SI
skipp Isaham
Sun, Jul 10, 2022 11:19 PM
Hello to the Group,
I'd like to get some opinions and war stories regarding GPS reliability at
high RF level and elevation locations.
Background: Three different hill-top GPS receivers, all different types, using
different antennas mounted on an outside fixiture, plain view of the open sky,
all stopped working.
Test antennas were brought in and placed on a fixture well away from the
original antennas, the recevers went back in to capture and lock.
From what I understand, the original antennas are what I would call straight
preamp with no pre-selection / filtering.
The ordered and now inbound replacements are said to contain a SAW filter
system. It is the intent of the client to just place these "improved antennas" in
to service and get on with life.
I would suspect a GPS antenna (and receiver) could be subject to RF overload
or blocking, however, we're assuming nothing major has changed at the site, nor
any nearby location. One might think there are more GPS receivers being pushed
out of reliable operation by the world around them, I'm just not hearing those stories
from a lot of people using them (GPS receivers).
Any new install GPS receiver antenna ordered will/should contain some pre-selection
to potentially avoid a problem, even some years down the road? Seems like that's
where things are going... no more off the shelf, wide band, (hot) preamplified GPS antennas
in busy locations?
Thank you in advance for any related comments and/or opions ...
cheers,
skipp
skipp025 at jah who dot calm
Hello to the Group,
I'd like to get some opinions and war stories regarding GPS reliability at
high RF level and elevation locations.
Background: Three different hill-top GPS receivers, all different types, using
different antennas mounted on an outside fixiture, plain view of the open sky,
all stopped working.
Test antennas were brought in and placed on a fixture well away from the
original antennas, the recevers went back in to capture and lock.
From what I understand, the original antennas are what I would call straight
preamp with no pre-selection / filtering.
The ordered and now inbound replacements are said to contain a SAW filter
system. It is the intent of the client to just place these "improved antennas" in
to service and get on with life.
I would suspect a GPS antenna (and receiver) could be subject to RF overload
or blocking, however, we're assuming nothing major has changed at the site, nor
any nearby location. One might think there are more GPS receivers being pushed
out of reliable operation by the world around them, I'm just not hearing those stories
from a lot of people using them (GPS receivers).
Any new install GPS receiver antenna ordered will/should contain some pre-selection
to potentially avoid a problem, even some years down the road? Seems like that's
where things are going... no more off the shelf, wide band, (hot) preamplified GPS antennas
in busy locations?
Thank you in advance for any related comments and/or opions ...
cheers,
skipp
skipp025 at jah who dot calm
TH
Tom Holmes
Mon, Jul 11, 2022 1:03 PM
Hey Skipp!
A couple of thoughts…
Why do you need an amplified antenna in a high and open spot, unless the coax run is longer than about 40’?
Is it practical to move one of the existing antennas away from the current location as a test to see if it’s a failure vs overload? Assuming it is physically practical to do so, of course.
From Tom Holmes, N8ZM
On Jul 11, 2022, at 8:49 AM, skipp Isaham via time-nuts time-nuts@lists.febo.com wrote:
Hello to the Group,
I'd like to get some opinions and war stories regarding GPS reliability at
high RF level and elevation locations.
Background: Three different hill-top GPS receivers, all different types, using
different antennas mounted on an outside fixiture, plain view of the open sky,
all stopped working.
Test antennas were brought in and placed on a fixture well away from the
original antennas, the recevers went back in to capture and lock.
From what I understand, the original antennas are what I would call straight
preamp with no pre-selection / filtering.
The ordered and now inbound replacements are said to contain a SAW filter
system. It is the intent of the client to just place these "improved antennas" in
to service and get on with life.
I would suspect a GPS antenna (and receiver) could be subject to RF overload
or blocking, however, we're assuming nothing major has changed at the site, nor
any nearby location. One might think there are more GPS receivers being pushed
out of reliable operation by the world around them, I'm just not hearing those stories
from a lot of people using them (GPS receivers).
Any new install GPS receiver antenna ordered will/should contain some pre-selection
to potentially avoid a problem, even some years down the road? Seems like that's
where things are going... no more off the shelf, wide band, (hot) preamplified GPS antennas
in busy locations?
Thank you in advance for any related comments and/or opions ...
cheers,
skipp
skipp025 at jah who dot calm
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
Hey Skipp!
A couple of thoughts…
Why do you need an amplified antenna in a high and open spot, unless the coax run is longer than about 40’?
Is it practical to move one of the existing antennas away from the current location as a test to see if it’s a failure vs overload? Assuming it is physically practical to do so, of course.
From Tom Holmes, N8ZM
> On Jul 11, 2022, at 8:49 AM, skipp Isaham via time-nuts <time-nuts@lists.febo.com> wrote:
>
> Hello to the Group,
>
> I'd like to get some opinions and war stories regarding GPS reliability at
> high RF level and elevation locations.
>
> Background: Three different hill-top GPS receivers, all different types, using
> different antennas mounted on an outside fixiture, plain view of the open sky,
> all stopped working.
