On 4/20/2016 12:01 PM, wrote:
In article rickman writes:
On 4/18/2016 5:43 PM, David Woolley wrote:
On 18/04/16 15:39, rickman wrote:
How important are time and frequency references to amateur radio
operators? I've been working on a radio controlled clock design that
would be capable of generating a 32.768 kHz, 60 kHz, 240 kHz, 1 MHz and
10 MHz frequency references in addition to providing the time and date.
Initially it would be capable of receiving the 60 kHz transmissions of
WWVB and MSF. With minor tweaks other stations could be received.

Would this be useful to others?


Anyone who wants high accuracy off air time and frequency standards
would use GPS these days. Even that is almost two decade old technology
in amateur radio usage: http://www.tapr.org/kits_tac2.html

Is there something about GPS that is inherently superior for a frequency
reference? For setting a time, GPS can provide a smaller offset, but I
don't see where it has any advantages over WWVB or similar station
broadcasts where you can receive them.

The main limitation of a GPS receiver is the need for an outside antenna
for many installations. A WWVB receiver is self contained and much
lower cost.

GPS allows accurate locking to frequency, WWVB no longer does,
since they use phase modulation on the WWVB signal. The "low
cost" WWVB receivers never could do that, they are only able to
be used for clock setting, not accurate frequency determination.

The present WWVB signal still allows phase locking, just not by a
simplistic algorithm.


The WWVB signals are much more affected by the ionosphere,
as daytime absorbtion can make the signal unusable to small
receve antennas.

Also, WWVB does need an antenna for good performance, especially
compared to small indoor antennas.

Every receiver needs an antenna. But the LF time signals are easily
received inside buildings without an external antenna while the GPS
signals are readily blocked by walls and roofs. There are even problems
receiving the GPS signals accurately based on geography and local terrain.


WWVB suffers from occasional interference on the east coast from MSF.

I think "occasional" is the right word, if that. From here it is 1460
miles to WWVB transmitting at 50 kW ERP (I'm near Washington, DC) and
3,462 to MSF in Anthorn transmitting 15 kW. The directions are not far
from orthogonal (120°). A loop stick antenna at my location would
receive more noise than signal from one when receiving the signal from
the other if the signal from Anthorn can be received at all.

--

Rick