Best location for a GPS antenna...?
On Wed, 11 Apr 2012 22:06:06 +0200
"Andrea Baldoni" erm1eaae7@ermione.com wrote:
I mean, rx external antenna -> preamp -> tx directional internal antenna -> big
air gap -> rx directional internal antenna -> receiver.
The preamp would not be so power hungry as the full thunderbolt and maybe
it could be powered via a magnetic link (or a little solar panel with a
lamp illuminating it).
Oh.. err.. sorry... i read that you would be modulating it onto a fiber
instead... Must be already half asleep ^^'
Yes, it would be possible. But you are not allowed to do it, because
you will be very strong GPS jammer. And don't count on the directivity
of antennas. They are not as directional as people think and the side
and back lobes will jam any receiver nearby
Attila Kinali
--
Why does it take years to find the answers to
the questions one should have asked long ago?
Hi
Putting the GPS on a fiber is fine, except you need a very large battery to
keep it running. As soon as you have a power line up to it, you are right
back to a metal conductor going to the wrong place(s).
Bob
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Attila Kinali
Sent: Wednesday, April 11, 2012 4:37 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Best location for a GPS antenna...?
On Wed, 11 Apr 2012 22:06:06 +0200
"Andrea Baldoni" erm1eaae7@ermione.com wrote:
On Wed, Apr 11, 2012 at 10:19:40AM -0400, Bob Bownes wrote:
I do like the optical isolation suggestion. While less than optimal,
perhaps the easiest solution is not to put the isolation between the
t'bolt
and the antenna, but to put the isolation between the t'bolt and the
distribution amplifier.
By the way, would it be possible to retransmit the GPS signal to isolate
it?
I mean, rx external antenna -> preamp -> tx directional internal antenna
-> big
air gap -> rx directional internal antenna -> receiver.
The preamp would not be so power hungry as the full thunderbolt and maybe
it could be powered via a magnetic link (or a little solar panel with a
lamp illuminating it).
Yes it would be. What you basically would need is to have a LNA,
a bandpass filter and something that converts the voltage into
light with very little noise. I think it would be easiest to down
mix it first to 100MHz or so, then modulate a laser diode. In the
house you'd have to mix it up to 1.5GHz again, of course.
I have no clue whether that is feasible from the noise this whole
circuitry will add or whether it would add so much noise that the
receiver would have no chance...
Attila Kinali
--
Why does it take years to find the answers to
the questions one should have asked long ago?
time-nuts mailing list -- time-nuts@febo.com
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On Wed, 11 Apr 2012 17:09:32 -0400
"Bob Camp" lists@rtty.us wrote:
Putting the GPS on a fiber is fine, except you need a very large battery to
keep it running. As soon as you have a power line up to it, you are right
back to a metal conductor going to the wrong place(s).
You are at the top list of things to hit for a lightning anyways.
No matter whether you have a ground connection or not. Just simply
because the antenna is up there.
Ie the antenna and everything connected to it is to be sacrificed in an
lightning strike. The question is, how much you have to replace and what
additional damage it can cause.
Attila Kinali
--
Why does it take years to find the answers to
the questions one should have asked long ago?
This is a great discussion. I have been trying to decide the best compromise between optimal reception and safety. Here in Boulder afternoon thunder stormers are often a daily occurrence.
I cannot afford to learn from my mistakes on this one.
Thomas Knox
Date: Wed, 11 Apr 2012 22:37:06 +0200
From: attila@kinali.ch
To: time-nuts@febo.com
Subject: Re: [time-nuts] Best location for a GPS antenna...?
On Wed, 11 Apr 2012 22:06:06 +0200
"Andrea Baldoni" erm1eaae7@ermione.com wrote:
On Wed, Apr 11, 2012 at 10:19:40AM -0400, Bob Bownes wrote:
I do like the optical isolation suggestion. While less than optimal,
perhaps the easiest solution is not to put the isolation between the t'bolt
and the antenna, but to put the isolation between the t'bolt and the
distribution amplifier.
By the way, would it be possible to retransmit the GPS signal to isolate it?
I mean, rx external antenna -> preamp -> tx directional internal antenna -> big
air gap -> rx directional internal antenna -> receiver.
The preamp would not be so power hungry as the full thunderbolt and maybe
it could be powered via a magnetic link (or a little solar panel with a
lamp illuminating it).
Yes it would be. What you basically would need is to have a LNA,
a bandpass filter and something that converts the voltage into
light with very little noise. I think it would be easiest to down
mix it first to 100MHz or so, then modulate a laser diode. In the
house you'd have to mix it up to 1.5GHz again, of course.
I have no clue whether that is feasible from the noise this whole
circuitry will add or whether it would add so much noise that the
receiver would have no chance...
Attila Kinali
--
Why does it take years to find the answers to
the questions one should have asked long ago?
