PicoScope 2104 & 2105 PC Oscilloscope User Guide
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Copyright 2006 Pico Technology Limited. All rights reserved.PS2100044-1.0
3.4.7
AC/DC operation
Using the ps2000_set_channel() function, the input can be set to either AC or DC
coupling. When AC coupling is used, any DC component of the signal is filtered out.
3.4.8
Oversampling
When the unit is operating in block mode at speeds less than the maximum, it is
possible to oversample, which means taking more than one measurement during a
time interval and returning an average. This reduces the effects of noise, and
increases the effective vertical resolution of the oscilloscope.
Setting an oversampling factor of n increases the time interval by a factor of n and
reduces the maximum number of samples by the same factor. At the same time it
increases the effective resolution by the amount given by the equation:
increase in resolution (bits) = ( log oversample ) / ( 2 log 2 )
For example, an oversampling factor of four increases the resolution by one bit.
The ps2000_run_block() function controls oversampling.
3.4.9
Scaling
PicoScope 2000 Series PC Oscilloscopes have a resolution of 8 bits, but the
oscilloscope driver normalises all readings to 16 bits. This enables it to take advantage
of noise reduction from oversampling, when this is enabled. The following table shows
the relationship between the reading from the driver and the voltage of the signal.
Reading Voltage
-32 767 Negative full scale
0 Zero volts
32 767 Positive full scale
