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192kHz sample-rate soundcard recommendations (ALSA compatible)
Redhatter 
24/7/08 4:20:16 PM
Hero
Titan


Hi

I was wondering what 192kHz sample-rate capable sound cards people have used and what their experiences are. Specifically, I'm after cards that are supported under the Advanced Linux Sound Architecture ( http://www.alsa-project.org ).

The application I have in mind is a software defined radio. Ideally I'd like to use an analogue data acquisition board -- but for anything decent you pay through the nose. 192kHz sampling is about the minimum I need to really make a useful receiver.

My plan is to build a upper-sideband receiver that can be switched between a number of fixed frequencies, the output of which is fed into the soundcard's line-in so the computer can sample it and demodulate signals within that 96kHz spectrum.

So for instance, I could tune the receiver to 7.000MHz, and listen to every amateur station operating between 7.000MHz and 7.096MHz. (Maybe I can only get as high as 7.080MHz... it beats only listening on one frequency at a time.)

The important thing is that I want the path between the outside world and the ADC to be mostly DC-clean. That is, I'd like a frequency response as close to DC (0Hz) as possible.

If anyone have any suggestions, I'd be interested to hear them.

Regards,

-----
Stuart Longland (aka. Redhatter, VK4FSJL)
I haven't lost my mind it's backed up on a tape somewhere...
http://atomicdoc.yi.org <-- AtomicDOC Wiki
Resident Coolie-hatted Gentoo geek. (Gentoo MIPS & Mozilla herd member)

The Fuzz damn you! 
30/7/08 9:12:01 AM
Mod
Hero

Immortal


I understood absolutely none of that, but damn I like how it sounds.

Let us know if you do manage to get the card you're after.

-----
You are about to begin reading The Fuzz's .sig. Relax. Concentrate. Dispel every other thought.
.....|...
..\...../
-- o o -- <<...steam from a piston covers the opening of the chapter...>>
../.....\
.._|..|_

-80 
30/7/08 7:39:36 PM
Banned

Yeah.....because I know nothing about alsa, I'm dumbfounded!
(maybe I should read that link when I get time)

-----
Mercury - you've got my number

robzy 
31/7/08 3:21:05 AM
Hero
Immortal


ALSA is linux's audio system.

To say "ALSA compatible" pretty much means "Native linux compatible"

Rob.

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&#1506;&#1501; &#1497;&#1513;&#1512;&#1488;&#1500; &#1495;&#1497;

Redhatter 
31/7/08 8:41:24 PM
Hero
Titan


Yes well... the thing is, I'm not trying to record audio that's been picked up by any kind of acoustic device, but rather, from an RF tuner.

So yeah, my application is rather different. As I mentioned before, I really want a data acquisition card for this -- like a sound card, but intended for accurate capture of analogue signals, and often capable of sample rates in excess of 1MHz. But they're highly expensive, in the order of $400 for a cheapie ( such as this one: http://www.linux-usb-daq.co.uk/prod2_duxfast/ ), or some of National Instruments' offerings (they start at $2000 for a 250kHz model).

I'd prefer PCI too... it's slightly more CPU-efficient than USB, but I'll settle for USB if that's all I can get.

-----
Stuart Longland (aka. Redhatter, VK4FSJL)
I haven't lost my mind it's backed up on a tape somewhere...
http://atomicdoc.yi.org <-- AtomicDOC Wiki
Resident Coolie-hatted Gentoo geek. (Gentoo MIPS & Mozilla herd member)

-80 
31/7/08 11:59:58 PM
Banned

I still have a mistrust of USB ans firewire for sound.
They can exhibit bizzare problems that seem impossible to fix.

-----
Mercury - you've got my number

Redhatter 
3/8/08 10:08:45 PM
Hero
Titan


Well this is a little different... this is USB for data acquisition.

I don't have a problem with it per se... but I'm conscious that USB is less CPU efficient than an IEEE1394 (Firewire) interface, which in turn is less efficient than a PCI interface.

