Hello John, >Although the amount of RAM may not be critical (provided you're not >paging), Yes I agree.
>the SPEED of the memory is probably the limiting factor. It could explain why my two PC at 2400 MHz have very different calculation speeds (a ratio larger than 2), the oldest being the slowest (as in real life). Thanks for the explanations and the WEB addresses. 73 Patrick ----- Original Message ----- From: "jcprout" <jcpr...@gmail.com> To: <digitalradio@yahoogroups.com> Sent: Monday, February 01, 2010 9:45 PM Subject: [digitalradio] Re: SDR-Radio with DM780 20M Digital Band > > > Patrick > > Although the amount of RAM may not be critical (provided you're not > paging), the SPEED of the memory is probably the limiting factor. The > summary is that in a modern cpu with multiple cores and pre-fetch pipeline > processing, the processor can execute instructions faster than they can be > retrieved from main memory. Access to the L1/L2/L3 caches is much faster > than access to main memory, so designing a program so that as much of it > and it's working memory will fit into the cache as possible can make a big > difference to performance. > > What this means for the discussion is that when comparing PCs, don't look > just at the cpu speed and amount of RAM; consider the speed of the RAM > too. I'm getting ready to buy a new PC now and it having DDR3 memory is > more impotent to me than the highest possible cpu speed. > > Sources - this presentation explains a lot about modern PC architecture > and performance: > http://www.infoq.com/presentations/click-crash-course-modern-hardware If > you really want the nitty-gritty, take a look at this classic paper, which > is LINUX oriented, but still applies to a Windows PC: "What every > programmer should know about memory" > http://people.redhat.com/drepper/cpumemory.pdf > > John - K6CKP > > --- In digitalradio@yahoogroups.com, "Patrick Lindecker" <f6...@...> > wrote: >> >> Hello Tony, >> >> According to my tests, it is only the capacity to do calculations which >> is the key, as a lot of digital processng is done (for example for SDR or >> Panoramics). I don't think RAM is important. I mean either you have >> sufficient memory or you have not (and you will have a message error). >> But if you have enough, having double or four more that the minimum does >> not change anything. >> >> Note: with or without BPSK31 panoramic, I have about 2 % of CPU usage. >> >> 73 >> Patrick >> >> >> ----- Original Message ----- >> From: Tony >> To: digitalradio@yahoogroups.com >> Sent: Saturday, January 30, 2010 4:35 AM >> Subject: Re: [digitalradio] SDR-Radio with DM780 20M Digital Band >> >> >> >> >> >> Patrick, >> >> Thanks for the information. As you may have read from my reply to Andy, >> my CPU usage seems to be very low with Multipsk. It's well below 10%. >> >> Is there a particular Multipsk mode or configuration that would tax the >> system? I'd like to try it and see how it affects CPU usage. >> >> Merci mon ami... >> >> Tony -K2MO >> >> ----- Original Message ----- >> From: Patrick Lindecker >> To: digitalradio@yahoogroups.com >> Sent: Friday, January 29, 2010 4:51 PM >> Subject: Re: [digitalradio] SDR-Radio with DM780 20M Digital Band >> >> >> >> >> Hello Tony, >> >> I have here two PC XP at about 2.4 GHz (single core): >> >> I have compare these two XP computers on the same file to decode (in >> 110A): >> * the first one (the oldest) which is an AMD Atlon 2500+ 1.09 GHz 768 >> Ko RAM takes 75 seconds to decode it, >> * the second one which is an AMD Atlon 2400+ 2 GHz 736 Ko RAM takes >> 20 seconds to decode it. >> >> On the most modern (about 3 years old) with SdR and RS ID detection >> on 44 KHz, the CPU load is about 35 to 40 %, but on the old one it is 100 >> % (the program does not work in fact). >> >> So normally with a modern PC it is OK. With an "old" PC, it can be >> problematic. >> >> Note: with my Vista laptop (dual core), the CPU load is about 25 % in >> the same conditions. >> >> 73 >> Patrick >> >> >> >> ----- Original Message ----- >> From: Tony >> To: digitalradio@yahoogroups.com >> Sent: Friday, January 29, 2010 8:36 PM >> Subject: Re: [digitalradio] SDR-Radio with DM780 20M Digital Band >> >> >> Andy, >> >> I plan on switching to SDR in the near future. My current PC is a >> dual CPU 2.2GHz Dell with 3 GHz RAM. Any idea what the minimum PC >> requirement is to run Multipsk with SDR? Could you also tell us what >> processor you're running now? >> >> Thanks, >> >> Tony -K2MO >> >> ----- Original Message ----- >> From: Andy obrien >> To: digitalradio >> Sent: Friday, January 29, 2010 9:11 AM >> Subject: [digitalradio] SDR-Radio with DM780 20M Digital Band >> >> >> >> One of the things that I wanted to accomplish with an SDR >> receiver, >> is the ability to keep an eye on the whole 14065 to 14115 >> frequency >> range. If I was down on 14074 monitoring ALE 400 traffic, I would >> miss Olivia signals that popped up in the 14109 area. I would >> also >> miss Hell signals at 14068. Now the SDR affords the opportunity >> to >> keep an eye all all at once. My venture in to SDR from a digital >> mode >> perspective has led to a discovery that, other than Multipsk, the >> current state of the art does not support direct monitoring of >> wider >> I/Q data. I'm also challenged in that my PC cannot cope with the >> Multipsk CPU demand when I try direct monitoring. So, at the >> moment I >> am visually monitoring signals with the SDR and using traditional >> software methods to decode the 3-4 kHz of audio that is fed from >> the >> SDR to applications like DM780 or Fldigi. >> >> At this screen shot http://www.obriensweb.com/sdrdm780.jpg >> >> you will see how it appears. I am simply using DM780 and >> SDR-Radio >> software together. When I need to transmit, I just use my TS2000 >> after dialing in the signal discovered by the SDR receiver. Simon >> HB9DRV will likely "integrate" these two applications later in >> 2010. >> >> I did catch a Russian on RTTY this morning that I would have >> otherwise >> missed while I was slumming it in PSK31-land.. Multisk does RS-ID >> over this entire 14065-14115 portion, and DM780 is likely going >> to >> include this ability in the future. If people use RS-ID often >> enough, >> it will be really "cool" to monitor 14065-14115 and get RS ID >> alerts. >> >> So, just over a week playing around with the SDR receiver... I >> see the >> potential... digital mode applications are not quite "there" yet. >> When they are "there" (as in Multipsk) my PC isn't. This $41.00 >> Ebay >> PC may eventually get retired for a slightly improved one with >> better >> CPU. OK, back to keeping an eye on 14065-14115. A-ha, an SV3 >> calling >> CQ RTTY, 14082. >> >> Andy K3UK >> > > > > ------------------------------------ > > Try Hamspots, PSKreporter, and K3UK Sked Page > http://www.obriensweb.com/skedpskr4.html > Yahoo! Groups Links > > > >
