PicoScope 7 Automotive
Available for Windows, Mac, and Linux, the next evolution of our diagnostic scope software is now available.
Thank you for that challenge as every day I study here at Pico, and I too, like us all, are learning about such techniques and features. Whilst digging and delving into the pro and cons of Vertical Resolution I found this great short video on our PicoTV channel on YouTube https://www.youtube.com/watch?v=EUcUKz5DTcI and it is a must see. I don't know about you guys but whilst I study the theory, actually seeing the effects such as in the video, brings it all home.HC_CDC wrote:“Resolution enhancement is a technique for increasing the effective vertical resolution of the scope at the expense of high–frequency detail. Selecting resolution enhancement does not change the scope’s sampling rate or the amount of data available.”
I assume Steve can explain this better but here is my understanding of the topic.
Looking at the T and M software this would appear to be the means by which you have to filter using the 2204 scope as the LowPass filter feature is not available under the channel options button (Probe selector) as with the PicoScope 6 automotive software. There is however a work around with the T and M software using a custom maths channels (LowPass A, 10) giving you the best of both worlds using Vertical resolution and low pass feature for the desired amount of filtering.HC_CDC wrote:Basically I sample at spec. resolution and then, when I look at static/saved data and the signal looks very dirty/noisy, I apply the enhancement by means of the probe selector (Channel Options Button) Often it helps to get a better idea of what’s happening using this adjustable filter and I find it very useful that it`s built-in. I find the Pico software incredibly good and I am sure I will find it better the more I discover what I can do with it, and I am not even talking about automotive.
This again is a point to note like over filtering, as it can disguise crucial areas of the waveform without careful analysis, which brings me ontoFat Freddy wrote:Would the 8 and 10 bit resolution settings alter these captures? I have seen injector captures displayed incorrectly using incorrect settings?
With the pressures we are under to resolve complex running issues I have found capturing the data dirty with no input from either LowPass or vertical resolution is the best method. Once removed from the turmoil of the workshop environment there is so much work to be done with the analysis that does require a clear head. The process is however reversible and should you apply filtering and resolution enhancement during capture you can remove the features during analysis.HC_CDC wrote:Quite often I look at the waveforms taken during a session a lot later and discover info that I had not even given a thought in the heat of trying to solve a problem quickly, this is how I found that you could apply the enhancement on an existing file.
We do have to tread very carefully with the T and M range of scopes when used in the automotive field, especially when it comes to the potential induced voltages with ignition primary. With our Cadillac the induced voltage does reach the 200 V point. via 10:1 attenuation is 20 V (Max input of your scope The overload however is 100 V). The scope 2204 is a pocket rocket for sure but it is vulnerable in this environment. 20:1 is better but still pushing the envelope with modern primary induced voltages at over 400 V. The amount of time the induced voltage is at a high level is very short but still places the scope at risk.HC_CDC wrote:The 2204 is an 8 bit scope, 20V, Freddy. I think I could reduce the voltage range to say 0 to 60 to get more real resolution of the firing line, only not sure if the 200V plus peak (20 after the 10:1 probe really) would not fry the scope which than would be set to receive 0-4 volts. Steve??
Thanks for the reply Steve, understand the delay in responding, have the same issues. Yes, the parts have arrived and engine is running smoothly as I will show in a capture later on..steve smith wrote: The burning question I have is, “Have the Cadillac parts arrived and if so how is the engine running?” (Do you any waveforms after fix?)
I think the form of the spark, which must be an irregular event, can easily be shorter or longer, must be the (at least part) cause of that.Looking at the waveform from the Cadillac I can see the area of concern surround the “points open” and why the oscillations? This event is also mirrored in the coil primary voltage suggesting current continues to flow (in some form) pointing towards condenser or condenser ground error.
Reading your notes attached to the waveform you have mentioned cleaning the points and installing donor points, and an issue in your post regarding an error in dwell of around 1ms.
This leads me onto distributer shaft bushing wear and “drive error” with “backlash” which are all relevant around the big events that take place at “points open” Whilst the dizzy is new/repaired why the 1 ms variation in dwell? (Food for thought as ever)
Yes, forgot to check current behaviour with electronic pickup after fitting the pickup/reluctor but will grab dwell accelerating if and when I get the chance. Before having done that cannot reply to any of the current questions.Interesting point you raised regarding the dwell period V charge time; I can imagine the issues that unfold at 4000rpm + with the errors above.
In your waveform notes you mentioned “resistance coil wire feed on coil”, this had me thinking about ballast ignition, is this relevant to this vehicle i.e. is it installed?
Noted that fitting the clamp on often hard to reach places and spaces the zeroing might be screwed up a bit, sometimes I have to zero a few times in sequence to really see zero on the waveform. But then, with the Hall sensor being close to other cables as well on many occasions, who knows what influences the clamp picks up really? Good to keep in mind in the future and maybe think a little more about such things when you place a clamp.I do have a question about your current value/shape as it never appears to “Zero” and remains around 140 mA with an uneven current ramp, how is your clamp on other switching circuits?
Thanks for that link, very interesting.steve smith wrote:Whilst digging and delving into the pro and cons of Vertical Resolution I found this great short video on our PicoTV channel on YouTube https://www.youtube.com/watch?v=EUcUKz5DTcI and it is a must see. I don't know about you guys but whilst I study the theory, actually seeing the effects such as in the video, brings it all home.
Tried this but not getting what I expected (yet), saw that the beta version has some new filtering options added, have to look at that too in detail when I have some time.Looking at the T and M software this would appear to be the means by which you have to filter using the 2204 scope as the LowPass filter feature is not available under the channel options button (Probe selector) as with the PicoScope 6 automotive software. There is however a work around with the T and M software using a custom maths channels (LowPass A, 10) giving you the best of both worlds using Vertical resolution and low pass feature for the desired amount of filtering.
HC_CDC wrote:The 2204 is an 8 bit scope, 20V, Freddy. I think I could reduce the voltage range to say 0 to 60 to get more real resolution of the firing line, only not sure if the 200V plus peak (20 after the 10:1 probe really) would not fry the scope which than would be set to receive 0-4 volts. Steve??
....The overload however is 100 V). The scope 2204 is a pocket rocket for sure but it is vulnerable in this environment. 20:1 is better but still pushing the envelope with modern primary induced voltages at over 400 V. The amount of time the induced voltage is at a high level is very short but still places the scope at risk.
To come back to your link, can I do the axis scaling with the 2204?steve smith wrote: Thank you for that challenge as every day I study here at Pico, and I too, like us all, are learning about such techniques and features. Whilst digging and delving into the pro and cons of Vertical Resolution I found this great short video on our PicoTV channel on YouTube https://www.youtube.com/watch?v=EUcUKz5DTcI and it is a must see. I don't know about you guys but whilst I study the theory, actually seeing the effects such as in the video, brings it all home.
We have to stay within the specified measuring range of the scope, (20 V) regardless of the overload protection. There is a first line of defence when the input voltage exceeds the maximum stated voltage in the form of a sacrificial F.E.T circuit that allows for a reasonable repair/recovery of your scope, but no short circuit protection regarding current flow, (unlike the automotive scopes).Thanks for the warning, duly noted... That the overload protection is 100 V could mean many things, basically with a 10:1 probe that would be 1 kV, for how long? Is there an in-house test that showed it would hold that level for a certain (limited) time or even unlimited? Is it protected by a 100 V Zener diode maybe and would that mean it remains undamaged at 95 V for unlimited time? Or does it mean that there is a 20 V Zener and that peaks up to 100 V are safe?