On Mon, 01 Dec 2003 19:17:04 GMT, Me wrote:

Again bull****! Would be nice if you knew anything about what your
talking about.

That's why, my little trollsmeg, I said "my understanding". Perhaps
you would enjoy taking the lid off that planet-sized intellect to
share your god-like insights with this NG?

Or just shut the **** up.

R.

In article ,
wrote:

On Mon, 01 Dec 2003 19:17:04 GMT, Me wrote:

Again bull****! Would be nice if you knew anything about what your
talking about.

That's why, my little trollsmeg, I said "my understanding". Perhaps
you would enjoy taking the lid off that planet-sized intellect to
share your god-like insights with this NG?

Or just shut the **** up.

R.


There isn't a "Commercial Radar" marketed in the USA that has anywhere
near enough Beam Energy Density to cook even your eyeballs, let alone
any other body parts of any mammal, while in operation, in a standard
installation. One is very much more likely to be hurt by the antenna
hitting them in the head, as it rotates than by the RF coming out of
the antenna. This has been well documented over the last 30 years, and
as the power of these radars has dropped due to the better receiver
technology, it is more true now than 30 years ago.

Next, The dashed arc's one sees displayed on radar screens are other
radars that have transmitting frequencies CLOSE to the receive frequency
of your radar. There is a wide range of frequencies that Xband radars
can and do use and the reciver bandwidth is much narrower than the
transmitter frequency range by 20X or so. Transmit frequencies are
determined by the physical properties of the Magnitron of each radar and
are fixed at the MFG, but do move around due to temp, age, ect. This
means that some show up on your screen and some don't. There are three
different bands that Maritime Radars use Sband, Xband, and KaBand. Of
the three Xband is by far the most cxommon. (Orders of Magnitude more)
Sband is only found on VERY BIG VESSELS, and Kaband is used mainly for
Wx search and is extremly rare aboard any vessels except Research
Vessels. None of the radars will cause interference except in their own
Band Class. The Arc's always show from the center of your display, and
don't have any range or direction information associated with them,
other than they TEND to not be there when you antenna isn't pointed
toward the other radar. Targets that have Dashes the trail the target
on your display are a differet thing altogether. They are Active Radar
Transponders, (Racon's) and are used as Position Identification devices.
These are put on significant Navigation Points and are also used for SAR
Activites and ARE required on Lifeboats of SOLAS Required Ships. Almost
all of these a Xband devices. I have seen one or two Sband
installations, but never any Kaband.

Now that your understanding has been expanded, ...... well ok...we'll
just let it go at that........


me

An interesting explanation, but this isn't the image I see. They appear from
medium sized vessels (tugs, CG, etc). They are roughly a 90 degree arc of a
circle centered on my vessel, and intersecting the target. Thus, the radius
indicates range, and the position of the arc is the approximate direction.
Although I always assumed it was something "active" on the target, I'm beginning
to think it might be entirely my radar. The fact that the arc is on both sides
of the target makes me think that my transmitter is radiating small side lobes
(if that's the correct term) that precede and follow the main beam. If the
target is a large reflector, and my gain is high, that might show as the arc.

-jeff


"Me" wrote in message
...
In article ,
wrote:

On Mon, 01 Dec 2003 19:17:04 GMT, Me wrote:

Again bull****! Would be nice if you knew anything about what your
talking about.

That's why, my little trollsmeg, I said "my understanding". Perhaps
you would enjoy taking the lid off that planet-sized intellect to
share your god-like insights with this NG?

Or just shut the **** up.

R.


There isn't a "Commercial Radar" marketed in the USA that has anywhere
near enough Beam Energy Density to cook even your eyeballs, let alone
any other body parts of any mammal, while in operation, in a standard
installation. One is very much more likely to be hurt by the antenna
hitting them in the head, as it rotates than by the RF coming out of
the antenna. This has been well documented over the last 30 years, and
as the power of these radars has dropped due to the better receiver
technology, it is more true now than 30 years ago.

Next, The dashed arc's one sees displayed on radar screens are other
radars that have transmitting frequencies CLOSE to the receive frequency
of your radar. There is a wide range of frequencies that Xband radars
can and do use and the reciver bandwidth is much narrower than the
transmitter frequency range by 20X or so. Transmit frequencies are
determined by the physical properties of the Magnitron of each radar and
are fixed at the MFG, but do move around due to temp, age, ect. This
means that some show up on your screen and some don't. There are three
different bands that Maritime Radars use Sband, Xband, and KaBand. Of
the three Xband is by far the most cxommon. (Orders of Magnitude more)
Sband is only found on VERY BIG VESSELS, and Kaband is used mainly for
Wx search and is extremly rare aboard any vessels except Research
Vessels. None of the radars will cause interference except in their own
Band Class. The Arc's always show from the center of your display, and
don't have any range or direction information associated with them,
other than they TEND to not be there when you antenna isn't pointed
toward the other radar. Targets that have Dashes the trail the target
on your display are a differet thing altogether. They are Active Radar
Transponders, (Racon's) and are used as Position Identification devices.
These are put on significant Navigation Points and are also used for SAR
Activites and ARE required on Lifeboats of SOLAS Required Ships. Almost
all of these a Xband devices. I have seen one or two Sband
installations, but never any Kaband.

