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Old 4th January 2013, 03:16 AM   #221
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Quote:
Originally Posted by pos View Post
That looks like some serious DSP power in there!
Not as much as it might seem at first glance; Blackfins are a 16 bit architecture with 32 bit extensions and it happens they lack a 32 bit MAC (that's presumably why there are no 32 bit functions in the DSP library). So if one wants 32 bit for accuracy the 2000MMACs on the ADSP-BF609 are comparable to perhaps 200MMACs on a SHARC (I'd have to check the instruction set in detail). In comparison, higher end Cortex M4s also hit 200MMACs and boards+programmer/debuggers start around a quarter of an entry level Blackfin eval setup. I'm being somehwat loose here; Cortex M4 MACs are 32 bit multiply, 64 bit accumulate which is a bit less powerful than the SHARC's 32 bit multiply, 80 bit accumulate. But the Blackfin number I mentioned is more of a 32 bit accumulate. There are also some tradeoffs among architectures in IIR versus FIR performance and interesting things one can do with putting Cortex M4s in parallel.

That said, SHARC eval boards may be the best option depending on what one's looking for; the ones for entry level 800+MMAC parts are ~25% more than the ADSP-BF609 EZ-Board. And both Blackfin and SHARC eval boards are cost effective ways to get an entry level VisualDSP++ license and make interesting miniSHARC alternatives.

Last edited by twest820; 4th January 2013 at 03:23 AM.
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Old 4th January 2013, 04:14 AM   #222
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How hard to get 32k taps, 8ch convolution for 48kHz, 32bit from SHARC platform, or other?
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Old 4th January 2013, 05:19 AM   #223
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Do the math. 32k taps * 48kHz * 8 / (12228 taps per 400MHz SHARC * 48kHz) = 21 400MHz SHARCs. You could maybe pull off the necessary 12.3GMACs with an 8 core desktop processor but looking into more efficient filtering approaches seems wise. I mentioned some IIR options in post 26 of this thread and there's a rich literature on computationally efficient FIR implementations that you can read up on. Another option would be to look at implementing convolution on GPUs. It doesn't massively parallelize all that well but with a couple hundred double precision TMACs available that doesn't really matter; various implementations are available.

This is all somewhat orthgonal to rePhase, though...
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Old 4th January 2013, 07:03 AM   #224
tomtom is offline tomtom  Slovakia
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If i do it again from scratch i go for exaSound Audio Design > e18 DAC > Overview + PC as DSP.

I know this is DIY site. But any reasonable converters with DSP with volume controls will cost you ca. same with questionable outcome + still somewhat limited DSP power.

It is very difficult to make "ultimate" digital XO. You find yourself bettween a lot problem. Most difficult proper asynchrous USB input and proper clock distribution between dacs DSP and input. Unless you make your own DPS for everything you will have to deal with SMD rework and it always is mess
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Old 4th January 2013, 07:05 AM   #225
tomtom is offline tomtom  Slovakia
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For POS

I use NSD1480N - HF Neodymium Driver

and horn loading work to ca. 300hz
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Old 4th January 2013, 10:16 AM   #226
more10 is offline more10  Sweden
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Quote:
Not as much as it might seem at first glance; Blackfins are a 16 bit architecture with 32 bit extensions and it happens they lack a 32 bit MAC (that's presumably why there are no 32 bit functions in the DSP library). So if one wants 32 bit for accuracy the 2000MMACs on the ADSP-BF609 are comparable to perhaps 200MMACs on a SHARC
Then the SHARC 21469 EZ-KIT LITE FOR THE ADSP-2146X SHARC FAMILY is a better choise. It has an ADSP-21469. The VisualDSP++ 5.0 Run-Time Library Manual for SHARC® Processors has a convolve function.

Unfortunately there is no uCLinux for the SHARC. I really don´t want to recompile just to change the impulse
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Old 4th January 2013, 10:28 AM   #227
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Just as a point of reference the Ultimate EQ can run 6 channels input, 8 out at 48K with 8192 tap FIR filters for each channel on my 2.8 G Hz Pentum 4 PC with 500 MB Ram.
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Last edited by john k...; 4th January 2013 at 10:48 AM.
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Old 4th January 2013, 11:49 AM   #228
pos is offline pos  Europe
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more10, why not use the miniSHARC plateform?
For the price of a single evaluation board (with software?) you could buy 3 of those miniSHARC.
The forthcoming plugin will probably be limited in power, but there is room for improvement (taps distribution accross channels, downsampling of some channels, FFT convolution, etc.)
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Old 4th January 2013, 11:50 AM   #229
more10 is offline more10  Sweden
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Chapter 28: Digital Signal Processors How Fast are DSPs?

Quote:
Since the real FFT requires about 12 clock cycles per sample, FFT convolution can be carried out in about 60 clock cycles per sample
Quote:
Notice that this is about the same as a 60 coefficient FIR filter carried out by conventional convolution. In other words, if an FIR filter has less than 60 coefficients, it can be carried out faster by standard convolution. If it has greater than 60 coefficients, FFT convolution is quicker.
Could someone experienced in DSP figure out how long taps can be executed on a SHARC using FFT convolution?
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Old 4th January 2013, 12:01 PM   #230
more10 is offline more10  Sweden
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more10, why not use the miniSHARC plateform?
Coding is fun?

Rumor wise the miniSharc will have eight I2S channels and a total 12k taps. For a 4 way stereo filter that means 1500 taps. Is 1500 taps enough?
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