Radar vs GPS/Sounder
 

On Mon, 24 Nov 2003 20:30:38 GMT, Bruce in Alaska
wrote (with possible editing):

In article ,
"Jeff Morris" wrote:

I often keep it in standby to save power and
magnetron time (they do wear out)

Just a point of note here. Leaving the radar in standby on most
civilian consumer radars does not save anything on Magnitron
Time. What wears out is the Filiment (heater) and that is
always ON whenever the Powersupply is on, even in Standby Mode.
To convise yourself of this, do this simple test. When you first
"Fire up" your radar, there is a timer that allows the Magnitron
to "Heat up and Stabalize", usually for three (3) minutes or so.
After that initial "Warm up Period", when going from "Standby"
to "Operate" does your radar require another "Warm up Period"?
If so, then you are correct on your Magnitron time statement.(Not very
likely to be this way) If not, then then "Standby" only save you
Transmit Power, and that's not really very much in most cases.
Most modern Magnitrons have between 2000 and 4000 hours of Service
Life and that is Filiment Life, really.

Bruce in alaska

No flame, Bruce, but what normally wears out a magnetron is depletion
of the cathode. The cathode is heated by the filament so that it will
emit electrons. As the tube ages, its ability to emit them decreases.
As radar operates in pulsed service, the tubes should last a good deal
longer. Often, a magnetron which is substantially dead, will still
"light up" just like the final output tubes in transmitters.
--

Larry
Email to rapp at lmr dot com

Radar vs GPS/Sounder
 

On Sun, 23 Nov 2003 09:07:50 -0800, "Lloyd Sumpter"
wrote:

Hi,

Thinking of getting radar for Far Cove, mainly for this planned trip to WCVI,
which has lots of fog.

Now, I've survived 20+ years of sailing Georgia Strait, etc. without radar.
If it's really foggy, I just stay put. If I venture out, I use several nav aids
including GPS to determine my position, blow my horn and listen.

I'm thinking that, even WITH radar, I wouldn't venture out in unfamiliar
waters in dense fog. And if I was out and the fog rolled in on me, I would think
that GPS, sounder and a good chart would be better to find that anchorage than
radar, assuming I could see at least 100 ft or so.

Under ideal conditions, you are correct. The benefit of radar,
however, is that you can see what you can't hear, i.e. other shipping
that has no intention of letting a little fog screw with the
schedule...

Also, to a lesser extent, you become visible to other shipping in a
way that a horn can't: precisely.

Finally, you can use a radar to get bearings on shore objects at night
if the GPS conks out and it's too cloudy to use celestial...which I
notice you didn't mention...G

I would say radar, sensibly used, complements but doesn't replace
paper, GPS, depth sounders, horns and good old seamanship. While it is
possible to get swamped with "too much information", particularly if
it doesn't agree, too little information is often what proves fatal to
the boat.

Comments?

Also, if I mount the radome on a post at the stern like most seem to, doesn't
the mast and sail interfere with it looking forward?

Yes, but barely, or at least not as much as you'd think. You can
offset the radome on a pole and gimbal off a stern quarter if you
wish, and then the "blind spot" would be 10 deg. port or starboard
looking forward.

I agree, a gimbal mount at the cross-trees is probably ideal, however,
but it's easier to get at stuff on a pole. Probably the nicest option
is an arch with the radar offset and a way to lash the boom, hang
bimini canvas, affix a GPS, VHF, etc., and yet keep all within easy
reach.

R.

Lloyd Sumpter
"Far Cove" Catalina 36

Radar vs GPS/Sounder
 

On Sun, 23 Nov 2003 09:07:50 -0800, "Lloyd Sumpter"
wrote:

Hi,

Thinking of getting radar for Far Cove, mainly for this planned trip to WCVI,
which has lots of fog.

Now, I've survived 20+ years of sailing Georgia Strait, etc. without radar.
If it's really foggy, I just stay put. If I venture out, I use several nav aids
including GPS to determine my position, blow my horn and listen.

I'm thinking that, even WITH radar, I wouldn't venture out in unfamiliar
waters in dense fog. And if I was out and the fog rolled in on me, I would think
that GPS, sounder and a good chart would be better to find that anchorage than
radar, assuming I could see at least 100 ft or so.

Under ideal conditions, you are correct. The benefit of radar,
however, is that you can see what you can't hear, i.e. other shipping
that has no intention of letting a little fog screw with the
schedule...

Also, to a lesser extent, you become visible to other shipping in a
way that a horn can't: precisely.

