BNC 630 - Manual (Page 30)

25
5.11 Burst Mode
The Burst mode generates a sinusoid burst of fixed frequency and level for a specified duration. Both continuous and triggered bursts
may be generated.
In the continuous burst mode, the 630 continuously gates the output sinusoid on and off according to the values entered in the On
and Off fields.
In triggered burst mode, the output frequency is set to 0 Hz and the unit awaits a trigger condition. When a trigger condition occurs,
the 630 delays for a time specified in the Off time field and then sets the output frequency to the specified value. When the time
specified in the On field has elapsed, the 630 resets the output frequency to 0 Hz and awaits another trigger condition.
The trigger can come from three sources:
1. Pressing the Trigger key
2. Applying a low-to-high transition on the Ext Trig In connector
3. Sending an ASCII "T" to the RS232 port
The 630 will simultaneously accept a trigger from all of the above sources.
Tip: An external digital signal can be used to generate bursts by switching to Sinewave mode and using the Ext. Gating In
connector to gate the output waveform on or off. The output is turned off when the input is at a logic high voltage (3V to 10V). This
input can be run up to 3 MHz.
Figure 5.11-1: Burst mode display
1. Continuous / Triggered Mode
This field selects whether the bursts will be generated on an ongoing or single event basis. To select Triggered mode, press 0 . To
select Continuous mode, press 1 . Pressing any arrow key or rotating the wheel will toggle this value.
2. Burst On Time (Duration)
The burst will last for the duration specified in this field before being switched off. You may enter a value from 1 mS to 99,999
mS in 1 mS steps.
3. Burst frequency
The output frequency is held at this value during the burst. You may enter from 0 Hz (DC) to 21.5000000 MHz in .01 Hz steps.
4. Burst Off Time (Delay)
The burst waveform will be held at 0V for the duration in this field before the sinewave is switched on. In triggered burst mode
this value may be viewed as a delay between the trigger event and when the output sinusoid is generated. You may enter a value
from 0 mS to 99,999 mS in 1 mS steps.
5. Level
In this field enter the 50 ohm loaded output level, from 4 mVp-p to 10 Vp-p or from -44.0 dBm to +24.0 dBm.
Offset
You can enter an offset voltage for the output waveform. For more information on refer to section 4.4.
Ext Gating Input
(rear panel connector)
In triggered burst mode this input functions as an external trigger input. A logic low-to-high transition on this input will trigger
the burst. This input has an internal pulldown resistor so that the input is held at a logic low when this input is left unconnected. See
section 2.0 for more information.
Burst Mode Trig Duration: 10,000 mS
20,000,000.00 Hz Dly: 5,000 mS -10.0 dBm
2
3 5
1
4