Now that your understanding has been expanded, ...... well ok...we'll
just let it go at that........


me

I'm going to assume you start your radar and adjust it at either 3 or
6 mile range, and when you see these arced targets, they are generally
larger, at relatively close range, or when you are on a lower range.
If so, first step, try increasing sea and/or rain clutter. If this
doesn't get rid of them, retune the set for lower ranges (that you may
be on) and reduce gain and/or intensity .... slightly.
As always, try to stay on the higher ranges ... Id only use 0.75 down,
for docking or running inside a marina (personal experience/choice), for
example, Oak Bluffs, Hyannis inner harbor, Boston Harbor marina.

otn

Jeff Morris wrote:
An interesting explanation, but this isn't the image I see. They appear from
medium sized vessels (tugs, CG, etc). They are roughly a 90 degree arc of a
circle centered on my vessel, and intersecting the target. Thus, the radius
indicates range, and the position of the arc is the approximate direction.
Although I always assumed it was something "active" on the target, I'm beginning
to think it might be entirely my radar. The fact that the arc is on both sides
of the target makes me think that my transmitter is radiating small side lobes
(if that's the correct term) that precede and follow the main beam. If the
target is a large reflector, and my gain is high, that might show as the arc.

-jeff

In this ill-tempered thread, Jeff's proposal is at least plausible.
Dishes have significant side lobes peaking nearer 90 degrees to the
side though.... Flat plate antennas do much better with smaller
side-lobes. Regular dishes sometimes get edges turned backwards to cut
the side lobes.

Brian W

On Tue, 2 Dec 2003 16:59:39 -0500, "Jeff Morris"
wrote:

An interesting explanation, but this isn't the image I see. They appear from
medium sized vessels (tugs, CG, etc). They are roughly a 90 degree arc of a
circle centered on my vessel, and intersecting the target. Thus, the radius
indicates range, and the position of the arc is the approximate direction.
Although I always assumed it was something "active" on the target, I'm beginning
to think it might be entirely my radar. The fact that the arc is on both sides
of the target makes me think that my transmitter is radiating small side lobes
(if that's the correct term) that precede and follow the main beam. If the
target is a large reflector, and my gain is high, that might show as the arc.

-jeff


"Me" wrote in message
...
In article ,
wrote:

On Mon, 01 Dec 2003 19:17:04 GMT, Me wrote:

Again bull****! Would be nice if you knew anything about what your
talking about.

That's why, my little trollsmeg, I said "my understanding". Perhaps
you would enjoy taking the lid off that planet-sized intellect to
share your god-like insights with this NG?

Or just shut the **** up.

R.


There isn't a "Commercial Radar" marketed in the USA that has anywhere
near enough Beam Energy Density to cook even your eyeballs, let alone
any other body parts of any mammal, while in operation, in a standard
installation. One is very much more likely to be hurt by the antenna
hitting them in the head, as it rotates than by the RF coming out of
the antenna. This has been well documented over the last 30 years, and
as the power of these radars has dropped due to the better receiver
technology, it is more true now than 30 years ago.

Next, The dashed arc's one sees displayed on radar screens are other
radars that have transmitting frequencies CLOSE to the receive frequency
of your radar. There is a wide range of frequencies that Xband radars
can and do use and the reciver bandwidth is much narrower than the
transmitter frequency range by 20X or so. Transmit frequencies are
determined by the physical properties of the Magnitron of each radar and
are fixed at the MFG, but do move around due to temp, age, ect. This
means that some show up on your screen and some don't. There are three
different bands that Maritime Radars use Sband, Xband, and KaBand. Of
the three Xband is by far the most cxommon. (Orders of Magnitude more)
Sband is only found on VERY BIG VESSELS, and Kaband is used mainly for
Wx search and is extremly rare aboard any vessels except Research
Vessels. None of the radars will cause interference except in their own
Band Class. The Arc's always show from the center of your display, and
don't have any range or direction information associated with them,
other than they TEND to not be there when you antenna isn't pointed
toward the other radar. Targets that have Dashes the trail the target
on your display are a differet thing altogether. They are Active Radar
Transponders, (Racon's) and are used as Position Identification devices.
These are put on significant Navigation Points and are also used for SAR
Activites and ARE required on Lifeboats of SOLAS Required Ships. Almost
all of these a Xband devices. I have seen one or two Sband
installations, but never any Kaband.

