FAA "Centers" have primary radar?

[Danny Deger]

In another thread I am in a discussion on radar capability for FAA
"Centers". My recollection is that they typically have no primary radar,
thus no capability to paint weather. Someone is telling me they do.
Anybody out there have the answer. Maybe some do and some don't, and the
ones I used in the past don't.

--
Danny Deger

NASA offered me $15,000 to take down my web site. Take a look and see why.
www.dannydeger.net

[Ian MacLure]

"Danny Deger" > wrote in
:

> In another thread I am in a discussion on radar capability for FAA
> "Centers". My recollection is that they typically have no primary radar,
> thus no capability to paint weather. Someone is telling me they do.
> Anybody out there have the answer. Maybe some do and some don't, and the
> ones I used in the past don't.

Centers have responsibility for large areas of airspace. Any radar
capability they have beyond their immediate vicinity would be the
result of fused results from a number of remote sites.

IBM

[Danny Deger]

"Ian MacLure" > wrote in message
...
> "Danny Deger" > wrote in
> :
>
>> In another thread I am in a discussion on radar capability for FAA
>> "Centers". My recollection is that they typically have no primary radar,
>> thus no capability to paint weather. Someone is telling me they do.
>> Anybody out there have the answer. Maybe some do and some don't, and the
>> ones I used in the past don't.
>
> Centers have responsibility for large areas of airspace. Any radar
> capability they have beyond their immediate vicinity would be the
> result of fused results from a number of remote sites.

Then they must have fused results, because everytime I have worked with a
Center, they can see my transponder. The question is -- do they have
primary radar capability?

Danny Deger

[Dave S]

Danny Deger wrote:

>
> Then they must have fused results, because everytime I have worked with
> a Center, they can see my transponder. The question is -- do they have
> primary radar capability?
>
> Danny Deger

This is not a direct answer to your question. Sorry.

When I toured Houston Center pre-911 there were Nexrad type weather
displays in one corner, at the traffic management/weather specialists
area. The individual sectors did not have this display.

I remember asking about primary versus secondary and was told there was
backup secondary radar, as well as primary capability at the sectors.

Also when on a long cross country wth an instructor (whom I will never
fly with again) we were in contact with center, trying to punch a front
line in IMC. It was either Fr Worth or Houston Center, and the
controller had some sort of weather return because my instructor was
asking for, and taking vectors through the line.

So I want to say yes to your question. But I cant prove it positively.

Dave

[Danny Deger]

"Bob" > wrote in message
...
> On Sun, 5 Aug 2007 15:43:29 -0500, "Danny Deger"
> > wrote:
>
>>In another thread I am in a discussion on radar capability for FAA
>>"Centers". My recollection is that they typically have no primary radar,
>>thus no capability to paint weather. Someone is telling me they do.
>>Anybody out there have the answer. Maybe some do and some don't, and the
>>ones I used in the past don't.
>
> "FAA Primary En Route Long Range Radar Restructuring Program
> The FAA currently uses and supports 126 primary en route radar
> facilities. The FAA is chartered to provide Primary radar services to
> all federal agencies requiring this data to meet their operational
> missions."
> http://www.faa.gov/asd/ia-or/longrangeradar.htm

Thanks for the link. I found it very useful. I think my confusion comes
from an accident where a friend of mine died because Washington Center lost
radar contact when he lost his transponder. He was out over the ocean in a
warning area. We were briefed Washington Center had no ability to skin
paint. I am starting to realize this probably had to do only with this
situation of being over the ocean in a warning area and Centers in general
have skin paint capable radars.

If anyone is interested in the details of this fatal flight, I put them in
my book, "Houston, You Have a Problem" and you can get it for free at
www.dannydeger.net

Danny Deger

[Danny Deger]

--
Danny Deger

NASA offered me $15,000 to take down my web site. Take a look and see why.
www.dannydeger.net
"Dave S" > wrote in message
...
> Danny Deger wrote:
>
>>
>> Then they must have fused results, because everytime I have worked with a
>> Center, they can see my transponder. The question is -- do they have
>> primary radar capability?
>>
>> Danny Deger
>
> This is not a direct answer to your question. Sorry.
>
> When I toured Houston Center pre-911 there were Nexrad type weather
> displays in one corner, at the traffic management/weather specialists
> area. The individual sectors did not have this display.
>
> I remember asking about primary versus secondary and was told there was
> backup secondary radar, as well as primary capability at the sectors.
>
> Also when on a long cross country wth an instructor (whom I will never fly
> with again) we were in contact with center, trying to punch a front line
> in IMC. It was either Fr Worth or Houston Center, and the controller had
> some sort of weather return because my instructor was asking for, and
> taking vectors through the line.
>
> So I want to say yes to your question. But I cant prove it positively.
>
> Dave

Thanks. This was very useful.

