[time-nuts] What's available in the way of DSP for new WWVB?

[paul swed]

Graham I appreciate the insights. I am literally just attempting to use
teensy for the wwvb AM time decode. The historic timecode is easily done
with a $2 chip if you could still get them.
I use the arduino IDE and the funny things you have to do with alternate
chips like STM arm...
Also the restrictions.
But this is about experimenting at 60 KHz and sampling. So I expect trouble
and failure. Perhaps a switch to something else. But I need to start
someplace and this was cheap enough. In theory it arrives today.
Regards
Paul.
WB8TSL

On Fri, Oct 16, 2020 at 2:04 PM Graham / KE9H <ke9h.graham at gmail.com> wrote:

> On Tue, Oct 13, 2020 at 12:19 PM paul swed <paulswedb at gmail.com> wrote:
>
> > Graham take a look earlier in the thread there are details about the
> > teensy. There is actually a lot of hardware out there today for little
> > money. Thats what makes the SDR DSP approach interesting and for me at
> > least the next thing to take a run at.
> > Regards
> > Paul
> > WB8TSL
> >
> >
> > Hi Paul:
>
> I have looked at the Teensy 4.0 for use as a WWVB SDR receiver.
>
> The problems I have are:
>
> 1.) PJRC (the designer/manufacturer) has gone out of their way to block
> access to the standard ARM SWD programming interface, and you must go
> through the unique USB loader executable and programming interface if you
> want to program the board. It is awkward to use a normal development
> environment such as NXP's MCUXpresso with a standard programming interface.
> It is really intended for use with the provided Arduino programming
> environment.
>
> 2.) If you use the provided Arduino IDE/environment, then the provided DSP
> functions are restricted to the 16 bit versions. I prefer the ARM 32 bit
> versions to go with my 19 to 24 bit data converter.
>
> 3.) I have found that the iMX RT1062 processor will only run at the
> advertised 600 MHz speed, if it is exclusively executing from onboard
> "tightly coupled RAM". If your program is large enough to require using the
> OCRAM, then it slows down to 1/4 speed.  If you need even more memory
> space, and you try to use the provided external QSPI Flash, then it slows
> down to about 1/32 speed. What it effectively does is run at some blend of
> those speeds as it fetches cache and variously accesses the different
> memories.  Memory planning is critical for maximum performance.
>
> --- Graham
>
> ==
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