The TiePie
HANDYPROBE
HP2
Troubleshooting electrical/electronic equipment in
the field can be a real pain in the proverbial. Lugging
large, supposedly “portable” and usually expensive
pieces of test equipment around the country can
really test the nerves – as well as the muscles. Could
this be the answer?
TiePie
engineering
Review by PETER SMITH
TiePie Engineering, a Dutch company which specialises in computer
controlled measuring equipment,
has come up with a unique solution
to this field service dilemma in the
Handyprobe 2.
The Handyprobe 2 incorporates a
storage oscilloscope, spectrum analyser, voltmeter and transient recorder
all in a package that fits in the palm
of your hand!
The probe plugs into the parallel
port of any PC and in conjunction with
DOS or Windows software provides a
comprehensive range of data acquisition functions.
It is powered directly from the parallel port connection (no external supply
or batteries are required) so is ideally
suited for use with laptop computers.
In fact, the probe together with its
integral cable could easily slide into a
spare spot in most laptop bags.
With an input range of 0.5V to 400V
full scale and a maximum sampling
speed of 20MHz (TiePie also produce 1,2,5 and 10MHz versions), the
Handyprobe can handle just about
anything you can throw at it.
To keep the cost down, TiePie have
provided only single-channel acquisition in the Handyprobe 2. As with
most storage ‘scopes, the Handyprobe
includes a reference channel that can
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be used to compare a stored measurement with a second (live) measurement, so a second channel is usually
not required. Instrument settings can
be saved and restored from disk at will.
Launching the Handyprobe 2 software displays a floating toolbar on
the Windows desktop (see Fig.1). The
toolbar provides access to all four of
the available instruments, as well as
to basic program settings (see Fig.2).
The ’scope, voltmeter and spectrum
analyser instruments can all be active
simultaneously, whereas the transient
recorder must run independently.
Let’s take a look at each of the instruments and their capabilities in a
little detail.
Storage oscilloscope
TiePie boast that their instruments
are “plug and measure”. We connected
the probe to our trusty Silicon Chip
Sine/Square Wave Generator, activated the oscilloscope and hit the Auto
SET button. In less than a second the
input was scaled nicely (both horizontally and vertically) and correctly
triggered (see Fig.3).
Auto SET places the instrument in
auto-ranging mode, so for many simple
measurements you may not need to do
any setup at all.
All instrument settings are available
Silicon Chip’s Electronics TestBench
from the main toolbar via pull-down
menus, with many often-used settings
also controllable with single-keystroke
shortcuts.
Vertical axis
The CH1 pull-down menu provides
access to all vertical axis settings.
Input sensitivity ranges from 0.5V
to 400V full scale, configurable from
the Sensitivity selection (see Fig.4).
Alternatively, hitting the F5/F6 keys
clicks over to the next lowest/highest
setting - a bit like using that rotary
switch on CRT-based oscilloscopes.
Measured values can be enlarged
or reduced using the “Software Gain”
function – TiePie calls this vertical axis
magnification.
A closely related function called
“Software Offset” applies a positive
or negative bias to the vertical axis.
Once again I was reminded of the conventional ‘scope and the equivalent
“position” knob (got to kick that habit).
Both the Software Gain and Offset can
also be changed directly on the display
by clicking and dragging points on the
vertical axis.
The Units of measure, Units of gain
and Units of offset functions provide
for custom vertical axis marking and
scaling, making tailoring for specific
measuring tasks quite simple.
Fig.1: the instrument toolbar provides a convenient way of
activating the instruments. All except the transient
recorder can be active simultaneously.
For example, suppose you have
a temperature probe whose output
changes by 1V for every 10 degrees
of temperature change. By setting the
Units of measure to “Degrees C” and
Units of gain to “10”, the vertical axis
displays temperature change directly
in degrees.
Other options on this menu allow
choices of true or inverted signal, and
either AC or DC signal coupling.
Horizontal axis
Unlike its more conventional analog
cousin, the digital scope’s timebase is
dependant on both the rate at which
the incoming signal is sampled and
how many samples are stored and
subsequently displayed across the
horizontal axis.
The Handyprobe 2 has a maximum
sampling rate of 20 million samples/
second and a memory depth (also
called record length) of 32,760. Both
the sample rate and record length are
configurable from the Timebase pulldown menu (see Fig.5).
Naturally, the Handyprobe software
automatically adjusts the time/div
values along the horizontal axis when
the sample rate and record length are
changed.
