Yes, that is exactly the approach I would take.
-Tim From: Spencer Borden [mailto:[email protected]] Sent: Friday, February 19, 2010 4:02 PM To: Tim Ellison Subject: Re: [Flexradio] P55-based motherboard users out there This brings up a question. After a system is up and running in Safe Mode 1, Sample rate 96kHz and buffer size 1024, what would be the course in incremental changes to reduce latency? Would it be to increase sample rate / decrease buffer size , in Safe Mode 1. Then try Normal mode, starting with the larger buffer sizes and slower sample rates? Spence AB1HO ________________________________ From: Tim Ellison <[email protected]> To: Lazy Senior <[email protected]>; "[email protected]" <[email protected]> Sent: Fri, February 19, 2010 3:34:46 PM Subject: Re: [Flexradio] P55-based motherboard users out there See my comments below -Tim -----Original Message----- From: [email protected]<mailto:[email protected]> [mailto:[email protected]<mailto:[email protected]>] On Behalf Of Lazy Senior Sent: Friday, February 19, 2010 2:49 PM To: [email protected]<mailto:[email protected]> Subject: Re: [Flexradio] P55-based motherboard users out there Perhaps you could define long duration. At what DPC duration does the DPC level start to affect PSDR performance? [Tim] Somewhere around 1500 us. Definitely in excess of 2000 us There really is a lot of misconception about this subject. I actually had a ham tell me a few days (on the air) that he would never buy a Flex because he had heard you had to have a new super fast computer with no latencys. His exact words. [Tim] This is the misinformation FlexRadio's competitors are spreading in an attempt to discredit them, because it is the only thing they can think of to attack. The software model of ever more improvements is a killer. They busted the artificial barrier to price vs. Performance with the FLEX-3000. Desperate people say desperate things. First time I ever heard that one. When I told him I was running an old 4yr old computer running Vista, I do not think he believed me. Since the Flex Driver with the DPC checker will tell you to run the normal mode with anything under 1000us, can I assume that 1000us is just fine and not considered long duration? [Tim] In 99% of the cases I have dealt with, anything under 1000 us is OK. The lower the number, the less latency you will hear in the MON when monitoring your transmissions. Also the lower the number the more "headroom" you have to absorb a spike if something is compounding the problem. I also am assuming that the different Safe 1,2,3 modes are for compensating for DPC latencys higher than 1000us? [Tim] Exactly. The modes "enforce" larger hardware buffers to hold the incoming or outgoing samples while the PC is taking a siesta waiting for some hardware component to relinquish control of the PC back to the operating system (the cause of DPCs). As long as we are on the Subject, why does the Flex Manual recommend Safe Mode 1 over normal mode? [Tim] Because it recommends using initial setting that are conservative to ensure that the radio will work without freezing for the lowest common denominator of PC configurations. You start out with conservative settings and get more aggressive once you understand the limits of your system and how to adjust them for lower internal latency (the listening in the MON or operating fast CW, both of which require low internal latency in PowerSDR). Stan K9IUQ Tim Ellison wrote: > If you have long duration DPCs it will do the following in order of severity > > 1.) Increase internal latency. Most likely heard in the monitor > 2.) Causes audio drop outs or "stuttering". Also described as a "motor > boating" sound. > 3.) Freeze the operation of PowerSDR > > > -Tim > > > _______________________________________________ FlexRadio Systems Mailing List [email protected]<mailto:[email protected]> http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flex-radio.com/ Homepage: http://www.flex-radio.com/ _______________________________________________ FlexRadio Systems Mailing List [email protected]<mailto:[email protected]> http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flex-radio.com/ Homepage: http://www.flex-radio.com/ _______________________________________________ FlexRadio Systems Mailing List [email protected] http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flex-radio.com/ Homepage: http://www.flex-radio.com/
