[Premium-Rx] HP Z3801A/Z3816 Freq Std as a Receiver Std

[Dave Emery]

On Fri, Jan 02, 2004 at 02:04:06PM -0800, refmon wrote:

> My experience has been that there is a noticeable increase in apparant
> sensitivity on HF ... I am using Cubic R3030's ... other receivers may or
> may not realize any change.  It's also nice to work in absolute frequency
> and have all your gear locked on the same frequency and phase.
> 
	I haven't observed much noise floor difference with my antique
Collins 851S1 GPS locked, but it is nice to be absolutely dead on
frequency.

> The next step is to move to the latest version of GPSCON which has
> facilities to put time synch on a LAN...almost disorienting to have the PC
> clocks read the same.  Of course then you need to become fluent in GPS time
> vs UTC time and the care and feeding of leap seconds, etc etc.  Actually
> pretty interesting.

	Shame on the GPSCON authors.   Most all GPS gear outputs UTC
precisely and not GPS time (which is currently 13 seconds off UTC).
The almanac information transmitted from the satellites contains the
value of this offset (which hasn't changed since 1999) and most
GPS receiver firmware performs the correction automagically.

	The only time one notices any of this is at midnight on Dec 31st
when the ball is dropping - for it is then that the leap second might
get inserted (but hasn't been needed recently).

	Many of us computer geek types have been locking our computers
to GPS time since the mid 90s (and to the net since the 80s) using
a protocol called NTP... current implementations on Linux/BSD will
correct the clock on the PC to keep the OS timebase with a few
microseconds of the incoming 1 PPS tick from GPS.   This means that
time of day on the machine is accurate to at least milliseconds if
not microseconds...

-- 
   Dave Emery N1PRE,  die at dieconsulting.com  DIE Consulting, Weston, Mass 02493