Friday, March 27, 2015

Re: [Discuss-gnuradio] Achievable Sampling Rate without Under/Overflows

Understood MarcusL. The question remains, what are some example sample rates your radio's can support? I'm requesting a reference.

Thanks,
Rich

On Fri, Mar 27, 2015 at 11:31 AM, Marcus D. Leech <mleech@ripnet.com> wrote:
On 03/27/2015 01:01 PM, Richard Bell wrote:
I need some understanding of what reasonably achievable sample rates are using GNU Radio to implement a packet base radio.

For example, I'm running into D's at only 430 k/samples. This is running a packet detecting radio using bpsk.

Those who have working OFDM radios, what sample rates does your system support without over/underflow? How about those with QPSK radios detecting packets, what samle rate can you support?

I'm not using a multi-rate approach, so I know there are gains to be had in my design. But for a BPSK radio with packet detection (and full synchronization), I'm surprised I'm hitting the low limits of what the USRP requires already.

Thanks,
Rich


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The answer is, unfortunately, "it depends". 

For example, I'm running a very simple radio astronomy "flow" on an Odroid XU3 at 2 x 11.5Msps,without overruns (except occasionally).

What type of computer are you using?   Have you made  certain that any filters you have in your flow don't have horrendous filter lengths?
  That's very often a cause of newcomers getting poor performance out of their signal flows.  They specify a filter with far-too-aggressive
  "skirts", which yields a filter that is 10 times longer than it really needs to be, for example.



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