Finally, you can use a radar to get bearings on shore objects at night
if the GPS conks out and it's too cloudy to use celestial...which I
notice you didn't mention...G

I would say radar, sensibly used, complements but doesn't replace
paper, GPS, depth sounders, horns and good old seamanship. While it is
possible to get swamped with "too much information", particularly if
it doesn't agree, too little information is often what proves fatal to
the boat.

Comments?

Also, if I mount the radome on a post at the stern like most seem to, doesn't
the mast and sail interfere with it looking forward?

Yes, but barely, or at least not as much as you'd think. You can
offset the radome on a pole and gimbal off a stern quarter if you
wish, and then the "blind spot" would be 10 deg. port or starboard
looking forward.

I agree, a gimbal mount at the cross-trees is probably ideal, however,
but it's easier to get at stuff on a pole. Probably the nicest option
is an arch with the radar offset and a way to lash the boom, hang
bimini canvas, affix a GPS, VHF, etc., and yet keep all within easy
reach.

R.

Lloyd Sumpter
"Far Cove" Catalina 36

Radar vs GPS/Sounder
 

On Mon, 24 Nov 2003 06:51:32 -0800, "Lloyd Sumpter"
wrote:


Final question: if the fog was thick (vis. maybe 100 ft) and you had radar (and
GPS, etc) would you go out?
If I thought there was clearer weather off shore, or at my
destination, or if I knew the waters and needed nav practice (like
shooting sun sights up through a hole in the fog!), sure I would. If
the fog is close to shore and you see 90% of your city/town rising out
of a solid bank, it's well worth that first mile of damp sailing to
get offshore a bit and look back.

Finally, particularly in summer, fog burns off. If you leave at 8 A.M.
and the fog's gone by 10:30 A.M., you are already well into your day's
cruising, and you'll have tons of searoom over the folks who waited
"until it clears up".

R.

Radar vs GPS/Sounder
 

On Mon, 24 Nov 2003 06:51:32 -0800, "Lloyd Sumpter"
wrote:


Final question: if the fog was thick (vis. maybe 100 ft) and you had radar (and
GPS, etc) would you go out?
If I thought there was clearer weather off shore, or at my
destination, or if I knew the waters and needed nav practice (like
shooting sun sights up through a hole in the fog!), sure I would. If
the fog is close to shore and you see 90% of your city/town rising out
of a solid bank, it's well worth that first mile of damp sailing to
get offshore a bit and look back.

Finally, particularly in summer, fog burns off. If you leave at 8 A.M.
and the fog's gone by 10:30 A.M., you are already well into your day's
cruising, and you'll have tons of searoom over the folks who waited
"until it clears up".

R.

Radar vs GPS/Sounder
 

On Tue, 25 Nov 2003 09:50:07 -0500, DSK wrote:



Our radar has proven to be a really good tool for use in marginal visibility and for
tracking ship traffic. When we first bought the boat I was not convinced of it's
usefulness, especially not that particular set. But now it works great.


One last thing I forgot to mention: Here on Lake Ontario many summer
storms appear as "pop-up" cumulonimbus thunderheads, with 50-60 knot
line squalls that can lay you flat if you have, as most do most of the
time, a full hoist...

There's only 20-30 miles to the west end of the lake here (Toronto)
and squalls that develop at that end (south to west, usually) can get
here in minutes.

A properly tuned radar will show squall lines quite sharply. If its
blasting at you at 48 knots and you catch it on radar aft at 12 NM,
you can shorten sail in a timely fashion and ride out an otherwise
very unpleasant, possibly expensive and potentially dangerous 15
minute surfing session.

And of course, if you can see rain bands, you can sail between them,
if the wind and waves allow.

R.

Radar vs GPS/Sounder
 

On Tue, 25 Nov 2003 09:50:07 -0500, DSK wrote:



Our radar has proven to be a really good tool for use in marginal visibility and for
tracking ship traffic. When we first bought the boat I was not convinced of it's
usefulness, especially not that particular set. But now it works great.


One last thing I forgot to mention: Here on Lake Ontario many summer
storms appear as "pop-up" cumulonimbus thunderheads, with 50-60 knot
line squalls that can lay you flat if you have, as most do most of the
time, a full hoist...

There's only 20-30 miles to the west end of the lake here (Toronto)
and squalls that develop at that end (south to west, usually) can get
here in minutes.

