So, I had a 17 Audi Q7 come in today with communication codes. I attempted to scope the network lines, and this is what I got:
The picture above is with the sampling rate maxed out at 5Ms. I tried switching to a single channel and cranking it up to 12.5Ms. Below is what I got:
Still doesn't look right. After doing some research, I learned that this system on this vehicle uses Flexray. Just for the hell of it, I hooked up the shop's Picoscope.
It looks slightly better, but still not great. After doing some reading, I found that special test leads are required for getting a good signal with high speed signals like this. Here are the Pico leads: https://www.autonerdz.com/Blue%20Site/t ... 5large.jpg
I have two questions. First, it seems like Flexray is pretty close to maxing out the capabilities of the Autoscope. With the proper leads, can the Autoscope get a good pattern on signals of this speed?
If so, does Autoscope sell an equivalent test lead? If not, could I use the Pico leads with an adapter?
Flexray
Flexray
- Attachments
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- 17 Q7 flexray3.mwf
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Re: Flexray
Yes, you can use the PIN3-BNC adapter together with the high-frequency oscilloscope probe, the distortion from the parasitic capacitance of the cable will be minimal.
PS:
Here, the pulse repetition frequency is 5 MHz, this is theoretically the upper possible limit of the bandwidth, which could be measured at a signal sampling frequency of 12.5 MHz.
In practice, the upper limit for USB Autoscope IV is 2 MHz.
PS:
Here, the pulse repetition frequency is 5 MHz, this is theoretically the upper possible limit of the bandwidth, which could be measured at a signal sampling frequency of 12.5 MHz.
In practice, the upper limit for USB Autoscope IV is 2 MHz.
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Re: Flexray
Acredito que voce precisará de sondas de osciloscópio Ativas. Estas sondas tem um alto custo financeiro.
https://www.rohde-schwarz.com/br/produt ... 29530.html
https://www.rohde-schwarz.com/br/produt ... 29530.html
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Re: Flexray
Eu capturei esta imagem em uma GM Montana 2015
Acredito ser baixa largura de banda do osciloscópio.
Acredito ser baixa largura de banda do osciloscópio.
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Re: Flexray
Hello friend ZAP !!!!
I would like to know more about this interesting topic. Do you have more information about this measurement?
I would like to know more about this interesting topic. Do you have more information about this measurement?
Re: Flexray
Hey Jorge,Jorge S. Viera wrote: ↑Mon Oct 14, 2019 10:48 pmHello friend ZAP !!!!
I would like to know more about this interesting topic. Do you have more information about this measurement?
Unfortunately, I don't have anything new to report. I did buy a set of cheap attenuated test probes, ( https://www.ebay.com/p/2229729394 ) but I haven't had any time to try them out.
I'll try to remember to take some waveforms the next time an appropriate vehicle gets left overnight.