[time-nuts] broadband MPX signal stereo

[Azelio Boriani]

Interesting the ESI sound card, I'll check where to buy one. Useful to
sample VLF time and frequency signals directly.

On Fri, Mar 16, 2012 at 7:26 AM, Dave Brown <tractorb at ihug.co.nz> wrote:

> EMU 0202 or 2020? I know what an 0202 is but what is a 2020?
> DaveB,NZ
>
> ----- Original Message ----- From: "Demian Martin" <demianm_1 at yahoo.com>
> To: <time-nuts at febo.com>
> Sent: Friday, March 16, 2012 6:53 PM
> Subject: Re: [time-nuts] broadband MPX signal stereo
>
>
>
>  I have tested a number of soundcards and while the EMU 2020 has issues
>> (serious jitter and noise from the USB interface) I can recommend the ESI
>> Juli@ as having flat response and good SNR up to 90 KHz. It's a PCI
>> card, no
>> USB. I have measured the performance of FM MPX adapters and tested FM
>> Transmitter performance with one. You get 24 bit at 192 X 2 continuously
>> as
>> long as you want. With some simple pre-filtering and gain you should be
>> able
>> to get some 60 KHz signal at very low levels. With a deep FFT I get to
>> -130
>> dBFS easily. With the demo board for the AKM AK5345a I am getting better
>> than -160dBFS. That has SPDIF out. Depending on the filter selection, most
>> chips have a flat option, there is no significant phase shift up to
>> frequencies close to the cutoff.
>>
>> I have tried and dumped a number of other sound cards that were dead ends.
>> The ESI Juli@ is usually around $120.
>>      Demian
>> ______________________________**____________
>> Chris Albertson writes:
>>
>> Some audio interfaces have a low pass filter to cut off at about 20KHz
>> but many don't have the filter.     The user manual should list the
>> bandwidth of the interface.  Mine claims to be flat out to 40KHz.  But
>> it varies.
>>
>> For example the EMU 2020 user manual reads
>> "Frequency Response (min gain, 20Hz-20kHz): +0.0/-0.07dB"
>> But what happens after 20KHz?  The specs don't say.   You have to test
>> it yourself and see.
>>
>>
>>
>>
>>
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