Stingray 2005 Scaricare Key Generator 32 Bits IT
Kym Cavrak
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Traditional scope vendors have greatly shrunk the size of their offerings. Some of Tektronix's products are a third the space of their predecessors. Yet when saddled with a display and sea of controls there are limits to how small , and how inexpensive, these units can ever be. But for developers and students looking for smaller and cheaper instruments there are a number of palm-sized units that substitute a USB connection and the PC's screen for the CRT. Some offer astonishing performance. All are brilliantly designed and utterly cool.
Only Parallax's unit came with any sort of probes because a decent one can easily run $100. Plenty of vendors do sell less expensive probes, but buy warily as a poor choice can distort signals and may be shoddily constructed.
None of these scopes offer the same ranges as your desktop Agilent or Tektronix. Feed more than a few tens of volts into the inputs and the smoke detectors will smother your yell of rage. But with a x10 probe that's still enough range to work with most circuits found in embedded systems.
All but one will save captured data to disk. My bench scope is nearly always connected to the PC for the very same reason, which makes me scratch my head and wonder if it's not possible to use a virtual instrument all of the time.
For $149 you can't expect much. At least that's what I thought till the Parallax (www.parallax.com) unit arrived, professionally packaged in a blister pack as part of an "Understanding Signals" kit. The iPod-sized scope alone is $129.
The unit isn't designed to meet the need of the serious developer, but it packs an awful lot of punch for the price. Two channels plus an external TTL trigger, 1 million samples per second when using a single channel, half that when both are on. It has a 200 KHz bandwidth with 8 bits of vertical resolution and a +/- 20 volt input range.
All of the other units I'll review have standard BNC input connectors. The Parallax scope, though, uses .157" cylindrical connectors and comes with crude probes. Eighteen inches of non-coaxial cable terminates in standard clip leads. But perhaps this is a reasonable tradeoff given the unit's 200 KHz bandwidth.
The GUI is simply beautiful and looks a lot like the front panel of an ordinary bench scope. Two big knobs control the vertical scale and time base. Drag them with the cursor. The single vertical does double duty for both input channels; I'd prefer two knobs.
Though all of the scopes were responsive, this one took my breath away. Updates at reasonable sample rates were instantaneous. One visitor noted that it took forever to update the screen . . . and then realized he was sweeping at 1 sec/div, requiring 30 seconds for a single acquisition.
At $129 this sounds like a toy scope, but the only toy-like features are the 200 KHz bandwidth and simple probes. I'd recommend the Parallax unit for low-speed applications, educational use, and to get your kids interested in electronics. At audio frequencies this is all the scope you'll ever need. The very well-thought out "Understanding Signals" kit for $20 more, plus a BASIC Stamp microcontroller, will teach newbies about scopes and analog and digital circuits. The kit's manual is on-line at
The Stingray's case is as sexy as its name, a streamlined wedge smaller than a CD. It comes in a faux-leather pouch which can hold a couple of probes as well as the instrument. They must have hired a marketing person from Apple.
The unit has two channels which accept +/- 50 volt signals, and an external trigger input that takes an input in the +/- 3.5 volt range. The analog bandwidth is 250 KHz with one million samples per second in single-shot mode, or 20 million for repetitive signals. Inputs are sampled with 12 bit resolution into a 32 Kb buffer, which works out to 8 K samples per channel. A nice feature lets one reduce the buffer depth to 1 K for faster updates at slow sweep rates.
The GUI is, if possible, even prettier than Parallax's, though cursor, FFT and meter buttons across the bottom are a bit clunky-looking. Again, two big knobs set vertical and horizontal ranges. And again, I'd sure prefer separate knobs for the two vertical channels. The cursors are particularly simple to use.
Easy-to-use horizontal and vertical cursors measure amplitude and time, though not frequency. You can enable up to 6 digital meters that display instantaneous, peak or RMS voltage, and frequency. That might be useful in a production environment where the technician must make routine measurements.
Interestingly, the external trigger input can also function as an output for a signal generator. The unit will generate sine, square, triangle, ramp and even custom waveforms you design yourself. It's limited to audio frequencies only, and the waveforms are more than a little rounded, so don't toss your bench signal generator. But for those on a tight budget with limited needs this is a handy feature.
