Fluke DDS Function Generator 271 - Manual (Page 29)

Getting Started
Using the Instrument
FSK Mode
The FSK (frequency shift keying) mode can also be driven
from the internal trigger generator. Setting up is very
straightforward; the following settings give a continuous
waveform which switches between 800 Hz and 1.2 kHz
twice every second.
The edit menu for the FSK mode includes the basic
settings for the trigger generator, so there is no need to
visit the trigger generator set-up screen itself. First, free
the internal trigger generator. This is most easily done by
returning to the factory default settings.
Press EDIT then FSK and enter the settings shown here:
FREQ A=800.0000 Hz
FREQ B=1.200000kHz
SOURCE=TGEN [FREE]
TGEN=250.ms 4.000 Hz
Then press FSK again to start the generator with the new
settings and turn the output on.
Special Waveforms
Staircases
The instrument can generate a staircase waveform with up
to 16 steps. To demonstrate the set-up process we will
create a signal that approximates a 625-line PAL TV line
signal. This is the signal applied to the Z-axis of the TV's
CRT to modulate the brightness of the spot.
The refresh rate in PAL TV is 25 Hz (40 ms), and the
screen is rasterized into 625 lines. Thus each line takes
64 µs and the line frequency is the inverse of this,
15.625 kHz.
By definition, the black level (called the "blanking level"
because it cuts off the electron beam completely) is 30 %
of peak amplitude and the white level is 100 %. These
levels usually correspond to +0.3 V and 1.0 V respectively.
The line sync pulse is negative-going and takes the level
down to 0 %. It is nominally 4.7 µs wide and it occurs in
the first few microseconds of the cycle, just before a
region called the "back porch" which precedes the scan.
The horizontal scan runs from 12.05 to 63.70 µs; outside
this period the CRT is blanked.
To produce an image on the TV screen we will divide the
scan period into five approximately equal segments and
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