Danny Deger

[Luke Skywalker]

On Aug 5, 3:43 pm, "Danny Deger" > wrote:
> In another thread I am in a discussion on radar capability for FAA
> "Centers". My recollection is that they typically have no primary radar,
> thus no capability to paint weather. Someone is telling me they do.
> Anybody out there have the answer. Maybe some do and some don't, and the
> ones I used in the past don't.
>
> --
> Danny Deger
>
> NASA offered me $15,000 to take down my web site. Take a look and see why.www.dannydeger.net

Danny.

Center Radar is a L Band search APSR-4 with skin paint capability of 1
meter at I think 60 miles...at 100 it is less...

These are old radars dating back to the first go at a radar center
system. The moderinzation project for the actual radar (not the data
display) started in (if memory serves) 1989...the idea was to improve
the reciever/transmitter section and split off a feed for digital wx
data much as has been done for the ASR-9 and 11...this required a new
feed horn for the RX to allow reception of circularly polarized (good
for airplane tracking) and linear returns (good for WX)...

I know the one at the FAA HQ in OKC has been done (it is a hugh
monster) and I think that ATL, HOU and I want to say ABQ centers have
had all of their sites modernized...

But as it goes everything went over budget and by 2001 they are
thinking about not modernizing the system and just going to a
secondary (ie transponder system)...then 9/11 happened and that ended
all that discussion.

A trip to OKC is pretty good. When I was there for safety school I
took the ATC tour and part of it is that a knowledgable person takes
you "outside" and points out what all the radars (there are a lot of
them I counted over 18) do.

I had driven up for safety school (and am a amateur radio operator)
and had my portable specturm analyser...that was an eye opener.

Robert

[BT]

you are asking the wrong question..
"Primary Radar" tuned to detect aircraft "skin paint" is not tuned to detect
weather.
Consider that if the Primary Radar where tuned to weather.. than a major
rain storm or thunder storm would cause radar attenuation and could not
detect the "skin paint" behind the weather.

There is a move afoot to have NEXRAD displays at the controller stations,
but those should not be used to direct an aircraft "between cells", but to
know where the less severe weather areas are to move traffic through and
avoid areas that aircraft do not like to fly through.

B

"Danny Deger" > wrote in message
...
> In another thread I am in a discussion on radar capability for FAA
> "Centers". My recollection is that they typically have no primary radar,
> thus no capability to paint weather. Someone is telling me they do.
> Anybody out there have the answer. Maybe some do and some don't, and the
> ones I used in the past don't.
>
> --
> Danny Deger
>
> NASA offered me $15,000 to take down my web site. Take a look and see
> why.
> www.dannydeger.net

[BT]

what was the altitude.. where you below the "radar horizon" for the range
from the antenna?
Was the "target aircraft" in a "blind radar area for the altitude" based on
a close in obstruction such as earth or building?

B

"Danny Deger" > wrote in message
...
> "Bob" > wrote in message
> ...
>> On Sun, 5 Aug 2007 15:43:29 -0500, "Danny Deger"
>> > wrote:
>>
>>>In another thread I am in a discussion on radar capability for FAA
>>>"Centers". My recollection is that they typically have no primary radar,
>>>thus no capability to paint weather. Someone is telling me they do.
>>>Anybody out there have the answer. Maybe some do and some don't, and the
>>>ones I used in the past don't.
>>
>> "FAA Primary En Route Long Range Radar Restructuring Program
>> The FAA currently uses and supports 126 primary en route radar
>> facilities. The FAA is chartered to provide Primary radar services to
>> all federal agencies requiring this data to meet their operational
>> missions."
>> http://www.faa.gov/asd/ia-or/longrangeradar.htm
>
> Thanks for the link. I found it very useful. I think my confusion comes
> from an accident where a friend of mine died because Washington Center
> lost radar contact when he lost his transponder. He was out over the
> ocean in a warning area. We were briefed Washington Center had no ability
> to skin paint. I am starting to realize this probably had to do only with
> this situation of being over the ocean in a warning area and Centers in
> general have skin paint capable radars.
>
> If anyone is interested in the details of this fatal flight, I put them in
> my book, "Houston, You Have a Problem" and you can get it for free at
> www.dannydeger.net
>
> Danny Deger

[[email protected]]

