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noise source for transmission measurement - RF Cafe Forums
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| Adi
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Post subject: noise source for transmission measurement
Posted: Wed Nov 01, 2006 4:09 pm
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Joined: Mon Aug 21, 2006
11:52 am
Posts: 6 |
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Hi all,
I have a question regqrding noise
sources.
I would like to do some measurements
of RF devices from MHz up to a few GHz. The best
would be of course to have a network analyzer. For
the near feature I was considering another option:
use a spectrum analyzer that is already available,
combined with a broadband noise source. Of course,
I will miss the phase information and also I cannot
measure reflection. I would greatly appreciate any
advice on this. Also, do you know how easy it is
to get a noise source at a decent price? Someone
warned me that a good noise source can also be quite
expensive (though I hope it is not that bad, since
I do not need a very flat spectral density and large
power for example).
Any tip is greatly appreciated,
Adi
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IR |
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Post subject:
Posted: Fri Nov 03, 2006 5:24 pm
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| Site Admin |
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Joined: Mon Jun 27, 2005
2:02 pm
Posts: 406
Location: Germany
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Hello, Don't mix between the use of Network
Analyzer and Spectrum Analyzer. Network Analyzer
won't help you to measure noise. Please provide
information on what kind of parameters you want
to measure? In the RF world one should have
a deep pocket for purchasing test equipment. There
are no cheap solutions for getting accurate and
reliable test results. Any compromise in the price
will come on the expense of quality
_________________
Best regards,
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IR
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Adi |
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Post subject:
Posted: Sun Nov 05, 2006 11:47 am
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Joined: Mon Aug 21, 2006
11:52 am
Posts: 6 |
Hello IR, Thank you for your reply. I see
that I did not manage o explain very well what I
wanted to do. The idea is that I want to set up
a measurement system and for characterization I
want to to measure transmission of various two port
components (amplifiers, transmission lines, etc).
Of course, I would normally use a network analyzer,
which gives both the amplitude and phase of the
transmission. The problem is that we do not have
a network analyzer. But, since we have a spectrum
analyzer, I was thinking of a different solution:
use a noise source to inject some broadband noise
at one port and the spectrum analyzer to measure
the transmitted noise at another port. This measurement
would give me the amplitude of the transmission
for that two port system (unfotunately I will still
miss the phase). So in the end I would need a
noise source to do the measurement. The requirement
would be that it generates noise in a broadband
(say from a few MHz to a few GHz) and that it has
an output impedance which is 50 ohm over this band.
Quote:
In the RF world one should have a deep pocket
for purchasing test equipment. There are no
cheap solutions for getting accurate and reliable
test results. Any compromise in the price will
come on the expense of quality
I completely agree with you. Adi
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sm7ovk |
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Post subject:
Posted: Sun Jan 14, 2007 2:18 pm
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| Captain |
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Joined: Thu Jan 11, 2007
12:59 pm
Posts: 16 |
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Hi,
if I understand you right you want to
see for an example a filter-curve on your spectrum
analyzer. This is possible. You will not, as you
mention your self, see the angle information.
What can be tricky though is to have enough power
from the noise source since these often have very
low output power. If you amplify this noise you
must be sure to have a good output match!
Hope this helped.
Regards
Jens
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Posted 11/12/2012
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