Tryout: Uni-T UTG962E Function/Arbitrary Waveform Generator

This waveform generator is small enough to fit on any bench and packs many useful features so long as you operate it from the physical or virtual front panel. The software, however, needs work.

Walking the exhibit floor at IMS 2024, I passed by the Uni-Trend (Uni-T) booth where the UTG962E Function/Arbitrary Waveform Generator caught my eye. It’s available in two variants, 30 MHz ($148) and 60 MHz ($182) and it packs a wide selection of functions into a surprisingly small package. Given its low price, I convinced management to approve the purchase of a review unit. After this tryout, we’ll void the warranty by opening the case for a teardown. That’s a story for another day.

Measuring 172 mm wide × 95 mm high × 25 mm deep and providing two channels, the UTG962E packs many useful features you need to evaluate audio and low-frequency RF circuits and components. Ordering the UTG962E was easy over the company website with the unit arriving in about five days. We also ordered a UTD2202CEX+, a two-channel, 200 MHz oscilloscope. We’ll look at that in a separate tryout.

Figure 1 shows the two BNC cables and AC mains power adapter that ship with the UTG962E. The power adapter has a USB-A power port. Thus, you can use any USB power adapter that can provide 5 V, 2 A. The power adapter comes with two interchangeable AC mains wall adapters, one for U.S. 115 V and one for Europe 230 V. A USB-to barrel-connector cable completes the set. I’d like to see a USB-C Power Delivery port instead of the barrel connector. That would make it easy to use any compatible cable if you need a spare.

Waveform generator sine wave — Figure 2. The Mode button lets you set signal parameters. Enter a number or dial it in then select its magnitude using the soft keys.

Figure 2 shows the front panel. The left side of the case holds the power connector, a USB-B connector for data, and the power switch. The right side holds the two outputs and the sync, all BNC connectors.

Basic operation

When operating the waveform generator, use the Wave button to select the output waveform: sine, square, pulse, ramp, Arb, noise, and DC. The Mode button lets you set the parameters such as frequency, amplitude, phase, modulation type, and modulation depth. Modulation types include AM, FM, PM phase-shift keying (PSK), line frequency sweep, and log frequency sweep. You can set select the options through the soft keys under the screen and set parameters using the knob and arrow buttons to navigate among them. You can also type in values with the numeric keys. The Utility key lets you set overall parameters such as output impedance (high or 50 Ω), and amplitude limit. Use the CH1 and CH2 buttons to activate the outputs.

Waveform generator cosine wave — Figure 3. Channel 2 produced a cosine wave due to a 90° phase shift.

I started by setting a 10 MHz, 2 V_P-P sine wave and later added AM with 75% depth. The waveform shown under CH2 is the selected waveform for CH1. How do you know? The CH1 box is highlighted. It’s a little confusing but you quickly get used to it.

After getting used to the controls, I enabled CH2. Using the phase setting, I set CH2’s output to 10 MHz at 90° thereby creating a quadrature pair. Figure 3 shows the CH2 settings on the display with the 90° phase shift while Figure 4 shows the quadrature pair.

Sweep mode

Having a frequency sweep lets you characterize the frequency response of passive and active components and systems. Setting a linear sine wave swept from 50 kHz to 10 MHz and later from 10 MHz to 50 MHz showed how the signal amplitude dropped with increasing frequency due to losses in the cables.

sine wave cosine wave — Figure 4. Using both channels with a sine wave and cosine wave produces a quadrature pair.

The video below shows amplitude changes using a 50 Ω BNC-to-BNC cable, then using a cable with alligator clips at one end connected to a banana-post-to-BNC adapter. As expected, the BNC-to-BNC produced less amplitude drop as frequency increases.

Using the alligator clips not only produced greater amplitude drop at higher frequencies, but also an amplitude rise that preceded the drop. That’s due to resonance, probably caused by stray capacitance or inductance. Connecting the alligator-clip end to the function generator as opposed to the oscilloscope made a significant difference. The last segment in the video shows the signal in the frequency domain, including some aliasing.

