Talk:Radar

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Contents 1 UK's vs US' contributions 2 MIT Rad Lab & I. I. Rabi 3 General vs military radar 4 French early contributions 5 Chain home; RDF1 book; WWII Proximity fuse 6 British (+German?) bias? 7 Frequency range(s) wanted 8 Scientific use of Radar 9 How to shorten the article since it's well above the 32k limit? 10 Radar Intrusion Detection Devices 11 i don't see the small square 12 Radar versus RADAR 13 Request for references 14 K band useless? 15 History 16 Civilan and military RADAR 17 neologism? 18 Band designations 19 Etymology 20 Radar history 21 LIDAR and RADAR interfering with one another 22 Functions and roles; civilian situation awareness systems missing 23 Continuous Wave, it can or can not measure distance? 24 Automated Review 25 ? 26 Any information on "Airadar"? 27 Sea Clutter

[edit] UK's vs US' contributions

There was a claim on the Manhattan Project page that radar was invented at MIT. I thought it was at least partly a British invention. Anybody got more details? --Robert Merkel

The key individual role (most such inventions are collaborative even if those responsible for the individual contributions never met each other) is credited to Robert Watson-Watt (1892-1973) of Brechin, Angus, Scotland. Moving from the Royal Aircraft Factory (Farnborough, Hampshire) to the Radio Research Station (later part of the National Physical Laboratory) in Slough, (then in Buckinghamshire, but now now part of Berkshire) and then to a new NPL site at Teddington (then in Middlesex, but now in Surrey), he was asked by the Air Ministry to investigate a counterpart to an alleged German aircraft-killing "death ray".

Concluding that the power needed made it impractical to fry bombers out of the sky, instead on 26 February 1935 he demonstrated the future radar by using the BBC's Daventry (Northamptonshire) short-wave radio transmitter and a receiver and oscilloscpe (housed in a former ambulance in a field seven miles away) to detect a Handley Page Heyford bomber at 27 km. Subsequently head of the Bawdsey research station in Felixstowe (Suffolk), Watson-Watt helped to develop the ring of radar stations established in 1938. He was knighted in 1942.

MIT's role came shortly afterward (1938-1940), developing in collaboration with Canadian researchers a fighter-borne system (the first British airborne experiment had been in September 1937, but still needed development). David Parker

[edit] MIT Rad Lab & I. I. Rabi

The following was floating around on the page, probably debris from an incomplete edit. Someone who knows this stuff could probably figure out where it belongs:

... especially at the Radiation Lab at MIT (I. I. Rabi) and played an important role in the outcome of the war.

--Ortolan88 12:56 Jul 25, 2002 (PDT)

It's from an old version, and has been replaced by a lengthy section of expanded text now. --Anonymous No.I

MIT still boasts that they are the ones that develiped it here's a video where MIT President Susan Hockfield says so... can anyone provide clarification on this? H0riz0n 02:01, 1 September 2006 (UTC)

[edit] General vs military radar

It seems useful to me to split this entry in two: one radar in general, and the other more focused on the military history side of it. I'm thinking of the link I'm about to make in an explicitly military context and seeing an article that doesn't deal with the stuff that it's appropriate to link to until you scroll quite a way down. And it's easy enough to imagine the contrary example, where you want to link to radar from an entry on a completely non-military area - microwave ovens or car safety devices or astronomomy, say. What do people think? Tannin 09:26 Jan 26, 2003 (UTC)

On the history section: it's a very good history of British and German developments, but US work deserves more mention, esp the Rad Lab stuff. Also, Watson-Watt gets too much prominence at present: he played an important role in the development of British radar, and an even more important role in the getting-to-say-who-invented-it-afterwards department, to the exclusion of several others. There is an excellent and fairly recent American history of the Rad Lab that covers this in detail. I have it here somewhere, just can't remember the title at the moment. Tannin 11:16 Jan 26, 2003 (UTC)

Found it! Added it to main article. Tannin

[edit] French early contributions

I should verify but according to some sources the French engineers of the CFS had active research on the radar before ww II, they gave their technology to the British in 1939. Ericd

There a PD article at http://www.vectorsite.net/ttwiz1.html you can cut and paste as you want. Ericd

here is a source about French researchs http://sjdangle.free.fr/societe/ponte.htm Ericd 12:10 Jan 26, 2003 (UTC) http://www.radar-france.net/Girardeau_memoire_radar.htm

[edit] Chain home; RDF1 book; WWII Proximity fuse

One of the big achievements of the British WWII radar system was in developing the handling of the information from the radar stations. They started work on this before the system was working fully. Chain Home might have been primitive in many ways but was in use right through WWII and was providing valuable information on V2 launches towards the end of the war.

