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

[Graham / KE9H]

There are inexpensive CODECs or A-->D converters that are designed for
audio, that can be clocked up to 192 ksps or 200 ksps with 24 bit
resolution. (Typically 18 or 19 effective bits, 3.0 V p-to-p full scale)
They have built in Nyquist filters that scale with the sampling frequency,
so a Nyquist frequency of 100 kHz is very comfortable for receiving a 60
kHz signal. They use standard I2S audio interface, although other
interfaces are typically options.

After that it is SMOP, as they say. (Simple Matter Of Programming).  :-)

--- Graham

==


On Fri, Oct 9, 2020 at 12:58 PM paul swed <paulswedb at gmail.com> wrote:

> after the bpsk is removed true. I have done that. A simple RC filter and a
> 100K over 50ohm divider to get the signal to a reasonable level. Add a
> coupling cap because all of the old receivers output a preamp voltage.
>
> On Fri, Oct 9, 2020 at 11:35 AM Bob kb8tq <kb8tq at n1k.org> wrote:
>
> > Hi
> >
> > For a full setup, you could do it a lot of ways. A setup of:
> >
> > Antenna -> front end -> ADC -> MCU -> D/A would be one approach. Various
> > bits like a local clock also would get into the design. There are *many*
> > other
> > approaches.
> >
> > ==========
> >
> > There are a lot of D/A’s that will clock in the 100’s of KHz range. If
> you
> > are only
> > trying to come up with an analog of a WWVB signal the “10 bit” D/A’s
> found
> > in
> > some MCU’s would do the trick. In the setup above, the ADC would likely
> be
> > harder to come up with than the DAC.
> >
> > Since you are only trying to come up with a carrier, the need for a D/A
> is
> > not
> > an absolute one. Taking a square wave of some sort and filtering it a bit
> > would
> > be adequate to drive most of these old WWVB receivers.
> >
> > Bob
> >
> > > On Oct 8, 2020, at 11:42 PM, Hal Murray <hmurray at megapathdsl.net>
> wrote:
> > >
> > >
> > > I assume it needs an antenna, front end, and D/A.
> > >
> > > What's available in the way of D/A that's good for 60KHz?  Is the
> > problem
> > > easier if the D/A box has external clocking?
> > >
> > > --
> > > These are my opinions.  I hate spam.
> > >
> > >
> > >
> > >
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