I sent the following to John Lowe of the NIST regarding the WWVB change
proposals. His comments follow.

Dear Sir,

I just read your whitepaper on the new modulation scheme proposed for WWVB.

It seems that you and the other authors of this paper have addressed the
concerns of people that use WWVB solely for use with wall clocks and the
like.

Have you done a study to see how the alteration of the modulation scheme
will affect those users that use WWVB for frequency standardization with
WWVB receivers like those manufactured by Tracor, Symetricom and the like?
I am sure that you must be aware of the widespread use of these venerable
receivers.

Do you have solutions or a work around so that those products will remain
useable?

It seems that a huge percentage of time users get their time from their
Cell or iPhone or even their internet connected computers.

Few people I know actually have WWVB clocks.Those that I know have been
happy with the way they work today.

Many people do not even wear watches these days. We have already given up
LoranC. I recently pulled my very expensive receiver out of the rack as it
is now a useless paper weight.

Why change something that has been working so well for frequency users for
many decades? I know that everyone wants to push GPS but in my opinion it
is prudent to have a back up plan. After all WWVL has been gone for many
years. If WWVB makes this change there will not be a usable VLF service for
frequency use.

Is this change up for comment or is it a done deal?

Sincerely,

Sam H. Reaves III

Response:

Thank you for your comments.  We are working on making an interface that
will keep these devices operational.  While it is true that there are WWVB
frequency reference devices out there, no manufacturer has made or
supported these devices in years.  They are all considered obsolete by
their own manufacturers.  It is estimated that over 12 million radio
receive clocks and watches have been sold in the US.  The new scheme will
allow new devices to be constructed that can receive the frequency also.

I will add your name to my list to be contacted when we have a work-around.

Thank you

So I gather from this they are working on something, but no details were
given.

Sam

One possibility for a workaround to keep the classical receivers happy
is to leave some residual carrier.  Instead of a 180-degree phase
shift, make it 90 or 120, so that the signal can be regarded as the
sum of a pure carrier and a smaller BPSK signal.

Would older receivers be OK with this?  They really should be tracking
on timescales much longer than one second anyway, so there's some hope
at least.

Cheers,
Peter