Re: [Discuss-gnuradio] B100 clock with UHD
I thought OpenBTS would use Transceiver52MHz to communicate with B100 and to configure the AD9522 to output 52MHz sampling clock. However, with OpenBTS working with B100 and WBX I measure 64MHz sampling clock. And I am confused here. I didnt compile OpenBTS with resampling option. So where does the resampling happen? Or, am I wrong thinking that OpenBTS uses Transceiver52MHz ? Where is the UHD in this chain ? Regards, Robert Gesendet:Dienstag, 21. Januar 2014 um 02:28 Uhr Von:Ben Hilburn b...@ettus.com An:Robert Light robert.li...@gmx.de Cc:GNURadio Discussion List discuss-gnuradio@gnu.org Betreff:Re: [Discuss-gnuradio] B100 clock with UHD Hi Robert - The B100 has a configurable clock rate, specifically so that applications that require specific clock rates can tune it accordingly (e.g., OpenBTS). You can pass master_clock_rate=rate into the args string of the device and set the master clock rate to what works for your application. I havent personally used OpenBTS recently, but if you arent resampling on the host, that is probably how the host is using the device. Cheers, Ben On Mon, Jan 20, 2014 at 8:29 AM, Robert Light robert.li...@gmx.de wrote: Hi, I run B100 with OpenBTS. I thought the reconfigurable clock on B100 board would run with OpenBTS at 52MHz but I actually measure the sampling clock as 64MHz. So, where is the resampling done? Is the driver Transceiver52MHz used with B100 or not? Can someone shine some light on how it actually works? ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] B100 clock with UHD
On Tue, Jan 21, 2014 at 5:45 AM, Robert Light robert.li...@gmx.de wrote: I thought OpenBTS would use Transceiver52MHz to communicate with B100 and to configure the AD9522 to output 52MHz sampling clock. However, with OpenBTS working with B100 and WBX I measure 64MHz sampling clock. And I am confused here. I didn't compile OpenBTS with resampling option. So where does the resampling happen? Or, am I wrong thinking that OpenBTS uses Transceiver52MHz ? Where is the UHD in this chain ? Please post subsequent questions to the OpenBTS mailing list. Note there is no longer any user configurable resampling option. Device specific rate configuration (clocking and sampling) is handled by the code internally. http://wush.net/trac/rangepublic/wiki/BuildInstallRun#AllOtherDevicesexceptforUSRP1 OpenBTS and B100 runs at 64 MHz. This was changed from 52 MHz because of significantly better performance and stability. https://wush.net/trac/rangepublic/wiki/USRP The host transceiver operates internally at 1.0833 Msps transmit and 270.833 ksps receive. These sample rates are converted and matched to device specific values on the host side in between the GSM processing and device I/O. For B100 the conversion rate is 65/96, which is selected to keep both halfband filters in place on the FPGA minimizing pass band distortion. The name 'Transceiver52M' is historical, which is admittedly confusing. The name originates from the initial public OpenBTS release, which only supported the USRP1. Back then, there were completely separate implementations for 64 MHz and 52 MHz for this single device. Eventually, all USRP code was merged into the 52 MHz code that is the active version remaining today. -TT ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] B100 clock with UHD
Hi, I run B100 with OpenBTS. I thought the reconfigurable clock on B100 board would run with OpenBTS at 52MHz but I actually measure the sampling clock as 64MHz. So, where is the resampling done? Is the driver Transceiver52MHz used with B100 or not? Can someone shine some light on how it actually works? ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] B100 clock with UHD
Hi Robert - The B100 has a configurable clock rate, specifically so that applications that require specific clock rates can tune it accordingly (e.g., OpenBTS). You can pass master_clock_rate=rate into the args string of the device and set the master clock rate to what works for your application. I haven't personally used OpenBTS recently, but if you aren't resampling on the host, that is probably how the host is using the device. Cheers, Ben On Mon, Jan 20, 2014 at 8:29 AM, Robert Light robert.li...@gmx.de wrote: Hi, I run B100 with OpenBTS. I thought the reconfigurable clock on B100 board would run with OpenBTS at 52MHz but I actually measure the sampling clock as 64MHz. So, where is the resampling done? Is the driver Transceiver52MHz used with B100 or not? Can someone shine some light on how it actually works? ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