Also accessible from the Timebase
menu are two options that allow
closer examination of any part of the
acquired signal. Record View Gain provides horizontal axis magnification,
whereas Record
View Offset allows display of a
particular section
of the record.
Note the scroll
bar directly be- Fig.2: settings common to all instruments are accessible
low the horizon- from the toolbar. Although not mentioned in the text,
tal axis – this instrument calibration data can be defined on the
Hardware tab.
provides a much
more convenient
Noisy signals and glitches
way of panning through the record
than manually entering the Record
Noisy signals can be “cleaned up”
View Offset.
by using Handyprobe’s signal averaging feature.
A feature in digital ‘scopes that I’ve
often found useful is their ability to
Spotting a glitch on a real-time
display a number of samples prior to display is often impossible – but Tietriggering.
Pie have the bases covered here, too.
On the Handyprobe, the number Envelope mode keeps a record of the
of pre-trigger samples can be set an- highest and lowest samples since last
ywhere from zero to the maximum reset and compares these values to
record size. A second scroll bar at the each successive sample.
bottom of the display allows this value
When a sample that exceeds either
to be changed instantly.
of these limits is detected, a vertical
line is drawn on the display at that
Triggering
point and the value is stored as the
As expected, the Handyprobe in- new lowest (or highest). Envelope
mode can be reset at any user-definable
cludes variable level triggering on a
rising or falling slope. Slope position, measurement interval – or it can run
level and hysteresis can all be set from indefinitely.
the Trigger pull-down menu. Easier
Saving settings & waveforms
still, these values can be changed by
clicking and dragging the trigger symThe good news is that once you’ve
bol next to the vertical axis - too easy!
got the instruments set up the way you
Auto level triggering is also selecta- want for a particular measuring task,
you can save those settings to disk for
ble; when active an “A” is visible next
later reuse. And there is no limit to
to the trigger symbol.
Fig.3: the “oscilloscope”. Comment balloons provide an
easy way of annotating waveforms before printing.
Fig.4: manually setting the input range.
Silicon Chip’s Electronics TestBench 125
Fig.5: selecting the sample frequency
(or rate) from the Time base menu. The
faster the sample rate, the less time it
takes to fill an entire record. As shown
here, at 10kS/sec the record is filled in
just 100ms.
the number of settings files you can
create, either.
Another indispensable feature
allows waveforms (both live and reference channels) to be saved on disk
for later examination.
Accurate measurements
A variety of useful measurements
can be made quickly and easily
by using mouse-moveable cursors.
These are enabled from the Cursors
pull-down menu and once enabled,
a dialog box appears, listing all the
measurements made at the current
cursor positions.
Hard copy
A faithful copy of the displayed
waveform can be made at any time
by using the Print feature. Comments
can be added anywhere on the display
area with the aid of user-definable
comment balloons.
Balloons can have arrows that point
wherever you like (see our “Clipping”
balloon example on Fig.3). Balloon
shape and colour are customisable,
too.
As shown in our example, a longer
(up to 3 lines) comment can also be
added to the top right of the printout.
Voltmeter
In voltmeter mode, data is presented
to the user in a similar manner to a
conventional digital voltmeter (DVM),
and includes triple displays with bargraphs (see Fig.7).
The input signal can be either AC or
Fig.18: the transient recorder instrument. Here we’ve used the Units of measure
and Units of gain settings to simulate a thermocouple reading in thousands of °C.
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Silicon Chip’s Electronics TestBench
DC-coupled, with a range of between
0.5 and 400V full scale. Autoranging
is also supported.
Measurements can be made in true
RMS, peak-to-peak, mean, maximum,
minimum, dBm, power, crest, frequency, duty cycle or instantaneous
value.
Quick “go-no go” tests can be made
by configuring the Set high value and
Set low value entries appropriately.
This function is also useful for monitoring a signal for out-of-range conditions, depending on how the sound
settings are configured.
To reduce duplication of settings
between instruments, TiePie have
slaved many of the settings together.
For example, the voltmeter actually
uses the record length and post-trigger
samples from the oscilloscope.
If either the oscilloscope or spectrum analyser is active though, their
settings override the voltmeter settings
as the voltmeter has lowest priority.
The frequency range setting is an
exception to this rule, as changing
it in the voltmeter affects all other
instruments. TiePie have included a
“use scope frequency” setting to avoid
potential frustration!