>
> Test antennas were brought in and placed on a fixture well away from the
> original antennas, the recevers went back in to capture and lock.
>
> From what I understand, the original antennas are what I would call straight
> preamp with no pre-selection / filtering.
>
> The ordered and now inbound replacements are said to contain a SAW filter
> system. It is the intent of the client to just place these "improved antennas" in
> to service and get on with life.
>
> I would suspect a GPS antenna (and receiver) could be subject to RF overload
> or blocking, however, we're assuming nothing major has changed at the site, nor
> any nearby location. One might think there are more GPS receivers being pushed
> out of reliable operation by the world around them, I'm just not hearing those stories
> from a lot of people using them (GPS receivers).
>
> Any new install GPS receiver antenna ordered will/should contain some pre-selection
> to potentially avoid a problem, even some years down the road? Seems like that's
> where things are going... no more off the shelf, wide band, (hot) preamplified GPS antennas
> in busy locations?
>
> Thank you in advance for any related comments and/or opions ...
>
> cheers,
>
> skipp
>
> skipp025 at jah who dot calm
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
CC
Chris Caudle
Mon, Jul 11, 2022 1:04 PM
On Sun, July 10, 2022 6:19 pm, skipp Isaham via time-nuts wrote:
Background: Three different hill-top GPS receivers, all different types,
using
different antennas mounted on an outside fixiture, plain view of the open
sky,
all stopped working.
Test antennas were brought in and placed on a fixture well away from the
original antennas, the recevers went back in to capture and lock.
Did you test the original antennas in a different environment to see if
they still work at all? Perhaps the amplifier in the antenna housing
failed on the original three antenna.
I would suspect a GPS antenna (and receiver) could be subject to RF
overload
or blocking, however, we're assuming nothing major has changed at the
site, nor
any nearby location.
If you are implying that you think the antenna are still working, but
cannot handle the RF environment at that location which is what caused the
GPS failure, I would be dubious. You said hilltop location, so my first
suspicion would be damage to the antenna induced by a nearby lightning
strike.
One might think there are more GPS receivers being
pushed
out of reliable operation by the world around them, I'm just not hearing
those stories
from a lot of people using them (GPS receivers).
Spectrum allocation is controlled reasonably tightly. If there were
widespread problems due to increased EMI then you would know relatively
quickly from the number of people using GPS every day.
--
Chris Caudle
On Sun, July 10, 2022 6:19 pm, skipp Isaham via time-nuts wrote:
> Background: Three different hill-top GPS receivers, all different types,
> using
> different antennas mounted on an outside fixiture, plain view of the open
> sky,
> all stopped working.
>
> Test antennas were brought in and placed on a fixture well away from the
> original antennas, the recevers went back in to capture and lock.
Did you test the original antennas in a different environment to see if
they still work at all? Perhaps the amplifier in the antenna housing
failed on the original three antenna.
> I would suspect a GPS antenna (and receiver) could be subject to RF
> overload
> or blocking, however, we're assuming nothing major has changed at the
> site, nor
> any nearby location.
If you are implying that you think the antenna are still working, but
cannot handle the RF environment at that location which is what caused the
GPS failure, I would be dubious. You said hilltop location, so my first
suspicion would be damage to the antenna induced by a nearby lightning
strike.
> One might think there are more GPS receivers being
> pushed
> out of reliable operation by the world around them, I'm just not hearing
> those stories
> from a lot of people using them (GPS receivers).
Spectrum allocation is controlled reasonably tightly. If there were
widespread problems due to increased EMI then you would know relatively
quickly from the number of people using GPS every day.
--
Chris Caudle
JA
John Ackermann
Mon, Jul 11, 2022 1:16 PM
Hi Skipp -- there is a lot of info about interference mitigation in the u-blox integration manual for the ZED--F9T (available under the docs at https://www.u-blox.com/en/product/zed-f9t-module). It might give you some clues, and I think might also point to another u-blox app note on the topic.
Most of the antennas I've seen that have an LNA also include a SAW filter. I also once found on either Amazon or eBay so e new-product, relatively inexpensive, high pass filters with cutoff around 1 GHz. Those would help knock down broadcast, trunking, etc. stuff. (But of course nothing will help with on-frequency crud coming from outside the GPS system.)
John
On Jul 11, 2022, 8:49 AM, at 8:49 AM, skipp Isaham via time-nuts time-nuts@lists.febo.com wrote:
Hello to the Group,
I'd like to get some opinions and war stories regarding GPS reliability
at
high RF level and elevation locations.
Background: Three different hill-top GPS receivers, all different
types, using
different antennas mounted on an outside fixiture, plain view of the
open sky,
all stopped working.
Test antennas were brought in and placed on a fixture well away from
the
original antennas, the recevers went back in to capture and lock.
From what I understand, the original antennas are what I would call
straight
preamp with no pre-selection / filtering.
The ordered and now inbound replacements are said to contain a SAW
filter
system. It is the intent of the client to just place these "improved
antennas" in
to service and get on with life.
