GPS measurement at 1.57GHz and noise floor -135dBm

Low Cost Spectrum Analyzer PC Software

GPS measurement at 1.57GHz and noise floor -135dBm

Postby alphay » Wednesday 1. December 2010, 00:58

hi
For GPS measurment ... 1.57GHz ...
(1) We need to setup the GPS measurement based on HF 60100 V4 X with LCS or MCS.
Frequency is 1.57GHz and nosie floor need to be below -135dB. how to setup it ? we can't use the external LNA 40dB.
(2) as I setup RBW 1kHz and VBW 1khz, it is around -120dB noise floor. but as I setup RBW 200Hz , the noise floor is a straight line without signal more.
What is wrong? and if you can have the RBW choose list add more 10Hz and 30Hz ?

Thanks

Alpha
alphay
 
Posts: 66
Joined: Monday 25. October 2010, 15:30

Re: GPS measurement at 1.57GHz and noise floor -135dBm

Postby Moderator » Wednesday 1. December 2010, 22:04

dB? You mean dBm...
Anyway thats not how a GPS measurement will work. You need to add a active GPS antenna which you get for about 15-20 Euros then it works fine.
Moderator
 
Posts: 1048
Joined: Tuesday 20. April 2010, 13:24
Location: Aaronia AG

Re: GPS measurement at 1.57GHz and noise floor -135dBm

Postby alphay » Thursday 2. December 2010, 00:21

hi
We are doing the platform noise test for product developing.
So the sensitivity test is very important test item. So that is why we need to have HF 60100 V4 X for noise floor -135dBm level.
Then we can do the measurement of platform EMI noise from main board.
So, please clarify the followingquestion:
(1) Can we have 10Hz and 30Hz for RBW ? how ?
(2) how to setup the noise floor below -135dBm without 40dB LNA ?

Thanks

Alpha
alphay
 
Posts: 66
Joined: Monday 25. October 2010, 15:30

Re: GPS measurement at 1.57GHz and noise floor -135dBm

Postby Moderator » Thursday 2. December 2010, 09:02

We will not add any smaller filter to the V4 so if you want a higher sensitivity you need to use our new very small 40dB preamp which you can connect directly to the V4 then it works fine for now.
Moderator
 
Posts: 1048
Joined: Tuesday 20. April 2010, 13:24
Location: Aaronia AG

Re: GPS measurement at 1.57GHz and noise floor -135dBm

Postby alphay » Saturday 4. December 2010, 13:20

Hi
Related to the SNR problem above is the fact that all
amplifiers produce noise of their own. This noise is seen by
later stages (or the receiver or spectrum) as a valid signal and
amplified right along with the regular signals. If the noise
level of the external amplifier is excessive, then the
overall SNR of the receiver is deteriorated. System noise
figures are dominated by the first stage in a cascade chain.
If the additional amplifier has a noise figure that is
significantly less than the noise figure of the receiver,
then some improvement might occur. Otherwise, there will be
either no change or a deterioration of the noise situation.
Preselectors, both active and passive, pre-tune the
signals desired. Some preselectors are single-frequency
devices and have a tuning knob. Others are essentially
bandpass filters that limit the incoming signals to a
specified band. In either case, some of the problems
attributed to wideband preamplifiers are somewhat mitigated
by the preselection that takes place. By limiting the input
frequencies allowed to enter the receiver both the natural
noise and unwanted signals are removed, so the receiver can
concentrate its resources on the desired signals.
So, do you think your super low noise LNA 40 dB can meet the requirements.
Or we need to design the preselector by ourslef for -135dB nosie floor issue ?

Thanks

Alpha
alphay
 
Posts: 66
Joined: Monday 25. October 2010, 15:30

Re: GPS measurement at 1.57GHz and noise floor -135dBm

Postby Moderator » Saturday 4. December 2010, 17:58

As mentioned before: With our 40dB preamp IT WORKS FINE or use the realtime spectrum analyzer SPECTRAN V5 which will be available in a view months. It will offer filter even much lower then 1Hz.
Moderator
 
Posts: 1048
Joined: Tuesday 20. April 2010, 13:24
Location: Aaronia AG

Re: GPS measurement at 1.57GHz and noise floor -135dBm

Postby alphay » Monday 6. December 2010, 11:00

Hi
As we are testing the GPS noise floor signal? We found that ambient have one GPS 1.575GHz noise. Where it is from ? We didn’t connect to any signal generator or antenna.
Could you please check it ?
Thanks

Alpha
alphay
 
Posts: 66
Joined: Monday 25. October 2010, 15:30

Re: GPS measurement at 1.57GHz and noise floor -135dBm

Postby Moderator » Monday 6. December 2010, 22:13

You allways have some frequencys where you can see a little bit more noise if you use a very small filter like that one you have posted. Its just impossible to avoide those.
Moderator
 
Posts: 1048
Joined: Tuesday 20. April 2010, 13:24
Location: Aaronia AG


Return to LCS

Who is online

Users browsing this forum: No registered users and 1 guest

cron