I quite agree that Robert Budari's book on the Rad Lab gives a good overall picture of radar in WWII. The best book that I have found on the British ground based radar system is ...

RDF1 by Michael Bragg Published by Hawkhead Publishing ISBN 0953154408 [1]

It follows the story in chronological order.

By the way, the WWII Proximity Fuse was not a true radar (i.e. pulse) device. It used a continuous carrier and the doppler effect to detect its proximity to an aircraft or the ground.

jmb

[edit] British (+German?) bias?

The article as it is written is very biased to British (and some German) radar work. As discussed in this article, technological advances seem to end about 1950. This simply isn't true.

When we look at the history, we certainly need to include in the early years - 1901 (I think) - Tesla delivers a paper before the Institution of Radio Engineers proposing, for the first time, radar. Maxwell developed the theory, Hertz was the first to show reflections of radio waves at UHF, and Tesla was the first to propose radar. The telemobiloscope of Hulsmeyer is not properly mentioned, and the shortcomings of the telemobiloscope that caused its economic and technical failure are not discussed. It is surely worthy of note that there were no real amplifiers until deForrest developed them and no good power sources for microwaves. The development of the first pulsed radar at the Naval Research Labs in 1924 to measure the height of the ionosphere is also quite worthy of note.

Developments in the early 1930s were not only done in Britain and Germany. The SCR-270 was in place and detected the Japanese attack on Pearl Harbor in 1941. US PBY Catalina aircraft detected the Bismarck for the British fleet, and it was this detection that allowed the sinking of the Bismarck. The Bismarck itself had an impressive targeting radar. By the early 1930s, there were excellent researchers in the United States, France, Italy, Russia, Britain, and Germany all working on radar. All achieved impressive results. The development of the SCR-584, which was the first modern anti-aircraft radar, in 1943, revolutionized aerial attacks. The SCR-584 at Anzio had, it is reported, a 70% probability of kill, eliminating German air attacks.

The airborne ground mapping radars, which reached their WWII height with the H2S and the H2X, should also be a part of this history. This is true not just because they were the first radars to show ground maps or because of their effectiveness, but because the whole idea of ground mapping from air or space is essentially overlooked in the article. The beginnings of ECM and ESM are also a critical development for radar.

After World War II, technology did not stop. Doppler radars came about in the 1960s, medium PRF in the 1970s, and the electronically scanned antenna mostly in the 1980s, a trend still going on today. Ground penetrating radars are another specialty area in which there has been considerable development. Vehicle navigation and anti-collision radars are worth a mention in the article. These are getting to be a big market. There are many CW radars in this subarea, and they do measure range with FM.

Well, that's just a few items. I would suggest that someone develop a credible outline for radar, then start fleshing it out. The current article looks like it was written by someone who does not understand the technical material, but has read a British history on the subject.

--Anonymous No.II

I agree with the previous post. I did some research on radar history, which has been documented in http://ghj-associates.co.uk/radar_history.html. To summerize my research, radar technology started with Karl Ferdinand Braun around 1897 when he invented oscilloscope tube and improved range of wireless. Marconi tried to steal Braun's patent and in the end Nobel prize for inventing wireless was awarded to both of them. In 1904 Christian Hulsmeyer filed a patent for radar. In 1929 German Navy, Reichsmarine started work on what we know today as sonar. This effort lead to the first magnetron build by Philips and establishing of GEMA, Gesellschaft für Elektroakustische und Mechanische a firm dedicated to radar research.

Dr. Hans Eric Hollmann, who worked on radar in Telefunken, filed some 300 patents on his work. All of Telefunken radar patents were filed in United States also, so any american radar developments were copies of Dr. Hans Eric Hollmann patents. In 1935 first radar was installed on the german ship "Welle". "Home Chain", which british started in 1937 operated on 27 MHz and compared to german radars operating at 125 MHz was a primitive device. In 1937 to 1938 germans installed hundreds of Freya radars as german early warning radar system with the range of between 60 to 120 km. In 1938 a new naval radar system instlaled on the battleship Admiral Graf Spee with a range of 11 miles, which operated on 375 MHz. During the war germany developed Wuerzburg radar to guide night fighters to the british bombers. This and many other radar developments started a jamming war between radar engineers on both sides of English Channel.

