GPS antenna selection
The real question is how much of a sky view you get.
Ideally you would like a clear view of the sky from
about NE clear around to NW (270 degrees).
That would opt for the balcony, as it faces north
and extends the slanted roof, so basically clear
view from NE to NW down to the horizon.
Take a look at (yes M$ Silverlight is needed...:( )
http://www.gnssplanningonline.com/
On "Settings" enter
1) your position (lat, lon, h) - or chose approx position from map.
2) change "cutoff" to 0 deg
3) change "Time span" to max (24h).
On "Satellite library"
1) Disable Glonass, Galileo, BeiDou and QZSS (only GPS remain selected)
Then view "Sky Plot". This is an illustration where the satellites can be
seen by your antenna, with no blocking from house, trees, mountains etc.
The blue outer circle represents the horizon, north up, etc. Circle center
is straigt up into the sky. The fainter grey circles shows 30 and 60 deg
elevation from the horizon.
- Moving the time-ruler (lower-right corner) will show the satellites
move over the selected position.
- While moving the time-ruler around, notice that there is a circle
from north horizon:ish and down (with a latitude of ca N45deg, where
there are never any satellites.
- Where this circle is depends on your latitude. (check N90deg -north
pole and N0deg (equator) to get a feel of how the priority
directions(azimuth)/elevations are.
You can model your specific obstruction environment at different possible
antenna sites with "Settings" -> "Obstructions".
What is an obstruction? it depends, but first order approx is that
anything that blocks your view will count.
What kind of GPS-receivers will you use? Old receivers (10+years) will
need better installations/locations. Modern high sensitivity receivers
will work decently within many houses. For long cable runs, older receiver
will be more picky, etc.
Good luck!
--
Björn
Unfortunately, an antenna, cable, or piece of electronics located indoors is just as susceptible to lightning surges as one that is outdoors.
Lightning-induced surges couple into these systems electromagnetically across a wide range (VLF to SHF) of frequencies. When you think about your home from an electromagnetic viewpoint, just imagine your structure with all non-conductive materials absent. For a typical wood or brick/stone house in North America, what you are left with is:
metal plumbing pipes and fixtures, with their geometry suspended in space
house wiring, CATV, Ethernet, and telephone cabling, and their service drops, all suspended in space
electrical & electronic circuits of every kind (WiFi note, computer, appliances), their power supplies and AC power cords, also suspended in space
metal furniture? That’s hanging out there, suspended in space, too.
any I-beam or other steel structural elements, some random aluminum flashing, door knobs, and other similar metal construction materials used in the home.
That is what an electromagnetic pulse sees as it approaches and sweeps over your home… all hovering over a lossy ground plane (earth) its varying dielectric constant.. Each one of those pieces of metal, hanging in space, is an unintentional antenna that experiences voltage differentials and current flows.
A GPS antenna and its coax line that is installed next to a window is no different from the same antenna/coax installed one meter outside the window… or 10 meters away outside the window. All three installations are effectively “outdoors” from an electromagnetic viewpoint, and all three need effective surge protection from lightning-, cloud-, and precipitation-induced voltage surges.
(N.B.: Snow can be particularly bad for voltage surges. I’ve seen thousands of volts per meter potential differences in moderate-to-heavy snowfall that produced very significant current flows on cables.)
Surge protection for your antenna, its attachment to your receiver(s), AC/DC power supply lines, and any other signal lines of significant length is cheap insurance.
My continuously-operating electronics lives in an enclosed rack cabinet — not too much worse than a proper Faraday cage. Every cable entering the cabinet has surge protection at the point of entry. The cabinet is bonded to earth ground by 2” copper flashing. In the past this system lived 22 years on a mountaintop home, 1200 ft above surrounding terrain. Lots of thunderstorms — zero damage/disruptions during that time… a sample size of one, admittedly, but during the first 18 months at that site I had two lightning-surge damaging events before I got serious about protection.
I have equipment at a coastal site with multiple 130-ft towers. That site had damage events every 2 years or so — even when cables to the “outside” were disconnected, and AC mains power was shut off at the main circuit breaker box. After implementing comprehensive surge protection, we have had zero damage over the last 12 years.
— Eric
On 2016 Aug 04, at 19:46 , Bob Camp kb8tq@n1k.org wrote:
Grounding the antenna is always a good idea.
