Datasheet

PicoScope 3000 Series PC Oscilloscopes
Hardware acceleration
Almost all PC oscilloscopes collect data faster than USB transfer speeds, so
data has to be stored in high-speed memory on the device. However, even
deep-memory devices are expected to have fast waveform update rates.
As an example, the PicoScope 3207B can sample at 1 GS/s for timebases
as long as 20 ms/div and still update several times per second.
Today’s PCs cannot process the raw data from a high-
performance oscilloscope without becoming a bottleneck,
whether this is the user’s PC connected to a USB oscilloscope or the
embedded PC in a bench-top oscilloscope. In both cases, hardware
acceleration is required to avoid having the PC’s CPU process every
sample.
The main task of hardware acceleration is to intelligently compress the
raw ADC data stored in the oscilloscope’s memory before transferring it
to the PC for display. Consider a waveform with 100 million samples being
displayed on a PC monitor with a horizontal resolution of 1000 pixels.
Some oscilloscopes perform a simple decimation where every nth sample
is transferred. This is easy to do but results in lost data and missing high-
frequency information. 99.999% of the data is never displayed.
PicoScope oscilloscopes with deep memory perform data aggregation,
where dedicated logic divides the memory into (for example) 1000 blocks
of 100,000 samples. The minimum and maximum values of each 100,000
sample block are transferred to the PC, preserving the high-frequency
data. If you now draw an area on the screen to zoom in and view in more
detail, the oscilloscope will again serve up 1000 min/max pairs of data but
from just the zoomed area of interest.
Both waveforms show the same signal using different types of hardware
acceleration. Top waveform: using aggregation, high-frequency spikes are
preserved. Bottom waveform: using decimation, signal data is lost.
If the full memory is not used for the waveform, the memory is
automatically configured as a circular buffer. For example, if only 1 million
samples are captured per waveform, the last 500 or so waveforms are
always stored in oscilloscope memory for review. Tools such as mask limit
testing can then be used to scan through each waveform to identify any
anomalies.
As the hardware acceleration is performed within an FPGA, we are able to
continue to make improvements through software upgrades even after the
product has been purchased. In parallel with the data aggregation, other
data such as average values are also returned to speed up measurements
and to reduce the number of occasions where we do have to use the PC’s
processor.
USB 3.0 oscilloscopes
In the 1990s most PC oscilloscopes
connected to the PC through the
25-pin parallel port connector. The
move to USB 2.0 in the early 2000s
was a significant step forward for
PC oscilloscopes, increasing transfer
rates by over 100 times and allowing many devices to be powered by the
USB port.
The PicoScope 3207A and B are the world’s first PC oscilloscopes with a
USB 3.0 interface. USB 3.0 offers a tenfold increase in theoretical transfer
speeds over USB 2.0. As explained above under ‘Hardware acceleration’,
PicoScope USB 2.0 deep-memory oscilloscopes are already optimized to
transfer data efficiently, but USB 3.0 has the potential to make this process
even faster. On many USB 3.0 systems, performance will depend on your
PC’s CPU and chipset rather than being limited by the USB port.
USB 3.0 has some immediate benefits: if your PC has a fast SSD drive, the
saving of large waveforms will be quicker. Another benefit is faster gap-
free continuous streaming of data to the PC. As CPU speeds continue to
increase, the full performance benefits of USB 3.0 for oscilloscopes will
be realised.
High signal integrity
Most oscilloscopes are built down to a price; ours are built up to a
specification.
Careful front-end design and shielding reduces noise, crosstalk and
harmonic distortion. Years of oscilloscope experience leads to improved
pulse response and bandwidth flatness.
We are proud of the dynamic performance of our products and publish
these specifications in detail. The result is simple: when you probe a circuit,
you can trust in the waveform you see on the screen.
High-speed data
acquisition and
digitizer
The drivers and software
development kit supplied allow
you to write your own software
or interface to popular third-
party software packages such as
LabVIEW.
If the 512 MS record length isn’t
enough, the driver supports data
streaming, a mode that captures
gap-free continuous data through the USB port directly to the PC’s RAM
or hard disk at a rate of over 10 MS/s (maximum speed is PC-dependent).
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