British transferred all their radar knowledge to americans in 1940, which started american efforts to build a vaiable radar in what was called "RadLab". "RadLab" designed all american radar devices and at the height of its operation employed 4000 people. I could not establish when the first american radar was produced but from my research it looks like 1941 would be the date. Americans could have purchased some radars from Telefunken in 1939 or even in 1940, since trade between war time germany and the rest of the world was vey active, but again I could not find any proof of that. Radars were also installed on polish bombers in 1939, most likely copies of german radars. From Polish Air Force radar technology most likely traveled to Russians, so it is prudent to assume that both Poles and Russians had german radar designs in 1939. From the first sonar development in German Navy radar was hidden behind a wall of military secresy and even today it is difficult to piece together the real order of events.

For the lack of proof of several important dates I do not feel competent to rewrite anglocentered propaganda of radar history page in Wikipedia, but it would be nice to have somebody with a better knowledge of the subject to present a true story of this fascinating device.

--Anonymous No.III

Seriously, add or edit a paragraph. It's easy to edit the Wiki one paragraph at a time. You've presented a good bit of information here, why not put SOME of that into the REAL page instead of the talk page. Rick Boatright 19:21, 7 Apr 2004 (UTC)

http://www.100-jahre-radar.de/vortraege/Holpp-The_Century_of_Radar.pdf --80.226.205.207 17:16, 8 November 2006 (UTC)

"US PBY Catalina aircraft detected the Bismarck for the British fleet""

Just to clarify things, it was a RAF Coastal Command Catalina with a USN pilot that detected the Bismarck. I don't think the Catalinas were supplied with radar fitted, that was probably done when they went to Saunders Roe at Beaumaris for preparation for RAF use. --jmb 17:54, 8 November 2006 (UTC)

The USA radar developing starting 1937 (the SCR 270 is copied German Freya Radar! ;) The first airborne radar's came from Great Britain. The multisegment magnetron inveted by Randall and Boot, Great Britain. --80.226.205.207 19:22, 8 November 2006 (UTC)

[edit] Frequency range(s) wanted

In the Frequency section, in addition to listings of a couple of 'bad' frequencies/frequency ranges, I would very much like to see an overview of the frequency range(s) used in all kinds of radar applications. That would make the article much more accessible and usable in a reference setting, I think. --Wernher 00:57, 26 Jun 2004 (UTC)

Thanks, Heron! :-) --Wernher 02:44, 5 Jul 2004 (UTC)

[edit] Scientific use of Radar

I'd like to see (or add) a section or a separate page on some of the current scientific uses for radar, particularly in my field of atmospheric/ionospheric research. In the ionosphere#Geophysics entry there is a link to Project HAARP, but there is much more to tell. The Arecibo Observatory was built to be a radar, a fact not obvious from the entry, and there is a handful of ionospheric incoherent scatter radars around the world. In addition, there is a large number of ionosondes and digisondes for automated ionospheric monitoring, and VHF meteor radars and coherent scatter radars for upper atmospheric research, as well as the SuperDARN radar chain of which the UK CUTLASS radar is just one pair of stations.

There is also the fascinating topic of passive radar, which probably deserves a section or page of its own.

I have read the various FAQs and tutorials for contributing to the 'pedia, and I'll be willing to contribute to these sections, if this is of interest. I'd appreciate opinions on structure, though. I.e., add a section or create separate page on scientific radar instruments, etc. Also, should I create an account before starting on such contributions?

--Tom Grydeland Tom.Grydeland@phys.uit.no

Thanks for your offer to contribute, Tom. I think we would all welcome your help. Here are my suggestions, which are by no means authoritative.

1. Get yourself a user account on Wikipedia (see Special:UserLogin). This is not obligatory, and some contributors manage fine without one, but it tends to encourage other users take you more seriously. You can advertise your email address, but many Wikipedians won't use it, preferring to keep all communications on the Wikipedia record.
2. Add a section to Radar summarising the scientific uses, and then, if you feel like going into more detail, add more articles on the more specialised topics. Personally, I feel that lots of medium-sized articles on the specific areas you mentioned, such as Cutlass, would be more interesting and easier to navigate than a huge amorphous article on "scientific radar", but others might disagree.
3. Beware of creating articles with ambiguous titles, such as "Cutlass". The convention here is to describe the most common sense of the term (i.e. the knife) in the article of that name, but to add a note at the top or bottom saying "See Cutlass (radar) for the scientific radar system."
4. Prepare yourself for lots of discussions and perhaps even arguments with other contributors, some better informed than others.

