Agilent Technologies 3458A User Manual page 142

10OUTPUT 722;"PRESET FAST"
20OUTPUT 722;"MEM FIFO"
30OUTPUT 722;"MFORMAT SINT"
40OUTPUT 722."SSDC 10"
45 !EVENT (DEFAULT EVENT)
50OUTPUT 722;"SWEEP l0E-9,4000"
60OUTPUT 722;"LEVEL 75 DC"
70OUTPUT 722;"SLOPE POS"
80OUTPUT 722;"SSRC LEVEL"
90OUTPUT 722; "TARM SGL"
100END
142 Chapter 5 Digitizing
Figure 33. Typical synchronizing signal for EXT sync source
The LEVEL sync source event (which is the power-on/default sync source
event) occurs when the input signal reaches a specified voltage level on the
specified slope (level triggering). Figure 31 shows the operation of the
LEVEL sync source event (for this example, the LEVEL is specified as 0%,
positive slope, AC-coupling). The first sync source event occurs when the
input signal crosses 0V with a positive slope. The multimeter then takes a
burst of samples (5 samples in this case). Following the next occurrence of
the sync source event (period 2 of the input signal) the multimeter delays the
trigger point and takes 5 more samples. This process repeats until the
specified number of samples are completed.
In the following example, the SSDC command is used to digitize a 1 MHz
signal with a peak value of 5V riding on a 5V DC level. The SWEEP
command instructs the multimeter to take 4000 samples with a
10-nanosecond effective_interval. Lines 60 through 80 program the voltage
level and the slope for the LEVEL sync source event. This will initiate
sampling when the first period of the input signal reaches 7.5 VDC (75% of
the 10V range). Line 90 satisfies the trigger arm event, which essentially
enables the sync source event.
!TARM SYN, TRIG AUTO, DINT FORMATS
!ENABLE READING MEMORY, FIFO MODE
!SINT READING MEMORY FORMAT
!SUB-SAMPLING, 10V RANGE, LEVEL SYNC SOURCE
!4000 SAMPLES, 10ns EFFECTIVE INTERVAL
!LEVEL TRIGGER AT 75% OF RANGE, DC-COUPLED
!LEVEL TRIGGER ON POSITIVE SLOPE
!LEVEL SYNC SOURCE EVENT
!ENABLE SAMPLING