On Aug 5, 3:58 pm, "Danny Deger" > wrote:
> "Bob" > wrote in message
>
> ...
>
> > On Sun, 5 Aug 2007 15:43:29 -0500, "Danny Deger"
> > > wrote:
>
> >>In another thread I am in a discussion on radar capability for FAA
> >>"Centers". My recollection is that they typically have no primary radar,
> >>thus no capability to paint weather. Someone is telling me they do.
> >>Anybody out there have the answer. Maybe some do and some don't, and the
> >>ones I used in the past don't.
>
> > "FAA Primary En Route Long Range Radar Restructuring Program
> > The FAA currently uses and supports 126 primary en route radar
> > facilities. The FAA is chartered to provide Primary radar services to
> > all federal agencies requiring this data to meet their operational
> > missions."
> >http://www.faa.gov/asd/ia-or/longrangeradar.htm
>
> Thanks for the link. I found it very useful. I think my confusion comes
> from an accident where a friend of mine died because Washington Center lost
> radar contact when he lost his transponder. He was out over the ocean in a
> warning area. We were briefed Washington Center had no ability to skin
> paint. I am starting to realize this probably had to do only with this
> situation of being over the ocean in a warning area and Centers in general
> have skin paint capable radars.

My understanding of FAA radar is the transponder is just used to ID
the aircraft and provide altitude information. A plane with a
defective transponder can be seen on radar, but no ID or altitude.
The transponder is pinged at 1030MHz, and responds on 1090MHz. I
believe the actually locating radar is in a different band. Note the
911 hijackers turned off the transponders, but the planes were still
tracked.

Someone mentioned secondary surveillance. This is mode-s. It is also
on 1030/1090Mhz. However, the reply from the transponder is more
detailed. It contains a unique code for each aircraft. The older
transponders simply return the squawk code that was assigned by ATC
and entered by the pilot. Some mode-s can return airspace and
location.

http://mit.edu/6.933/www/Fall2000/mode-s/
http://adsb.tc.faa.gov/




>
> If anyone is interested in the details of this fatal flight, I put them in
> my book, "Houston, You Have a Problem" and you can get it for free atwww.dannydeger.net
>
> Danny Deger

[150flivver]

On Aug 6, 1:56 am, wrote

> Someone mentioned secondary surveillance. This is mode-s. It is also
> on 1030/1090Mhz. However, the reply from the transponder is more
> detailed. It contains a unique code for each aircraft. The older
> transponders simply return the squawk code that was assigned by ATC
> and entered by the pilot. Some mode-s can return airspace and
> location.
>
> http://mit.edu/6.933/www/Fall2000/mode-s/http://adsb.tc.faa.gov/

Secondary radar is the term for any transponder mode radar--A, C or S.

[ATControlr]

On Aug 5, 4:43 pm, "Danny Deger" > wrote:
> In another thread I am in a discussion on radar capability for FAA
> "Centers". My recollection is that they typically have no primary radar,
> thus no capability to paint weather. Someone is telling me they do.
> Anybody out there have the answer. Maybe some do and some don't, and the
> ones I used in the past don't.
>
> --
> Danny Deger
>
> NASA offered me $15,000 to take down my web site. Take a look and see why.www.dannydeger.net

FAA Centers do have the capability to paint primary targets. The
quality of radar coverage for primary targets is somewhat spotty. A
primary may or may not be painted depending on a lot of different
circumstances. Weather affects this capability too. Since we do have
primary capability, it can paint flocks of birds, weather, non-
transponder equipped planes, etc. We have recently gotten an upgrade
to our scopes that allows better weather depiction. Previously weather
depiction was very inaccurate. Our radar antennas turn at a speed
twice that or normal weather radar so our depiction used to be very
poor. I am an air traffic controller - 27+ years.

[Danny Deger]

"BT" > wrote in message
...
> what was the altitude.. where you below the "radar horizon" for the range
> from the antenna?
> Was the "target aircraft" in a "blind radar area for the altitude" based
> on a close in obstruction such as earth or building?

Good question, but wouldn't the things you talk about affect the secondary
radar as well.

They were out over the Atlantic Ocean in a miltary Warning Area under the
control of Washington Center. After the acident, we were all briefed if we
lost our transponder Washington Center could not paint us. Apparently this
is not true for Centers in general. Maybe it had to do with Washington
Center's radar coverage out over the Atlantic.

You can read the details in my free book you can get at my web site
www.dannydeger.net. Look on page 31. I have lots of other good flying
stories in the book you might enjoy.

Danny Deger
>
> B
>
> "Danny Deger" > wrote in message
> ...
>> "Bob" > wrote in message
>> ...
>>> On Sun, 5 Aug 2007 15:43:29 -0500, "Danny Deger"
>>> > wrote:
>>>
>>>>In another thread I am in a discussion on radar capability for FAA
>>>>"Centers". My recollection is that they typically have no primary
>>>>radar,
>>>>thus no capability to paint weather. Someone is telling me they do.
>>>>Anybody out there have the answer. Maybe some do and some don't, and
>>>>the
>>>>ones I used in the past don't.
>>>
>>> "FAA Primary En Route Long Range Radar Restructuring Program
>>> The FAA currently uses and supports 126 primary en route radar
>>> facilities. The FAA is chartered to provide Primary radar services to
>>> all federal agencies requiring this data to meet their operational
>>> missions."
>>> http://www.faa.gov/asd/ia-or/longrangeradar.htm
>>
>> Thanks for the link. I found it very useful. I think my confusion comes
>> from an accident where a friend of mine died because Washington Center
>> lost radar contact when he lost his transponder. He was out over the
>> ocean in a warning area. We were briefed Washington Center had no
>> ability to skin paint. I am starting to realize this probably had to do
>> only with this situation of being over the ocean in a warning area and
>> Centers in general have skin paint capable radars.
>>
>> If anyone is interested in the details of this fatal flight, I put them
>> in my book, "Houston, You Have a Problem" and you can get it for free at
>> www.dannydeger.net
>>
>> Danny Deger
>
>

