5142 8/16/32 bit

[madd]

Hello
 
1- I am working with Ni 5142 Digitizer. i want to stream complex data, for which i have enabled DDC and rest of the Pentameters. I want to acquire Like Binary width example vi in Examples of niscope.Now the problem is when I fetch the data in 8/16/32 bit format in 1D format vi gives the error

Possible reason(s):
Driver Status:  (Hex 0xBFFA0010)
Invalid value for parameter or property.

Device: Digitizer
Property: Binary Sample Width
Invalid Value: 8
Possible Values: 32

Status Code: -200077

which is true that it works for 32bit only.

2- Now when i made the fetch vi to fetch in 2D 8/16/32 it works fine what's wrong with the 1D fetch? what is coming out I don't Know but as long as vi is concerned it is running fine.

3-When I am not using Binary sample width in property node and fetching in 8/16/32 manually  it works fine for 1D as

    well as 2D.... Whyy?

[Kyle_A.]

Hi madd,

I have a few things I would like to clarify from you.  When you are fetching data, are you specifying both channels on the card or just one channel?  Also, for testing purposes, if you specify Binary Width but set your DDC Enable to False, I would be interested to see if you still receive the same error.

[Andy_Hinde]

Hello,

Attached is an example in LV 2009 format that streams binary data from the 5142 to host RAM when the onboard OSP is enabled.

Regards,

Andy Hinde

RF Systems Engineer

National Instruments

[Andy_Hinde]

Hi Madd,

Did this work for you?

Thanks,

Andy

[madd]

Hello

NO I have labview 8.6 with me and this is on labview 9.0.

1- Another question I was working with pxi-5142_spectrum_analyzer.vi . I have been told before that DDC and

    Frequency translation enable will shift my center frequency to "0" with bandwidth around it. What is this frequency shift

    for in this vi.Is it just to show (what frequency is translated to "0" like) 10MHZ while actually it is being at "0"HZ'S or

    something else am asking this because. I want to use DFD toolkit for filtering my signal. This frequency shift is creating

    a doubt that weather to set the CF to 10M or "0" and rest of parameters like Upper stopband and lower stop band

    etc.if i set the freuency shift property to "0" am i getting true spectrum which is around "0"HZ's.

2- if frequency translation set the spectrum to "0" frequency then can I give lowerstop  band parameter in negative

    frequency using DFD toolkit.

3- pxi-5142_spectrum_analyzer.vi  In this vi fetch type is complex cluster spectrum is looking fine if I change it to 1D16

    it looks like that it is inverted.How would I get same spectrum by setting (DDC fetch interleaved IQ sample property to

    true) and fetch type to 1D16

Regards

[Andy_Hinde]

Hi Madd,

 Attached is a version for LabVIEW 8.6.

1- Another question I was working with pxi-5142_spectrum_analyzer.vi . I have been told before that DDC and

    Frequency translation enable will shift my center frequency to "0" with bandwidth around it. What is this frequency shift

    for in this vi.Is it just to show (what frequency is translated to "0" like) 10MHZ while actually it is being at "0"HZ'S or

    something else am asking this because. I want to use DFD toolkit for filtering my signal. This frequency shift is creating

    a doubt that weather to set the CF to 10M or "0" and rest of parameters like Upper stopband and lower stop band

    etc.if i set the freuency shift property to "0" am i getting true spectrum which is around "0"HZ's.

 The IQ data returned by the PXI-5142 with niScope Fetch is centered at 0 Hz. The frequency shift parameter is simply for Spectral Measurements Toolkit (SMT) so it can shift the X axis of the graph correctly. If the frequency shift parameter were set to 0, the power spectrum shown on the graph would be centered at 0 Hz, instead of the original signal's center frequency. The IQ dat aitself is still centered at 0 Hz though.

2- if frequency translation set the spectrum to "0" frequency then can I give lowerstop  band parameter in negative

    frequency using DFD toolkit.

 The DFD tooklit should have documentation for working with complex data centered at baseband. If you are trying to bandpass filter the signal, I would try using a DFD lowpass filter with the cutoff frequency set to one-half the bandwidth you want.

3- pxi-5142_spectrum_analyzer.vi  In this vi fetch type is complex cluster spectrum is looking fine if I change it to 1D16

    it looks like that it is inverted.How would I get same spectrum by setting (DDC fetch interleaved IQ sample property to

    true) and fetch type to 1D16

Please see the attached VI which should answer your question.