Spectrum analyser
If you work with filters, amplifiers,
oscillators, mixers, modulators, or detectors, you need a spectrum analyser.
Whereas oscilloscopes display signals
in the time domain (which is fine for
determining amplitude, time and phase
information) spectrum analysers display signals in the frequency domain.
The frequency domain contains certain information that is just not visible
in the time domain. To borrow several
examples from the Handy-probe user
manual:
(1). A sine wave may look good in
the time domain, but in the frequency
domain harmonic distortion is visible.
(2). A noise signal may look totally
random in the time domain, but in the
frequency domain one frequency may
be dominantly present.
(3). In the frequency domain it is
easy to determine carrier frequency,
modulation frequency, modulation
level and modulation distortion from
an AM or FM signal.
Fig.8 shows what a 200kHz square
wave looks like on the spectrum
analyser. Square waves are (theoretically) composed of an infinite number
of harmonics, some of which you can
Fig.7: the voltmeter alone could make
the TiePie Handyprobe an indispensable
instrument for all service personnel.
see on the left and right of the 200kHz
peak.
Without going into complicated
explanations, suffice to say that the
Handyprobe software uses Fast Fourier Transforms (FFT) to calculate the
spectral components of the sampled
signal.
Measuring harmonics
An important feature of this instrument is its ability to measure Total
Harmonic Distortion (THD). This is
set up and displayed from the Measure pull-down menu. The number
of harmonics used to calculate the
THD is user definable and the results
can be displayed in decibels or as a
percentage.
As with the oscilloscope, cursors
are provided for easy waveform measurement.
A multitude of other features match
those that we have already described
for the oscilloscope instrument.
These inlude display zooming, signal
averaging, copying live to reference
memory, saving waveforms to disk,
hardcopy output and saving/restoring
instrument settings.
Transient recorder
If you need to measure slowly
changing signals over a period of time,
the transient recorder is the instrument
of choice (see Fig.6).
Unlike the other instruments in
the package, the transient recorder
is direct registering. This means that
it displays each measurement as it
is made, rather than waiting for an
Fig.8: the spectrum analyser instrument really expands the
usefulness of the package.
entire record to be acquired. This is
necessary because at the lowest sample rate, it can take up to 189.6 days
to fill a record!
The different measurement and
display techniques used also mean
that other instruments cannot be active
when the transient recorder is active.
Many features of this instrument
are common to those found on the
oscilloscope and spectrum analyser,
so we’ll concentrate mainly on the
unique ones here.
Recording speed
Sampling time can be set anywhere
from 0.01 second to 500 seconds, with
a complete record variable from 1 to
32,760 samples.
The recording process can be interrupted at any time and the results
saved to disk or printed. It is also
possible to have the recorder run
continuously and automatically save
to disk at the end of each complete
record acquisition.
Note that at very high measuring
speeds, TiePie state that some data
samples may be lost due to the overhead of disk access.
During recording, the display can be
set to roll left as the trace reaches the
rightmost edge of the screen – a great
feature that reminds me of mechanical chart recorders with their drums
and pens.
Data gathered from the recorder will
most often be used for documentation
purposes, so the vertical axis custom
isation features really shine in this
instrument. Pre-defined choices for the
units of measure include Volt, Amp,
Degree C, Degree F, Watt, Percent,
Meter, Kilogram, Newton, Coulomb,
Bar and Hertz.
If you can’t find what you want in
that lot you can define your own in
five characters or less.
Text balloons of variable shape,
size and colour can be positioned
anywhere on the display, and colour
printer output is supported, too!
Need more speed?
If the Handyprobe 2 sounds great but
you need more bandwidth or another
channel, TiePie also offer the TiePieSCOPE HS801. This instrument is not
quite as portable as the Handyprobe,
but it adds a second channel, has five
times the sample rate (100M samples/
sec) and includes an arbitrary waveform generator (AWG) instrument.
Software for the TiePieSCOPE
is practically identical to the
Handyprobe, notwithstanding the
additional support for the second
channel and the AWG.
Where to get it!
Self-running demos and complete
user manuals for the Handyprobe 2
and TiePieSCOPE are available for
free download from Tiepie’s web site
at www.tiepie.nl
Our review unit came from the
Australian distributors of TiePie Engineering products,Melbourne-based
RTN, phone/fax (03) 9338 3306; email
nollet<at>enternet.com.au.
A phone call to RTN will give you
the latest pricing.
SC
Silicon Chip’s Electronics TestBench 127
