How to measure the bandwidth of the signal?

[gemstone]

Hi,
Sorry that I have delayed to clarify the question.I want to show all narrowband signals in Labview.The whole bandwidth is 24M.There are many narrowband signals within the 24M signal.First I want to find how many narrowband signals(I think that the problem is to find the proper reference level).then measure the bandwidth of each narrowband signal.How can I finish it?I know that it is very complex bacause it involves mathematic statistic knowledge.
Thank you.

[Kent Leung]

Hi,

I'm not sure if I completely understand your question but here's some input anyway.

First of all, to sample a 24Mhz signal properly, you would need at least a 48Mhz sample rate. This rate may be difficult to find on any current hardware offering.

To find the number of narrowband signals, you could use the Waveform Peak Detection.vi to find the number of peaks in the FFT of your signal.

According to dspguru.com, the bandwidth of a bandpass filter is "typically defined as the frequency difference between the upper and lower -3 dB points". If you apply this to a signal you could do a Power Spectrum FFT on each of the "narrowband signals" and take the difference between the -3dB points.

This is all assuming you can bring in the 24Mhz signal pro
perly.

Hope this was of some help.

Kent