I would suspect a GPS antenna (and receiver) could be subject to RF
overload
or blocking, however, we're assuming nothing major has changed at the
site, nor
any nearby location. One might think there are more GPS receivers
being pushed
out of reliable operation by the world around them, I'm just not
hearing those stories
from a lot of people using them (GPS receivers).
Any new install GPS receiver antenna ordered will/should contain some
pre-selection
to potentially avoid a problem, even some years down the road? Seems
like that's
where things are going... no more off the shelf, wide band, (hot)
preamplified GPS antennas
in busy locations?
Thank you in advance for any related comments and/or opions ...
cheers,
skipp
skipp025 at jah who dot calm
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
Hi Skipp -- there is a lot of info about interference mitigation in the u-blox integration manual for the ZED--F9T (available under the docs at https://www.u-blox.com/en/product/zed-f9t-module). It might give you some clues, and I think might also point to another u-blox app note on the topic.
Most of the antennas I've seen that have an LNA also include a SAW filter. I also once found on either Amazon or eBay so e new-product, relatively inexpensive, high pass filters with cutoff around 1 GHz. Those would help knock down broadcast, trunking, etc. stuff. (But of course nothing will help with on-frequency crud coming from outside the GPS system.)
John
On Jul 11, 2022, 8:49 AM, at 8:49 AM, skipp Isaham via time-nuts <time-nuts@lists.febo.com> wrote:
>Hello to the Group,
>
>I'd like to get some opinions and war stories regarding GPS reliability
>at
>high RF level and elevation locations.
>
>Background: Three different hill-top GPS receivers, all different
>types, using
>different antennas mounted on an outside fixiture, plain view of the
>open sky,
>all stopped working.
>
>Test antennas were brought in and placed on a fixture well away from
>the
>original antennas, the recevers went back in to capture and lock.
>
>From what I understand, the original antennas are what I would call
>straight
>preamp with no pre-selection / filtering.
>
>The ordered and now inbound replacements are said to contain a SAW
>filter
>system. It is the intent of the client to just place these "improved
>antennas" in
>to service and get on with life.
>
>I would suspect a GPS antenna (and receiver) could be subject to RF
>overload
>or blocking, however, we're assuming nothing major has changed at the
>site, nor
>any nearby location. One might think there are more GPS receivers
>being pushed
>out of reliable operation by the world around them, I'm just not
>hearing those stories
>from a lot of people using them (GPS receivers).
>
>Any new install GPS receiver antenna ordered will/should contain some
>pre-selection
>to potentially avoid a problem, even some years down the road? Seems
>like that's
>where things are going... no more off the shelf, wide band, (hot)
>preamplified GPS antennas
>in busy locations?
>
>Thank you in advance for any related comments and/or opions ...
>
>cheers,
>
>skipp
>
>skipp025 at jah who dot calm
>_______________________________________________
>time-nuts mailing list -- time-nuts@lists.febo.com
>To unsubscribe send an email to time-nuts-leave@lists.febo.com
LJ
Lux, Jim
Mon, Jul 11, 2022 1:25 PM
On 7/10/22 4:19 PM, skipp Isaham via time-nuts wrote:
Hello to the Group,
I'd like to get some opinions and war stories regarding GPS reliability at
high RF level and elevation locations.
Background: Three different hill-top GPS receivers, all different types, using
different antennas mounted on an outside fixiture, plain view of the open sky,
all stopped working.
Test antennas were brought in and placed on a fixture well away from the
original antennas, the recevers went back in to capture and lock.
From what I understand, the original antennas are what I would call straight
preamp with no pre-selection / filtering.
The ordered and now inbound replacements are said to contain a SAW filter
system. It is the intent of the client to just place these "improved antennas" in
to service and get on with life.
I would suspect a GPS antenna (and receiver) could be subject to RF overload
or blocking, however, we're assuming nothing major has changed at the site, nor
any nearby location. One might think there are more GPS receivers being pushed
out of reliable operation by the world around them, I'm just not hearing those stories
from a lot of people using them (GPS receivers).
yes, this happens. We used to have a Pendulum timing receiver with a
typical "small white cone" type amplified antenna - if someone was on
the roof with a cellphone, it lost lock, presumably from the (way out of
band) emissions.
As to where the interfering source is - it doesn't take much, and it
could be some distance away. After all, this was the big deal with
LightSquared - it was moderately high powered terrestrial broadcast
transmitters in the satellite downlink band next to GNSS.
Any new install GPS receiver antenna ordered will/should contain some pre-selection
to potentially avoid a problem, even some years down the road? Seems like that's
where things are going... no more off the shelf, wide band, (hot) preamplified GPS antennas
in busy locations?
Thank you in advance for any related comments and/or opions ...
cheers,
skipp
skipp025 at jah who dot calm
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
On 7/10/22 4:19 PM, skipp Isaham via time-nuts wrote:
> Hello to the Group,
>
> I'd like to get some opinions and war stories regarding GPS reliability at
> high RF level and elevation locations.
>
> Background: Three different hill-top GPS receivers, all different types, using
> different antennas mounted on an outside fixiture, plain view of the open sky,
> all stopped working.
