ANTENNA CONFIGURATION FOR GPS

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matteo.cutugno
Posts: 1
Joined: Thu Oct 11, 2018 3:14 am

ANTENNA CONFIGURATION FOR GPS

Post by matteo.cutugno » Thu Oct 11, 2018 3:18 am

Hi
i tried to run gnss-sdr for real time acquisition.
I have a nuand bladerf x40 with u-blox active antenna.
Gnss-sdr can't track satellite and reports loss of lock in every channel continuously.
I tried a lot of different conf files and now i begin to think that is an antenna issue.
On gnss sdr site they say that:
"you will need an active antenna (that is, an antenna with an integrated low noise amplifier delivering a gain in the band of interest greater than 20 dB, with a noise figure below 2 dB), and you will need to feed it."
U-blox antenna is an active antenna with Built in low noise amplifier with 29 dB gain and 0.9dB noise figure so i think is suitable.
The problem is that i don't know if i have to feed it externally (maybe with a bias-tee) or it is auto feed by front-end.
Can you list the specification of bias-tee needed
Thank you in advance for your answer.
MC

yoshimifuj
Posts: 15
Joined: Wed May 07, 2014 8:59 pm

Re: ANTENNA CONFIGURATION FOR GPS

Post by yoshimifuj » Thu Oct 11, 2018 5:03 am

Hi,
Actually, you need a bias-T to feed the active antenna.
https://ebay.us/KmpI1L

As you may know, bladeRF2.0 micro has built-in bias-T.

In my experience, you need extra LNA(20dB+ at L1 frequency) after active antenna.
Such as: http://a.co/d/eHU44nj

This LNA is equipped with GPS filter and be powered with USB/bias-T.
https://ebay.us/7Bi4EY

Regards,
Yoshimi

odrisci
Posts: 5
Joined: Wed Oct 10, 2018 1:47 am

Re: ANTENNA CONFIGURATION FOR GPS

Post by odrisci » Thu Oct 11, 2018 10:04 pm

In my experience the antenna LNA should be sufficient, once you have the bias tee. Just make sure to crank the rxlna and rxvga gains right up on the bladerf. No need for a second external LNA.

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