivalent to setting the test level in manual
mode using
before running the sequence and makes all output relative to the test
level, including the FSK. For example using the sequence:
/-17 %600,1 TrC+4ENz
the FSK will be output at -17dBm (-10.98dBu into 600 matched load), segment T will
be at -17dBm, segment C at -13dBm and distortion segment E will be at -8dBm and
-27dBm (+9 and -10dB relative to test level).
Temporary test level Test level − set in sequence Setting test level
When the sequence has finished the original test level will be restored as this segment
only sets a temporary test level for the duration of the sequence.
4.22 Channel Segment (:) Channel segment : segment (set channel) Sequence channel Channel switching Output channel
The channel may be selected using :n,m which selects physical channel n and logical
channel m. n should be 0 for MUTE, 1 for Left, 2 for Right or 3 for both channels (L+R)
or omitted for no change. m should be 1 for Left, 2 for Right, 3 for both channels or
omitted to make it default to the same setting as the physical channel.
Channel number Mute
The physical channel determines which output channel the signal will be on. Normally
the signal is on both channels (except during noise or crosstalk segments) but it is
possible to define a sequence with a tone on one channel only. For example, to generate a
1kHz test tone on the R channel only:
:2 !1000,0
To generate the special ITV channel identification signal for Betacam/stereo recordings
which consists of 1kHz steady tone on the right channel and 3s 1kHz pulses on the left
channel separated by 250ms of silence:
Channel ID for Betacam Betacam channel identification
!1000,3000,0,,0 :2 !1000,250,0,,0 :3 <<
The logical channel determines which channel the LA101 will instruct the LA102 to
make measurements on (via FSK) and also how many times the sequence will run. It is
normally set by pressing the
key on the LA101 before running a sequence but this
segment overrides any selection made with the
key. For example, a test sequence
for a mono circuit can select single channel operation within the sequence:
:1,1 T O E N
This sequence will only ever run on the left channel regardless of the L+R setting.
When measuring distortion on FM transmitter systems it is best to generate the test signal
on one channel only to obtain the maximum difference signal and hence test the system at
its limits. Generating the tone on both channels simultaneously (as Lindos sequences
normally operate) results in a zero amplitude difference signal giving less valid results.
84
4. User Defined Sequences
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