>
> Test antennas were brought in and placed on a fixture well away from the
> original antennas, the recevers went back in to capture and lock.
>
> From what I understand, the original antennas are what I would call straight
> preamp with no pre-selection / filtering.
>
> The ordered and now inbound replacements are said to contain a SAW filter
> system. It is the intent of the client to just place these "improved antennas" in
> to service and get on with life.
>
> I would suspect a GPS antenna (and receiver) could be subject to RF overload
> or blocking, however, we're assuming nothing major has changed at the site, nor
> any nearby location. One might think there are more GPS receivers being pushed
> out of reliable operation by the world around them, I'm just not hearing those stories
> from a lot of people using them (GPS receivers).
yes, this happens. We used to have a Pendulum timing receiver with a
typical "small white cone" type amplified antenna - if someone was on
the roof with a cellphone, it lost lock, presumably from the (way out of
band) emissions.
As to where the interfering source is - it doesn't take much, and it
could be some distance away. After all, this was the big deal with
LightSquared - it was moderately high powered terrestrial broadcast
transmitters in the satellite downlink band next to GNSS.
>
> Any new install GPS receiver antenna ordered will/should contain some pre-selection
> to potentially avoid a problem, even some years down the road? Seems like that's
> where things are going... no more off the shelf, wide band, (hot) preamplified GPS antennas
> in busy locations?
>
> Thank you in advance for any related comments and/or opions ...
>
> cheers,
>
> skipp
>
> skipp025 at jah who dot calm
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>
PS
paul swed
Mon, Jul 11, 2022 1:27 PM
Skipp
I am aware at least in the US that there is the possibility of 5G
interference along with newer possible bands that 5G can use. I have read
several articles in a publication called GNSS.
Thats why I am using wwvb at 60 KHz. Humor intended.
Regards
Paul
WB8TSL
On Mon, Jul 11, 2022 at 8:49 AM skipp Isaham via time-nuts <
time-nuts@lists.febo.com> wrote:
Hello to the Group,
I'd like to get some opinions and war stories regarding GPS reliability at
high RF level and elevation locations.
Background: Three different hill-top GPS receivers, all different types,
using
different antennas mounted on an outside fixiture, plain view of the open
sky,
all stopped working.
Test antennas were brought in and placed on a fixture well away from the
original antennas, the recevers went back in to capture and lock.
From what I understand, the original antennas are what I would call
straight
preamp with no pre-selection / filtering.
The ordered and now inbound replacements are said to contain a SAW filter
system. It is the intent of the client to just place these "improved
antennas" in
to service and get on with life.
I would suspect a GPS antenna (and receiver) could be subject to RF
overload
or blocking, however, we're assuming nothing major has changed at the
site, nor
any nearby location. One might think there are more GPS receivers being
pushed
out of reliable operation by the world around them, I'm just not hearing
those stories
from a lot of people using them (GPS receivers).
Any new install GPS receiver antenna ordered will/should contain some
pre-selection
to potentially avoid a problem, even some years down the road? Seems like
that's
where things are going... no more off the shelf, wide band, (hot)
preamplified GPS antennas
in busy locations?
Thank you in advance for any related comments and/or opions ...
cheers,
skipp
skipp025 at jah who dot calm
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
Skipp
I am aware at least in the US that there is the possibility of 5G
interference along with newer possible bands that 5G can use. I have read
several articles in a publication called GNSS.
Thats why I am using wwvb at 60 KHz. Humor intended.
Regards
Paul
WB8TSL
On Mon, Jul 11, 2022 at 8:49 AM skipp Isaham via time-nuts <
time-nuts@lists.febo.com> wrote:
> Hello to the Group,
>
> I'd like to get some opinions and war stories regarding GPS reliability at
> high RF level and elevation locations.
>
> Background: Three different hill-top GPS receivers, all different types,
> using
> different antennas mounted on an outside fixiture, plain view of the open
> sky,
> all stopped working.
>
> Test antennas were brought in and placed on a fixture well away from the
> original antennas, the recevers went back in to capture and lock.
>
> From what I understand, the original antennas are what I would call
> straight
> preamp with no pre-selection / filtering.
>
> The ordered and now inbound replacements are said to contain a SAW filter
> system. It is the intent of the client to just place these "improved
> antennas" in
> to service and get on with life.
>
> I would suspect a GPS antenna (and receiver) could be subject to RF
> overload
> or blocking, however, we're assuming nothing major has changed at the
> site, nor
> any nearby location. One might think there are more GPS receivers being
> pushed
> out of reliable operation by the world around them, I'm just not hearing
> those stories
> from a lot of people using them (GPS receivers).
>
> Any new install GPS receiver antenna ordered will/should contain some
> pre-selection
> to potentially avoid a problem, even some years down the road? Seems like
> that's
> where things are going... no more off the shelf, wide band, (hot)
> preamplified GPS antennas
> in busy locations?
>
> Thank you in advance for any related comments and/or opions ...
