Attanuation in 5142

[madd]

Hello

Question. I am using baseband example of niscope(5142) to acquire two sine waves from channel 0 and channel 1. when I look at the waveform and spectrum of the signals. Signal acquired from channel 0 is attenuated almost 45db w.r.t channel 1. niscope express VI gives the same result.(when coupling is DC and resistance is 50ohm, when auto setup is enabled then working fine). Wile using the above mentioned example. If I set the coupling to Ac and resistance to 1Mohm. Type of acquisition is not supported error comes.Why is this attenuation there on channel 0 i there any software based attanuator in here or ???

Regards

Madd

[John_P1]

Hi Madd,

It sounds like the Auto Setup feature eliminates the attenuation problem.  This would seem to indicate that the settings you are using are different from those that are set by the Auto Setup.  You can run the Auto Setup feature in the Express VI to set the parameters--does this correct the attenuation you are experiencing?

Keep in mind that the channels on your 5142 can be configured individually.  My guess is that when you are manually setting the properties of your scope, you are configuring one channel differently from the other.  AC Coupling is only supported for 1 MOhm input impedance on the 5142 according to page 5 of the detailed specifications.  Could you post a screenshot of the error message to provide more details?  I am not immediately sure what type of acquisition the message is referring to if it does not mention 50 Ohm impedance and AC Coupling.

If the above does not provide any insight, could you post a simple example of the code you are using to perform the acquisition?  I would like to take a look at the settings you are using.

-John 

[madd]

Hello

 

Here I have attached the vi’s print Screen. I have set min sample rate =100Ms/s, vertical coupling =DC , input impedance =50Ohm ,min record  length=100, max freq = -1 . Channel 0 is a sine wave with 20Mhs frequency and Vp-p=3.40v similar is the case with channel 1. since I have checked on oscilloscope about frequency and voltages. if i try to use autosetup then my acqusition type which is complex is not supported.

Regards

Madd

[John_P1]

Hi Madd,

Could you tell me more about what you are using to source the signal?  Perhaps it cannot supply enough current to drive a 50 Ohm load.

-John 

[Chris_W.]

Hello Madd,

Because your question on this post is the same as on other threads, we would like to consolidate your posts to one thread so that everyone who is interested can follow the progress of your issue. All further activity on this issue will continue on thread linked HERE. Thanks.

Chris W