Post by antigua on Jul 28, 2019 22:48:26 GMT -5
I just bought an "Analog Discovery 2" USB oscilloscope by Digilent www.amazon.com/gp/product/B07G8LG3JX/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1 , which apparently has been on the market since August of 2018. It's intended to be used with their WaveForms software, which is rather feature rich, compared to other USB oscilloscopes on the market. One of the features is network analysis with real time scripting interaction of the measured values. Ken Willmott created a hardware integrator kenwillmott.com/blog/archives/284 in order to remove the +6dB/oct slope that occurs when plotting the impedance of a pickup, so that the frequency response of a tested pickup is depicted as being mostly flat where it's inductive, ahead of the LC resonance. A USB device that can perform calculations on the incoming data points and present them in plotted form should remove the need for an intermediate integration device.
Here is the Analog Discovery 2 starter kit, with probes and BNC interface:
Installing the software, and clicking on "Network" mode, I had some luck plotting the impedance of a pickup, and then applying some math to produce a plot that looks integrated:
To apply scripting, you click "Custom One" or "Custom Two", then click the text input line at the bottom, which opens a prompt where code can be entered. I'm not sure which mathematical formula is required to calculate the integration, but I came up with " ( Gain / sqrt( 1 + sqr( Freq ) ) ) ", and it produces a result that looks familiar. A fair number of things about it confuse me though, such as what is presented by the vertical "Y" units, I see that the values are very tiny, far below "1".
As for using this for routine testing of pickups, I'm currently using the Velleman PCSU200, which has it's own drawbacks, primarily being that it produces small plot images, lacks customization and of course, manipulation of input data via script. But for the purpose of pickup testing, the WaveForms software probably wouldn't work too well, because, for example, it doesn't allow for multiple, overlapping plot lines, and has no horizontal reference markers. What makes the Velleman software very powerful is the the overlapping plot feature, maing compare and contrast tasks very easy to conduct, and a clean "screen capture" feature which allows the generated plots to be shared with online via simple cut and paste. If the WaveForms software were to receive these features at some point, it might come out on top. The WaveForms software does have a screen capture feature, but it also screen grabs the UI elements around the plot, in addition to the plot, which makes for unnecessary visual noise, and I would be tasked with cropping it out of every plot image I were to make.
The WaveForms software does offer a very high degree of customizability though, and also offers phase view, and the scripting engine comes with an IDE style debugger, and some default output scripts:
so this could be useful for quality control, or other types of pickup research, where the limitation of the Velleman or the Sys-Comp USB oscilloscopes might fall short.
Here is the Analog Discovery 2 starter kit, with probes and BNC interface:
Installing the software, and clicking on "Network" mode, I had some luck plotting the impedance of a pickup, and then applying some math to produce a plot that looks integrated:
To apply scripting, you click "Custom One" or "Custom Two", then click the text input line at the bottom, which opens a prompt where code can be entered. I'm not sure which mathematical formula is required to calculate the integration, but I came up with " ( Gain / sqrt( 1 + sqr( Freq ) ) ) ", and it produces a result that looks familiar. A fair number of things about it confuse me though, such as what is presented by the vertical "Y" units, I see that the values are very tiny, far below "1".
As for using this for routine testing of pickups, I'm currently using the Velleman PCSU200, which has it's own drawbacks, primarily being that it produces small plot images, lacks customization and of course, manipulation of input data via script. But for the purpose of pickup testing, the WaveForms software probably wouldn't work too well, because, for example, it doesn't allow for multiple, overlapping plot lines, and has no horizontal reference markers. What makes the Velleman software very powerful is the the overlapping plot feature, maing compare and contrast tasks very easy to conduct, and a clean "screen capture" feature which allows the generated plots to be shared with online via simple cut and paste. If the WaveForms software were to receive these features at some point, it might come out on top. The WaveForms software does have a screen capture feature, but it also screen grabs the UI elements around the plot, in addition to the plot, which makes for unnecessary visual noise, and I would be tasked with cropping it out of every plot image I were to make.
The WaveForms software does offer a very high degree of customizability though, and also offers phase view, and the scripting engine comes with an IDE style debugger, and some default output scripts:
so this could be useful for quality control, or other types of pickup research, where the limitation of the Velleman or the Sys-Comp USB oscilloscopes might fall short.