While the overhead is possibly small... if it can be avoided, I'd prefer to do so. ;-)

-----
Stuart Longland (aka. Redhatter, VK4FSJL)
I haven't lost my mind it's backed up on a tape somewhere...
http://atomicdoc.yi.org <-- AtomicDOC Wiki
Resident Coolie-hatted Gentoo geek. (Gentoo MIPS & Mozilla herd member)

Squidy 
3/8/08 10:17:38 PM
Hero
Colossus


Quote by -80
I still have a mistrust of USB ans firewire for sound.
They can exhibit bizzare problems that seem impossible to fix.




I used to think so too, I still hate USB, however firewire has come a long way. I'm using an M-Audio FW410 and absolutely love it.

-----
JESUS CHRIST ITS A LION!

/Gets in the car

Roses are red, violets are blue, I'll fuck you with a rake

-80 
3/8/08 10:33:41 PM
Banned

Quote by Squidy
Quote by -80
I still have a mistrust of USB ans firewire for sound.
They can exhibit bizzare problems that seem impossible to fix.




I used to think so too, I still hate USB, however firewire has come a long way. I'm using an M-Audio FW410 and absolutely love it.


I've had a lot of issues with Presonus firewire gear.
Would only work with certain firewire chips and not others.....then was still a bit iffy!

-----
Mercury - you've got my number

Squidy 
3/8/08 10:56:58 PM
Hero
Colossus


Yeah, Presonus has that issue. M-audio works better on NEC chips but still works amazing on my onboard firewire.

-----
JESUS CHRIST ITS A LION!

/Gets in the car

Roses are red, violets are blue, I'll fuck you with a rake

robzy 
5/8/08 1:04:37 AM
Hero
Immortal


The wonderful thing about USB audio is that it makes it easier to isolate the DAC/amplifier from the noisy PSU power.

Rob.

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&#1506;&#1501; &#1497;&#1513;&#1512;&#1488;&#1500; &#1495;&#1497;

Redhatter 
9/8/08 11:46:34 AM
Hero
Titan


The same can be said about Firewire.

And if sound-card manufacturers designed their cards properly, a noisy PSU wouldn't be an issue. How hard is it to install a big fat DC choke on the power rails? All it consists of is some turns of wire around a ferrite core.

Xl = wL -- meaning impedance increases with frequency. Make L sufficiently big, and anything above DC (w = 0 rad/sec) and it gets blocked completely.

(edit: Gah... can't type omega properly. Substitute w with the greek lowercase character, omega in the above.)


Edited by Redhatter: 9/8/2008 11:48:57 AM

-----
Stuart Longland (aka. Redhatter, VK4FSJL)
I haven't lost my mind it's backed up on a tape somewhere...
http://atomicdoc.yi.org <-- AtomicDOC Wiki
Resident Coolie-hatted Gentoo geek. (Gentoo MIPS & Mozilla herd member)

Musto 
19/8/08 4:28:31 PM
Serf
hey dude.

check out M-Audio's cards. http://www.m-audio.com/index.php?do=products.family&ID=PCIinterfaces

there is a 192kHz pci card, but it doesn't have a linux driver (yet)

i picked up a 2496 for about AU$150 on e-0bay. it's 96kHz and has linux drivers.

good luck with your project

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robzy 
23/8/08 1:35:38 AM
Hero
Immortal


RedHatter, in theory that is true, but in practice just how useful would a choke be when dealing with an - essentially ultranoisy - PC PSU?

If all it took was a big choke then all equipment could be powered off any old power supply :P

Rob.

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&#1506;&#1501; &#1497;&#1513;&#1512;&#1488;&#1500; &#1495;&#1497;

Redhatter 
23/8/08 8:56:17 PM
Hero
Titan


Musto: 96kHz really isn't that great for this application... I can cover 48kHz of the band with that... bugger all. But otherwise, it'd be worth a look, and I appreciate the pointers.

I'm thinking a data acquisition board is sounding better and better.

-----
Stuart Longland (aka. Redhatter, VK4FSJL)
I haven't lost my mind it's backed up on a tape somewhere...
http://atomicdoc.yi.org <-- AtomicDOC Wiki
Resident Coolie-hatted Gentoo geek. (Gentoo MIPS & Mozilla herd member)

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