A properly tuned radar will show squall lines quite sharply. If its
blasting at you at 48 knots and you catch it on radar aft at 12 NM,
you can shorten sail in a timely fashion and ride out an otherwise
very unpleasant, possibly expensive and potentially dangerous 15
minute surfing session.

And of course, if you can see rain bands, you can sail between them,
if the wind and waves allow.

R.

Radar vs GPS/Sounder
 

wrote in message
...
...
Also, to a lesser extent, you become visible to other shipping in a
way that a horn can't: precisely.


This is a point I've wondered about: it seems that vessels with active radar
appear on my radar with a large arc centered on the vessel's blip. I've assumed
this is an interaction between their radar and mine. Does this also mean that
my radar also enhances my picture on their screen?

-jeff

Radar vs GPS/Sounder
 

wrote in message
...
...
Also, to a lesser extent, you become visible to other shipping in a
way that a horn can't: precisely.


This is a point I've wondered about: it seems that vessels with active radar
appear on my radar with a large arc centered on the vessel's blip. I've assumed
this is an interaction between their radar and mine. Does this also mean that
my radar also enhances my picture on their screen?

-jeff

Radar vs GPS/Sounder
 

On Tue, 25 Nov 2003 21:42:50 -0500, "Jeff Morris"
wrote:

wrote in message
.. .
...
Also, to a lesser extent, you become visible to other shipping in a
way that a horn can't: precisely.


This is a point I've wondered about: it seems that vessels with active radar
appear on my radar with a large arc centered on the vessel's blip. I've assumed
this is an interaction between their radar and mine. Does this also mean that
my radar also enhances my picture on their screen?

-jeff




Don't count on it. The arc that you see from the other guys radar is
from interference from his transmitter. Your radar is picking up your
transmitters echo and his transmitter directly. His pulses are not
synchronized with yours so you see the trail of pulses from his
transmitter while your transmitter is between pulses. It will give
neither of you any indication of where the other is.

This only happens if the two transmitters are very close to the same
frequency. Even though the two radar's may be exactly the same type of
radar, they may or may not be close enough to the same frequency. The
magnetrons are all tuned slightly different and drift somewhat.

On most radar's there is also an interference filter on the receivers
that eliminate or reduce that type of interference.

Then too the other ship may be using a radar in a completely different
band. No interference to either of you.

Regards
Gary

Radar vs GPS/Sounder
 

On Tue, 25 Nov 2003 21:42:50 -0500, "Jeff Morris"
wrote:

wrote in message
.. .
...
Also, to a lesser extent, you become visible to other shipping in a
way that a horn can't: precisely.


This is a point I've wondered about: it seems that vessels with active radar
appear on my radar with a large arc centered on the vessel's blip. I've assumed
this is an interaction between their radar and mine. Does this also mean that
my radar also enhances my picture on their screen?

-jeff




Don't count on it. The arc that you see from the other guys radar is
from interference from his transmitter. Your radar is picking up your
transmitters echo and his transmitter directly. His pulses are not
synchronized with yours so you see the trail of pulses from his
transmitter while your transmitter is between pulses. It will give
neither of you any indication of where the other is.

This only happens if the two transmitters are very close to the same
frequency. Even though the two radar's may be exactly the same type of
radar, they may or may not be close enough to the same frequency. The
magnetrons are all tuned slightly different and drift somewhat.

On most radar's there is also an interference filter on the receivers
that eliminate or reduce that type of interference.

Then too the other ship may be using a radar in a completely different
band. No interference to either of you.

Regards
Gary

Radar vs GPS/Sounder
 

Jeff Morris wrote:
wrote in message
...

...
Also, to a lesser extent, you become visible to other shipping in a
way that a horn can't: precisely.



This is a point I've wondered about: it seems that vessels with active radar
appear on my radar with a large arc centered on the vessel's blip. I've assumed
this is an interaction between their radar and mine. Does this also mean that
my radar also enhances my picture on their screen?

-jeff



This may also be due to having the gain/intensity, turned up too high
for the given range scale you are using. It can sometimes be countered
with the anti clutter controls, alone.

Radar vs GPS/Sounder
 

Jeff Morris wrote:
wrote in message
...

...
Also, to a lesser extent, you become visible to other shipping in a
way that a horn can't: precisely.



This is a point I've wondered about: it seems that vessels with active radar
appear on my radar with a large arc centered on the vessel's blip. I've assumed
this is an interaction between their radar and mine. Does this also mean that
my radar also enhances my picture on their screen?

-jeff



This may also be due to having the gain/intensity, turned up too high
for the given range scale you are using. It can sometimes be countered
with the anti clutter controls, alone.