>
> cheers,
>
> skipp
>
> skipp025 at jah who dot calm
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>
AT
Andy Talbot
Mon, Jul 11, 2022 1:43 PM
I have had one, and possibly two, low cost active antennas go unstable and
start oscillating. These are the magnetic car mount type with a ceramic
patch antenna. The ceramic patch has quite a high Q and determines the
frequency the unstable RF front end takes off at - which is obviously at
1575.42 plus / minus a few tens of kHz. Needless to say, all local GPS
receivers are jammed
I also heard a case of a GPS antenna going unstable, oscillating and taking
out most of the boats in a marina. The Radio Communications Agency (as
our enforcement body was then, before it became Ofcom) had to be called
out to identify the problem.
Andy
www.g4jnt.com
On Mon, 11 Jul 2022 at 14:37, Lux, Jim via time-nuts <
time-nuts@lists.febo.com> wrote:
On 7/10/22 4:19 PM, skipp Isaham via time-nuts wrote:
Hello to the Group,
I'd like to get some opinions and war stories regarding GPS reliability
high RF level and elevation locations.
Background: Three different hill-top GPS receivers, all different
different antennas mounted on an outside fixiture, plain view of the
all stopped working.
Test antennas were brought in and placed on a fixture well away from the
original antennas, the recevers went back in to capture and lock.
From what I understand, the original antennas are what I would call
preamp with no pre-selection / filtering.
The ordered and now inbound replacements are said to contain a SAW filter
system. It is the intent of the client to just place these "improved
to service and get on with life.
I would suspect a GPS antenna (and receiver) could be subject to RF
or blocking, however, we're assuming nothing major has changed at the
any nearby location. One might think there are more GPS receivers being
out of reliable operation by the world around them, I'm just not hearing
from a lot of people using them (GPS receivers).
yes, this happens. We used to have a Pendulum timing receiver with a
typical "small white cone" type amplified antenna - if someone was on
the roof with a cellphone, it lost lock, presumably from the (way out of
band) emissions.
As to where the interfering source is - it doesn't take much, and it
could be some distance away. After all, this was the big deal with
LightSquared - it was moderately high powered terrestrial broadcast
transmitters in the satellite downlink band next to GNSS.
Any new install GPS receiver antenna ordered will/should contain some
to potentially avoid a problem, even some years down the road? Seems
where things are going... no more off the shelf, wide band, (hot)
preamplified GPS antennas
I have had one, and possibly two, low cost active antennas go unstable and
start oscillating. These are the magnetic car mount type with a ceramic
patch antenna. The ceramic patch has quite a high Q and determines the
frequency the unstable RF front end takes off at - which is obviously at
1575.42 plus / minus a few tens of kHz. Needless to say, all local GPS
receivers are jammed
I also heard a case of a GPS antenna going unstable, oscillating and taking
out most of the boats in a marina. The Radio Communications Agency (as
our enforcement body was then, before it became Ofcom) had to be called
out to identify the problem.
Andy
www.g4jnt.com
On Mon, 11 Jul 2022 at 14:37, Lux, Jim via time-nuts <
time-nuts@lists.febo.com> wrote:
> On 7/10/22 4:19 PM, skipp Isaham via time-nuts wrote:
> > Hello to the Group,
> >
> > I'd like to get some opinions and war stories regarding GPS reliability
> at
> > high RF level and elevation locations.
> >
> > Background: Three different hill-top GPS receivers, all different
> types, using
> > different antennas mounted on an outside fixiture, plain view of the
> open sky,
> > all stopped working.
> >
> > Test antennas were brought in and placed on a fixture well away from the
> > original antennas, the recevers went back in to capture and lock.
> >
> > From what I understand, the original antennas are what I would call
> straight
> > preamp with no pre-selection / filtering.
> >
> > The ordered and now inbound replacements are said to contain a SAW filter
> > system. It is the intent of the client to just place these "improved
> antennas" in
> > to service and get on with life.
> >
> > I would suspect a GPS antenna (and receiver) could be subject to RF
> overload
> > or blocking, however, we're assuming nothing major has changed at the
> site, nor
> > any nearby location. One might think there are more GPS receivers being
> pushed
> > out of reliable operation by the world around them, I'm just not hearing
> those stories
> > from a lot of people using them (GPS receivers).
>
> yes, this happens. We used to have a Pendulum timing receiver with a
> typical "small white cone" type amplified antenna - if someone was on
> the roof with a cellphone, it lost lock, presumably from the (way out of
> band) emissions.
>
>
> As to where the interfering source is - it doesn't take much, and it
> could be some distance away. After all, this was the big deal with
> LightSquared - it was moderately high powered terrestrial broadcast
> transmitters in the satellite downlink band next to GNSS.
>
>
> >
> > Any new install GPS receiver antenna ordered will/should contain some
> pre-selection
> > to potentially avoid a problem, even some years down the road? Seems
> like that's
> > where things are going... no more off the shelf, wide band, (hot)
> preamplified GPS antennas
> > in busy locations?
> >
> > Thank you in advance for any related comments and/or opions ...
