trasfer function and PSD in 0-500kHz

[Luca_Romano]

Hello everyone,

I would like to measure the Frequency Response and the Power Spectral Density with regard of a communication' channel ( it's a cable of 3/4 meters ) in the band 0-500kHz .
Is this measure feasible with a spectrum analyzer ? any suggested VNA to use?
Or how I could carry out this type of measurement?
Thank you all!
Luca

 

[BigBoss]

Frequency Response can be found with a LF VNA.It's Ok but what will you do PSD ??? It's just a cable...
Is there anything that I misunderstood ??

 

[Luca_Romano]

Hello BigBoss,
thanks for your quick reply. You're right: my post is not so clear and complete. I'm asking with regard to noise PSD too because I would like to investigate a car DC bus for powerline application. I guess now it's clear.
Sorry about my lack of knowledge on this subject: is not possible to use a spectrum analyzer instead of a LF VNA? Furthermore: I saw some LF VNA adapter..what do you think about them?
Thanks

 

[BigBoss]

If I understood well ...

You're trying to examine the noise immunity of a transmission environment ( a cable ???) against Noise Source(s) ??? Right ??
So that this transmission medium works in a harsh/noisy/dirty environment and you would like to obtain predicted signal quality over that ..??

 

[Luca_Romano]

Hello BigBoss,
yes: I would like to know in which 0-500kHz sub-band the transmission medium should work better.
I would like to investigate the trasmission channel (non considering impulsive noise).

 

[BigBoss]

Hello BigBoss,
yes: I would like to know in which 0-500kHz sub-band the transmission medium should work better.
I would like to investigate the trasmission channel (non considering impulsive noise).

The frequency response of this transmission medium standalone can be measure with a Low Frequency Scalar Network Analyzer.So you may have an idea how much your transmission medium is immune against the "internal" disturbing signals in this band.
But in order to predict this immunity against "external" disturbing signals you should create a measurement setup in a -particularly- EM chamber and it's not easy at all.
This is known as "EMI Test" and only specialized laboratories can do that.

But in my opinion, trying to create a measurement test bench is better to physically observe these impacts.For instance if you send a digital data over a cable, insert a disturbing signal and make BER tests to obtain the immunity.There may also be other different techniques but this is simplest one.

 

[Luca_Romano]

Hi BigBoss,
thanks again for your post. Yes, I agree: it's better to create a measurement test bench and experimentally evaluate the impact.
Regards,
Luca