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Product Tryout: Rigol Technologies mixed-signal oscilloscope (Part 1 of 3)
September 19, 2007
DS1102CD two analog+16 logic channel portable 100 MHz, 400 Msample/s mixed-signal oscilloscope (MSO). Rigol Technologies, www.rigolna.com. Price: $1499.
Although it’s not much larger than the handheld oscilloscopes I reviewed, the DS1102CD is definitely a bench unit because it’s line-powered only. Upon opening the box, I found a European power cord. Fortunately, the DS1102CD uses a standard (HP) style power connector, so I substituted a US-style cord. When unit powered up, its rather noisy fan made it clear that the instrument was on. In a lab where you have lots of equipment, you probably wouldn’t notice the noise, but you will in a quiet office setting. I like the small size, for it consumes little bench space. Just don’t put anything on top of the MSO because you’ll block the air-intake vents and you’ll hide the power button.
The front-panel controls are easy to understand. To conserve space, the instrument has a single set of vertical adjustment knobs: vertical position and sensitivity (V/div). A set of five buttons lets you select CH1, CH2, math, REFerence, and LA (logic analyzer). You can turn any or all on at the same time with the buttons.
Pressing the CH1 or CH2 button, located in the “Vertical” section of the panel, lets you select the oscilloscope’s analog channels. When you press either channel button, a menu appears and you can navigate the menus with five soft keys and a knob. To remove the menus, use the dedicated “Menu off” button. Analog-input menus include bandwidth limit, digital filtering, probe attenuation (1X, 10X, 100X, and 1000X). When you disable a channel, its menu also disappears from the screen.
The MSO’s math menu lets you select A+B, A-B, AxB, and FFT. I always find it confusing when an oscilloscope uses numbers for its input channels, then switches to letter for math. Consistency would help. To select a math (or any other) option, use the DS1102CD’s scroll knob, the one with a circular arrow that illuminates when active. When you’ve made your choice, just push on the knob to change the setting.
The front panel also has a “Menu” area where you can select Measure, Cursor, Acquire, Storage, Display, or Utility. The Measure menu lets you see 15 measurements such as Vpk-pk, Vrms, rise time, fall time, and frequency. The Acquire menu lets you select normal, average or peak detect, real-time or equivalent-time sampling, and memory depth. When you change memory depth between normal and long, the instrument changes sample rate. For example, a 2 us/div, long-memory depth (1 Msample for one channel, 512 ksamples per channel for two channels) setting produces a 100 Msample/s sample rate. Normal memory depth (2 ksample for one channel, 1 ksample per channel for two channels) reduces the sample rate to 25 Msamples/s. The Storage option lets you save waveforms to internal or external memory, where external refers to a USB flash drive.
Rigol supplied a demo board that I used to generate sine wave, square wave, triangle waves, AM and FM signals, and video signals. I connected the board and found the Analog signals difficult to trigger. By stopping an acquisition, I found that the “square wave” was actually a digital pulse train with several pulse widths and the triangle wave contained several different rise and fall times. These waveforms help demonstrate the instrument’s triggers. I needed to use a pulse-width trigger to stabilize the square wave on the screen. The cursor menu, accessible with a dedicated button, let me find the shortest pulse width (2.28 μs) and then set the instrument to trigger on pulse width greater than 2.22 μs.
You can save waveform images to a USB flash drive. When I plugged in the flash drive, I discovered that the front-panel USB connector is upside down. Thus, the activity light on the drive is out of view. To save a waveform to the flash drive, I selected the “Storage” button on the front panel and then selected the New File option from the soft keys. That bought up a screen to name my file. I found a virtual keyboard that I could type a file name by using the scroll knob and pressing it when I had the letter selected. I was able to navigate the selections and save a waveform “test0001.wfm” to the USB drive. (The oscilloscope limits file names to the 8.3 naming convention.) I then loaded the waveform back into the scope.
Next, I tried the “Acquire” menu and found the default sampling set to “Equ. Time.” I changed it to Real Time. Then, I tried triggering on a rise time with the signal source set to Ramp but it has a glitch. I was able to trigger on a short rising edge of the glitch.
Continue to Part 2: Logic inputs
Posted by Martin Rowe on September 19, 2007 | Comments (1)