Signal measurements

When evaluating a waveform generator, you should check its basic accuracy. I checked the amplitude and frequency of a sine wave output at 1 MHz using an HP34401A, a classic true-RMS multimeter. The Uni-T UTG962E lets you set the signal’s amplitude using peak-to-peak or RMS settings. If you use one setting and switch to the other, the waveform generator will automatically calculate the equivalent value and display it. For example, setting the output to 2 V_P-P results in 0.707 V_RMS when you switch to RMS. Table 1 shows the measurement results.

Waveform generator 10 MHz FFT — Figure 5. An FFT with a rectangular window shows peaks between the first and second harmonic.

While making measurements on a sine wave to create Table 1, I found that the signal amplitude on the oscilloscope was one-half of the setting. That is, I expected a signal of 2 V_P-P but the oscilloscope display set to 500 mV/div showed 1 V_P-P. Pressing the Mode button fixed the problem, but why?

I also checked the frequency accuracy at 100 Hz, 200 kHz, 1 MHz, and 1.2 MHz. The meter would not measure frequency any higher, which requires a frequency counter.

Waveform generator Hanning Window — Figure 6. An FFT with a Hanning window shows peaks between the fundamental at 10 MHz and second harmonic.

In addition to measuring amplitude and frequency of a sine wave, I wanted to look at the sine wave in the frequency domain. Figure 5 shows a 10 MHz sine wave using a rectangular FFT window while Figure 6 shows the same signal through a Hanning window. In each figure, the center frequency is 10 MHz with 5 MHz/div. Note the unexpected evenly spaced peaks occurring at intervals of one-third and two-thirds from the fundamental frequency to the second harmonic at 20 MHz, which shows a higher peak.

Arb function

The UTG962E also has an arbitrary waveform function that includes 24 built-in waveforms including staircase, cardiac, voice, and radar. Finding the built-in functions was easy.

Waveform generator rising edge ringing — Figure 7. The arb function TriDown signal shows ringing from the rising edge.

The downward triangle (TriDown) wave is another built-in arb function. Looking at the waveform revealed some ringing at the peak, just when the amplitude begins to drop. Figure 7 shows 321 mV of ringing. No ringing occurred when the signal reached its lowest amplitude and began to rise. That could have to do with the relatively slow fall time as opposed to the faster rise time.

Software

To go beyond the supplied waveforms, you need to create or capture a waveform, which requires Uni-T’s Device Manager software. The Device Manager needs work. Here’s why.

Uni-T’s download page provides software and documentation: user manuals, data sheets, SCPI programming guide, Device Manager software, waveform generator firmware, and software manual. Downloading and installing the Device manager software and running the install program provides access to the software user manual. As of this writing, the Device manager app and manual were written mostly for Uni-T’s oscilloscopes. That left me confused because the software took me to functions such as waveform analysis, which is not for the waveform generator.

During the software installation, a window appeared saying that some software components needed installation. The install wizard pointed to NI VISA Runtime v5.4 and CH341SER. NI VISA provides the USB driver needed to communicate with the waveform generator. CH342SER is a serial port-to-USB driver. The install wizard found and installed both.

Another unusual occurrence came when the installer wanted to install Device Manager onto my D: drive, which HP uses for recovery. I manually changed the installation to a folder on the C: drive.

Waveform generator software screen — Figure 8. The Uni-T Device Manager software detected the waveform generator on a USB port.

With the software installed, I had access to the user manual. Good thing too because the Device Manager software isn’t all that intuitive. On startup, the software asks you to connect to your test instrument (Figure 8). The screen will display Uni-T instruments connected over LAN, USB, and serial ports. That covers the company’s other instruments, for the waveform generator has a USB port only. If you have more than one Uni-T instrument connected to the computer, you should see all of them. I clicked on the waveform generator from the startup screen but nothing happened. I needed to right click to complete the connection. Keep that in mind if you use this software.