[Luke Skywalker]

On Aug 6, 1:56 am, wrote:
>
>
> Someone mentioned secondary surveillance. This is mode-s. It is also
> on 1030/1090Mhz. However, the reply from the transponder is more
> detailed. It contains a unique code for each aircraft. The older
> transponders simply return the squawk code that was assigned by ATC
> and entered by the pilot. Some mode-s can return airspace and
> location.
>
> http://mit.edu/6.933/www/Fall2000/mode-s/http://adsb.tc.faa.gov/
>
>
>
Secondary "radar" is any type of system where the target is an active
particpant in the radio direction and ranging system. In the US civil
airways system this can be mode a/c/s and it is all the same (more or
less) technical description...

aka the main Secondary system sends out an interrogation pulse on one
frequency and the target replies on another. The times are measured
(ie time main pulse went out and secondary pulse recieved) and hence
range is achieved. Direction is based on the pointing of the primary
interrogator.

"Beacon" Antennas are commonly (but not always) co located with main
primary radar...they will generally be the "flat" rectangle on top of
the main (larger) antenna. They can stand alone...and that is common
in places like Canada and Austrailia...they require far less power
then primary or skin paint radars.

Beacon (ie secondary radar) was a US invention in WWII...It was called
"IFF" identification friend or foe".

What seperates a primary radar for ATC and one for WX are the
characteristics of the radar. Frequency is important but more so are
pulse repetition rate (PRR), polarization, and antenna rotation rate.
Most people think that there is one "echo returned" from a
target...this is not correct.

The PRR and antenna rotation rate are designed to maximise the number
of "Paints" of a target on a particular sweep.

Robert

[Luke Skywalker]

On Aug 6, 8:30 am, ATControlr > wrote:
> On Aug 5, 4:43 pm, "Danny Deger" > wrote:
>
> > In another thread I am in a discussion on radar capability for FAA
> > "Centers". My recollection is that they typically have no primary radar,
> > thus no capability to paint weather. Someone is telling me they do.
> > Anybody out there have the answer. Maybe some do and some don't, and the
> > ones I used in the past don't.
>
> > --
> > Danny Deger
>
> > NASA offered me $15,000 to take down my web site. Take a look and see why.www.dannydeger.net
>
> FAA Centers do have the capability to paint primary targets. The
> quality of radar coverage for primary targets is somewhat spotty. A
> primary may or may not be painted depending on a lot of different
> circumstances. Weather affects this capability too. Since we do have
> primary capability, it can paint flocks of birds, weather, non-
> transponder equipped planes, etc. We have recently gotten an upgrade
> to our scopes that allows better weather depiction. Previously weather
> depiction was very inaccurate. Our radar antennas turn at a speed
> twice that or normal weather radar so our depiction used to be very
> poor. I am an air traffic controller - 27+ years.

You seem amazingly lucid for having been a controller for almost 30
years. Congratulations. I would have blown a fuse in about 2 days!

Robert

[Danny Deger]

I would like thank everybody for all of the information. I have made
changes to my book to reflect Centers in general have skin paint capability.
There must be something unique about Washington Center's radar out over the
Atlantic Ocean Warning Areas that prevented them from getting a skin paint
on my friend's F-4.

The short summary of my friend's fatal flight is: he lost all electrical
power and decided to rejoin on another F-4 in the warning area. The lights
he picked out were not an F-4, but an airliner out over the ocean headed to
Miami (we were off the coast of North Carolina). By the time they realized
their mistake, they didn't have enough fuel to get back to land and ended up
bailing out in the ocean. 6 days later a fishing trawler picked up the back
seater and the front seater was never found. Without a skin paint, the
search and rescue forces looked in the wrong place.

More details in my book you can get for free from my web site. Feel free to
download and email to your friends.

