Standard Waveform Operation
This sections deals with the use of the instrument as a standard function generator, i.e.
generating sine, square, triangle, dc, ramp, haversine, cosine, havercosine and sinx/x waveforms.
All but squarewave are generated by DDS which gives 7-digit frequency precision; squarewave is
generated by Clock Synthesis which results in only 4-digit frequency resolution. Refer to
Principles of Operation in the previous section for a fuller explanation of the differences involved.
The
STANDARD WAVEFORMS
screen also includes arbitrary and sequence for simplicity of
switching between these and standard waveforms; they do, however, have their own screens
(accessed by pressing ARB and SEQUENCE respectively) and are described in detail in their
appropriate sections. Pulse and pulse-train are also accessed from the ‘standard waveforms’
screen but are sufficiently different to justify their own section in the manual.
Much of the following descriptions of amplitude and offset control, as well as of Mode, Sweep,
etc., in following sections, apply to arbitrary and sequence as well as standard waveforms; for
clarity, any differences of operation with arbitrary, sequence, pulse and pulse-train are described
only in those sections.
Setting Generator Parameters
Waveform Selection
STANDARD WAVEFORMS
♦
sine
◊
square
◊
triangle
Pressing the STD key gives the
STANDARD WAVEFORMS
screen which lists all the waveforms
available; the rotary control or cursor keys can be used to scroll the full list back and forward
through the display. The currently selected waveform (sine with the factory defaults setting) is
indicated by the filled diamond; the selection is changed by pressing the soft-key beside the
required waveform.
Frequency
STANDARD FREQUENCY
10·00000 kHz
♦
freq period
◊
Pressing the FREQ key gives the
STANDARD FREQUENCY
screen. With
freq
selected as
shown above, the frequency can be entered directly from the keyboard in integer, floating point or
exponential format, e.g. 12·34 kHz can be entered as 12340, 12340·00, or 1·234 exp 4 etc.
However, the display will always show the entry in the most appropriate engineering units, in this
case 12·34000 kHz.
With
period
selected instead of
freq
the frequency can be set in terms of a period, e.g.
123·4µs can be entered as ·0001234 or 123·4e-6; again the display will always show the entry in
the most appropriate engineering units. Note that the precision of a period entry is restricted to 6
digits; 7 digits are displayed but the least significant one is always zero. The hardware is
programmed in terms of frequency; when a period entry is made the synthesised frequency is the
nearest equivalent value that the frequency resolution and a 6-digit conversion calculation gives.
If the frequency is displayed after a period entry the value may differ from the expected value
because of these considerations. Further, once the setting has been displayed as a frequency,
converting back again to display period will give an exact 6-digit equivalent of the 7-digit
frequency, but this may differ from the period value originally entered.
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