[time-nuts] new WWVB BPSK dev board

[Attila Kinali]

Moin,

On Mon, 3 Dec 2018 18:11:30 -0800
"Tom Van Baak" <tvb at LeapSecond.com> wrote:

> At long last, a complete WWVB 60 kHz BPSK dev board is available:
> 
> https://universal-solder.ca/product/everset-es100-cob-wwvb-60khz-bpsk-receiver-kit-with-2-antennas/
> 
> Note it includes the antenna(s). Also has links to documentation.


As this is becoming a topic again, and the EverSet people still
claim that the BPSK modulation of WWVB makes it more resilient
to jamming and easier to receive, I would like to restate
what I've written some years ago [1,2]:

BPSK by itself does not improve timing. At most it improves reception
by having a constant power envelope. But in case of WWVB, where
the AM modulation is still kept, this is not the case. The phase
changes do not help reception at all. In order to help reception,
one needs to send a _known_ bit string in order for a corrolator
in the receiver to pick the signal out of the noise. The only
known bits in the BPSK signal are the first 12 bits of each minute.
Compare this to DCF77 which encodes 512 bits every _second_.
Ie while DCF77 gets something like 10-20dB  easier to pick out
of noise, but when using BPSK, WWVB gets... uhmm..  zero improvement.

All the BPSK modulation of WWVB does is
1) Make the signal unusable for any carrier phase tracking receiver
2) Add a second type of bit stream onto the signal for additional
   information to be encoded
3) Generate a revenue stream for companies who sell new WWVB receivers.

For more information, read [2]

			Attila Kinali

[1] https://www.febo.com/pipermail/time-nuts/2013-July/060456.html
[2] https://www.febo.com/pipermail/time-nuts/2013-July/060471.html


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