A surge suppressor in the line could save you some
real cost if there is a lightning strike.
I did a quick search for SMA/BNC/TNC based surge
protectors and not much did come up, any suggestions
what to use there?
There are a lot of them on eBay. Many of them have N connectors on them.
I don’t know about Austria, but here in the US,
both are required.
Outside definitely, "inside" I'm not sure, but it
won't hurt to have additional protection for the
receiver(s).
It is a good bet that the antenna will be outside. I’d plan it that way.
Hi
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).
Bob
On Aug 5, 2016, at 10:37 AM, Eric Scace eric@scace.org wrote:
Unfortunately, an antenna, cable, or piece of electronics located indoors is just as susceptible to lightning surges as one that is outdoors.
Lightning-induced surges couple into these systems electromagnetically across a wide range (VLF to SHF) of frequencies. When you think about your home from an electromagnetic viewpoint, just imagine your structure with all non-conductive materials absent. For a typical wood or brick/stone house in North America, what you are left with is:
metal plumbing pipes and fixtures, with their geometry suspended in space
house wiring, CATV, Ethernet, and telephone cabling, and their service drops, all suspended in space
electrical & electronic circuits of every kind (WiFi note, computer, appliances), their power supplies and AC power cords, also suspended in space
metal furniture? That’s hanging out there, suspended in space, too.
any I-beam or other steel structural elements, some random aluminum flashing, door knobs, and other similar metal construction materials used in the home.
That is what an electromagnetic pulse sees as it approaches and sweeps over your home… all hovering over a lossy ground plane (earth) its varying dielectric constant.. Each one of those pieces of metal, hanging in space, is an unintentional antenna that experiences voltage differentials and current flows.
A GPS antenna and its coax line that is installed next to a window is no different from the same antenna/coax installed one meter outside the window… or 10 meters away outside the window. All three installations are effectively “outdoors” from an electromagnetic viewpoint, and all three need effective surge protection from lightning-, cloud-, and precipitation-induced voltage surges.
(N.B.: Snow can be particularly bad for voltage surges. I’ve seen thousands of volts per meter potential differences in moderate-to-heavy snowfall that produced very significant current flows on cables.)
Surge protection for your antenna, its attachment to your receiver(s), AC/DC power supply lines, and any other signal lines of significant length is cheap insurance.
My continuously-operating electronics lives in an enclosed rack cabinet — not too much worse than a proper Faraday cage. Every cable entering the cabinet has surge protection at the point of entry. The cabinet is bonded to earth ground by 2” copper flashing. In the past this system lived 22 years on a mountaintop home, 1200 ft above surrounding terrain. Lots of thunderstorms — zero damage/disruptions during that time… a sample size of one, admittedly, but during the first 18 months at that site I had two lightning-surge damaging events before I got serious about protection.
I have equipment at a coastal site with multiple 130-ft towers. That site had damage events every 2 years or so — even when cables to the “outside” were disconnected, and AC mains power was shut off at the main circuit breaker box. After implementing comprehensive surge protection, we have had zero damage over the last 12 years.
— Eric
On 2016 Aug 04, at 19:46 , Bob Camp kb8tq@n1k.org wrote:
Grounding the antenna is always a good idea.
A surge suppressor in the line could save you some
real cost if there is a lightning strike.
I did a quick search for SMA/BNC/TNC based surge
protectors and not much did come up, any suggestions
what to use there?
There are a lot of them on eBay. Many of them have N connectors on them.
I don’t know about Austria, but here in the US,
both are required.
Outside definitely, "inside" I'm not sure, but it
won't hurt to have additional protection for the
receiver(s).
It is a good bet that the antenna will be outside. I’d plan it that way.
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To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Herbert Poetzl wrote:
I'm currently investigating my options regarding
GPS antennae (of course for time related purposes)
and I'm really confused by the variety they come
in ... (my apologies in advance for the long post).
Yes, lots of variety! See: http://leapsecond.com/museum/gps-ant/
/tvb
Flying a plane with a plexiglas windshield through a snowstorm will give
you a lightning show on your windshield.
Willy
On 8/5/2016 10:37 AM, Eric Scace wrote:
Unfortunately, an antenna, cable, or piece of electronics located indoors is just as susceptible to lightning surges as one that is outdoors.
