Custom Y-axis range

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amartino
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Custom Y-axis range

Post by amartino »

Hi,

It is possible to select a range of +-50mV for the channel which would result to around 0.4mV minimal step. (2*50mV/256steps).

Is it possible to set this range with a constant DC component so that I can observe a range [1050 - 1100]mV while still having the minimal step of around 0.4mV?

Martyn
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Re: Custom Y-axis range

Post by Martyn »

A number of our scopes have the option to apply a DC offset to the input signal.

Which device do you have ?
Martyn
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amartino
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Re: Custom Y-axis range

Post by amartino »

2205A

alan
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Re: Custom Y-axis range

Post by alan »

If its a constant DC component you want to remove why not AC couple?

springburo
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Re: Custom Y-axis range

Post by springburo »

Most commercial scope add a dc offset to the Yaxis automatically so the full displayed window can be used and measured. Often we measure with the Yaxis 0V at the bottom of the screen, eg voltage over a transistor, with a 0-80V i could use a 0-100V scale/ 10V/div. With the picoscope I then have use a range +/100V and loose resolution. Would it be possible to automatically add the Dc offset in picoscope when the Yaxis is offset so that i could then measure from 0-100V with the full resolution.
Also having the option to snap the Yaxis offset at logical points say 20 would make life much easier

Gerry
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Re: Custom Y-axis range

Post by Gerry »

Hi springburo,

You're essentially correct. In our PicoScopes, the Analogue-to-Digital Converter (ADC) performs the conversion single ended to give ADC values from zero up to the maximum value for whatever resolution is being used. PicoScope 6 then effectively applies a DC offset to place 0V at a half-way value, and from that point on provides a double ended (split, positive and negative going) display. This is fundamental to the PicoScope 6 Scope view, so any further adjustments, such as software DC offsets, are made afterwards and won't preserve the resolution. To preserve any resolution an additional DC offset must be applied in hardware (before the ADC), which is only available in a few of our fuller featured hardware PicoScopes (unfortunately this doesn't include the entry level PicoScope 2205A).

Just to clarify, what I believe you're asking is "would it be possible to incorporate the user requested DC offset into the automatic DC offset that splits the display (giving a display that isn't split in the middle), so that any user requested DC offset (up to half of the voltage range) won't reduce the resolution", and "would it be possible to have, say 20, discrete values (grid lines) that the 0V line can be dragged and dropped to, in order to perform a number of quick adjustments". So, I will submit a software enhancement request, for this, and let you know the outcome. Thanks for the suggestion.

Gerry
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Gerry
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pslovely
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Re: Custom Y-axis range

Post by pslovely »

Springburo is right to request an option to snap the Yaxis offset at logical points (i.e. round numbers). This is a dreadfully awkward problem with the Picoscope that hampers me every time I use it with the vertical scales for two channels offset. I can see the level and amplitude of a signal clearly at a glance with a scale that uses round numbers. But, without the right "idiot savant" mental talents, it is very hard for me to mentally subtract two numbers with three decimal places in an instant. This problem has existed for years, and I'm surprised it isn't fixed by now.

Gerry, did you submit a software enhancement request? If someone rejected that, please put me in touch with them and I will deliver a more detailed sales pitch. This should be fixed in the interest of service to your customers and more efficient use of your products.

Martyn
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Re: Custom Y-axis range

Post by Martyn »

This is being worked on so should be available in a future release of the software :)
Martyn
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