Now that your understanding has been expanded, ...... well ok...we'll
just let it go at that........


me

On Tue, 2 Dec 2003 16:59:39 -0500, "Jeff Morris"
wrote:

An interesting explanation, but this isn't the image I see. They appear from
medium sized vessels (tugs, CG, etc). They are roughly a 90 degree arc of a
circle centered on my vessel, and intersecting the target. Thus, the radius
indicates range, and the position of the arc is the approximate direction.
Although I always assumed it was something "active" on the target, I'm beginning
to think it might be entirely my radar. The fact that the arc is on both sides
of the target makes me think that my transmitter is radiating small side lobes
(if that's the correct term) that precede and follow the main beam. If the
target is a large reflector, and my gain is high, that might show as the arc.

-jeff

I do see what you describe occasionally with a Raytheon SR 70. I never
have seen the other phenomenon, and I never saw this one with the
previous Furuno 1720.

I don't think it indicates an active radar on the target, because I
have had it happen with big rocks. It usually goes away pretty soon.




Rodney Myrvaagnes J36 Gjo/a

"That idiot Leibniz, who wants to teach me about the infinitesimally small! Has he therefore forgotten that I am the wife of Frederick I? How can he imagine that I am unacquainted with my own husband?"

In article ,
Rodney Myrvaagnes wrote:

I do see what you describe occasionally with a Raytheon SR 70. I never
have seen the other phenomenon, and I never saw this one with the
previous Furuno 1720.

I don't think it indicates an active radar on the target, because I
have had it happen with big rocks. It usually goes away pretty soon.

What this seems to be is Magnitron Double-Pulsing. This is where,
as the Magnitron ages, and the Modulator Parts age, they get into
a multiple pulse state, and produce a very ragged and multiple peaked
pulse, that shows up as multiple echos in near vacinity of a REAL Target.
The fix for this is, to replace the Magnitron, and the Pulse Forming
Capacitors in the modulator. Not usually found in Noncommercial Marine
Service, because these units typically die of mechanical age, long
before the electronics age out.

Well se what "Me" has to say on the subject.


Bruce in alaska
--
add a 2 before @

On Wed, 03 Dec 2003 19:44:00 GMT, Bruce in Alaska
wrote:

In article ,
Rodney Myrvaagnes wrote:

I do see what you describe occasionally with a Raytheon SR 70. I never
have seen the other phenomenon, and I never saw this one with the
previous Furuno 1720.

I don't think it indicates an active radar on the target, because I
have had it happen with big rocks. It usually goes away pretty soon.

What this seems to be is Magnitron Double-Pulsing. This is where,
as the Magnitron ages, and the Modulator Parts age, they get into
a multiple pulse state, and produce a very ragged and multiple peaked
pulse, that shows up as multiple echos in near vacinity of a REAL Target.
The fix for this is, to replace the Magnitron, and the Pulse Forming
Capacitors in the modulator. Not usually found in Noncommercial Marine
Service, because these units typically die of mechanical age, long
before the electronics age out.

I doubt that. This is the new replacement for an ancient Furuno that
never did it.


Well se what "Me" has to say on the subject.


Bruce in alaska




Rodney Myrvaagnes J36 Gjo/a

"That idiot Leibniz, who wants to teach me about the infinitesimally small! Has he therefore forgotten that I am the wife of Frederick I? How can he imagine that I am unacquainted with my own husband?"

On Wed, 03 Dec 2003 19:44:00 GMT, Bruce in Alaska
wrote:

In article ,
Rodney Myrvaagnes wrote:

I do see what you describe occasionally with a Raytheon SR 70. I never
have seen the other phenomenon, and I never saw this one with the
previous Furuno 1720.

I don't think it indicates an active radar on the target, because I
have had it happen with big rocks. It usually goes away pretty soon.

What this seems to be is Magnitron Double-Pulsing. This is where,
as the Magnitron ages, and the Modulator Parts age, they get into
a multiple pulse state, and produce a very ragged and multiple peaked
pulse, that shows up as multiple echos in near vacinity of a REAL Target.
The fix for this is, to replace the Magnitron, and the Pulse Forming
Capacitors in the modulator. Not usually found in Noncommercial Marine
Service, because these units typically die of mechanical age, long
before the electronics age out.

I doubt that. This is the new replacement for an ancient Furuno that
never did it.


Well se what "Me" has to say on the subject.


Bruce in alaska




Rodney Myrvaagnes J36 Gjo/a

"That idiot Leibniz, who wants to teach me about the infinitesimally small! Has he therefore forgotten that I am the wife of Frederick I? How can he imagine that I am unacquainted with my own husband?"

In article ,
Rodney Myrvaagnes wrote:

I do see what you describe occasionally with a Raytheon SR 70. I never
have seen the other phenomenon, and I never saw this one with the
previous Furuno 1720.

I don't think it indicates an active radar on the target, because I
have had it happen with big rocks. It usually goes away pretty soon.

Hmmm, sounds like maybe your Magnitron is getting old. Been know to
cause mutiple echo's from a single boat, or rock. If they are infront
of and behind the real target, it is reflections. If it is right or left,
could be what is known as Multiple Pulsing.

Me