Radar vs GPS/Sounder
 

"Lloyd Sumpter" wrote in message
...
Hi,

Thinking of getting radar for Far Cove, mainly for this planned trip to
WCVI,
which has lots of fog.

Now, I've survived 20+ years of sailing Georgia Strait, etc. without
radar.
If it's really foggy, I just stay put. If I venture out, I use several nav
aids
including GPS to determine my position, blow my horn and listen.

I'm thinking that, even WITH radar, I wouldn't venture out in
unfamiliar
waters in dense fog. And if I was out and the fog rolled in on me, I would
think
that GPS, sounder and a good chart would be better to find that anchorage
than
radar, assuming I could see at least 100 ft or so.

Comments?

Also, if I mount the radome on a post at the stern like most seem to,
doesn't
the mast and sail interfere with it looking forward?

Lloyd Sumpter
"Far Cove" Catalina 36


You may not plan to venture out there if its foggy but what if you are
already in transit or need to get from A to B?

There is a fellow in my Nanaimo marina who spent all year fitting out his
36' Seabird to sail it down to Mexico this Fall. This is the second time
he's tried. Last year they got into a vicious storm off Washington and
turned back. This year they set out from Victoria and got into pea soup fog
somewhere West. Had no radar and decided they couldn't risk colliding with
shipping. Turned back again. Maybe having radar would save a lot of
planned trips as well as make trips-in-progress safer.
Darned expensive though compared to a chart plotter, especially if you go
high-tech for the radome mount and pay someone else to install it all. I
have the radar but I'm still saving for the mount.

As for pole mounts, there does not seem to be an issue with blind spots.
Aside from simplifying the installation I've been told that a malfunctioning
radar often results from problems in the radome so a pole or backstay mount
simplifys removing this unit for servicing. I've also been advised to use a
2" diameter pole to reduce vibration and not to go too high for the same
reason.
Gord

Radar vs GPS/Sounder
 

"Lloyd Sumpter" wrote in message
...
Hi,

Thinking of getting radar for Far Cove, mainly for this planned trip to
WCVI,
which has lots of fog.

Now, I've survived 20+ years of sailing Georgia Strait, etc. without
radar.
If it's really foggy, I just stay put. If I venture out, I use several nav
aids
including GPS to determine my position, blow my horn and listen.

I'm thinking that, even WITH radar, I wouldn't venture out in
unfamiliar
waters in dense fog. And if I was out and the fog rolled in on me, I would
think
that GPS, sounder and a good chart would be better to find that anchorage
than
radar, assuming I could see at least 100 ft or so.

Comments?

Also, if I mount the radome on a post at the stern like most seem to,
doesn't
the mast and sail interfere with it looking forward?

Lloyd Sumpter
"Far Cove" Catalina 36


You may not plan to venture out there if its foggy but what if you are
already in transit or need to get from A to B?

There is a fellow in my Nanaimo marina who spent all year fitting out his
36' Seabird to sail it down to Mexico this Fall. This is the second time
he's tried. Last year they got into a vicious storm off Washington and
turned back. This year they set out from Victoria and got into pea soup fog
somewhere West. Had no radar and decided they couldn't risk colliding with
shipping. Turned back again. Maybe having radar would save a lot of
planned trips as well as make trips-in-progress safer.
Darned expensive though compared to a chart plotter, especially if you go
high-tech for the radome mount and pay someone else to install it all. I
have the radar but I'm still saving for the mount.

As for pole mounts, there does not seem to be an issue with blind spots.
Aside from simplifying the installation I've been told that a malfunctioning
radar often results from problems in the radome so a pole or backstay mount
simplifys removing this unit for servicing. I've also been advised to use a
2" diameter pole to reduce vibration and not to go too high for the same
reason.
Gord

Radar vs GPS/Sounder
 

"otnmbrd" wrote in message news:_I4xb.15704
This is a point I've wondered about: it seems that vessels with active
radar
appear on my radar with a large arc centered on the vessel's blip. I've
assumed
this is an interaction between their radar and mine. Does this also mean
that
my radar also enhances my picture on their screen?

This may also be due to having the gain/intensity, turned up too high
for the given range scale you are using. It can sometimes be countered
with the anti clutter controls, alone.


Who said I wanted to get rid of it? Its kind of nice have a special identifier
for some vessels. How can I enhance it?

