Thanks very much for advice. My application is about sampling design for FFT about 5G SDR implementation, but I may still try arbitrary resampler.
Best Regards J.Jeffson ---------------- ---------- Origin message ---------- >From："Brian Padalino" <[email protected]> >To：[email protected] >Subject：Re: [USRP-users] Is there any method for X310 to support 122.88M >Sampling rate? >Date：2018-12-01 00:39:27On Fri, Nov 30, 2018 at 11:29 AM Marcus Müller via >USRP-users < [email protected]> wrote: > Hi J. Jeffson, > > to answer quickly: see below. > On Fri, 2018-11-30 at 11:36 +0800, 蒋逸凡 via USRP-users wrote: > > Hi all > > I'm trying to use USRP X Series (2943/2954) in my project. I > > want to try 122.88MHz sampling rate, but ettus.com says that only > > 200MHz and 184.32MHz and the corresponding integer divisor. > > > exactly. > > > Is updating fpga image by uhd_image_downloader.py helpful? > > > > no. > > > Is there any way to re-write fpga image so that it can > > support? > > no. This is a restriction of the clocking architecture and analog > components. > > > > Really appreciate if someone suggests me some solution to it. > > Hm, if my head calculation doesn't betray me: > 122.88 MHz = 2¹⁶ · 5⁴ · 3¹ Hz > 200 MHz = 2 · 10⁸ Hz > = 2⁹ · 5⁸ Hz > > Hence, 200 MHz / 122.88 MHz = 2⁻⁷·5⁴·3⁻¹ > > So you could build a rational resampler that interpolates by 2⁷·3 = 384 > and decimates by 5⁴ = 625. > > That is not a nice filter! > > Don't know if I'd generally recommend an MCR of 184.32 MHz but, let's > try: > > 184.32 MHz = 2¹⁵ · 5⁴ · 3² Hz > > Hence, 184.32 MHz / 122.88 MHz = 2⁻⁶ · 5⁴ · 3⁻² > So you could build a rational resampler that interpolates by 2⁶·3² = > 576 > and decimates by 5⁴ = 625. > > So, that's even worse. > Something seems off here. 184.32 * 2 / 3 = 122.88 That shouldn't be too terrible to do on the host system, or to potentially even build into an FPGA? Brian
_______________________________________________ USRP-users mailing list [email protected] http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
