Re: [Openbts-discuss] B200 useless without GPSDO?

[Ralph A. S. d. <ra...@sc...>]

I never used a GPSDO, and it works without problems. The offset usually is responsible when you even do not find the network, but when the network is seen, the phone is able to sync, and the RF layer should be fine. It must be something with the software, with UHD or openbts.

 

Ralph.

 

From: Alexander Schmidt [mailto:ale...@ya...] 
Sent: Saturday, March 12, 2016 4:50 PM
To: ope...@li...
Subject: [Openbts-discuss] B200 useless without GPSDO?

 

Hey Folks,

 

I was wondering if my USRP B200 without GPSDO and without extra power supply is completely useless for getting phones to camp on my network?

All of my phones can see the network, but cant connect.

Maybe the offset is just to large?

I did all the correct settings, also added subscribers manually, but the phones just wont join the network.

 

Maybe it also has to do with the clocks inside german mobiles or the german frequencies?

 

Here https://wush.net/trac/rangepublic/wiki/USRP it says:

 

"Use of an external 10 MHz reference is recommended, but not mandatory, in order to run OpenBTS. When no external reference is available, the TCXO on the USRP B200 series is rated at +/- 2.0 ppm, which may cause instabilities with handset camping and registration. Please consider this factor during testing."

 

How is the last sentence to be understood? If I will add the GPSDO/TCXO I will maybe still have problems?!

 

Thanks for helping!

 

Best regards,

Alex