Note the “More” option in Figure 8. You must click on that to reach the Arb Editor and Waveform Analyzer apps. You also get access to direct communications with the waveform generator through SCPI commands. In the next version, Uni-T should replace “More” with either a menu icon or display buttons that take you directly to the Arb Editor and Waveform Analyzer.

Sending the *IDN SCPI command initiated a response, which proved that communication was established. That produced a padlock icon on the waveform generator screen with a message saying to press the Utility button to disconnect if you need to use the front-panel controls. The message disappeared too quickly.

Unfortunately, Windows would, from time to time, send a notification that USB communication was removed but was quickly restored. While that’s annoying, it could be a problem if you’re operating the waveform generator under software control. Uni-T’s engineers should investigate that.

The Arb Editor lets you create waveforms in many of the usual ways:

Import a waveform file from an oscilloscope
Import a waveform stored on a csv file
Create a waveform using math
Draw a waveform with a mouse

Waveform generator math functions — Figure 9. The Arb Editor app lets you create waveforms from math functions.

Figure 9 shows the math screen. As you can see, the math editor provides a wide range of math functions, more than fit in the window. To reach the hidden functions at the bottom, you need to scroll down using a mouse wheel. Uni-T doesn’t provide a slider along the right side of the window. That should be added in the next revision.

As you click the buttons to build an equation, you’ll see the function, numbers, parentheses, and so on appear in the Expression line in Figure 9. You can edit them manually as well. While using the keyboard’s Backspace key, I went too far. That resulted in part of the word “Expression” disappearing. Indeed, keeping my finger on the Backspace key caused the instructions to vanish as well. That’s another bug for Uni-T to fix in the next revision.

Waveform generator hand drawn signal — Figure 10. You can create your own waveforms by simply drawing them in the Arb Editor.

Next, I randomly drew a waveform (Figure 10) to see if I could download it to the waveform generator. Drawing the waveform was easy but downloading it was impossible. Here’s what happened.

The communication link (top) and corresponding icon (third from bottom left) open a communication window that should let me download the waveform that I drew and saved. Clicking on the Device List icon to the right of the words momentarily produced some unreadable text at the bottom of the window. I say “unreadable” because not enough of the text was visible and even that quickly disappeared, replaced by “Disconnect Other Signal Devices!” in Figure 11. Given that I had just one connected device, there is no need to remove others. The software should have detected that. After clicking the Send button, I checked the waveform generator but found no added waveforms. This renders the software useless for generating custom waveforms.

Wavform generator software communications — Figure 11. A communication window should let you download saved waveforms to the waveform generator. Another message appeared but not enough of the characters were visible to read them.

Other notables:

On the hardware side, Uni-T should consider replacing the barrel connector with a USB-C port. That would also eliminate the need for a separate USB data connector. A teardown might reveal why Uni-T used the USB-B port that you often find on printers.
When trying to save a waveform, I found the Windows file manager path field unstable. It “flickered” up and down uncontrollably for a few seconds, then settled down. That needs fixing in the next software revision.
The settings screen contains some folder icons that didn’t work. To change the default folder settings, I had to copy and paste them in from the Windows file system window.

I conclude that the Device Manager software is mostly unusable for the waveform generator. It may be better for an oscilloscope. We’ll find out in that tryout. You can use Device Manager as a virtual front panel. It’s not a perfect match of the waveform generator’s front panel, but it’s close enough to use. You can also use the Device Manager to send SCPI commands and read responses. Given that you need NI VISA, you should be able to write your own application to control the waveform generator.

Most of the issues I found in this tryout originated in the software. The waveform generator itself is a handy tool for hobbyists, repair technicians, or anyone with a crowded bench.

Have you tried the UTG962E? What do you think? Leave a comment below.