Best wishes, -- Heron 17:32, 27 Jun 2004 (UTC)

[edit] How to shorten the article since it's well above the 32k limit?

I wanted to make a small change but refrained due to the warning that it's already 38k and should be shortened or split up. Are there any ideas on how to do that? None looked obvious to me, but splitting it up seems prefereable to just shortening it, since all the information looks to be well worth keeping. Maybe split off the frequency bands since that is a very specialized thing that is probably not of interest to most readers, or condense the history section and move the contents to a radar history article? And does this Talk page count against the limit (probably not since it is a separate page, but just verifying)? Spalding 12:31, Sep 6, 2004 (UTC)

The 32k limit is a technical thing to work around a bug in some older browsers. If you want to make a small change in the short term, just go ahead. If the article is already 38k, then you won't make the problem any worse by expanding it to 39k. In the longer term, I would agree with splitting off the history section, although I would leave a single-paragraph summary here to satisfy the casual reader. Finally, the Talk page doesn't count towards the 32k. Thanks for taking the trouble to ask. --Heron 12:56, 6 Sep 2004 (UTC)

Spun lots material out to more appropiate seperate pages. Dan100 13:14, Jan 3, 2005 (UTC)

[edit] Radar Intrusion Detection Devices

I would like to see more about the use of radar as intrusion detection devices. I have been researching them as I am a Security Consultant and the literature that is out there is either slim or very old and out-dated. I have been trying to find the frequency range of a paticular device that is used as a short range, low crawl detector. It is a Doppler short-beam radar. The specs do not give a frequency, they give a range of 32 feet and a delay of .5 to 2 seconds. I'm a security specialist, not an engineer.

If I happened to have missed this within the pages of this article, forgive me. If not, please guide me....

ALWAYS LEARNING

[edit] i don't see the small square

"Several types of radars on the frigate Duquesne, notably a navigation radar (small square) and the big radome which protects the DRBI 23 air sentry radar." - Omegatron 17:14, Jan 2, 2005 (UTC)

As the picture became 'missing', I've removed it. Dan100 13:18, Jan 3, 2005 (UTC)

[edit] Radar versus RADAR

Shouldn't we change the title of this page from "Radar" to "RADAR" since RADAR is an acronym?--P Todd 04:35, 7 Apr 2005 (UTC)

There appear to be planty of examples of acronyms written in lower case documented in Wikipedia. --SC 20:15, 23 Apr 2005 (UTC)

Going by the rules of English and the treatment of acronyms on Wikipedia, RADAR is in fact supposed to be all caps. Just because other articles don't do it, doesn't excuse this one. The others may have special reasoning for non-all caps (i.e. business name, indeterminable as an acronym, etc.), or may in fact be in error themselves and are in need of editing. I say update it, or at least add something to the article stating the use of 'radar' in non-capped form.Dannybu2001 19:22, 31 October 2005 (UTC)

Yep, everywhere I've looked says acronyms are to be capitalized, and Wikipedia says to follow the standard rules of English. As such, it should be 'RADAR' not 'radar'. I'm moving it unless someone has a reason why it shouldn't, then just revert it. But please think about it and actually research tbe rules instead of assuming that Wiki-articles aren't supposed to do all caps at all, this is not what they say, in fact, the Manual of Style says something to the effect "don't make new rules" not "don't ever all-cap a word."Dannybu2001 20:21, 31 October 2005 (UTC)

Originally "RADAR" was an acronym. It's acknowledged as a word in its own right, now, so lower case is correct. —Preceding unsigned comment added by 71.218.244.86 (talk) 02:07, 18 December 2007 (UTC)

[edit] Request for references

Hi, I am working to encourage implementation of the goals of the Wikipedia:Verifiability policy. Part of that is to make sure articles cite their sources. This is particularly important for featured articles, since they are a prominent part of Wikipedia. Further reading is not the same thing as proper references. Further reading could list works about the topic that were not ever consulted by the page authors. If some of the works listed in the further reading section were used to add or check material in the article, please list them in a references section instead. The Fact and Reference Check Project has more information. Thank you, and please leave me a message when a few references have been added to the article. - Taxman 19:23, Apr 22, 2005 (UTC)

[edit] K band useless?