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Hi
If the antenna is no higher than your house, it's no more likely to get hit than the house. If it's higher than the house by a few feet, the increase in hit probability is vanishingly small. Provided the antenna is grounded as well as your house power (as in very poorly) it's no more a hazard than any other conductor in your home. Run it down to ground level and through a proper protector and it's less of a hazard than the rest of the conductors in the house.
Food for thought: do you have metal downspouts on the gutters? A metal lining in the chimney? Metal heating ducts ? Any bets on how they are grounded...
Bob
On Apr 11, 2012, at 5:34 PM, Tom Knox wrote:
This is a great discussion. I have been trying to decide the best compromise between optimal reception and safety. Here in Boulder afternoon thunder stormers are often a daily occurrence.
I cannot afford to learn from my mistakes on this one.
Thomas Knox
Date: Wed, 11 Apr 2012 22:37:06 +0200
From: attila@kinali.ch
To: time-nuts@febo.com
Subject: Re: [time-nuts] Best location for a GPS antenna...?
On Wed, 11 Apr 2012 22:06:06 +0200
"Andrea Baldoni" erm1eaae7@ermione.com wrote:
On Wed, Apr 11, 2012 at 10:19:40AM -0400, Bob Bownes wrote:
I do like the optical isolation suggestion. While less than optimal,
perhaps the easiest solution is not to put the isolation between the t'bolt
and the antenna, but to put the isolation between the t'bolt and the
distribution amplifier.
By the way, would it be possible to retransmit the GPS signal to isolate it?
I mean, rx external antenna -> preamp -> tx directional internal antenna -> big
air gap -> rx directional internal antenna -> receiver.
The preamp would not be so power hungry as the full thunderbolt and maybe
it could be powered via a magnetic link (or a little solar panel with a
lamp illuminating it).
Yes it would be. What you basically would need is to have a LNA,
a bandpass filter and something that converts the voltage into
light with very little noise. I think it would be easiest to down
mix it first to 100MHz or so, then modulate a laser diode. In the
house you'd have to mix it up to 1.5GHz again, of course.
I have no clue whether that is feasible from the noise this whole
circuitry will add or whether it would add so much noise that the
receiver would have no chance...
Attila Kinali
--
Why does it take years to find the answers to
the questions one should have asked long ago?
time-nuts mailing list -- time-nuts@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@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
There are commercial "re-radiators" for GPS. I found these on Google:
http://www.gps-repeating.com/?gclid=COTV88D6rq8CFcwTfAodhSKvmQ
http://gpsnetworking.com/GPS-re-radiating-kits.asp
One of my old suppliers in the UK was marketing a range of these, but I seem
to remember some problem in getting approval in the UK, and they had to drop
them. Things may have changed as this was a few years ago.
Rob Kimberley
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Andrea Baldoni
Sent: 11 April 2012 21:06
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Best location for a GPS antenna...?
On Wed, Apr 11, 2012 at 10:19:40AM -0400, Bob Bownes wrote:
I do like the optical isolation suggestion. While less than optimal,
perhaps the easiest solution is not to put the isolation between the
t'bolt and the antenna, but to put the isolation between the t'bolt
and the distribution amplifier.
By the way, would it be possible to retransmit the GPS signal to isolate it?
I mean, rx external antenna -> preamp -> tx directional internal antenna ->
big air gap -> rx directional internal antenna -> receiver.
The preamp would not be so power hungry as the full thunderbolt and maybe it
could be powered via a magnetic link (or a little solar panel with a lamp
illuminating it).
Best regards,
Andrea Baldoni
time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
On 4/12/12 2:09 AM, Rob Kimberley wrote:
There are commercial "re-radiators" for GPS. I found these on Google:
http://www.gps-repeating.com/?gclid=COTV88D6rq8CFcwTfAodhSKvmQ
http://gpsnetworking.com/GPS-re-radiating-kits.asp
One of my old suppliers in the UK was marketing a range of these, but I seem
to remember some problem in getting approval in the UK, and they had to drop
them. Things may have changed as this was a few years ago.
Interestingly I've just been looking into this... Why would you need
anything special to reradiate.. It's not like you need a particular
antenna pattern or constant gain or something. What about something like
a fat monopole against a ground plane, with a attenuator at the feed to
provide a good terminating impedance for the LNA/Line driver.
If it's L1 only, you don't even need particularly wide bandwidth (<1%)
Yes, I've seen setups at JPL where they reradiate with D&M or Ashtech
chokering antennas (or even helibowls), but that might be because we've
got a bunch of them sitting around, so why not use it.
You must read:
http://transition.fcc.gov/eb/Orders/2005/DA-05-2998A1.html
Which discusses a FCC complaint with Navtech for selling GPS receivers.
An exert is presented below:
``Please note: re-radiation kits are currently only
available for purchase to International Customers and in
cases where the U.S. Government is the end user.''
