LabWindows/CVI

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rfsa error

Moses,

 

As for the first warning, you should be able to remedy this by doing the suggestion in the error. You could try reducing the amplitude of your input signal using an attenuator, or increase your power level (i.e. vertical range). Have you tried changing these settings? 

 

For your second question, either of the functions you described will work to fetch IQ data. It will depend on if you are doing a continuous acquisition (multiple records) or just a finite acquisition (single record). If you want to acquire continuously and send the IQ data to a file, then MultiRecordComplex is probably what you want.

 

Regards

Robert Barnes

Robert B
RF Product Support Engineer
National Instruments
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Message 11 of 56
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Hi Robert,

I made the changes as you advised and the error is gone but when i run the code below with MultiRecordComplex with no. of records been three 

checkWarn (
niRFSA_FetchIQMultiRecordComplexF64 (
rfsaSession,
0,
0,
NUMBER_OF_RECORDS,
numberOfSamples,
15,
waveform,
&wfmInfo));

 

if i try to printf("%d", waveform); I get the result as -1089471672.What can i do to stream as binary data i.e 1110011 since my variable waveform is a NIComplex.

 

Thanks ,

moses

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Message 12 of 56
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Moses,

 

Are you using LabWindows/CVI by chance? There is a "StreamBinaryIQDataToDisk" example that sounds like what you want.

 

Otherwise, you'll likely have to use the Win 32 File I/O functions to stream the data you're collecting to a binary file. That's something I'm not all that familiar with, unfortunately. You might try looking on stackoverflow or looking into the Win32 File I/O API. Maybe this link below can give you some information to get you started.

 

http://msdn.microsoft.com/en-us/library/windows/desktop/aa364232(v=vs.85).aspx

Robert B
RF Product Support Engineer
National Instruments
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Message 13 of 56
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Hi Robert,

First i appreciate all the assistance you have accorded me so far and hope you can forward me your email if you dont mind.

Back to the above discussion, i realised its good to first be able to capture a continuous data which is lacking in the above case.My acquisition only returns a single data and it remains the same data returned even after consecutive runs making me doubt its accuracy.What can i do to capture continous data?

am using the function niRFSA_FetchIQMultiRecordComplexF64 () but still gets this single data.

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Message 14 of 56
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Hi Robert,

A continuation of the above question,i want a situation where the number of samples and the number of records are infinite but i dont know how to configure this as for finite its working ok.

 

 

Thanks,

Moses.

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Moses,

 

Are you using LabWindows/CVI for your development environment?

 

In general, you should be able to loop over the niRFSA_FetchIQMultiRecordComplex64() function. You could do this with a while loop or a for loop, depending on the behavior you want. If you want to control when it stops, then you'll want to use a while loop. If you want to acquire a specific number of records, then you'll want a for loop.

Robert B
RF Product Support Engineer
National Instruments
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Message 16 of 56
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Hi Robert,

So far things worked and i have been able to capture and save the signals.But i still want to bother you further with the following questions:-

1. If i want to configure hardware to capture two different signals under the same session,what procedure is required?

2. Since my signals are in machine readable form and i would prefer them in binary form(1 or 0), how can i convert them to this form. Is this procedure what we refer as signal processing?

 

Thanks,

Moses.

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Message 17 of 56
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Moses,

 

Are you trying to acquire two signals using a single 5663E? This will not be possible since the 5663E only has a one channel. If you have two 5663E devices, you'll set up two sessions.

 

As far as I am understanding, you are using the niRFSA_FetchIQMultiRecordComplex64() function which returns a comples 64-bit floating point data type. What do you mean by "machine readable" code? Are you converting this data somehow in your code? Converting data types is not typically referred to as signal processing.

 

You can write any data type to a binary file. All the binary file does is keep track of the 1's and 0's. As long as you use the same format to read it back as you do to write it, you'll be able to get all of the information back without trouble. I'm not an expert on how to do this in C. You'll probably have to use the Win32 library or something to do it. You might look into StackOverflow or some other C language forums for ideas.

Robert B
RF Product Support Engineer
National Instruments
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Message 18 of 56
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HI Robert,

For two signals i.e GSM uplink signals & downlink signals, it means i have to add a new downcoverter & digitizer to the chassis?

 

Yes am using  niRFSA_FetchIQMultiRecordComplex64() function which gives me the following result which i was referring as machine readable.

€¤-§°B¿ÓXDýˆ­P¿\¦¹øJ?¼ª0’‰ëH¿ú·ÖL?µ˜ûO;üF?÷;hi·Q;¿Zúšü"çR?¥ â}WR¿Ê©”c“¿2ÍŸ@å· ¿ ¿NN¨S¿ï‘¾+T–Q?çCO—û¬6¿¦
º$ºB?R~ŽÅ”P?‹i´ñ؝I¿Ž=c?øcJ?4;söO¿?+øtgaB¿Yz…ËÀ6?·‰¡uÍ'P¿Zúšü"çR?8uýÛ#D?—#GÏe-?Ùµ lOkR?ñ°¦ë*R¿môÿp»??ßÇB®ZD¿6 &5áN¿Œ Å`ÏI?,»jþ–ÈK¿¸> IUYP?¥ëvª÷%B?Ó

 

This is the data type  i want to convert to understand.

 

Thanks,

Moses

 

 

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Moses,

 

What is your overall goal here? Is it to test GSM signals? Are you trying to generate and acquire these signals or are you testing some other sort of hardware?

 

Also, it would be very helpful to see the code you are using and the data file where this data came from. If you could upload these things, it might help me make sense of some of this.

 

What you're referring to as "machine readable" is simply ASCII representations of non-displayable characters. You would see something similar if you tried to open a .xlsx or a .exe in notepad.

Robert B
RF Product Support Engineer
National Instruments
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