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PicoScope 3000 series
11
3.4
Triggering
The PicoScope 3000 series oscilloscope can either start collecting data immediately, or it can be
programmed to wait for a trigger event to occur. In either case, you need to use the
ps3000_set_trigger ()
threshold voltage, or when an external trigger input crosses a threshold voltage. The trigger event
can be either a rising or a falling edge.
The external trigger input uses the same physical connection as the signal generator output, so
these two functions cannot be used at the same time. It is possible, however, to use the output from
the signal generator as a trigger. Triggering is available in block mode only. Any calls to the
ps3000_set_trigger ()
3.5
ETS (Equivalent Time Sampling)
ETS is a way of increasing the effective sample rate when working with repetitive signals. It is not
possible to use ETS with one-shot signals. ETS is controlled via use of the
and
ps3000_set_ets()
ps3000_set_trigger ()
intervals, the
ps3000_get_values ()
3.6
Voltage ranges
It is possible to set the gain for each channel with the
an input voltage range of between 100mV and 20V. The external trigger has a fixed input range of
20V.
3.7
AC/DC operation
Using the
ps3000_set_channel
When AC coupling is used, any DC component of the signal is filtered out.
3.8
Oversampling
When the oscilloscope is operating in block mode at speeds that are less than maximum, it is
possible to oversample. Oversampling is taking more than one measurement during a time interval
and returning an average. This reduces the effects of noise, and increases the resolution of the
oscilloscope.
3.9
Scaling
Oscilloscopes from the PicoScope 3000 series are 8-bit. To take advantage of noise reduction due
to oversampling (if enabled), the oscilloscope driver returns 16-bit readings. The following table
shows the relationship between the reading from the driver and the voltage of the signal.
Reading
-32767
0
32767
3.10
Signal generator
PicoScope 3000 series oscilloscopes have a built-in signal generator which is set using
ps3000_set_siggen
waveform can be set to sine, square or triangle and can be swept back and forth in frequency.
These are selected under software control.
The signal generator output is physically the same as the external trigger input, so these two
functions cannot be used at the same time. It is possible, however, to use the output from the signal
generator as a trigger. Note: The signal generator function is not available on all PicoScope 3000
function. A trigger event can occur when the channel A or B input crosses a
function has no effect in streaming mode.
functions. ETS is available in block mode only. Calls to the
function have no effect in streaming mode. As ETS will return random time
ps3000_get_times_and_values ()
function will return FALSE (0).
function, each channel can be set to either AC or DC coupling.
Voltage
Minimum
Zero volts
Maximum
(). It produces a selection of accurate frequencies from 100 Hz to 1 MHz. The
function must be used. The
ps3000_set_channel()
Copyright 2005 Pico Technology Limited. All rights reserved.
ps3000_set_trigger ()
function. This will give
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