On 08/05/2016 01:45 PM, Bob Camp wrote:
A ten foot long antenna cable is no more or less an issue indoors than a ten
foot serial cable
to a laptop or a ten foot test lead running off of a DVM. They all will pick up
a spike if the field
is strong enough. If you are in a high risk location, then yes you will need to
go to extremes
for all of those cables. In some cases the only real answer is an external
faraday cage around
the entire structure (plus a lot of other stuff).
My outside GPS aerial came with the NTBW50AA that's still available
from RDR Electronics. It is on a plastic pole tied to the corner of my
deck and is about 12 feet above the ground. It works with the Lucent
RFTG-u pair as well. The 70 ohm cable is about 40 feet long and both
GPSDOs lock quickly from cold in my cellar lab/shack.
My first venture with GPS was with my Trimble Flightmate Pro that
I bought in October 1993. I knew GPS was supposed to be a precise time
signal. I had built and programmed a Science of Cambridge SC/MP
(INS8060) based computer that decoded the MSF Rugby (no longer there)
60 kHz signal in 1979, still using it in 1994. Comparing it to the
received GPS time on the Trimble, I was dismayed. My records show
that on 1994 June 23 1700 UTC, GPS, or the Trimble, was a whopping
3 seconds slow,vbehind. 1994 July 03 1538 UTC, zero, seemed to be
synchronous. Same day, 1545, 1/2 a second slow. 1552, 2 seconds slow.
1556 1/2 a second slow. I suspect this was due to Selective Availability
that was not turned off until President Clinton ordered it off
in May 2000.
I have a Navsync CW12-TIM that I bought in 2009. Its diminutive
antenna sticks magnetically to a steel filing cabinet in my office.
I get a good signal and lock there.
In August 2003, I put my hand out of the back door to test the rain.
A lightning bolt split a tree 60 feet away - my wife called me Thor
for many years. The doorbell rang, the garage door control board was
fried and needed replacing, a router in my upstairs office was
blackened, and in 2003, every television and computer monitor in the
house was a CRT - every one of them had to go through several degaussing
sessions.
Best wishes,
Ian, G4ICV, AB2GR
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