[time-nuts] broadband MPX signal stereo

Dave Brown tractorb at ihug.co.nz
Fri Mar 16 06:26:28 UTC 2012


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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