In the article it says that K-band is useless because of its absorbtion by water vapor. When I went into my friend's car, which has a radar detector, it has a feature that allows the detection of radar detectors in the K-band. I know my knowledge is limited, but nowhere in the article does it mention police radar guns, and these should be placed somewhere in the article.

To be correct, K-band is not useless but is strongly attenuated by water vapor in long range target detection. The attenuation is greater than 0.2 dB/km centered mostly about 1.3 cm wavelength. So short range use is still usable for specific or meteorological applications. It should be noted that the permanent magnetic dipole moment of the oxygen molecule coupled with the electric dipole moment of water has a greater attenuation effect on radio frequency waves in the 0.5 cm or mm-band, than the water vapor does in the K-band. Greater than 10 dB/km. --13:35, 9 July 2006 (UTC)radarguy

Actually, it would not hurt to mention that the "old" WWII K-band was split into three bands, Ku, K, Ka specifically to address this problem. -- Larks 27 March 2008

[edit] History

Shouldn't there be at least a short section on the history of radar in this article? I realize there is a seperate article, but it is in dreadful shape, would be nice to see a crisp paragraph or two outlining the history.

I second that. Would be nice to start with a short history section as most tech articles do.

I third that. I came here looking for info on the Anglo-American Radar partnership and missed having a History section.

[edit] Civilan and military RADAR

civilan radar I belive just picks up other radar military detects an object Dudtz 8/25/05 6:47 PM EST

[edit] neologism?

Can we really still consider a word so well established in the English language to be a neologism 65 years after it was coined? Every word was a neologism once; when it is no longer neo? --Kgf0 17:30, 8 November 2005 (UTC)

As I see it "RADAR" was a neologism. "Radar", as it is used today, is a good ole plain word. Since for informational purposes the first line uses "RADAR", it seems only fit to note how it came to be (by describing a pre-existing technology). I suppose you could modify it to say "originally a neologism", but by your own omission, all words were once neologisms - so it'd be redundant. ¦ Reisio 18:40, 8 November 2005 (UTC)

I agree! Just do a search on laser which is a much newer neologism and there is not even a discussion about it being a word or an acronym. This is my daily work and I edit and review military technical documents all the time and radar is simply a word in common usage. --radarguy 13:43, 9 July 2006 (UTC)

[edit] Band designations

These are the old band designations arent they? Anyone think we should put the new ones in as well?--Light current 07:30, 11 February 2006 (UTC)

The old designations are still widely used, especially in the US. For example, a Google search for C-band satellite dish yields almost 700,000 hits, but together G-band satellite dish or H-band satellite dish only produce around 500 hits. It might be worth making another column in the table, but it could turn the table into a complicated alphabet soup. --Dual Freq 16:37, 11 February 2006 (UTC)

I believe they were changed about 25 yrs ago!--Light current 21:04, 11 February 2006 (UTC)

The old (US) designations are still widely used, but please when people want to look up stuff in an encyclopedia, how to convert between new and old designations is really important. It's like going to a discussion on temperature scale and only being told about Fahrenheit. Tlsmith5a 13:42, 10 October 2007 (UTC)

It's the first I have heard about a G band. Looks like the old designations are almost exclusively used, but you are right the encyclopedia should explain this sort of thing, but not push the new designations. Graeme Bartlett 21:36, 10 October 2007 (UTC)

[edit] Etymology

I notice that the origin of word "radar" has been changed from "The term RADAR was coined in 1941 as an acronym for Radio Detection and Ranging. This acronym of American origin replaced the previously used British abbreviation RDF (Radio Direction Finding). The term has since entered the English language as a standard word, radar, losing the capitalization in the process." to "The term RADAR was coined in 1941 as an acronym for Radio Assisted Direction And Range. This acronym of American origin replaced the previously used British abbreviation RDF (Radio Direction Finding). The term has since entered the English language as a standard word, radar, losing the capitalization in the process." The Oxford English Dictionary gives the etymology as "[f. radio detection and ranging.]". Is there evidence of the etymology? The earliest example quote by the OED does not give the etymology - "1941 N.Y. Times 18 Nov. 8/4 The Navy undertook a special enlistment campaign today to recruit men for training in maintenance of the radio device known as ‘Radar’, which is used to locate ships and aircraft that are hidden by fog or darkness. " jmb 15:12, 24 April 2006 (UTC)