--
Danny Deger

NASA offered me $15,000 to take down my web site. Take a look and see why.
www.dannydeger.net

[Luke Skywalker]

On Aug 6, 11:34 am, "Danny Deger" > wrote:
> I would like thank everybody for all of the information. I have made
> changes to my book to reflect Centers in general have skin paint capability.
> There must be something unique about Washington Center's radar out over the
> Atlantic Ocean Warning Areas that prevented them from getting a skin paint
> on my friend's F-4.
>
> The short summary of my friend's fatal flight is: he lost all electrical
> power and decided to rejoin on another F-4 in the warning area. The lights
> he picked out were not an F-4, but an airliner out over the ocean headed to
> Miami (we were off the coast of North Carolina). By the time they realized
> their mistake, they didn't have enough fuel to get back to land and ended up
> bailing out in the ocean. 6 days later a fishing trawler picked up the back
> seater and the front seater was never found. Without a skin paint, the
> search and rescue forces looked in the wrong place.
>
> More details in my book you can get for free from my web site. Feel free to
> download and email to your friends.
>
> --
> Danny Deger
>
> NASA offered me $15,000 to take down my web site. Take a look and see why.www.dannydeger.net

Danny

I would add this "thing" ...it might not be all that unique. it just
might be "how it is"...for all centers.

The SSR range for a "radar" is (because of the active particpant) must
longer then skin paint. I dont know what year it was, but the
"computer" system probably rejected the target in part because of some
"angle" issues (ie two systems were painting it and it fell out of a
"cell" ie both radars present information to the computer and the
computer gets confused because it cannot corelate teh target(s) and
just drops the target).

On 9/11 when the airlines went "primary" it was only some really
quick thinking by the folks at NY center that held them as targets.

The sad thing (different topic) is that more or less the FAA worked
"as advertised" on 9/11. They were about the only one.

Robert

[Eeyore[_2_]]

Danny Deger wrote:

> In another thread I am in a discussion on radar capability for FAA
> "Centers". My recollection is that they typically have no primary radar,
> thus no capability to paint weather.

There is no connection whatever between 'primary radar' and 'weather radar'.

The ability to detect storm clouds is related purely to the wavelength of the
radar transmission. A radar that was swamped by cloud returns would be utterly
useless as a primary radar !

Graham

[[email protected]]

In rec.aviation.piloting Danny Deger > wrote:
> I would like thank everybody for all of the information. I have made
> changes to my book to reflect Centers in general have skin paint capability.
> There must be something unique about Washington Center's radar out over the
> Atlantic Ocean Warning Areas that prevented them from getting a skin paint
> on my friend's F-4.

Or the F-4 was too small to paint, or the radar was broken that day, or
lots of other things could have been in play.

Having spent more hours than I care to remember behind military air
defense radar systems, I can say with some authority that a single
fighter is tough for any radar to see at long ranges.

--
Jim Pennino

Remove .spam.sux to reply.

[[email protected]]

In rec.aviation.piloting Eeyore > wrote:


> Danny Deger wrote:

> > In another thread I am in a discussion on radar capability for FAA
> > "Centers". My recollection is that they typically have no primary radar,
> > thus no capability to paint weather.

> There is no connection whatever between 'primary radar' and 'weather radar'.

> The ability to detect storm clouds is related purely to the wavelength of the
> radar transmission. A radar that was swamped by cloud returns would be utterly
> useless as a primary radar !

Bzzzt, wrong answer.

The ablility of radar to detect weather is related to frequency, antenna
polarization, antenna sweep rate, type (as in pure pulse versus doppler)
and signal processing (if any).

Most search radar used for finding airplanes won't see ordinary clouds
at all and are generally marginal for seeing precipitation unless you've
put something in the design to do both.



--
Jim Pennino

Remove .spam.sux to reply.

[Morgans[_2_]]

<jimp> wrote

> Having spent more hours than I care to remember behind military air
> defense radar systems, I can say with some authority that a single
> fighter is tough for any radar to see at long ranges.

Yeah, and I even heard that they now make fighters nearly impossible to see
on primary radar, ON PURPOSE ! ! ! <g>
--
Jim in NC

[Luke Skywalker]

On Aug 6, 12:10 pm, Eeyore >
wrote:
> Danny Deger wrote:
> > In another thread I am in a discussion on radar capability for FAA
> > "Centers". My recollection is that they typically have no primary radar,
> > thus no capability to paint weather.
>
> There is no connection whatever between 'primary radar' and 'weather radar'.
>
> The ability to detect storm clouds is related purely to the wavelength of the
> radar transmission. A radar that was swamped by cloud returns would be utterly
> useless as a primary radar !
>
> Graham

No...the least useful measure of what kind of radar a device is is its
frequency.

the "innards" mostly are what determines what kind of radar a
particular device is.

