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How to lower noise floor? - RF Cafe Forums
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| NewAlf
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Post subject: How to lower noise floor?
Posted: Tue May 30, 2006 10:50 pm
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Joined: Sun May 28, 2006
6:29 pm
Posts: 3 |
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Hello everyone,
I am working at the GigaHertz
ragne with an antenna that produces a noise floor
of -60dB. The expected signal has a peak of -58dB.
Just wondering, how can i lower the noise floor
to observe a clean signal?
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karthik |
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Post subject:
Posted: Wed May 31, 2006 12:00 am
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Joined: Tue Apr 11, 2006
8:13 pm
Posts: 34 |
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Hi,
Just wanted a clarification. What are
you measuring? Are you measuring the signal at the
output of the antenna or the output of a receiver?
How are you measuring it? The -60 dBm level that
you have indicated looks like the noise floor of
the spetrum analyzer that you are using. If that
is the case, then turn averaging on and also reduce
the video bandwidth of the spec analyzer.
Karthik
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NewAlf |
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Post subject:
Posted: Wed May 31, 2006 2:07 am
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Joined: Sun May 28, 2006
6:29 pm
Posts: 3 |
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The antenna is being used to receive any singals
from surroundings. The antenna is simply connected
to the spec anal...I'll try turning averaging on
and play with VBW...thnx for your reply..
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nubbage |
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Post subject:
Posted: Wed May 31, 2006 10:00 am
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| General |
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Joined: Fri Feb 17, 2006
12:07 pm
Posts: 218
Location: London UK
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You could also buy an LNA covering the bandwidth
of interest, then screen the antenna sidelobes from
any hot sources such the earth, surrounding buildings
etc.
The sensitivity/MDS level of -60dBm could
be substantially improved on. The theoretical limit
is calculated using the formula for noise power
in a restistive load at temperature T in degrees
Kelvin.
P = K*T*B*N Watts
Effectively
N (the noise ratio of the LNA) adds to the temperature
T when all parameters are converted to decibels,
or just add the LNA noise temperature to the background
temperature of the source (often the sky around
a star). B is the system bandwidth in Hertz, and
K is Boltzman's Constant.
Maybe the level
you mention is because in your case B, the bandwidth,
is very large.
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asoft |
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Post subject: spectrum analyzer measurements near noise floor.
Posted: Wed Jun 21, 2006 3:09 am
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Joined: Sun Mar 05, 2006
10:38 am
Posts: 1 |
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hi, what is the noise floor atainable with your
spectrum analyzer? You can try reducing the frequency
bandwidth, and increasing the RBW. If you know the
exact frequency of the signals to be measured, it
is suggested to reduce the frequecy and RBW sufficiently
to get a clear signal. However, if -60db is the
best you can get with lowest RBW and frequency span,
it may be difficult to measure the signals. By the
way, which spectrum analyzer are you using? (make
and model)?
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sivajo |
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Post subject: Re: spectrum analyzer measurements near noise floor.
Posted: Mon Nov 06, 2006 10:54 pm
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Joined: Mon Nov 06, 2006
10:40 pm
Posts: 2
Location: Shenzhen China
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asoft wrote:
hi, what is the noise floor atainable with your
spectrum analyzer? You can try reducing the
frequency bandwidth, and increasing the RBW.
If you know the exact frequency of the signals
to be measured, it is suggested to reduce the
frequecy and RBW sufficiently to get a clear
signal. However, if -60db is the best you can
get with lowest RBW and frequency span, it may
be difficult to measure the signals. By the
way, which spectrum analyzer are you using?
(make and model)?
also try reducing ur spectum's attenation's
pre-attenuation.
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Posted 11/12/2012
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