As someone who works in this field, Radio Detection and Ranging as always been the description I've encountered as the definition of Radar. A good reference on radar that could help on that is "Radar in Meteorology by David Atlas", published by the American Meteorological Society Pierre_cb 03:43, 26 April 2006 (UTC)

In letters written from 1941, my mother who worked as a member of the WAAF (453616 ACW/2 Shaw M) refers to what was to become Radar as Radio Location - RADAR being an American term that came into use later on during WW2. ix 20:06, 3 November 2007 (UTC)

[edit] Radar history

Another wikiuser deleted some changed I had introduced in this article in the description section saying that it was historical information that was out of place and not documented enough. His comment made sense, however he left this part which is is obviously historical and not documented:

The use of radio waves to detect "the presence of distant metallic objects via radio waves" was first implemented in 1904 by Christian Hülsmeyer, who demonstrated the feasibility of detecting the presence of ships in dense fog and received a patent for radar as Reichspatent Nr. 165546. Another of the first working models was produced by Hungarian Zoltán Bay in 1936 at the Tungsram laboratory.

• There is a link to radar history in wikipedia at the bottom of the article. This is a very good article and I think that the above paragraph should be deleted and its information, if pertinent, be moved there.

• In order to avoid further such add-on, I was wondering if the link to radar history should not be put just under the description section as just a HISTORY section with the link as the only item.

Since I'm not sure of the right way to do it and I don't want to offend any contributor to this excellent article, has anybody have a comment on that?Pierre_cb 2006/04/28 00:23 UTC

• Quite an interesting discussion on early radars runs on newsgroup: [2]. It mentions article from 1935 [3] and lists website about early radars [4]. Pavel Vozenilek 16:06, 30 August 2006 (UTC)

[edit] LIDAR and RADAR interfering with one another

In the context of speed detection, does anybody know if lidar and radar were fixed on the same target from roughly the same place if they could mess with each other? —The preceding unsigned comment was added by 69.156.43.137 (talk • contribs) .

I answered this very question on Talk:LIDAR (to sum it up here: "no, it's impossible"). However, in future please remember that Wikipedia is an encyclopedia project and not a discussion forum. Thank you. Friendly Neighbour 05:59, 2 June 2006 (UTC)

[edit] Functions and roles; civilian situation awareness systems missing

Noticed that situation awareness systems, like those used on commercial and pleasure boats, is missing from here. In fact, the roles section seems to have a significant military spin, with a few non-military tacked onto the end. How does everyone feel about fixing this? I thought since this was FA already I'd post here before making any additions myself. - Davandron | Talk 21:11, 16 February 2007 (UTC)

[edit] Continuous Wave, it can or can not measure distance?

Continuous wave is listed as not being able to measure distance, however the radar altimeter is described as continuous wave device since it does not pulse its output. There is an inconsistency here since the altimeter measures distance! Is continuous wave meant to be "unmodulated"? How are the two systems handled / termed in citable publications?

Note: My quick searches indicate that an altimeter is considered a modulated continuous wave device, so I don't think this is resolved by simply redefining the radar altimeter. - Davandron | Talk 18:55, 22 February 2007 (UTC)

I agree. Most Radalts works by frequency modulating with a sawtooth the carrier and then comparing the frequency of the returned signal to the frequency of the transmitted signal at that time. If the modulation rate and the height are compatible, (eg the aircraft doesn't fly too high (the time it takes for the signal to return is less than the modulation period)), then the difference is proportional to frequency. By tradition, if nothing else, continuous wave refers to pure sinusoidal carriers. Terry C 19:14, 22 February 2007 (UTC)

I've done a bit more research. None of the books in my possession have any references to CW radar, (FM or otherwise), so I cannot cite any references. A search on the Internet seems to classify CW radar in exactly the same way as the Wikipedia article Continuous wave radar, that is the use of frequency modulation is mentioned under the general heading, but discriminated by the term FMCW. I personally would also prefer to see the section clarified, but without more proof I'll wait and see what others might think. BTW I've always been careful to talk about radio altimeter when referring to FM Radalts and radar altimeter when referring to pulsed Radalts (as I recall, the APN/171 was an example of this). Terry C 20:00, 22 February 2007 (UTC)

The following is from Chuck Bradley. I wanted to provide a reference that might be of use to the experts that change this article, but my comments seem to have butted into a more detailed discussion. Sorry about that. I am not a radar expert. There seems to be a lack of agreement about the history of radar. A book entitled "Tuxedo Park" contains some information about American work and the transfer of British work to U.S. I do not know how accurate it is. The book is about five years old and is more a biography of Alfred Loomis than a history.