Robert

[Eeyore[_2_]]

wrote:

> In rec.aviation.piloting Eeyore > wrote:
> > Danny Deger wrote:
>
> > > In another thread I am in a discussion on radar capability for FAA
> > > "Centers". My recollection is that they typically have no primary radar,
> > > thus no capability to paint weather.
>
> > There is no connection whatever between 'primary radar' and 'weather radar'.
>
> > The ability to detect storm clouds is related purely to the wavelength of the
> > radar transmission. A radar that was swamped by cloud returns would be utterly
> > useless as a primary radar !
>
> Bzzzt, wrong answer.
>
> The ablility of radar to detect weather is related to frequency, antenna
> polarization, antenna sweep rate, type (as in pure pulse versus doppler)
> and signal processing (if any).

Mainly frequency actually. If not ENTIRELY frequency. The effect was found by
accident during WW2 btw.

Graham

[William R. Frensley]

Danny Deger wrote:
> I would like thank everybody for all of the information. I have made
> changes to my book to reflect Centers in general have skin paint
> capability. There must be something unique about Washington Center's
> radar out over the Atlantic Ocean Warning Areas that prevented them from
> getting a skin paint on my friend's F-4.
>
There is one other aspect of primary radar that does not seem to have
been discussed: Most, if not all, airspace surveillance radars use a
"Moving Target Indicator" system to filter out the returns from fixed
terrain and structures. In essence this is a very narrow notch filter
centered at the radar's transmit frequency. Only returns that are
doppler-shifted a detectable amount from the transmit frequency are
painted on the display. This makes it difficult to detect turbojet
aircraft that are moving tangentially to the radar site. Rotating
propellers, on the other hand, usually produce a nice
frequency-broadened return and are usually easy to detect.

- Bill Frensley

[[email protected]]

In rec.aviation.piloting Eeyore > wrote:


> wrote:

> > In rec.aviation.piloting Eeyore > wrote:
> > > Danny Deger wrote:
> >
> > > > In another thread I am in a discussion on radar capability for FAA
> > > > "Centers". My recollection is that they typically have no primary radar,
> > > > thus no capability to paint weather.
> >
> > > There is no connection whatever between 'primary radar' and 'weather radar'.
> >
> > > The ability to detect storm clouds is related purely to the wavelength of the
> > > radar transmission. A radar that was swamped by cloud returns would be utterly
> > > useless as a primary radar !
> >
> > Bzzzt, wrong answer.
> >
> > The ablility of radar to detect weather is related to frequency, antenna
> > polarization, antenna sweep rate, type (as in pure pulse versus doppler)
> > and signal processing (if any).

> Mainly frequency actually. If not ENTIRELY frequency. The effect was found by
> accident during WW2 btw.

Nonsense.

When you have a few years with L, S, X, and Ku band radars come back
and tell me what you have learned about the real world.

While you're at it, read up on linear polarization versus circular
polarization.

--
Jim Pennino

Remove .spam.sux to reply.

[Luke Skywalker]

On Aug 6, 1:52 pm, "William R. Frensley" >
wrote:
> Danny Deger wrote:
> > I would like thank everybody for all of the information. I have made
> > changes to my book to reflect Centers in general have skin paint
> > capability. There must be something unique about Washington Center's
> > radar out over the Atlantic Ocean Warning Areas that prevented them from
> > getting a skin paint on my friend's F-4.
>
> There is one other aspect of primary radar that does not seem to have
> been discussed: Most, if not all, airspace surveillance radars use a
> "Moving Target Indicator" system to filter out the returns from fixed
> terrain and structures. In essence this is a very narrow notch filter
> centered at the radar's transmit frequency. Only returns that are
> doppler-shifted a detectable amount from the transmit frequency are
> painted on the display. This makes it difficult to detect turbojet
> aircraft that are moving tangentially to the radar site. Rotating
> propellers, on the other hand, usually produce a nice
> frequency-broadened return and are usually easy to detect.
>
> - Bill Frensley

Excellent point...I was trying desperatly to stay out of MTI!...

Most of the MTI's I am aware of occur in the baseband data
processing...but I suspect that the APRS 4 has a notch filter...or
did.

Robert

[Bertie the Bunyip[_19_]]

Eeyore > wrote in
:

>
>
> Danny Deger wrote:
>
>> In another thread I am in a discussion on radar capability for FAA
>> "Centers". My recollection is that they typically have no primary
>> radar, thus no capability to paint weather.
>
> There is no connection whatever between 'primary radar' and 'weather
> radar'.
>
> The ability to detect storm clouds is related purely to the wavelength
> of the radar transmission. A radar that was swamped by cloud returns
> would be utterly useless as a primary radar !
>
> Graham
>
>



Wrong


Bertie

[Bertie the Bunyip[_19_]]

Eeyore > wrote in
:

>
>
> wrote:
>
>> In rec.aviation.piloting Eeyore
>> > wrote:
>> > Danny Deger wrote:
>>
>> > > In another thread I am in a discussion on radar capability for
>> > > FAA "Centers". My recollection is that they typically have no
>> > > primary radar, thus no capability to paint weather.
>>
>> > There is no connection whatever between 'primary radar' and
>> > 'weather radar'.
>>
>> > The ability to detect storm clouds is related purely to the
>> > wavelength of the radar transmission. A radar that was swamped by
>> > cloud returns would be utterly useless as a primary radar !
>>
>> Bzzzt, wrong answer.
>>
>> The ablility of radar to detect weather is related to frequency,
>> antenna polarization, antenna sweep rate, type (as in pure pulse
>> versus doppler) and signal processing (if any).
>
> Mainly frequency actually. If not ENTIRELY frequency. The effect was
> found by accident during WW2 btw.


