500kHz sample rate?

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Videogamer555
Posts: 43
Joined: Wed May 25, 2011 2:28 am

500kHz sample rate?

Post by Videogamer555 »

I see that GoldWave supports input and output sample rates of up to 500khz (if the hardware is able to do it). What DAC (digital to analog converter) or ADC (analog to digital converter) is actually capable of 500khz sampling? I thought the highest was 192khz for audio equipment. Any idea on 500khz, where I could buy one, and how much it would cost?
Tristan
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Re: 500kHz sample rate?

Post by Tristan »

Do you like extremely large files, for some reason? 384kHz is the highest rate at which I've ever seen anything sampled. All you have to do is Google for the DAC's if you're interested.
I don't want to read the manual either, but, then, it isn't my problem, is it?
DougDbug
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Location: Silicon Valley

Re: 500kHz sample rate?

Post by DougDbug »

I've never heard of 500kHz audio sampling hardware. I've got a digital oscilloscope at work that samples at 1GHz, but of course it doesn't have an audio interface or audio drivers.

Sometimes the hardware works at a fixed sample rate (such as 48kHz) and bit depth (such as 16-bits) and the driver upsamples or downasmples to the requested sample rate. This allows the soundcard manufacture to claim 24-bit/96kHz support even if the hardware doesn't truly do it.

Windows may have a limit. I believe there are a limited number of standard sample rates allowed by the driver protocol. I don't think windows allows "oddball" sample rates like 50Khz.

Since GoldWave is software, it just "doing math" (digital signal processing) so there is theoretically no limit to how high you could go... It's up to Chris (GoldWave's developer) to decide how high the sample rate can go... But since it's a Windows program, it doesn't make sense to support anything that Windows doesn't support...

I'm sure a program like MATLAB (which is not specifically an audio program) will take any sample rate you type-in.

For regular audio, 16-bit/44.1kHz is better than human hearing. The pro studio standard seems to be 24/96. If you are doing something "scientific" unrelated to audio & human hearing, MATLAB or one of the free MATLAB clones is probably more appropriate than GoldWave
Videogamer555
Posts: 43
Joined: Wed May 25, 2011 2:28 am

Re: 500kHz sample rate?

Post by Videogamer555 »

Tristan wrote:Do you like extremely large files, for some reason? 384kHz is the highest rate at which I've ever seen anything sampled. All you have to do is Google for the DAC's if you're interested.
On searching for 384khz sampling rate audio hardware, I've found this device http://samtechonline.com/hida20a32dac.h ... 8283950120

But it only allows OUTPUT. What hardware supports 384khz input (or both input and output at 384khz)?
DougDbug
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Location: Silicon Valley

Re: 500kHz sample rate?

Post by DougDbug »

Googling "384kHz ADC" got several hits starting with this one.

Of course, anything like this is likely to be very expensive. It's going to be aimed at the audiophile market (the more expensive the better for most "audiophiles"), or it's going to be scientific equipment, or maybe pro audio equipment (but 384kHz is rare in pro audio).

Also, you may also need a fast computer or some specialized recording equipment, especially if you are recording at 24-bits (or more) and depending on the number of channels you are recording... The more data you're trying to capture the harder it becomes, especially for a general-purpose computer with a multitasking operating system.
DewDude420
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Re: 500kHz sample rate?

Post by DewDude420 »

Just a few words on this topic:

You won't really see more than 24/192 on consumer formats; that's the current highest consumer supported format. 24/384 is more of a professional format; but what it actually is double the 192khz, or 4x 48khz.

The highest rate you'll usually see in audio production is 24/352, which is known as the "DXD" format. It's used as the PCM-stage in SACD production.

But 500khz? Not in audio. But I can tell you goldwave supports it.

I started playing around with cheap SDR's over christmas; got an RTL-SDR setup. These dongles stream what's known as I/Q data to the computer from the ADC inside the RTL2832U chip. I/Q data is complicated; it's basically a spectrum of the RF along with phase information that's quadrature sampled by your radio software. Oh, and this chip sends the PC data at up to 3.2msps (million samples per second); although anymore more 2.8msps gets unreliable. You can record this raw I/Q data in what's called a baseband recording; it's a recording of the entire RF chunk you're sending the software; and it does so to WAV.

These wave files are huge; they're the sample rate you're sending the dongle out...and they're using 8-bit samples. So if you're running your dongle at 2msps; you're generating a 2048khz sample rate 8-bit PCM File.

Goldwave will in fact open it. You won't really hear much; it's quadrature sampled RF and isn't supposed to be listened to directly...let alone messed with in an audio editor (because it's not audio). But it's still PCM data; and Goldwave will in fact do stuff with it. It has no complaints about opening a file that large. I've even filtered the results and have gotten usable I/Q data out of it.

Now, mind you...this is solely for RF data. I don't think the ADC would be suited for working with audio. In theory; you can tap in to the I/Q inputs of the ADC in the dongle...but I do not know what would happen if you tried to pipe audio. The whole thing is designed for dealing with RF; and that's the only time I can think of you're going to see sample rates this high; and, as I mentioned...that's RF...so it shouldnt' be in an audio editor in the first place.

But, the point is; Goldwave will open them. Here's a screeshot of goldwave having opened a 2048khz file.
http://rtl-sdr.better-than.tv/files/gw.png
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