Note: Since now there are surface movement radars (SMR) that uses CW to detect objects in an A-SMGCS environment, it is clear that they can measure distance. AENA (responsible for the air traffic control in Spain, http://en.wikipedia.org/wiki/Aena) has bought at least one of them to give service in the Palma de Mallorca Airport.

Some additional information about CW development can be found here (summaries are writen in english, full text in spanish) http://w3.iec.csic.es/ursi/articulos_oviedo_2006/articulos/sesionRAD-II-14small.pdf.

I cannot read Spanish, but the summaries seem to refer to FMCW systems, which have already been discussed above and mentioned in the article. Perhaps there is more information elsewhere in English? The point of this discussion is that returns from a true CW trabsmitter cannot yield sufficient information to derive distance; some form of modulation is needed for that.

You are totally right. This systems should be CW-FM, because modulation is needed to measure distance! As that comment induces some mistakes, maybe it should be deleted? With a CW radar, delay in the echo response can't be used to measure distances since the radar is always transmiting.217.127.201.198 21:12, 31 July 2007 (UTC)

Would these surface movement radars be using Doppler? Clearly, distance could be derived from velocity, but this has problems due to angular errors. --Terry C 07:54, 22 July 2007 (UTC)

Doppler (which can be easily obtained from a pure-tone CW transmitter) will indeed give you velocity (or rather its projection along your line of sight), which is also the rate of change of distance. While you can in principle use this to keep track of how distance to a scatterer changes, you will not know what it changed from! (I.e. you know that something is approaching at 100 m/s, so it comes 100 m closer every second. It is 6 km closer than a minute ago, but that does not tell you how far away it is.) --Togr 08:05, 22 July 2007 (UTC)

Good point. I wasn't thinking when I wrote that :-) --Terry C 20:20, 22 July 2007 (UTC)

Without knowing exactly what is meant by CW in every context, I can assure you that unless your transmitted signal is modulated in some way, there is no way of measuring distance. There is simply nothing that distinguishes any piece of the transmission from any other. Without any context or further qualification, I would take 'CW Radar' to mean one with a pure carrier wave transmitter (i.e. no modulation), and such an instrument would clearly be incapable of measuring distance. In some contexts, however (e.g. if making a distinction between pulsed and continuous-transmission radars), 'CW' would simply mean 'not pulsed' or 'continuous transmission', and I have even used the term in that way myself! (abstract and proceedings paper from URSI general assembly a few years back.) In this application, the signal would certainly be modulated, such that range information would be available. --Togr 08:00, 22 July 2007 (UTC)

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[edit]  ?

whats the acronym for radar? —Preceding unsigned comment added by 68.47.58.215 (talk) 22:25, 27 September 2007 (UTC)

"RAdio Detection And Ranging" - it's in the first paragraph of the article. Bistromathic 12:40, 2 October 2007 (UTC)

[edit] Any information on "Airadar"?

Around 1970, Flying Magazine reviewed something called "Airadar". This was a phased array radar for light aircraft, with electronic scanning, a fast-refresh display, and a conformal antenna. Today, that's not unusual, but it was way ahead of its time. So far ahead that it was classified and disappeared from the commercial market. Any info on this would be appreciated. No, it's not in Google. --John Nagle (talk) 20:11, 14 December 2007 (UTC)

[edit] Sea Clutter

At high resolutions and low grazing angles the occurance of spikes significantly increases the clutter RCS. Waashwal (talk) 21:37, 24 March 2008 (UTC)

Note CFAR is not a form of AGC as stated in the article. AGC is used to optimise dynamic range in the receiver and is normal combined with STC curves to prevent saturation in the receiver amplifiers/digitiser. CFAR is used to gain a constant false alarm rate and has no so respective of signal’s dynamic range as it occurs in the signal processor and is a threshold above the noise level distribution. Changes in ACG will affect the signal level and should leave the noise level and distribution unchanged. So AGC effect signal and leaves noise invariant, and CFAR is threshold to the noise floor in-order to detect signal. There are other errors in this article —Preceding unsigned comment added by 213.120.209.210 (talk) 08:14, 29 April 2008 (UTC)