Defining The Sequence And Timing; Running The Sequence; Timing Considerations - Metrix GX1010 Notice De Fonctionnement

4.8.2. Defining the Sequence and Timing

All 16 steps always contain a set-up, even if this is only the default setting. When set to run
the HOP sequence will start at step 00 and execute steps in chronological order up to the
step number defined in the LAST= field, after which it will go back to step 00 and start
again; the desired sequence should therefore be set starting at step 00 and the LAST=
field should be set to the last valid step number.
Both the control mode (internal, external or manual/remote) and internal timing (if selected)
are set with the edit cursor in the rightmost field of the top line of the display; the diagram
shows the default setting of 1s internal interval. Note that each step can be set to a
different length or a different mode; it is therefore possible to mix internally timed steps
with externally triggered or manually initiated steps. The internal timer can be set from 2ms
to 65s in 1ms increments using the rotary control or direct keyboard entry; see Timing
Considerations section for further information. With the interval set to 00·002s (2ms),
further anticlockwise movement of the rotary control will select EXTERNAL then MANUAL;
alternatively they can be directly selected from the keyboard by entering 1ms and 0ms,
respectively. In EXTERNAL mode the sequence is stepped on at each rising edge of the
trigger signal connected to the front panel EXT TRIG socket. In MANUAL mode the
sequence is stepped on with each press of the MAN/SYNC key or appropriate remote
command.
A synchronising signal is provided at the rear panel TRIG/SWEEP OUT socket. At the
entry to each step the signal goes low, followed by a rising edge after the frequency and
waveshape have changed for the new step. However, the rising edge will generally occur
before an amplitude or offset change (if specified) has been completed, see Timing
Considerations section.

4.8.3. Running the Sequence

To run the HOP sequence the edit cursor must be positioned in the HOP field; alternate
presses of the DIGIT keys will then toggle HOP between ON and OFF. With HOP:ON the
edit cursor is suppressed and no editing is possible. Exiting HOP, by pressing ESCAPE,
automatically sets HOP:OFF and returns the generator to the setting used before HOP was
selected.
When HOP is running the HOP display will show the waveform parameters for each step
which is manually stepped or has a duration >500ms; the display will not track the changes
of shorter steps or externally triggered steps.

4.8.4. Timing Considerations

The time to set up the waveform at each step will depend on the nature of the change. The
approximate timings for each change, from the trigger edge, are as follows:
• Frequency only : 0·5ms. Frequency changes are phase-continuous.
• Frequency and waveshape : 3ms, but longer if the filter is switched as well.
• Amplitude and Offset :Up to 40ms.
If the new amplitude setting involves an attenuator change the output is switched off for
45ms whilst the change is made to prevent any transients appearing at the output.
The synchronising signal at the rear panel TRIG/SWEEP OUT socket is a low-going pulse
whose falling edge occurs at the start of each step; this is about 1ms after an external
trigger. The rising edge occurs just after the completion of a frequency or waveshape
change, i.e. 0·5ms or 3ms later respectively. For an amplitude and/or offset change the
rising edge occurs slightly later but well before the 40ms delay needed to guarantee the
change has been completed; however, if the amplitude change causes the attenuator to be
switched, the rising edge will occur after the attenuator has changed and the output has
been switched back on.
GX1010 II - 33