You're sitll wrong


Bertie

[Owen[_4_]]

Danny Deger wrote:

> In another thread I am in a discussion on radar capability for FAA
> "Centers". My recollection is that they typically have no primary radar,
> thus no capability to paint weather. Someone is telling me they do.
> Anybody out there have the answer. Maybe some do and some don't, and the
> ones I used in the past don't.

The answer is "it depends." Many enroute U.S. radar sites DO have primary
radar coverage. However there are also plenty so-called "beacon only" sites
that only interogate transponders. These sites are less expensive to install,
particularly in remote areas where installations and electric is at a premium.
The long term trend of FAA was to have less and less full blown primary radar
coverage, similar to what many other countries were already doing for their
civil aviation. The FAA's strategy changed in September, 2001. Primary
coverage will be with us to stay, and may even be expanded in some areas.

Air traffic control radar is optimized and sized for finding airplanes, not
rain drops. Newer center facilities use weather radar (Nexrad) to provide
their weather information on their screens.

I highly recommend taking a tour of any local TRACON and ARTCC facilities. You
will need a pre-approved appointment and may have to provide your information
well in advance. Participating as part of a small group (such as an instrument
ground school course) may be helpful.

The new center and approach faciltiies have wonderful equipment and radar
displays. I cringe whenever I hear a politician say that we haven't invested a
penny in air traffic control for forty years. It took a long time, yes, but
the upgrades are paying dividends. Now to redesign the airspace maps......

[[email protected]]

On Aug 6, 8:49 am, Luke Skywalker > wrote:
> On Aug 6, 1:56 am, wrote:
>
> > Someone mentioned secondary surveillance. This is mode-s. It is also
> > on 1030/1090Mhz. However, the reply from the transponder is more
> > detailed. It contains a unique code for each aircraft. The older
> > transponders simply return the squawk code that was assigned by ATC
> > and entered by the pilot. Some mode-s can return airspace and
> > location.
>
> >http://mit.edu/6.933/www/Fall2000/mode-s/http://adsb.tc.faa.gov/
>
> Secondary "radar" is any type of system where the target is an active
> particpant in the radio direction and ranging system. In the US civil
> airways system this can be mode a/c/s and it is all the same (more or
> less) technical description...
>
> aka the main Secondary system sends out an interrogation pulse on one
> frequency and the target replies on another. The times are measured
> (ie time main pulse went out and secondary pulse recieved) and hence
> range is achieved. Direction is based on the pointing of the primary
> interrogator.
>
> "Beacon" Antennas are commonly (but not always) co located with main
> primary radar...they will generally be the "flat" rectangle on top of
> the main (larger) antenna. They can stand alone...and that is common
> in places like Canada and Austrailia...they require far less power
> then primary or skin paint radars.
>
> Beacon (ie secondary radar) was a US invention in WWII...It was called
> "IFF" identification friend or foe".
>
> What seperates a primary radar for ATC and one for WX are the
> characteristics of the radar. Frequency is important but more so are
> pulse repetition rate (PRR), polarization, and antenna rotation rate.
> Most people think that there is one "echo returned" from a
> target...this is not correct.
>
> The PRR and antenna rotation rate are designed to maximise the number
> of "Paints" of a target on a particular sweep.
>
> Robert

Are you saying FAA radar determines the position from the l-band
interrogation signal? This is not the case. The primary radar is
around 2.8GHz.

[Newps]

Owen wrote:
The FAA's strategy changed in September, 2001.


Yes.



Primary
> coverage will be with us to stay, and may even be expanded in some areas.


Radar's days are limited. After ADS-B gets rolled out radar sites will
be decommissioned.

[Morgans[_2_]]

"Newps" <> wrote

> Radar's days are limited. After ADS-B gets rolled out radar sites will be
> decommissioned.

So, will all GA aircraft be required to have an ADS-B system onboard?
--
Jim in NC

[Bob Noel]

In article >,
Newps > wrote:

> Primary
> > coverage will be with us to stay, and may even be expanded in some areas.
>
> Radar's days are limited. After ADS-B gets rolled out radar sites will
> be decommissioned.

