Interference and Signal Strenght

Javad

Administrator
Staff member
5PLS
#1
Now the U4 button in the front panel is active. It shows the signal strengths of satellites and the effect of interference on them. The "0" (blue) level is when the received signals match the normal performance. 3 dB less is shown with the green color. 6 dB less is shows with the red color.
There is 10 minutes of averaging in the background.
 

Matt Johnson

Well-Known Member
5PLS
#2
Is there any reason why we don't use green for normal, yellow for -3dB and red for -6bB? Green is the color that is usually used to indicate good for many things and yellow and red usually correspond to medium hazard and high hazard.
 

Javad

Administrator
Staff member
5PLS
#3
Is there any reason why we don't use green for normal, yellow for -3dB and red for -6bB? Green is the color that is usually used to indicate good for many things and yellow and red usually correspond to medium hazard and high hazard.
To be compatible with Satellite screen. Green was not that visible in small fonts. Most of the time we have good numbers (in blue). We used blue, green, red.
 

Matt Johnson

Well-Known Member
5PLS
#4
What if we use blue, yellow and red for good, fair and poor? Green being used as -3dB is confusing. If we make this change the Satellite screen should be changed as well.
 

Javad

Administrator
Staff member
5PLS
#5
What if we use blue, yellow and red for good, fair and poor? Green being used as -3dB is confusing. If we make this change the Satellite screen should be changed as well.
As I said, we wanted to be compatible with the Satellite screen. If this is a big issue, we can change in both places. But, later!
 

Javad

Administrator
Staff member
5PLS
#6
As I said, we wanted to be compatible with the Satellite screen. If this is a big issue, we can change in both places. But, later!
The important factor is the length of the line and the number written on it.
 

Matt Johnson

Well-Known Member
5PLS
#9
Maybe blue, black and red would be better if yellow does not show up well. Yellow would not be used often in the Satellite screen. Right now we are using green for -3dB. I would think yellow should show up similar to green.
 

Javad

Administrator
Staff member
5PLS
#10
Maybe blue, black and red would be better if yellow does not show up well. Yellow would not be used often in the Satellite screen. Right now we are using green for -3dB. I would think yellow should show up similar to green.
Yellow will not show up good in Satellite screen at all.
 
#12
About Network Online Visualisation of Accuracy (NOVA) Maps:

Is it possible to add in J-Field a option to view NOVA Maps?
Of course we can exit J-Field and use for example a Google search engine from Triumph LS platform.

But somehow together with Spectrum Analysis, NOVA Maps and other instruments we can better figure in the field the changing environment in wich we take measurements day by day.
 

Javad

Administrator
Staff member
5PLS
#13
For GNSS applications, the ultimate criteria are the numbers in the U4 button. Nothing else matters. If you want to see the reason, you can look at the spectrum view. I don't know how NOVA map can add anything. Please explain.
 
#14
Thanks for your attention.

What I mean is that in the real environment of GNSS measurements there is a combined effect of interferences and ionosphere/troposphere every day.
Total Electronic Content and Ionospheric Scintillation affect GNSS signals.
http://www.ngdc.noaa.gov/stp/iono/ustec/
http://gnss.rompos.ro/spiderweb/frmIndex.aspx

In terms of interferences:
Here we do not have J-Shield. There are some areals where we use metal plate between receiver and the source of interferences (it's funny) and it works.
Without metal plate we cannot obtain a fix solution.

In terms of ionosphere/troposphere effect:
Look at the file attached. It shows a Ionosphere (NRTK) plot type today 12/09/2014 - 09:20:16 (UT+3.0).

I think there is a combined effect in some areas (interesting such a study) and I wish these indicators on my receiver.

Thank you very much.
 

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Matt Johnson

Well-Known Member
5PLS
#15
There are some areals where we use metal plate between receiver and the source of interferences (it's funny) and it works.
Without metal plate we cannot obtain a fix solution..
I have thought about trying this before. What sources of interference are you attenuating with a metal plate? How do you prevent the metal plate from causing multipath back to the receiver?
 
#16
Dear Matt,

Nice to meet you here,

Look, I cannot send you pictures or coordinates because those places are restricted military areas.
You can see something similar attached.
There are old fashion military rotative radars, but can you belive they cut off my satellites? We are at 1-2 km distance from them.
When the radars are inactive I can measure.

One day we tried a metal plate (dimensions about 1m x 1.5m) hold vertical between receiver and those radars at about 2 meters from receiver.
It seems to work, but I do not trust the results. Plus, we look somehow ancestrals...

I will try to bring some more informations, but you know, it is difficult..

Thank you very much,

Sorin.
 

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#17
Dear friends,

I posted some personal suggestions as a day by day surveyor.
For meny years we encounter problems that our receiver could not figured out in terms of interferences.

Now we have access to a Triumph VS receiver.
The spectrum analyser is a great tool for GNSS applications.

We do not have a Triumph LS yet, but we can see that LS dedicate over 100 channels to continuous interference monitoring.
In other words, this is some kind of a real-time spectrum analyzer. Is this correct?

If yes, congratulations, if no, congratulations anyway!


Sorin.
 

Matt Johnson

Well-Known Member
5PLS
#18
Hi Sorin,

I was just curious what the source of your interference. I don't need the coordinates of it. It doesn't surprise me that a powerful radar site can cause interference and prevent RTK from working. I believe the spectrum analyser is the same for both the LS and VS.
 

Kelly Bellis

ME PLS 2099
5PLS
#19
Dear friends,
The spectrum analyser is a great tool for GNSS applications.

We do not have a Triumph LS yet, but we can see that LS dedicate over 100 channels to continuous interference monitoring.
In other words, this is some kind of a real-time spectrum analyzer. Is this correct?
Sorin.
Yes :)
VKB_GPSL1_20140917-19.54.27.png

VKB_GPSL1_20140917-19.54.27.png
VKB_GPSL2_20140917-19.54.29.png

VKB_GPSL5_20140917-19.54.30.png

VKB_GLNL1_20140917-19.54.32.png

VKB_GLNL3_20140917-19.54.36.png

VKB_GLNL2_20140917-19.54.34.png


Very cool stuff!

BTW, loved the YouTube you posted :)
 
#20
Hi,

These advanced receivers from Javad have collateral effects. They could transform us in "signal hunters".
Even there is a reward here.. http://www.javad.com/jgnss/javad/news/pr20140812.html
(Like in old westerns).

There is another options that we discuss with Javad last year in Essen.
To make maps of interferences and to show them maybe as a background in the receivers.

Surveyors usually use maps.
This is one of a possible final product of spectral analysis.

Thank you very much,

Sorin.
 

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