The channel selection segment (:) can be used to allow for this special case. If 16 is
added to the physical channel number, before a distortion segment, then that distortion
segment will only put the tone on the channel which is being measured and will MUTE
the other channel. Sequence 17 (the FM transmitter test) makes use of this feature:
"FM TEST" "ONE CHAN MTD FOR THD" V R A :19,0 G N Y
4.23 Subroutine Segment (>) Subroutine segment > segment (call subroutine) Call another sequence
Sequences can call other sequences using the > segment (like a computer subroutine).
When
>n is encountered in a sequence, sequence n is run as though it were a single
segment and then the original sequence continues. The sub-sequence will only run on a
single channel each time it is called, but will be called for each channel the main sequence
runs on. For example:
SEQ 1:
T>2NWZ
SEQ 2: RCI
Running sequence 1 will run segments +TRCINWZ on the left channel and TRCIN on
the right. This facility is intended to allow complicated
! tone segments which require
more than 250 characters, and is especially useful where a particular sequence of tones
occurs at several places (tunes for example!). If the sequence consists entirely of
! tone
segments with no letter segments, the sequence will run once only, as usual.
Sub-sequences may call other sub-sequences, but an error will occur if a sequence calls
itself recursively.
4.24 Pause Segment (?) ? segment (pause) Pause until a key is pressed
A pause segment is available to wait for user input. A question mark (?) will cause the
LA101 to stop and wait for a key to be pressed. Press
to continue running the
sequence, or
or to abort the sequence. The message "1=CONTINUE
SEQ=STOP
" will be displayed to indicate this unless the ? is preceded by a message
segment. For example:
"100, 1k AND 10kHz" !100,0 ? !1000,0 ? !10000,0 "PRESS 1 TO REPEAT"? <<
4.25 Sweep Headroom (^n)
When receiving a frequency sweep segment it is important that the LA102 uses a suitable
level range. For most normal frequency responses the LA102 will do this automatically.
However, problems can arise where a system has large peaks (eg steep filters, equalisers,
loudspeaker crossovers etc). If the range chosen is too low then clipping will occur,
causing part of the frequency response curve to be missed and producing RANGE?
messages. If the range chosen is too high, accuracy and resolution will be reduced. This
is explained in section 3.14, but a better solution is the ^n control segment.
85
4. User Defined Sequences
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