Radar vs GPS/Sounder
 

"otnmbrd" wrote in message news:_I4xb.15704
This is a point I've wondered about: it seems that vessels with active
radar
appear on my radar with a large arc centered on the vessel's blip. I've
assumed
this is an interaction between their radar and mine. Does this also mean
that
my radar also enhances my picture on their screen?

This may also be due to having the gain/intensity, turned up too high
for the given range scale you are using. It can sometimes be countered
with the anti clutter controls, alone.


Who said I wanted to get rid of it? Its kind of nice have a special identifier
for some vessels. How can I enhance it?

Radar vs GPS/Sounder
 

Jeff Morris wrote:
"otnmbrd" wrote in message news:_I4xb.15704

This is a point I've wondered about: it seems that vessels with active

radar

appear on my radar with a large arc centered on the vessel's blip. I've

assumed

this is an interaction between their radar and mine. Does this also mean

that

my radar also enhances my picture on their screen?


This may also be due to having the gain/intensity, turned up too high
for the given range scale you are using. It can sometimes be countered
with the anti clutter controls, alone.



Who said I wanted to get rid of it? Its kind of nice have a special identifier
for some vessels. How can I enhance it?

Problem is, what I feel you are describing, may not be due to
interference from another radar.
In the past, when I experienced interference, it showed more as a spoke
coming towards me, or a series of dots, behind the target (it tends to vary.
What you are are describing, sounds more like "side lobe" effect, in
which case it's not something you'd want to enhance .... course, I could
be miss reading/understanding your description.

otn

Radar vs GPS/Sounder
 

Jeff Morris wrote:
"otnmbrd" wrote in message news:_I4xb.15704

This is a point I've wondered about: it seems that vessels with active

radar

appear on my radar with a large arc centered on the vessel's blip. I've

assumed

this is an interaction between their radar and mine. Does this also mean

that

my radar also enhances my picture on their screen?


This may also be due to having the gain/intensity, turned up too high
for the given range scale you are using. It can sometimes be countered
with the anti clutter controls, alone.



Who said I wanted to get rid of it? Its kind of nice have a special identifier
for some vessels. How can I enhance it?

Problem is, what I feel you are describing, may not be due to
interference from another radar.
In the past, when I experienced interference, it showed more as a spoke
coming towards me, or a series of dots, behind the target (it tends to vary.
What you are are describing, sounds more like "side lobe" effect, in
which case it's not something you'd want to enhance .... course, I could
be miss reading/understanding your description.

otn

Radar vs GPS/Sounder
 

On Tue, 25 Nov 2003 21:42:50 -0500, "Jeff Morris"
wrote:


This is a point I've wondered about: it seems that vessels with active radar
appear on my radar with a large arc centered on the vessel's blip. I've assumed
this is an interaction between their radar and mine. Does this also mean that
my radar also enhances my picture on their screen?

My understanding is that this is reliant on the radar band in which
they are operating their active radar, and/or whether they have a
receiver that goes ping (or whatever) when glanced by "yachtie" radar.

R.

Radar vs GPS/Sounder
 

On Tue, 25 Nov 2003 21:42:50 -0500, "Jeff Morris"
wrote:


This is a point I've wondered about: it seems that vessels with active radar
appear on my radar with a large arc centered on the vessel's blip. I've assumed
this is an interaction between their radar and mine. Does this also mean that
my radar also enhances my picture on their screen?

My understanding is that this is reliant on the radar band in which
they are operating their active radar, and/or whether they have a
receiver that goes ping (or whatever) when glanced by "yachtie" radar.

R.

Radar vs GPS/Sounder
 

On Wed, 26 Nov 2003 18:41:14 GMT, "Gordon Wedman"
wrote:
I've also been advised to use a
2" diameter pole to reduce vibration and not to go too high for the same
reason.

Just go higher than six feet or so or the button on your cap gets
overly warm G.

Of course, cooking is a breeze when you hold a weenie on a stick in
front of the radome G

R.

Radar vs GPS/Sounder
 

On Wed, 26 Nov 2003 18:41:14 GMT, "Gordon Wedman"
wrote:
I've also been advised to use a
2" diameter pole to reduce vibration and not to go too high for the same
reason.

Just go higher than six feet or so or the button on your cap gets
overly warm G.

Of course, cooking is a breeze when you hold a weenie on a stick in
front of the radome G

R.

Radar vs GPS/Sounder
 

In article ,
wrote:

Just go higher than six feet or so or the button on your cap gets
overly warm G.

Of course, cooking is a breeze when you hold a weenie on a stick in
front of the radome G

R.

Bull****!!!!

