hi, first step to give an answer is to know the frequency range you want to
investigate and then to choose a high speed sampling card. To make the right
choice is also important to know the frequency range of the signals coming
into the sampling board. Most high speed sampling board don't have any input
filter so that you may incur into the aliasing problem. According to the
sampling theorem you get an accurate sampling only if your signal is band
limited to the half of the sampling rate. If your signals has frequency
components higher than that, those components will produce artifacts. If you
signal (or the device that receives and transmit it to the sampling board)
is not band limited you need to add a sharp low pass filter.
many sampling boards for audio recording go up to 192kHz sampling to
correctly sample frequencies up to 96kHz (normally something less because
filters are not sharp and begin to cut at lower frequencies, say, 80 kHz,
even 60 kHz in some cases, you have to check before to buy). If you need
more, there are many sampling boards (e.g. from National Instruments) under
1000$ that sample up to 1 MHz. All these don't have filters.
You can choose to add a low pass filter, or to go up with the sampling rate
at frequencies higher than the highest frequency of your signal. With very
high sampling rate you may have the problem of streaming to disk millions of
bytes every second.
In my experience you don't have any problem up to more than 1 MHz sampling
even with very standard PCs and even laptops. If you need only short
recording you can just record into RAM and then flush to disk.
tape recorders are no more used for these type of recordings. used until few
years ago, they were bulky and expensive, and noisy, and eating a lot of
tape.
be aware that DSD recorders are not suitable, even if they declare >1MHz
bandwidth. they sample at high rates, 2.8MHz or 5.6MHz, but with 1 bit only.
this technology gives much less than it promises; the main problem is noise
that increases above 40 kHz: the signal to noise ratio could decrease to
less than 50 dB above 80 kHz.
Gianni
University of Pavia, Italy
2008/3/11, Thomas Ashcraft <>:
>
>
>
> Question : I want to do some *super* high speed audio recording and
> wonder what sort of technology is available for this these days? Is
> anything available to the "prosumer" maybe?
>
> My application is to audio record Jovian radio bursts and then look as
> deep as possible into one second's worth of time. I have seen
> spectrographs of audio recordings where they ran tape at many many
> inches per second. ( I can't remember exactly how many inches per second
> but maybe 100 inches or maybe 300 inches per second . Not sure about the
> actual speed but *fast* in any case. )
>
> I thank you in advance for pointing me to any information or resources.
>
> Thomas Ashcraft
>
>
>
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