RF signal measurement

[km76107]

Is there a way to measure the RF signal strength using LabView 7.0?  I am using a mobile 802.11b/g transceiver that talks to my wireless laptop (running Windows XP).  How can I measure the attenuation, bit error rate, signal to noise ratio using labview?

Thanks in advance.

km

[Andy_Hinde]

Hello KM,
National Instruments can definitely help you with this. The PXI-5660 RF Vector Signal Analyzer can be used to capture the 802.11 b/g signals, and the Spectral Measurements Toolkit and Modulation Toolkit can be used to perform the analysis.
The Spectral Measurements Toolkit would be used for the frequency domain analysis (e.g. atenuation, SNR) and the Modulation Toolkit would be used for the bit-error rate (BER) measurement. The Spectral Measurements Toolkit comes with the PXI-5660 and the Modulation Toolkit is sold separately. Everything mentioned here is supported under LabVIEW 7.0.

PXI-5660 Product Page:
http://sine.ni.com/nips/cds/view/p/lang/en/nid/12591

Modulation Toolkit Product Page:
http://sine.ni.com/nips/cds/view/p/lang/en/nid/12855

[km76107]

Thanks for the prompt response.  I am in a very basic prototype stage with limited budget.  In addition,  the signal strength display is not a requirement of my demo. It's just an added feature I'd like to show.

Is there a way i could do this without the Spectral Measurements Toolkit and Modulation Toolkit?

[Andy_Hinde]

Hi KM,
The algorithms for doing this are present in these toolkits, so in order to avoid using them you would have to create the algorithms yourself. If you have a way of capturing the signal data and bringing it into LabVIEW you could probably use some built in tools to do atteuation and SNR, but the BER measurement requires you to know the transmitted and received bit pattern. If you have access to the transmitted and received bit patterns then you could do a BER measurement in LabVIEW but would have to write the algorithm yourself - LabVIEW doen't have a built in BER measurement utility.

Regards,
Andy Hinde
National Instruments

[km76107]

Hi Andy,

By capturing the signal data, do you mean using Spectrum Analyzers to record the waveforms of the transmit and receive patterns and then interface the analyzer to LabView?

KM

[Andy_Hinde]

Hello KM,
This would be one method of acquiring the data - via GPIB into the local host PC. This would be the method using traditional instruments. I will assume this is your use case and that you are not using any PCI or PXI based instruments.

If you have the data representing a power spectrum on the host PC, then you could write code to measure the signal and noise components and write a SNR routine. This would require knowledge of the proper way to perform this measurement of course, with this knowledge implemented into the algorithm you develop. LabVIEW's SNR tools work off of time domain data so your frequency domain data precludes the use of this.

As for BER, you would not be able to do this measurement with frequency domain data.

Regards,
Andy Hinde
National instruments

[km76107]

Thanks Andy. I'll try it out and let you know the outcome.

KM

[nearboston]

I would like to revive this topic rather than start a new one.

I need to measure the signal strength from multiple sources using "cordless phone" technology.  That description isn't mine, that was all the information I was given.  Right now I need the basic information to go forward,and am not getting a lot of details other than the client uses LABView 8.6, is in a pre-development stage and just wants to prove concept.  They want to measure the signal strength from more than one cordless telephone, and save the data in a file to be used later.

Can I get some inforrmation to get started? 

Thanks in advance. 

[johnsold]

That sounds like a client that you should say "No" to!

If they will not define the problem any more clearly than that, make sure they will pay you to do it for them.

1. I have never heard of a cordless phone with any kind of interface for connecting to a computer.  While a few may have signal strength indicators, I doubt those are common or that the data is accessible to an external computer.  How much reverse engineering of the phones are they going to pay you to do?

2. Which cordless phone frequency band(s) are involved?

3. Do you have access to any rf measurement equipment or any commercial receivers which cover the frequency bands of interest? Will they rent it if they do not have it?

4. How will you detect and compensate for interference from other phones (not the ones you are trying to measure) and other devices which happen to be operating nearby on the same frequencies?

I can think of a variety of ways to do some of the things they may be asking, but without pinning things down a bit (OK, a lot), it will be hard to know where to start.

Lynn

[Odiniz]

Hi All!

I'm to transmit and receive an output bit stream, by modulating and demodulating an RF signal.

I'm using MT RFSG Generate FSK.vi and MT niRFSA FSK Trellis Diagram.vi.

How to measure SNR of the channel using a Spectral Measurements Toolkit? 

I'm using PXIe-5663 RF VSA and PXI-5671 RF VSG with an antenna

The carrier frequency is 1.8 GHz. 

Thanks in advance!