ublox max m8q : cno (Carrier to noise ratio)

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Hi,

I have 2 questions concerning the "cno" [Carrier to noise ratio (signal strength)] which is measured in dBHz and supposed to be in range [0-99]

 

1) Is this measure a good indication of the signal quality when arriving to the chip ? We have tuned the antenna and the RF path and are searching for an estimation of the whole system quality (signal -> antenna -> RF path -> chip)

2) Is this field "linear" (in respect to the log scale) ? Assuming that for a fixed noise the cno is at 25, will it be at 35 for a signal 10x more powerfull

 

Kind regards,

Jonathan Muller
by jonathan_muller asked Nov 29, 2018
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The u-blox document "GPS Compendium" describes the signal computations in more detail.
1) under normal circumstances with a good antenna and good design/implementation your statement is correct.  In the presence of RF interference or on-board coupling of EM fields or noisy/unstable VCC, other detrimental effects occur.
2) Under normal circumstances, generally correct but the influencing factors are pure antenna gain (inviolate laws of physics) and all the noise contributions. With strong interference, metrics go out the window.
by grampy answered Nov 29, 2018
by jonathan_muller selected Nov 30, 2018
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Best answer
Thank you for your quick reply.
This is exactly the kind of response I was expecting.

Have a good day
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