[hpsdr] Janus Prototype Status

[Ahti Aintila]

Congratulations Phil and Bill!

With Cirrus CS5381 we seem to achieve the dynamic level matching
(possibly exceeding)  the performance of AK5394A (see
<http://www.cirrus.com/en/pubs/appNote/an234-1.pdf>). With my
experience when using Waveterminal 192X, I realistically expect noise
levels much below the -160 dBm when you go to the proper buffering
with the CS5381.

Dont care so much of the cost, the 120 dB (plus) dynamic range  is
worth of dollars and euros. BTW, your 30 dB$ may be exaggerated. Is
dB$ equal to 10*log(a$/b$) or 20*log(a$/b$)? Whichever,  go ahead - I
will follow as soon as my time permits.

73,
Ahti OH2RZ


On 11/04/06, Bill Tracey <bill at ewjt.com> wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> Just a quick note out here on progress on the Janus (I/Q. mic, and monitor
> IO) work going on as we've been a little quiet out here of late.
>
> The Wolfon and PCM4202  chips have been built and tested with a Xylo and
> PowerSDR in a 2in, 2out configuration at 48 khz and seem to be working
> pretty well.  The PCM 4202 looks to be better than the Wolfson in terms of
> performance and is a bit easier to deal with.
>
> Work is ongoing on the Cirrus CS 5381   VK Phil and I have both built
> CS5381 prototypes - mine seemed a bit spurry, so Phil's done one now as
> well and initially saw some of the same spur issues I did.  The CS5381
> seems to be very sensitive to the input stage in front of it, and Phil has
> now puit a front end in front of his CS5381.  Still has some issues,  but
> the noise floor looks spectacular (close to -160 dbm on Phil's
> latest).   Next step on the 5381 is for Phil to build the opamp input stage
> Cirrus recommends in their app notes.  It calls for some specific op amps
> from LT that I've  ordered and will FedEx them to Phil as soon as they come
> in -- will probably be next week by the time he gets 'em.     By the time
> Phil gets done the CS5381 may be the best performer - but the additional
> complexity and cost (2x for the A/\D compared to the PCM4202, plus 4 op
> amps at $5 each) may make us decide to use the PCM4202.  As Phil puts it we
> may get 10 db better performance but at a 30 db increase in cost and
> aggravation.
>
> We will do the bake off on the chips at 48 and 96 klhz  - and perhaps 192
> khz.  Don't want to find out we've got a Presonus style 24 khz roll off
> problem on one of these after the fact.  We've got FPGA code for 48 and 96,
> PowerSDR code for 48khz 2in 2out - I'm currently working on 3in 4out at
> 48khz for PowerSDR and will then move on to 96 khz so we can do the bake
> off.
>
> Regards,
>
> Bill
>
>
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