> >
> > cheers,
> >
> > skipp
> >
> > skipp025 at jah who dot calm
> > _______________________________________________
> > time-nuts mailing list -- time-nuts@lists.febo.com
> > To unsubscribe send an email to time-nuts-leave@lists.febo.com
> >
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
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Andy Talbot
Mon, Jul 11, 2022 1:45 PM
There is a 3G/4G Supplementary Downlink allocation at 1492MHz in some
countries. Close enough to cause problems.
Andy
www.g4jnt.com
On Mon, 11 Jul 2022 at 14:40, paul swed via time-nuts <
time-nuts@lists.febo.com> wrote:
Skipp
I am aware at least in the US that there is the possibility of 5G
interference along with newer possible bands that 5G can use. I have read
several articles in a publication called GNSS.
Thats why I am using wwvb at 60 KHz. Humor intended.
Regards
Paul
WB8TSL
On Mon, Jul 11, 2022 at 8:49 AM skipp Isaham via time-nuts <
time-nuts@lists.febo.com> wrote:
Hello to the Group,
I'd like to get some opinions and war stories regarding GPS reliability
high RF level and elevation locations.
Background: Three different hill-top GPS receivers, all different types,
using
different antennas mounted on an outside fixiture, plain view of the open
sky,
all stopped working.
Test antennas were brought in and placed on a fixture well away from the
original antennas, the recevers went back in to capture and lock.
From what I understand, the original antennas are what I would call
straight
preamp with no pre-selection / filtering.
The ordered and now inbound replacements are said to contain a SAW filter
system. It is the intent of the client to just place these "improved
antennas" in
to service and get on with life.
I would suspect a GPS antenna (and receiver) could be subject to RF
overload
or blocking, however, we're assuming nothing major has changed at the
site, nor
any nearby location. One might think there are more GPS receivers being
pushed
out of reliable operation by the world around them, I'm just not hearing
those stories
from a lot of people using them (GPS receivers).
Any new install GPS receiver antenna ordered will/should contain some
pre-selection
to potentially avoid a problem, even some years down the road? Seems like
that's
where things are going... no more off the shelf, wide band, (hot)
preamplified GPS antennas
in busy locations?
Thank you in advance for any related comments and/or opions ...
cheers,
skipp
skipp025 at jah who dot calm
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
There is a 3G/4G Supplementary Downlink allocation at 1492MHz in some
countries. Close enough to cause problems.
Andy
www.g4jnt.com
On Mon, 11 Jul 2022 at 14:40, paul swed via time-nuts <
time-nuts@lists.febo.com> wrote:
> Skipp
> I am aware at least in the US that there is the possibility of 5G
> interference along with newer possible bands that 5G can use. I have read
> several articles in a publication called GNSS.
>
>
> Thats why I am using wwvb at 60 KHz. Humor intended.
> Regards
> Paul
> WB8TSL
>
> On Mon, Jul 11, 2022 at 8:49 AM skipp Isaham via time-nuts <
> time-nuts@lists.febo.com> wrote:
>
> > Hello to the Group,
> >
> > I'd like to get some opinions and war stories regarding GPS reliability
> at
> > high RF level and elevation locations.
> >
> > Background: Three different hill-top GPS receivers, all different types,
> > using
> > different antennas mounted on an outside fixiture, plain view of the open
> > sky,
> > all stopped working.
> >
> > Test antennas were brought in and placed on a fixture well away from the
> > original antennas, the recevers went back in to capture and lock.
> >
> > From what I understand, the original antennas are what I would call
> > straight
> > preamp with no pre-selection / filtering.
> >
> > The ordered and now inbound replacements are said to contain a SAW filter
> > system. It is the intent of the client to just place these "improved
> > antennas" in
> > to service and get on with life.
> >
> > I would suspect a GPS antenna (and receiver) could be subject to RF
> > overload
> > or blocking, however, we're assuming nothing major has changed at the
> > site, nor
> > any nearby location. One might think there are more GPS receivers being
> > pushed
> > out of reliable operation by the world around them, I'm just not hearing
> > those stories
> > from a lot of people using them (GPS receivers).
> >
> > Any new install GPS receiver antenna ordered will/should contain some
> > pre-selection
> > to potentially avoid a problem, even some years down the road? Seems like
> > that's
> > where things are going... no more off the shelf, wide band, (hot)
> > preamplified GPS antennas
> > in busy locations?
> >
> > Thank you in advance for any related comments and/or opions ...
> >
> > cheers,
> >
> > skipp
> >
> > skipp025 at jah who dot calm
> > _______________________________________________
> > time-nuts mailing list -- time-nuts@lists.febo.com
> > To unsubscribe send an email to time-nuts-leave@lists.febo.com
> >
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>
CA
Carsten Andrich
Mon, Jul 11, 2022 2:09 PM
The u-blox SAW filtering is great. We've carried out various RF
measurements with +40 dBm EIRP at 2.53 and 3.75 GHz with some u-blox
ANN-MB within <2m of the Tx antennas. While we haven't conducted
in-depth comparisons with a superior ground-truth, my current conclusion
is that the u-blox RTK performance is not (noticeably) affected by
strong out-of-band emissions. Without extensive filtering the Tx power
would likely steamroll any LNA/receiver. Of course, as John pointed out,
this won't help against in-band interference.