Regards,

Andy Hinde

RF Systems Engineering

National Instruments

Message Edited by Andy Hinde on 03-15-2010 09:50 AM

[madd]

 Hello

1-The vi u have attached here is what I have done before that acquisition is working fine as long as fetch vi data type is

    not changed in a particular acquisition setting Also I am talking about complex acquisition with DDC and FT enable

    where channel input is from Channel 0 only.

2- About Complex baseband filtering I am not getting any help from NI. I have got DFD toolkit with me. But for complex

    filtering I am getting nothing.why do i need this is? Suppose I have acquired 10Mhz bandwidth with CF at zero. There r

    some signal which are at lower frequency than my CF "0". Suppose at -2Mhz with BW 500K. When I ll apply filter i

    need to give some frequency range for filtering. Who would i do this filtering since my frequency range is in negative

    frequencies. Any other alternate suggestion for this filtering problem will be highly appreciated...

 Regards

[madd]

Hello

One more question. This type cast function ur using in the VI attached is taking too much of time that backlog reaches in 2/3 sec when I try to increase the sampling rate(like 10M) or span.i have 5142 with 512MB OBM. And if i disable the type cast function the backlog is not increasing an vi runs much more time than with typecast enable. Is there an alternate and quick method to change the data type except the Flatten, unFlatten and type Cast.

Regards 

[Andy_Hinde]

1-The vi u have attached here is what I have done before that acquisition is working fine as long as fetch vi data type is

    not changed in a particular acquisition setting Also I am talking about complex acquisition with DDC and FT enable

    where channel input is from Channel 0 only.

 If that acquisition is working fine, then I don't understand the reason for this thread. This code demonstrates how to stream complex, binary IQ data to RAM. I understand you are talking about complex acquisition using channel 0 only, as the VI I have attached acquires compelx data that is a digitally downconverted representation of the signal on channel 0. 

2- About Complex baseband filtering I am not getting any help from NI. I have got DFD toolkit with me. But for complex

    filtering I am getting nothing.why do i need this is? Suppose I have acquired 10Mhz bandwidth with CF at zero. There r

    some signal which are at lower frequency than my CF "0". Suppose at -2Mhz with BW 500K. When I ll apply filter i

    need to give some frequency range for filtering. Who would i do this filtering since my frequency range is in negative

    frequencies. Any other alternate suggestion for this filtering problem will be highly appreciated...

 I've only seen one previous question regarding complex filtering on this thread, which was responded to, and if you have other threads discussing this problem that you are not receiving responses from, then you should link them here. I'll install the DFD Toolkit and see what I find.

 3. One more question. This type cast function ur using in the VI attached is taking too much of time that backlog reaches in 2/3 sec when I try to increase the sampling rate(like 10M) or span.i have 5142 with 512MB OBM. And if i disable the type cast function the backlog is not increasing an vi runs much more time than with typecast enable. Is there an alternate and quick method to change the data type except the Flatten, unFlatten and type Cast.

This is not surprising. The only purpose of the typecast in the VI is to show how to convert the binary data from raw I16 to scaled voltage values. If you are not writing the binary values to disk, like in a stream to disk application, and instead you are processing the IQ data inline, there is no point in you using the Binary Fetch VIs in NI-Scope instead of the normal Fetch which returns normal voltage values. If you are streaming to disk, then you simply write the binary values to disk and do not call Typecast.

Message Edited by Andy Hinde on 03-18-2010 08:17 AM

[Andy_Hinde · Accepted solution]

Hi Madd,

Attached is the same example as before, which streams 5142 complex IQ datato RAM, with the addition of some complex filtering via the Digital Filter Design Toolkit.

The DFD Toolkit does not have support for native complex data types, but this is no problem. To bandpass filter a complex signal at baseband 0 Hz, you simply use a low pass filter design with the cutoff frequency and stopband attenuation you want, and then use this same filter design on the individual I and Q data streams.

I've also changed the front panel so that now it shows a power spectrum so you can see the effect the DFD filter is having on the IQ data. Since your application needs to run as fast as possible, you will eventually want to remove everything but the Fetch and any processing you must perform on the IQ data from the nested While Loop. This includes the computation of the power spectrum and the graphing of any data.

Hope this helps.

Regards,

Andy Hinde

RF Systems Engineer

National Instruments