Primary radar will remain in the NAS until the US Air Defense Sectors aren't
required to monitor the NAS. Civilian ATC might not use them, the NORAD, etc
will still require primary radars.

--
Bob Noel
(goodness, please trim replies!!!)

[Peter Dohm]

"Luke Skywalker" > wrote in message
ps.com...
> On Aug 6, 8:30 am, ATControlr > wrote:
> > On Aug 5, 4:43 pm, "Danny Deger" > wrote:
> >
> > > In another thread I am in a discussion on radar capability for FAA
> > > "Centers". My recollection is that they typically have no primary
radar,
> > > thus no capability to paint weather. Someone is telling me they do.
> > > Anybody out there have the answer. Maybe some do and some don't, and
the
> > > ones I used in the past don't.
> >
> > > --
> > > Danny Deger
> >
> > > NASA offered me $15,000 to take down my web site. Take a look and see
why.www.dannydeger.net
> >
> > FAA Centers do have the capability to paint primary targets. The
> > quality of radar coverage for primary targets is somewhat spotty. A
> > primary may or may not be painted depending on a lot of different
> > circumstances. Weather affects this capability too. Since we do have
> > primary capability, it can paint flocks of birds, weather, non-
> > transponder equipped planes, etc. We have recently gotten an upgrade
> > to our scopes that allows better weather depiction. Previously weather
> > depiction was very inaccurate. Our radar antennas turn at a speed
> > twice that or normal weather radar so our depiction used to be very
> > poor. I am an air traffic controller - 27+ years.
>
> You seem amazingly lucid for having been a controller for almost 30
> years. Congratulations. I would have blown a fuse in about 2 days!
>
> Robert
>

I share your sentiments, and your limitation, but you still owe me a
keyboard!

Peter

[Luke Skywalker]

On Aug 6, 10:29 pm, Newps > wrote:
> Owen wrote:
>
> The FAA's strategy changed in September, 2001.
>
> Yes.
>
> Primary
>
> > coverage will be with us to stay, and may even be expanded in some areas.
>
> Radar's days are limited. After ADS-B gets rolled out radar sites will
> be decommissioned.

Maybe but my guess is maybe not. Air Traffic Control might "primary"
off of some other form of "radio direction and ranging" but 9/11
pointed out that "primary" still does its job. I am 40...if I Live as
long as my Father has (so far) or my Great Grandfather (106) I suspect
that "primary" is still radiating.

Robert

[[email protected]]

On Aug 6, 9:34 am, "Danny Deger" > wrote:
> I would like thank everybody for all of the information. I have made
> changes to my book to reflect Centers in general have skin paint capability.
> There must be something unique about Washington Center's radar out over the
> Atlantic Ocean Warning Areas that prevented them from getting a skin paint
> on my friend's F-4.
>
> The short summary of my friend's fatal flight is: he lost all electrical
> power and decided to rejoin on another F-4 in the warning area. The lights
> he picked out were not an F-4, but an airliner out over the ocean headed to
> Miami (we were off the coast of North Carolina). By the time they realized
> their mistake, they didn't have enough fuel to get back to land and ended up
> bailing out in the ocean. 6 days later a fishing trawler picked up the back
> seater and the front seater was never found. Without a skin paint, the
> search and rescue forces looked in the wrong place.
>
> More details in my book you can get for free from my web site. Feel free to
> download and email to your friends.
>
> --
> Danny Deger
>
> NASA offered me $15,000 to take down my web site. Take a look and see why.www.dannydeger.net

F-4. Is this some old event? That certainly changes the discussion.
At least mode-s is out of the question.

[Danny Deger]

> wrote in message
oups.com...
> On Aug 6, 9:34 am, "Danny Deger" > wrote:
snip

> F-4. Is this some old event? That certainly changes the discussion.
> At least mode-s is out of the question.
>

It happened in about 1983. You can read up on the details in my book you
can download for free.

Danny Deger
www.dannydeger.net

[David Lesher]

Newps > writes:



>Owen wrote:
> The FAA's strategy changed in September, 2001.

> Primary
>> coverage will be with us to stay, and may even be expanded in some areas.


>Radar's days are limited. After ADS-B gets rolled out radar sites will
>be decommissioned.


I doubt that. I've no doubt they'll be downgraded, but as much as the FAA
would love to unplug them, other folks will object.

That said, while the primary radar exists; I hear it's less and less well
maintained. Hopefully it can still spot invading Zeppelins but lesser
targets...?

[Pre WWII, the Germans flew the Graf Zeppelin airship around looking
to see if the British had radar. Trouble was, they were not listening
anywhere near the ~30 Mhz freq. used by the Brit's system.. Needless to
say, to Chain Home it must have looked like a parachute flare in a pitch
black darkroom...]

--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433