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Step 2Key Specs
As promised, here a short discussion some of the DPScope's key features:
First, it is a two-channel instrument. This is a very important feature. Many low-end oscilloscopes offer only a single channel, which is a severe handicap: It doesn't allow you to look at two signals in relation to each other (e.g. clock signal and data signal), e.g. to see which one changes first and by how much. It also prevents you from triggering on a signal different from the one you want to look at. Thus I consider two channels an absolute must for any serious oscilloscope; everything else is a toy, not a real instrument.
Second, the bandwidth - the DPScope has about 1.3 MHz. While that may sound small compared to "big iron" scopes, it actually is quite usable for a large variety of tasks (in parentheses I show the approximate maximum frequency in the particular application):
- audio (20 kHz)
- infrared remote control signals (38 kHz)
- ultrasound (200 kHz)
- servo signals (a few kHz)
- bio signals, medical instruments (< 100 Hz)
- I2C (1 MHz)
- RS-232 (115 kHz)
- one-wire
- SPI (as long as <= 1 MHz)
The capture rate is a very important measure as well; it needs to be fast enough so ideally you instantly any changes on the signal or to the scope settings - this makes for a very responsive feel during practical use of the scope. Now that means it should at least be around 15 - 20 records per second (your eye isn't much faster than that anyway). The DPScope manages to do around 35 - 40 frames/sec (assuming a sufficiently fast timebase setting), so passes that criterion easily.
The DPScope also offers a datalogger mode (roll mode) for slow sample rates (between 10 samples/sec and 1 sample/hour); in that mode the waveform continuously scrolls to the left, and you can record it directly into a file. That's very useful to record slow-varying signals, e.g. temperature.
But now let's dive into the design, and start with some pictures!
First, it is a two-channel instrument. This is a very important feature. Many low-end oscilloscopes offer only a single channel, which is a severe handicap: It doesn't allow you to look at two signals in relation to each other (e.g. clock signal and data signal), e.g. to see which one changes first and by how much. It also prevents you from triggering on a signal different from the one you want to look at. Thus I consider two channels an absolute must for any serious oscilloscope; everything else is a toy, not a real instrument.
Second, the bandwidth - the DPScope has about 1.3 MHz. While that may sound small compared to "big iron" scopes, it actually is quite usable for a large variety of tasks (in parentheses I show the approximate maximum frequency in the particular application):
- audio (20 kHz)
- infrared remote control signals (38 kHz)
- ultrasound (200 kHz)
- servo signals (a few kHz)
- bio signals, medical instruments (< 100 Hz)
- I2C (1 MHz)
- RS-232 (115 kHz)
- one-wire
- SPI (as long as <= 1 MHz)
The capture rate is a very important measure as well; it needs to be fast enough so ideally you instantly any changes on the signal or to the scope settings - this makes for a very responsive feel during practical use of the scope. Now that means it should at least be around 15 - 20 records per second (your eye isn't much faster than that anyway). The DPScope manages to do around 35 - 40 frames/sec (assuming a sufficiently fast timebase setting), so passes that criterion easily.
The DPScope also offers a datalogger mode (roll mode) for slow sample rates (between 10 samples/sec and 1 sample/hour); in that mode the waveform continuously scrolls to the left, and you can record it directly into a file. That's very useful to record slow-varying signals, e.g. temperature.
But now let's dive into the design, and start with some pictures!
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