[time-nuts] BPSK Receiver & GPS Antenna siting

[Bob Camp]

Hi

Flag poles are prohibited.

Bob

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Randy D. Hunt
Sent: Thursday, September 27, 2012 10:24 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] BPSK Receiver & GPS Antenna siting

On 9/27/2012 4:20 PM, Bob Camp wrote:
> Hi
>
> At least in my back yard, a 6' tall tripod would be very noticeable from a
number of directions. There are many others in similar situations. If I were
to interpret the restrictions literally as written, an antenna that was
inside the house, but visible through an open window is also a violation.
>
> Bob
>
>
> On Sep 27, 2012, at 7:11 PM, johncroos at aol.com wrote:
>
>> Various comments -
>>
>> Hal mentioned SNR for the scheme I suggested. A PLL can be a coherent
demodulator of arbitrary
>> bandwidth. Thus the PLL at the output of the doubler can have a small
bandwidth since at that point
>> there is no PSK, it having been removed by the doubler. So given a stable
VCXO you can probably get down
>> to 1 Hz and thereby achieve a good SNR. There is a lot of stuff out there
on phase tracking receivers
>> that do exactly that. You know the frequency so the loop does not have to
search far and the BW can be increased
>> for acquisition and closed up for tracking.
>>
>> On writing reams of code - my point was that it is not required to used
the admittedly more powerful software
>> techniques to do this job - I noted that one reason to write reams of
code is for the fun of it, this is after all
>> a hobby.
>>
>> GPS Antenna Siting -
>>
>> Lets not make this so hard. Mine is at 6 ft elevation and is blocked to
an elevation angle of 20 to 30 degrees by a house
>> within 15 ft and a forest of trees. I have room and no restrictions but I
also have severe thunderstorms - so the house
>> plays lightning protect for the antenna. My T bolt tracks a Rb to better
than 1e-12 over 24  hours with no serious 10 MHz phase bumps
>> as plotted on a  strip chart recorder.
>>
>> Sooooo  -
>>
>> Put your antenna at 6 ft in back yard. Start out on a photo tripod - who
is gonna notice?
>> set up a t bolt at EL=5 AMU=0 Damping = 1.2 and Time Constant = 100 sec.
>> get the t bolt manual
>> get Tbolt monitor
>> get Lady Heather and read all that stuff.
>>
>> Run Lady Heather antenna survey (command SAS)  for at least two days -
you get a map of signal level in dBc vs elevation
>> Reset the Tbolt elevation mask to reject anything that is shown as
blocked using the signal
>> level map. Likewise experiment with the AMU setting to reject the weak =
poor signals. Mine works good
>> with AMU all the way up to 10 as fewer good satellites are better than
lots of weak ones.
>>
>> The satellites are in high orbits so masking those below 25 degrees is OK
and the AMU sets the acceptable signal
>> level - at AMU 10 my setup throws out those below about 40 dBc - the
strong guys go up to 50. This is a function
>> of you antenna performance so some experimentation is required.
>>
>> -73 john k6iql
>>
>>
>>
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
Put up a flagpole.

Randy, KI6WAS

_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.