GW Instek GFG-3015 - Manual (Page 55)

GFG-3015 p.51
(8) Sweep Function
1. LIN Sweep
The procedure of generating the LIN Sweep functions is similar to that of
generating the FM function, except that the Ramp waveform is the only signal
source.
2. LOG Sweep
The procedure of generating the LOG Sweep functions is similar to that of
generating the LIN Sweep functions, except that the signal source will pass a
LOG wave shaper circuit (This circuit be included MOD function generator
block).
(9) Trigger Function
The Trigger Signal Generator will generate special signal that can instruct the
VCF unit to generate/stop waveform.
The Signal obtained from the internal independent function generator must go
through a TTL level shaper, as this block only accepts TTL compatible level. So
can use the Frequency (Rate) and the Duty (Symmetry) of this generator to set
the trigger phase and other parameters of Trigger Function.
The output of VCF is to correct Trigger waveform and pass the waveform choice,
the output amplifier, the ATT, and the output through the Main Out terminal.
This function includes the internal and external Trigger with the same operation
procedure, except that the Trigger signal will be obtained from the external
Trigger input terminal.
(10) Frequency Counter
GW has designed its own full function counter chip, GFC-9701, with high
frequency test range for the system.
The counter has the internal and external counter mode for GFG-3015. The most
important function for the internal counter mode is to show the main frequency
(VCF) on the display. So we take a square signal from Square shaper and change
the level to TTL compatible level by TTL shaper block, then the signal will connect
with the counter (GFC-9701). Because the counter directly connects with the
MPU system, so the MPU can get the correct frequency and show it on the
Display.
In addition, as the MPU can get the correct frequency anytime, so it can monitor
the output frequency at all the time to keep the accuracy of output frequency.
This function includes the internal and external counter mode with the same
operation procedure, except that the external test signal has to pass a
preamplifier circuit and change it to TTL compatible level.