Best regards,
Carsten
On 11.07.22 15:16, John Ackermann via time-nuts wrote:
Hi Skipp -- there is a lot of info about interference mitigation in the u-blox integration manual for the ZED--F9T (available under the docs at https://www.u-blox.com/en/product/zed-f9t-module). It might give you some clues, and I think might also point to another u-blox app note on the topic.
Most of the antennas I've seen that have an LNA also include a SAW filter. I also once found on either Amazon or eBay so e new-product, relatively inexpensive, high pass filters with cutoff around 1 GHz. Those would help knock down broadcast, trunking, etc. stuff. (But of course nothing will help with on-frequency crud coming from outside the GPS system.)
John
On Jul 11, 2022, 8:49 AM, at 8:49 AM, skipp Isaham via time-nuts time-nuts@lists.febo.com wrote:
Hello to the Group,
I'd like to get some opinions and war stories regarding GPS reliability
at
high RF level and elevation locations.
Background: Three different hill-top GPS receivers, all different
types, using
different antennas mounted on an outside fixiture, plain view of the
open sky,
all stopped working.
Test antennas were brought in and placed on a fixture well away from
the
original antennas, the recevers went back in to capture and lock.
From what I understand, the original antennas are what I would call
straight
preamp with no pre-selection / filtering.
The ordered and now inbound replacements are said to contain a SAW
filter
system. It is the intent of the client to just place these "improved
antennas" in
to service and get on with life.
I would suspect a GPS antenna (and receiver) could be subject to RF
overload
or blocking, however, we're assuming nothing major has changed at the
site, nor
any nearby location. One might think there are more GPS receivers
being pushed
out of reliable operation by the world around them, I'm just not
hearing those stories
from a lot of people using them (GPS receivers).
Any new install GPS receiver antenna ordered will/should contain some
pre-selection
to potentially avoid a problem, even some years down the road? Seems
like that's
where things are going... no more off the shelf, wide band, (hot)
preamplified GPS antennas
in busy locations?
Thank you in advance for any related comments and/or opions ...
cheers,
skipp
skipp025 at jah who dot calm
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
The u-blox SAW filtering is great. We've carried out various RF
measurements with +40 dBm EIRP at 2.53 and 3.75 GHz with some u-blox
ANN-MB within <2m of the Tx antennas. While we haven't conducted
in-depth comparisons with a superior ground-truth, my current conclusion
is that the u-blox RTK performance is not (noticeably) affected by
strong out-of-band emissions. Without extensive filtering the Tx power
would likely steamroll any LNA/receiver. Of course, as John pointed out,
this won't help against in-band interference.
Best regards,
Carsten
On 11.07.22 15:16, John Ackermann via time-nuts wrote:
> Hi Skipp -- there is a lot of info about interference mitigation in the u-blox integration manual for the ZED--F9T (available under the docs at https://www.u-blox.com/en/product/zed-f9t-module). It might give you some clues, and I think might also point to another u-blox app note on the topic.
>
> Most of the antennas I've seen that have an LNA also include a SAW filter. I also once found on either Amazon or eBay so e new-product, relatively inexpensive, high pass filters with cutoff around 1 GHz. Those would help knock down broadcast, trunking, etc. stuff. (But of course nothing will help with on-frequency crud coming from outside the GPS system.)
>
> John
>
> On Jul 11, 2022, 8:49 AM, at 8:49 AM, skipp Isaham via time-nuts <time-nuts@lists.febo.com> wrote:
>> Hello to the Group,
>>
>> I'd like to get some opinions and war stories regarding GPS reliability
>> at
>> high RF level and elevation locations.
>>
>> Background: Three different hill-top GPS receivers, all different
>> types, using
>> different antennas mounted on an outside fixiture, plain view of the
>> open sky,
>> all stopped working.
>>
>> Test antennas were brought in and placed on a fixture well away from
>> the
>> original antennas, the recevers went back in to capture and lock.
>>
> >From what I understand, the original antennas are what I would call
>> straight
>> preamp with no pre-selection / filtering.
>>
>> The ordered and now inbound replacements are said to contain a SAW
>> filter
>> system. It is the intent of the client to just place these "improved
>> antennas" in
>> to service and get on with life.
>>
>> I would suspect a GPS antenna (and receiver) could be subject to RF
>> overload
>> or blocking, however, we're assuming nothing major has changed at the
>> site, nor
>> any nearby location. One might think there are more GPS receivers
>> being pushed
>> out of reliable operation by the world around them, I'm just not
>> hearing those stories
> >from a lot of people using them (GPS receivers).
>> Any new install GPS receiver antenna ordered will/should contain some
>> pre-selection
>> to potentially avoid a problem, even some years down the road? Seems
>> like that's
>> where things are going... no more off the shelf, wide band, (hot)
>> preamplified GPS antennas
>> in busy locations?
>>
>> Thank you in advance for any related comments and/or opions ...
