You'll need a more fine-grained indicator of CPU usage; try Googling.
When you have multiple applications decoding the same incoming stream, peak
CPU loads are likely to occur simultaneously. To assure an
"apples-and-apples" comparison, run each application on a dedicated PC.
73,
Dave, AA6YQ
-----Original Message-----
From: [email protected] [mailto:[EMAIL PROTECTED]
Behalf Of Tony
Sent: Saturday, October 04, 2008 3:11 AM
To: [email protected]
Subject: Re: [digitalradio] Comparing data modes
Dave,
> The question is whether any app is being starved for CPU
> resources during critical operations.
Is there a way to tell if that is happening?
Tony, K2MO
----- Original Message -----
From: "Dave AA6YQ" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Friday, October 03, 2008 10:19 PM
Subject: RE: [digitalradio] Comparing data modes
> If you're referring to CPU usage as reported by the Windows Task Manager,
> that's an average. The question is whether any app is being starved for
> CPU
> resources during critical operations.
>
> 73,
>
> Dave, AA6YQ
>
> -----Original Message-----
> From: [email protected] [mailto:[EMAIL PROTECTED]
> Behalf Of Tony
> Sent: Friday, October 03, 2008 6:35 PM
> To: [email protected]
> Subject: Re: [digitalradio] Comparing data modes
>
>
>
> Dave,
>
>> when running more than one digital mode app on the same processor, one or
>> both apps may be starved for CPU cycles and as a result underperform.
>> 73, Dave, AA6YQ
>
> For what it's worth, the CPU usage hovers around 30% while running 5
> different digital mode programs and the HF path simulator. Throughput is
> the
> same for each program whether they are tested individually or all at once.
>
> Not sure if the performance monitor is telling the whole story when it
> comes
> to CPU usage, but I would assume the processor is loafing along at 30%.
>
> Tony, K2MO
>
>
> ----- Original Message -----
> From: "Dave AA6YQ" <[EMAIL PROTECTED]>
> To: <[email protected]>
> Sent: Tuesday, September 30, 2008 3:01 PM
> Subject: RE: [digitalradio] Comparing data modes
>
>
>> Stelios's note raises another point independent of sampling rate issues:
>> when running more than one digital mode app on the same processor, one or
>> both apps may be starved for CPU cycles and as a result underperform.
>>
>> Given all the unknowns, I wouldn't consider a comparison between two
> digital
>> mode applications to be "apples and apples" unless the test was
> accomplished
>> on two identically configured PCs, each processing the same data stream.
> If
>> the data stream can be recorded and replayed, then of course the tests
>> can
>> be run serially on a single PC.
>>
>> 73,
>>
>> Dave, AA6YQ
>>
>> -----Original Message-----
>> From: [email protected]
>> [mailto:[EMAIL PROTECTED]
>> Behalf Of Stelios Bounanos
>> Sent: Tuesday, September 30, 2008 9:03 AM
>> To: [email protected]
>> Cc: Tony
>> Subject: Re: [digitalradio] Comparing data modes
>>
>>
>>>>>>> On Tue, 30 Sep 2008 00:04:19 -0400, Tony <[EMAIL PROTECTED]> said:
>>
>>>> What were the sampling rates used by each of those 5 applications,
>>>> Tony?
>>>> 73, Dave, AA6YQ
>>
>>> The sample rates were 11025 Hz for Mixw and IZ8BLY MT63 terminal. Looks
>> like
>>> 8000 Hz for DM780 and Multipsk. Not sure what's going on with Fldigi.
>>> I'm
>>> using the Vista version.
>>
>> The MT63 modem works at 8000 Hz as Simon noted.
>>
>> However, fldigi's default behaviour is to open the sound card at its
>> default (native) sample rate, usually 48 or 44.1 KHz, and then resample
>> to/from the modem rate using one of the converters from Erik de Castro
>> Lopo's excellent libsamplerate. The converter is chosen based on a
>> short speed test that is done the first time fldigi is run. On all
>> reasonably recent processors, that converter will be one of the "good"
>> SINC interpolators. It can always be changed later.
>>
>> We basically did this to avoid the not too uncommon situation where a
>> sound card/driver combination claims to support the modem's sample rate
>> only to return mangled audio.
>>
>> To really open the sound card at the modem frequency, which is currently
>> 11025 Hz for Thor and DominoEX 5/11/22, and 8000 Hz for everything else,
>> use the Capture and Playback menus in the Audio settings. The default
>> value is Native (see above). Auto will try the modem rate first and, if
>> that fails, fall back to Native. You may want to try Auto if you know
>> that the OS can do better/faster resampling.
>>
>> The other options in those menus are the rates supposedly supported by
>> the sound card. I say "supposedly" because the driver may be telling
>> some slight fibs here, i.e., if it reports the hardware native rates
>> together with those that it can resample to in software. It's almost
>> certainly doing that if it lists every standard rate from 8KHz up to
>> 192KHz.
>>
>> Experience suggests that we can trust the default (native) sample rate,
>> at least on the cards and platforms tested so far. The other rates give
>> audio of uncertain quality.
>>
>> Anyway, if you force a rate that is different to the current modem's,
>> fldigi will need to resample. It will also resample, using the same
>> configured conveter, if the TX or RX ppm corrections are nonzero. Of
>> course it's smart enough to combine both kinds of resampling into one
>> step.
>>
>> I don't know enough about Vista's audio system to be able to say what
>> happens if you run multiple programs that want different rates.
>> Possibly some of them will see slightly increased latency.
>>
>> Regarding CPU usage, you should make sure that you have enough CPU
>> cycles for everything; maybe aim to keep the system load at < 50%.
>> Fldigi can tell you if it's dropping audio because the CPU is too busy
>> but only in debug builds; perhaps something to change in a future
>> version.
>>
>> 73,
>> Stelios, M0GLD.
>>
>>
>>
>>
>
>
>
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Announce your digital presence via our Interactive Sked Page at
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