Aim-TTI TGA1240 Series, Инструкция по эксплуатации, Страница: 37 / 103

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The phase can be set with a precision of 0.1
°
but the actual resolution is limited with some
waveforms and at certain waveform frequencies as detailed below. To indicate when this is the
case the actual phase is shown in brackets as a non
−
editable field below the programmed value.
To achieve start phase precision all waveforms are run in Clock Synthesis mode, i.e. as if they
were arbitrary waveforms, when Gated mode is specified; this limits actual frequency resolution
to 4 digits for all waveforms although the normally DDS generated waveforms are still entered
with 7
−
digit precision. Sine/cosine/haversine/etc. waveforms are created as if they were arbitrary
waveforms with the first point of the waveform exactly at the start phase; each time the phase or
frequency is changed the waveform is recalculate which can cause a slight lag if these
parameters are being changed quickly with the rotary knob.
The phase resolution of true arbitrary waveforms is limited by the waveform length since the
maximum resolution is 1 clock; thus waveforms with a length >3600 points will have a resolution
of 0.1
°
but below this number of points the maximum resolution becomes 360
°
number of points.
Square waves, pulse, pulse trains and sequences have no start phase adjustment; phase is fixed
at 0
°
. Refer to the table in the Triggered Burst section for a summary of start phase capabilities.
Sync Out in Triggered Burst and Gated Mode
When Triggered Burst or Gated modes are selected the SYNC OUT source automatically
defaults to
trigger ; trigger
is a positive
−
edged signal synchronised to the actual trigger
used whether internal (from the Internal Trigger Generator or an adjacent channel) or external of
either polarity.
Alternatively, SYNC OUT can be set to
burst done
on the
SYNC OUT
setup screen; sync
out then provides a signal which is low while the waveform is running and high at all other times.