six frequencies (40Hz, 100Hz, 315Hz, 1kHz, 6.3kHz and 10kHz) but it takes 18s. As
usual, all measurements are THD (plus noise). Segment G is similar to segment F but it
has 50µs de-emphasis to avoid overloading FM transmitter systems.
Tape azimuth
4.11 Wow & Flutter Segment (W) Wow & flutter segment W&F measurement flutter measurement
Segment W measures the peak and mean weighted wow & flutter and speed error (on the
3125Hz tone) and makes use of essential settling time to take a mean phase reading at
3125Hz; useful as an azimuth check. Note that a speed of -99.9%, or a phase of -999°
indicates that the measurement failed because the signal was too noisy.
Speed measurement Tape speed
4.12 Phase Segments (Y, Z, z) Phase segments
Segment Z measures mean phase at 40Hz, 100Hz, 1kHz, 6.3kHz, 10kHz and 15kHz, and
because of slow averaging it is more accurate than manual measurement. A result of
‘-999°’ occurs if the phase for a particular tone could not be measured (typically because
the system is very noisy). Segment Y is similar but has 50µs de-emphasis to avoid
overload on FM transmitter systems. Segment z measures phase difference between
channels at 40, 100, 315, 1k, 6.3k, 10k and 15kHz (the same as segment Z with 315Hz
added).
Note: although phase can be measured at any frequency, the frequencies in this segment
should not be changed (using the ‘!’ segment) as the LA102 expects them and is
optimised for them to give very accurate phase measurement.
4.13 User Level Segment (K) User level segment Filter testing Equaliser testing
Segment K is a general 6 tone level test which accurately records the level of six 1s tones
(with autoranging and averaging). It can be used to test compression effects on
compandors, tape machines, limiters and noise reduction systems, and to accurately test
the frequency response of filters and equalisers over a large dynamic range (where the
frequency sweep segments may not be as accurate because they cannot change range in
mid-sweep).
The levels default to 0, -10, -20, -30, -40 and -50dB but any 6 levels can be specified by
the user (with a resolution of 0.01dB). For example:
K +10,0,-30,-37,-47,-55
If any levels are omitted they default to 10dB below the previous level (so K+20 would
generate levels at +20, +10, 0, -10, -20 and -30dB). As with all segments these levels are
relative to the LA101 test level - see sections 3.7, 3.10 and 4.21.
The first level is treated as the segment measurement level (see section 4.5) and is
transmitted in the FSK segment header. The LA102 displays this in the segment title for
reference, but the level at which the other tones are sent is not transmitted or displayed, so
the user must know which levels were used in order to interpret the results. However, it is
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4. User Defined Sequences
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