Me

Radar vs GPS/Sounder
 

In article ,
wrote:

Just go higher than six feet or so or the button on your cap gets
overly warm G.

Of course, cooking is a breeze when you hold a weenie on a stick in
front of the radome G

R.

Bull****!!!!

Me

Radar vs GPS/Sounder
 

In article ,
wrote:

On Tue, 25 Nov 2003 21:42:50 -0500, "Jeff Morris"
wrote:


This is a point I've wondered about: it seems that vessels with active
radar
appear on my radar with a large arc centered on the vessel's blip. I've
assumed
this is an interaction between their radar and mine. Does this also mean
that
my radar also enhances my picture on their screen?

My understanding is that this is reliant on the radar band in which
they are operating their active radar, and/or whether they have a
receiver that goes ping (or whatever) when glanced by "yachtie" radar.

R.

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

me

Radar vs GPS/Sounder
 

In article ,
wrote:

On Tue, 25 Nov 2003 21:42:50 -0500, "Jeff Morris"
wrote:


This is a point I've wondered about: it seems that vessels with active
radar
appear on my radar with a large arc centered on the vessel's blip. I've
assumed
this is an interaction between their radar and mine. Does this also mean
that
my radar also enhances my picture on their screen?

My understanding is that this is reliant on the radar band in which
they are operating their active radar, and/or whether they have a
receiver that goes ping (or whatever) when glanced by "yachtie" radar.

R.

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

me

Radar vs GPS/Sounder
 

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.

Radar vs GPS/Sounder
 

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.

Radar vs GPS/Sounder
 

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

Radar vs GPS/Sounder
 

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

Radar vs GPS/Sounder
 

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

Radar vs GPS/Sounder
 

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

Radar vs GPS/Sounder
 

Rodney Myrvaagnes wrote:

Or, to put it differently, what ELSE is radar good for? Can I use it to
determine if a freighter 10 miles away is on a collision course with me? Do
others normally run with radar on, even if it's clear? Why?

That is actually a different question, because a radar has value for
measurement even when you can see.

Example 1: If you need to anchor in a confined space, and the
obstructions all show on the radar, you can maximize your scope by
finding the center of a range circle that just kisses the three
nearest obstructions.

2) Your chart shows you the safe distance from a headland. You put a
circle of that radius on the screen. and steer so it doesn't
intersect.

3) When you see a ship, you can put a bearing line on it and a range
circle. If the ship comes inside the circle without moving off the
bearing line you need to take action.

In general, you will find that an accurate plan view of the
surroundings is a valuable supplement to eyeballs.

Radar vs GPS/Sounder
 

Rodney Myrvaagnes wrote:

Or, to put it differently, what ELSE is radar good for? Can I use it to
determine if a freighter 10 miles away is on a collision course with me? Do
others normally run with radar on, even if it's clear? Why?

That is actually a different question, because a radar has value for
measurement even when you can see.

Example 1: If you need to anchor in a confined space, and the
obstructions all show on the radar, you can maximize your scope by
finding the center of a range circle that just kisses the three
nearest obstructions.

2) Your chart shows you the safe distance from a headland. You put a
circle of that radius on the screen. and steer so it doesn't
intersect.

3) When you see a ship, you can put a bearing line on it and a range
circle. If the ship comes inside the circle without moving off the
bearing line you need to take action.

In general, you will find that an accurate plan view of the
surroundings is a valuable supplement to eyeballs.

Radar vs GPS/Sounder
 

On Tue, 02 Dec 2003 19:18:13 GMT, Me wrote:

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.

Good summary, thanks. One might just add that the lifeboat equipment
is called SARTs , Search And Rescue Transponder. Echoes 9 dots if I
remember correctly. Luckily never seen one.


/Marcus

--
Marcus AAkesson
Gothenburg Callsigns: SM6XFN & SB4779
Sweden
Keep the world clean - no HTML in news or mail !

Radar vs GPS/Sounder
 

On Tue, 02 Dec 2003 19:18:13 GMT, Me wrote:

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.

Good summary, thanks. One might just add that the lifeboat equipment
is called SARTs , Search And Rescue Transponder. Echoes 9 dots if I
remember correctly. Luckily never seen one.


/Marcus

--
Marcus AAkesson
Gothenburg Callsigns: SM6XFN & SB4779
Sweden
Keep the world clean - no HTML in news or mail !

Radar vs GPS/Sounder
 

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

Radar vs GPS/Sounder
 

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

Radar vs GPS/Sounder
 

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