Pursuant to Section 15.201(b) of the Rules, 47 C.F.R. §
15.201(b), intentional radiators must be authorized in accordance
with the FCC's certification procedures prior to the initiation
of marketing in the United States. However, GPS re-radiators
operate within the restricted frequency bands listed in Section
15.205(a) of the Rules, 47 C.F.R. § 15.205(a).4 Thus, GPS re-
radiators cannot comply with the FCC's technical standards and
therefore cannot be certificated or marketed for use by the
general public or non-federal government entities. Accordingly,
it appears that Navtech has violated Section 302(b) of the Act
and Sections 2.803 and 15.205(a) of the Rules by marketing in the
United States radio frequency devices that are not eligible to
receive a grant of certification.
You should be aware that the Commission has recently
addressed a Petition for Rulemaking and a Request for Waiver
seeking amendment of FCC regulations to permit the marketing of
GPS re-radiation kits.5 By Order released July 6, 2005, the
FCC's Office of Engineering and Technology (OET) denied the
Petition for Rulemaking and Request for Waiver.6 OET noted that
the Petition raised significant issues that needed further study
and therefore did not warrant consideration at the time.
Accordingly, Navtech is reminded that at this time GPS re-
radiating devices are not permitted to be sold to the general
public or to state or local governments.
John WA4WDL
From: "Jim Lux" jimlux@earthlink.net
Sent: Thursday, April 12, 2012 9:51 AM
To: time-nuts@febo.com
Subject: Re: [time-nuts] Best location for a GPS antenna...?
On 4/12/12 2:09 AM, Rob Kimberley wrote:
There are commercial "re-radiators" for GPS. I found these on Google:
http://www.gps-repeating.com/?gclid=COTV88D6rq8CFcwTfAodhSKvmQ
http://gpsnetworking.com/GPS-re-radiating-kits.asp
One of my old suppliers in the UK was marketing a range of these, but I
seem
to remember some problem in getting approval in the UK, and they had to
drop
them. Things may have changed as this was a few years ago.
I meant to type GPS repeaters not GPS receivers
John WA4WDL
From: "jmfranke" jmfranke@cox.net
Sent: Thursday, April 12, 2012 12:28 PM
To: time-nuts@febo.com
Subject: Re: [time-nuts] Best location for a GPS antenna...?
You must read:
http://transition.fcc.gov/eb/Orders/2005/DA-05-2998A1.html
Which discusses a FCC complaint with Navtech for selling GPS receivers.
An exert is presented below:
``Please note: re-radiation kits are currently only
available for purchase to International Customers and in
cases where the U.S. Government is the end user.''
Pursuant to Section 15.201(b) of the Rules, 47 C.F.R. §
15.201(b), intentional radiators must be authorized in accordance
with the FCC's certification procedures prior to the initiation
of marketing in the United States. However, GPS re-radiators
operate within the restricted frequency bands listed in Section
15.205(a) of the Rules, 47 C.F.R. § 15.205(a).4 Thus, GPS re-
radiators cannot comply with the FCC's technical standards and
therefore cannot be certificated or marketed for use by the
general public or non-federal government entities. Accordingly,
it appears that Navtech has violated Section 302(b) of the Act
and Sections 2.803 and 15.205(a) of the Rules by marketing in the
United States radio frequency devices that are not eligible to
receive a grant of certification.
You should be aware that the Commission has recently
addressed a Petition for Rulemaking and a Request for Waiver
seeking amendment of FCC regulations to permit the marketing of
GPS re-radiation kits.5 By Order released July 6, 2005, the
FCC's Office of Engineering and Technology (OET) denied the
Petition for Rulemaking and Request for Waiver.6 OET noted that
the Petition raised significant issues that needed further study
and therefore did not warrant consideration at the time.
Accordingly, Navtech is reminded that at this time GPS re-
radiating devices are not permitted to be sold to the general
public or to state or local governments.
John WA4WDL
From: "Jim Lux" jimlux@earthlink.net
Sent: Thursday, April 12, 2012 9:51 AM
To: time-nuts@febo.com
Subject: Re: [time-nuts] Best location for a GPS antenna...?
On 4/12/12 2:09 AM, Rob Kimberley wrote:
There are commercial "re-radiators" for GPS. I found these on Google:
http://www.gps-repeating.com/?gclid=COTV88D6rq8CFcwTfAodhSKvmQ
http://gpsnetworking.com/GPS-re-radiating-kits.asp
One of my old suppliers in the UK was marketing a range of these, but I
seem
to remember some problem in getting approval in the UK, and they had to
drop
them. Things may have changed as this was a few years ago.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Rerad-systems are getting controlled in Europe too.
http://www.etsi.org/deliver/etsi_en/302600_302699/302645/01.01.01_60/en_302645v010101p.pdf
Any reports on how quick this is going? Where I live, there are rules, but
not many are aware of them.
Björn
You must read:
http://transition.fcc.gov/eb/Orders/2005/DA-05-2998A1.html
Which discusses a FCC complaint with Navtech for selling GPS reradiating
kits.
An exert is presented below:
``Please note: re-radiation kits are currently only
available for purchase to International Customers and in
cases where the U.S. Government is the end user.''