AUTOSCOPE.EU

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?

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.

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

Eu capturei esta imagem em uma GM Montana 2015

Acredito ser baixa largura de banda do osciloscópio.

Hello friend ZAP !!!!

I would like to know more about this interesting topic. Do you have more information about this measurement?

Jorge S. Viera wrote: ↑

Mon Oct 14, 2019 10:48 pm

Hello friend ZAP !!!!

I would like to know more about this interesting topic. Do you have more information about this measurement?

Hey Jorge,

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.

FlexRay signals can definitely be challenging to capture accurately without the right tools. Using high-frequency probes or attenuated test leads can make a big difference in minimizing distortion.