Bursts - Stanford Research Systems DS360 Operating Manual And Programming Reference

Operation 3-13
(from the TRIGGER IN, computer interface or front panel) and the actual beginning of
the sweep. The SWEEP OUT BNC signal, which goes high at the beginning of the
sweep, should be used if it is necessary to synchronize the DS360 with an external
device, instead of the triggering signal. In addition, there is a dead time of between 0 and
0.317 ms between successive sweeps. If a trigger comes during a sweep or during the
dead time following a sweep, it will be treated as an error and ignored. These factors
limit the maximum rate that a sweep can be triggered externally (or singly) to somewhat
less than for internally triggered sweeps. To never miss a trigger, the maximum external
(or single) trigger rate is given by: 1/(Ext Sweep Freq) = 1/(Sweep Rate) + 0.634 ms.
Sweeps can be triggered somewhat faster than this if it is permissible to skip triggers.
Trigger errors simply indicate that a trigger has been ignored, but do not effect the output
signal in any way.
Start and Stop Frequencies
The DS360 can sweep over any portion of its frequency range, from 0.001 Hz to 200.000
kHz. To display the current start or stop frequency, press the [START] or [STOP] key.
To change the start or stop frequency, type a new value using the numeric keypad,
followed by the appropriate units (Hz or kHz). If an out of range frequency is entered,
the DS360 will beep, display " F REQ Err" and flash the ERR LED.

Bursts

Bursts are active for sinewaves, squarewaves, white noise and pink noise. A burst of
sines or squares consists of a certain number of complete cycles at a particular level (the
"ON" level), followed by another number of cycles at a reduced level (the "OFF" level).
Time intervals (instead of number of cycles) are used for noise signals. This pattern can
be triggered, either internally, externally, or on a single-shot basis. Additionally the
output can be gated on and off by an external signal.
Bursts are programmed in # of counts for sine and square waves and in seconds for noise
signals. The "ON" time is entered as the Burst Count. The Burst Rate is the combination
of both the "ON" and "OFF" times as shown below.
BURST RATE = BURST COUNT + OFF CYCLES
The burst "OFF" level is set in percent or dB relative to the "ON" level and can range
from 0 to 100% in 0.1% increments or from 0dB to -60dB in 0.1dB increments. The
DS360 has a BURST output on the rear panel that can be used to synchronize an
oscilloscope or other external device to the DS360 burst output. This signal remains a
TTL high for the duration of the "ON" time and a TTL low for the "OFF" time. Use the
MODIFY FUNC [ON/OFF] key to begin or end bursting.
Burst Trigger Source
Bursts can be continuously triggered, externally triggered or singly triggered. Internally
triggered bursts use an internal burst rate generator (see the BURST RATE described
below) to set the repetition rate. Externally triggered bursts begin on the rising edge of a
TTL signal supplied by the user to the TRIGGER/GATE IN BNC on the front panel.
Singly triggered bursts begin by pressing the front panel [TRIGR] key or from one of the
DS360 Ultra Low Distortion Function Generator