Lightning-induced surges couple into these systems electromagnetically across a wide range (VLF to SHF) of frequencies. When you think about your home from an electromagnetic viewpoint, just imagine your structure with all non-conductive materials absent. For a typical wood or brick/stone house in North America, what you are left with is:
metal plumbing pipes and fixtures, with their geometry suspended in space
house wiring, CATV, Ethernet, and telephone cabling, and their service drops, all suspended in space
electrical & electronic circuits of every kind (WiFi note, computer, appliances), their power supplies and AC power cords, also suspended in space
metal furniture? That’s hanging out there, suspended in space, too.
any I-beam or other steel structural elements, some random aluminum flashing, door knobs, and other similar metal construction materials used in the home.
That is what an electromagnetic pulse sees as it approaches and sweeps over your home… all hovering over a lossy ground plane (earth) its varying dielectric constant.. Each one of those pieces of metal, hanging in space, is an unintentional antenna that experiences voltage differentials and current flows.
A GPS antenna and its coax line that is installed next to a window is no different from the same antenna/coax installed one meter outside the window… or 10 meters away outside the window. All three installations are effectively “outdoors” from an electromagnetic viewpoint, and all three need effective surge protection from lightning-, cloud-, and precipitation-induced voltage surges.
(N.B.: Snow can be particularly bad for voltage surges. I’ve seen thousands of volts per meter potential differences in moderate-to-heavy snowfall that produced very significant current flows on cables.)
Surge protection for your antenna, its attachment to your receiver(s), AC/DC power supply lines, and any other signal lines of significant length is cheap insurance.
My continuously-operating electronics lives in an enclosed rack cabinet — not too much worse than a proper Faraday cage. Every cable entering the cabinet has surge protection at the point of entry. The cabinet is bonded to earth ground by 2” copper flashing. In the past this system lived 22 years on a mountaintop home, 1200 ft above surrounding terrain. Lots of thunderstorms — zero damage/disruptions during that time… a sample size of one, admittedly, but during the first 18 months at that site I had two lightning-surge damaging events before I got serious about protection.
I have equipment at a coastal site with multiple 130-ft towers. That site had damage events every 2 years or so — even when cables to the “outside” were disconnected, and AC mains power was shut off at the main circuit breaker box. After implementing comprehensive surge protection, we have had zero damage over the last 12 years.
— Eric
On 2016 Aug 04, at 19:46 , Bob Camp kb8tq@n1k.org wrote:
Grounding the antenna is always a good idea.
A surge suppressor in the line could save you some
real cost if there is a lightning strike.
I did a quick search for SMA/BNC/TNC based surge
protectors and not much did come up, any suggestions
what to use there?
There are a lot of them on eBay. Many of them have N connectors on them.
I don’t know about Austria, but here in the US,
both are required.
Outside definitely, "inside" I'm not sure, but it
won't hurt to have additional protection for the
receiver(s).
It is a good bet that the antenna will be outside. I’d plan it that way.
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 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
Hi Eric,
On Fri, 5 Aug 2016 10:37:28 -0400
Eric Scace eric@scace.org wrote:
A GPS antenna and its coax line that is installed next to a window is no
different from the same antenna/coax installed one meter outside the window…
or 10 meters away outside the window. All three installations are
effectively “outdoors” from an electromagnetic viewpoint, and all three need
effective surge protection from lightning-, cloud-, and precipitation-
induced voltage surges.
Please please please do NOT spread dangerous information like this!
While it is true, that an indoor antenna is suceptible to surges like
an outdoor antenna, it is not true that an outdoor antenna is equivalent
to an indoor antenna when it comes to lightning protection.
Because an outdoor antenna can be directly hit by a lightning.
To protect the house and its inhabitants from the lightning strike,
an external antenna needs to be either lower than any lightning rod
and within its 45m ball or needs its own conductor and grounding
to discharge any lightning energy and thus preventing it from following
the antenna cable into the house.
Please be aware that the grounding of the antenna is not to protect
the equipment from surges, but to prevent conduction of the lightning
into the house that could cause electrocution and fires.
Attila Kinali
--
Malek's Law:
Any simple idea will be worded in the most complicated way.
Yo Attila!
On Fri, 5 Aug 2016 22:51:06 +0200
Attila Kinali attila@kinali.ch wrote:
While it is true, that an indoor antenna is suceptible to surges like
an outdoor antenna, it is not true that an outdoor antenna is
equivalent to an indoor antenna when it comes to lightning
protection.
