recording at a higher sampling rate than 192Khz

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ubxf

Well-known member
Joined
Sep 3, 2004
Messages
796
Location
los angeles
Hello,
i need to record dolphins with an hydrophone. The signals are above 100Khz so my Sound Devices recorder set at 192Khz won't be able to capture all of the signal. I found this interface http://www.avisoft.com/usg/usg116hb.htm
but i was wondering if there is anything else that exists.
Thanks for any suggestions
 
sounds cool, but not all ADC's are capable of capturing up to their nyquist frequency. I know of few ADC's that can actually capture 96kHz content linearly at 192kHz.

/R
 
i see that the Ti PCM4202 has a max Sampling rate of 216kHz . i wonder if Avisoft uses video chips to go up to 1MHz sampling rate
 
Also some chips for scopes can of much higher in frequency and some of them have decent bit rate, but hard to manage on a simple project as audio converters, also you need a dedicated software for that task. Even 8bit could be enough if always all of them used, applying a compressor on the input, you could use a second slower (or not) converter to record the CV of that compressor and then recreate the dynamics if wanted, but I think you are looking for a commercial product, in which case I know a couple but high quality audio stuff which are too expensive for what you are looking I guess.

JS
 
of course i'm trying to be mindful of the budget but if the only option is costly i have to go for it. So if you have high quality audio recommendations i'm all ears. Btw my Sound Devices 744T recorder is not exactly the bottom pick but i'm looking for something better.
 
The Avisoft looks very reasonable for what it offers.  It appears designed for EXACTLY what you want.
 
i've been looking at bat recorders to see if i could replace the electret with the hydrophone
 
384kHz sampling rate converters in some units, but I don't really know it's freq response, they should get over 100kHz but I don't know the real filter they have.

The first brand I know doing this is antelope, here is a link, no freq response charts. I remember it always but I've heard about others I can't remember now.
http://www.antelopeaudio.com/en

M2TECH also use that sampling freq for example, 10Hz to 90kHz ± 0.1dB, don't how is the filter over that.
http://www.m2tech.biz/young.html

This are much expensive that what you posted and I think it's fine for you cause seems to be designed for that.

JS
 
How close are you working?

Sea water becomes progressively more lossy as frequency increases, so to get much at HF you need to be fairly close to your targets, particularly with something like a D70  or similar rather then some sort of directional array.

You could consider something like a http://redpitaya.com/ or any one of many data acquisition cards from the likes of NI.

Whatever you use, getting the preamp right at the transducer helps in particular with low frequency response (Most suppliers or transducers have a range with built in preamps).

Regards, Dan (Who used to do sonar transducers for a living).
 
Thanks for all the suggestions, antelope and m2tech look interesting but probably not by the pool where we are going to record . I'll definitely give a good look at acquisition cards. I'm using a preamp with very high impedance (100 Meg )  pretty close to the hydrophone ( a Reson TC 4013 http://www.teledyne-reson.com/products/hydrophones/tc-4013/ )
 
pucho812 said:
what about the korg stereo recorder that does dsd?  It's portable... But only does stereo

I don't know about the Korg specifically but generally with DSD there is very high noise at higher frequencies...
 
That Korg MR-2 looks nice but it is discontinued. The current format is DXD still PCM at 384kHz
http://www.digitalaudio.dk/AX24-ADDA-Converter.1492.aspx
 
I dont know its freq. response either, but the first thing I thought about was the Horus:
http://www.merging.com/horus

Used with Pyramix, it samples at 352.8 kHz (DXD), or maybe even higher (they call it DSD256).

I have not used this system myself, but maybe you should check out the detailed specs...

Best,
12dBLow.

PS: Of course this system is not really portable at all :/ that might be a problem in your case..
 
ubxf said:
i've been looking at bat recorders to see if i could replace the electret with the hydrophone

The one time I got to use a bat listening device, it worked in real time. Which meant, it has some pitch shifting happening on board. It has an ultrasonic microphone that captures the incoming signal, then shifts it down by a couple octaves, and then outputs that shifted sound.

Seems like that would be the way to go – do your pitch shifting before capture. Then you don't have to seek out a device capable of a super high sampling rate. And you save on a ton of data space as well!
 

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