PC-hosted instruments can have functionality limited only by the imagination and software. In this case an "EasyLogger" feature captures data and displays it like a strip chart recorder (remember those?) and to a file.
The bottom line: 250 KHz bandwidth is too narrow for most of us working on the digital end of an embedded system. But if your processor is slow (and a lot are) or you need a handy scope for routine analog work, this device will suit most users fine. Slip it into your pocket for travel and have fun convincing the TSA folks that the device isn't a threat to national security.
Picotech is UK-based, which perhaps explains why I wrestled so hard with the 82 page .pdf manual. As one wag noted, we're two peoples divided by a common language, which in this case means Norteamericanos will glean little of use from the documentation. Since "tips" don't appear when mousing over menus I spent a lot of time in the not terribly helpful help file.
A 200 MHz analog bandwidth and 100 million samples/second data collection (200 million when using only one channel) makes the 3206 quite the speed demon. On repetitive signals it'll suck in an effective 10 billion samples/sec. In all modes it has 8 bits of vertical resolution, and a 1 meg data buffer. The trigger can be positioned at any point in the buffer, a very important feature needed to capture pre- and post-trigger events.
The GUI makes no attempt to imitate the knobs on a traditional scope. It's somewhat clumsier than the other user interfaces, though the signals are displayed with a hard-to-describe but breathtaking clarity. This interface is all about the displayed data, not the controls.
The unit is very responsive and has fast screen updates.. . except when there's a spectrum analyzer window and one or more scope views open at the same time. Then things get sluggish. Close a window and the speed issues disappear.
A zoom feature that expands and pans through the deep 1 meg buffer works well, and is very fast. Suppose you capture a signal with the time base set to 50 msec/division and need to look at an edge in more detail. Just zoom . . . and zoom . . . and zoom, up to 1000x, without recapturing.
A single mouse click selects the two horizontal and vertical cursors (confusingly called "rulers" in the help file) which enable the usual spectrum of measurements. But Picotech adds much more - you can display averages and even standard deviations of the data, and can select which parts of the signal contribute to the calculations. Displaying a color burst or swept waveform? Measurements on most scopes are meaningless since the frequency varies across the screen. On the 3206 just pop up a dialog to select where to take data.
Variable persistence lets signals stay on-screen forever or fade from view after a specified time. In digital color mode areas of the trace that repeat frequently are red; those that don't head towards the blue. It's easy to spot infrequent events like a glitch.
The 3206's internal signal generator creates sine, square and triangle waves at speeds to 1 MHz. Under 500 KHz frequency their frequency stability was 1% or better; above 500 KHz stability degenerated.
This instrument is a hermaphrodite, a Mixed Signal Oscilloscope (MSO) that's both 8 channel logic analyzer and two-input DSO. MSOs shine in the embedded world where digital and analog signals interact in strange and mysterious ways. An MSO will display both domains on the same screen, and can trigger on either a digital condition or at some analog voltage level. There's no better way to see how the logic and analog relate.
It requires 12 volts from an external power supply, which isn't a wall wart but is the preferable in-line design with a cord that plugs into the wall. There's no power switch, unfortunately. The unit is housed in a solid aluminum powder-coated case which feels very substantial for such a small (6" x 4" x 2") device.
The specs are impressive. Analog bandwidth is 100 MHz, though the A/D's is 75 MHz. A note explicitly claims "[the] BS300 includes compensation for this convertor (sic) to achieve 100 MHz bandwidth throughout." I'm not sure what that means. Max sample rate is 40 Msps (million samples per second), a departure from usual scope specifications where the analog bandwidth is several times lower than the sample rate. But the BitScope uses a single flash A/D multiplexed between the two channels dumping data into a 128Ks (kilosample) deep buffer. 8 digital channels go into their own 128Ks buffer.
The A/D has 6.8 to 7.6 effective bits of resolution. At lower speeds the software averages data boosting resolution to either 9.5 bits (according to the manual) or 11.5 (from the web site). Max input voltage is 5.5 with a X1 probe. Get a decent X10 and you'll be able to probe most embedded systems without loading the signals unduly.
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