>>
>> cheers,
>>
>> skipp
>>
>> skipp025 at jah who dot calm
>> _______________________________________________
>> time-nuts mailing list -- time-nuts@lists.febo.com
>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
DG
David G. McGaw
Mon, Jul 11, 2022 2:11 PM
With the new 5G hardware, we are seeing all manner of new interference,
some of it quite broad-band. A good antenna with sharp SAW filter may
help, but not if the emmisions are in-band. Besides broad-band, there
also can be 2nd harmonic emissions that cause interference. We had this
problem with an Iridium ground station (just above the GPS L1 frequency)
for scientific balloon data that had a new cell installation placed
nearby. We had (and thankfully were able to) have the cell base station
shut down while we were flying.
73,
David N1HAC
On 7/11/22 9:27 AM, paul swed via time-nuts wrote:
Skipp
I am aware at least in the US that there is the possibility of 5G
interference along with newer possible bands that 5G can use. I have read
several articles in a publication called GNSS.
Thats why I am using wwvb at 60 KHz. Humor intended.
Regards
Paul
WB8TSL
On Mon, Jul 11, 2022 at 8:49 AM skipp Isaham via time-nuts <
time-nuts@lists.febo.com> wrote:
Hello to the Group,
I'd like to get some opinions and war stories regarding GPS reliability at
high RF level and elevation locations.
Background: Three different hill-top GPS receivers, all different types,
using
different antennas mounted on an outside fixiture, plain view of the open
sky,
all stopped working.
Test antennas were brought in and placed on a fixture well away from the
original antennas, the recevers went back in to capture and lock.
From what I understand, the original antennas are what I would call
straight
preamp with no pre-selection / filtering.
The ordered and now inbound replacements are said to contain a SAW filter
system. It is the intent of the client to just place these "improved
antennas" in
to service and get on with life.
I would suspect a GPS antenna (and receiver) could be subject to RF
overload
or blocking, however, we're assuming nothing major has changed at the
site, nor
any nearby location. One might think there are more GPS receivers being
pushed
out of reliable operation by the world around them, I'm just not hearing
those stories
from a lot of people using them (GPS receivers).
Any new install GPS receiver antenna ordered will/should contain some
pre-selection
to potentially avoid a problem, even some years down the road? Seems like
that's
where things are going... no more off the shelf, wide band, (hot)
preamplified GPS antennas
in busy locations?
Thank you in advance for any related comments and/or opions ...
cheers,
skipp
skipp025 at jah who dot calm
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
With the new 5G hardware, we are seeing all manner of new interference,
some of it quite broad-band. A good antenna with sharp SAW filter may
help, but not if the emmisions are in-band. Besides broad-band, there
also can be 2nd harmonic emissions that cause interference. We had this
problem with an Iridium ground station (just above the GPS L1 frequency)
for scientific balloon data that had a new cell installation placed
nearby. We had (and thankfully were able to) have the cell base station
shut down while we were flying.
73,
David N1HAC
On 7/11/22 9:27 AM, paul swed via time-nuts wrote:
> Skipp
> I am aware at least in the US that there is the possibility of 5G
> interference along with newer possible bands that 5G can use. I have read
> several articles in a publication called GNSS.
>
>
> Thats why I am using wwvb at 60 KHz. Humor intended.
> Regards
> Paul
> WB8TSL
>
> On Mon, Jul 11, 2022 at 8:49 AM skipp Isaham via time-nuts <
> time-nuts@lists.febo.com> wrote:
>
>> Hello to the Group,
>>
>> I'd like to get some opinions and war stories regarding GPS reliability at
>> high RF level and elevation locations.
>>
>> Background: Three different hill-top GPS receivers, all different types,
>> using
>> different antennas mounted on an outside fixiture, plain view of the open
>> sky,
>> all stopped working.
>>
>> Test antennas were brought in and placed on a fixture well away from the
>> original antennas, the recevers went back in to capture and lock.
>>
>> From what I understand, the original antennas are what I would call
>> straight
>> preamp with no pre-selection / filtering.
>>
>> The ordered and now inbound replacements are said to contain a SAW filter
>> system. It is the intent of the client to just place these "improved
>> antennas" in
>> to service and get on with life.
>>
>> I would suspect a GPS antenna (and receiver) could be subject to RF
>> overload
>> or blocking, however, we're assuming nothing major has changed at the
>> site, nor
>> any nearby location. One might think there are more GPS receivers being
>> pushed
>> out of reliable operation by the world around them, I'm just not hearing
>> those stories
>> from a lot of people using them (GPS receivers).
>>
>> Any new install GPS receiver antenna ordered will/should contain some
>> pre-selection
>> to potentially avoid a problem, even some years down the road? Seems like
>> that's
>> where things are going... no more off the shelf, wide band, (hot)
>> preamplified GPS antennas
>> in busy locations?
>>
>> Thank you in advance for any related comments and/or opions ...
>>
>> cheers,
>>
>> skipp
>>
>> skipp025 at jah who dot calm
>> _______________________________________________
>> time-nuts mailing list -- time-nuts@lists.febo.com
>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
