On Tue, 22 May 2012 11:49:04 +0000 (UTC), "Geoffrey S. Mendelson"
wrote:

The are using the improved modulation to keep relevant. In most large cities,
the noise from computer and home electronic equipment, BPL (still very much
in use but not for internet to customers), aDSL, etc has made it next
to impossible to receive a signal.

Many switching power supplies run at about 60KHz. I have one
somewhere around my computer/TV pile, which kills WWVB reception if I
get anywhere near it.

They exist today because people are willing to accept the poor service they
get as it is the only game in town at that price tag. Most users never
pay attention to how often they get sync, if ever.

Most WWVB devices have an indicator on the LCD display to show that
the clock was recently synced with WWVB time. My weather stations and
assorted digital clocks all have this feature.

If they have to pay $100-$150 for a BPSK decoding clock, GPS or Wifi NTP clocks
will seem a lot better deal.

It's my understanding that only the modulation scheme will change, not
the encoded data. A universal chip that works using both system
should be possible without a major price jump.

I'm a bit mystified with the "new type of PM receiving antenna"
mentioned in:
http://www.nist.gov/pml/newsletter/radio.cfm
I didn't know that antennas were modulation specific.

I'd love to know how they came up with the number of clocks in use. Anyone
have an idea?

Same as how they get wi-fi device numbers. Marketing research firms,
that specialize in selling industry statistics and predictions, survey
the chip manufacturers for how many chips they've sold. In this case,
the leading manufactory is C-Max:
http://www.c-max-time.com
I suspect the largest numbers are in "atomic time" wris****ches.

The accuracy of sales statistics are always questionable, but are
usually accurate within an order of magnitude. The problem is while
sales statistics are fairly simple to generate, devices in use are
not. One could add up all the sales from the last 10 years, assume
that few of the devices were trashed, and produce a very large number
in use. Whether it has any value is very doubtful. Besides, sales
statistics is what companies are willing to pay for, and that's what
the marketing research firms tend to produce.


--
Jeff Liebermann
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Santa Cruz CA 95060 http://802.11junk.com
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