I agree there are differences. But not as mmuch as you think.
Because an outdoor antenna can be directly hit by a lightning.
And so can an indoor antetnna. I live it lightning country, and it is
common for a lightning bolt to travel right through an asphalt roof to
hit metal pipes and/or wire inside a house.
I have seen this many times, it has happened to my next door neighbor and
to my son. If you are lucky your homeowners insurance will cover a lot of
the damage.
Please be aware that the grounding of the antenna is not to protect
the equipment from surges, but to prevent conduction of the lightning
into the house that could cause electrocution and fires.
A direct hit on an antenna will laugh at your surge protector. Nothing
at all can protect your electrical system from a direct hit.
I have seen 440V main switchboards exploded from lightning hits. The
mess is incredible. The switchboard case looks like a large bomb went off
inside and the cover leaves a dent on the far wall.
The surge protector on your antenna coax will try to limit the static
voltage on the center conductor to about 1,500V. Now you have turned
your antenna into a passable lightning rod.
To protect the house and its inhabitants from the lightning strike,
an external antenna needs to be either lower than any lightning rod
and within its 45m ball or needs its own conductor and grounding
to discharge any lightning energy and thus preventing it from following
the antenna cable into the house.
If you have any doubt about lightning you need to get some lightning rods
on your roof. A usually passable solution is to run #8 wire from your
offical building ground directly up to an antenna mast or two on your
roof. Best if it can be done with zero splices.
The point of the lightning rod is not to dissipate a lightning strike,
nothing can do that. Instead it bleeds away static before it becomes
a lightning strike.
In the midwest in the winter the humidity in a house can get well below
5% and 1,500V of statis is quite common. So indoor surge protectors
can also be useful.
RGDS
GARY
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
gem@rellim.com Tel:+1 541 382 8588
lightening protection:
http://www.ul.com/wp-content/uploads/2014/04/LightningProtectionAG.pdf
73
KJ6UHN
Alex
On 8/5/2016 1:51 PM, Attila Kinali wrote:
Hi Eric,
On Fri, 5 Aug 2016 10:37:28 -0400
Eric Scace eric@scace.org wrote:
A GPS antenna and its coax line that is installed next to a window is no
different from the same antenna/coax installed one meter outside the window…
or 10 meters away outside the window. All three installations are
effectively “outdoors” from an electromagnetic viewpoint, and all three need
effective surge protection from lightning-, cloud-, and precipitation-
induced voltage surges.
Please please please do NOT spread dangerous information like this!
While it is true, that an indoor antenna is suceptible to surges like
an outdoor antenna, it is not true that an outdoor antenna is equivalent
to an indoor antenna when it comes to lightning protection.
Because an outdoor antenna can be directly hit by a lightning.
To protect the house and its inhabitants from the lightning strike,
an external antenna needs to be either lower than any lightning rod
and within its 45m ball or needs its own conductor and grounding
to discharge any lightning energy and thus preventing it from following
the antenna cable into the house.
Please be aware that the grounding of the antenna is not to protect
the equipment from surges, but to prevent conduction of the lightning
into the house that could cause electrocution and fires.
Attila Kinali
You guys, well some of you are mixing to things
-
the building code requirement to ground an antenna is for the protection
of the building. The building code don't care if you electronics is fried
or not. The wire and ground rod keep the antenna mast at earth potential. -
Those surge protectors and grounding your electronics to a common point
an al other advice then grounding the most to a rod by the nearest route
down the side of the house. These are different things
So, outdoor antenna are different from indoor antenna in that if you indoor
antenna is struck the house is already pretty much toasted. You still
might want a surge protector to protect the receiver.
The question is if you need to buy a $40 surge protector for your $8
Motorola Encore receiver? But no question if you need a group wire in the
mast, even for that $8 gps receiver because that wire protects the house
Part of the equation is where you live. In many years of living in Redondo
Beach, CA I never hear of anyone or anything being =damaged by lightening.
We don't even get lighting here but twice a year if that. On the other
hand I had god protection on my sailboat as that 60 for aluminum mast might
be the highest thing around on the ocean for miles. That mast has a very
solid connection straight to saltwater. You have to evaluate the risk and
consequence. You get different answer in Orlando Florida then I get here.