Talk:Synthetic-aperture radar

message: First of all I found it amazing that holograms were being used to perform analog computations on datasets. How long ago was this being done? Does anyone know?
Seondly the resolution quoted in the article is 0.6 meter. If we were doing it at 0.6m resolution back then what's the maximum resolution attainable now? —Preceding unsigned comment added by 24.80.86.98 (talk) 18:58, 22 January 2008 (UTC)
replies: text: I saw the JPL laser in 1977 and it was still there in 1982.  Can't say about others.  Resolution depends on the balance of wavelength, and other system design factors.  Lots of interest in X-band isn't based on a shorter wavelength than say L-band. 171.66.48.97 (talk) 00:32, 27 May 2010 (UTC)
replies: text: Regarding the first paragraph above -- the optical hologram idea was older than the radar developments described, but was incomplete. E. Leith devised the successful radar data-processing scheme, for turning film-recorded coherent-radar data into visual images, before applying his understanding of that process to turning film-recorded coherent light-wave data into visual images. See particularly the historical article by Leith that is in the list of references.Oldteched (talk) 01:56, 12 May 2012 (UTC)
thread_title: Maximum Resolution

message: What's an Inverse Synthetic Aperture Radar?  Ojw 10:56, 6 October 2005 (UTC)
replies: text: Inverse SAR uses the motion of the target to create a image. We plot range and doppler shift. Ships at sea can be imaged very easily, but since the velocity is not known ahead the images are pretty distorted. Dominick 11:40, 6 October 2005 (UTC)
thread_title: ISAR

message: The section on UWB SAR contains two false statements that I will correct:
First, "Interpretation of the [narrow band radar] results is also eased by the fact that the material response must be known only in a narrow range of frequencies", is false in that the frequency response information is still present in a UWB echo, and can easily be considered in processing.
Strangely, the writer goes on to admit this fact, and presents it as a disadvantage!...
Second, "but much of the information is concentrated in relatively low frequencies (with long wavelengths). Thus such systems require very large receiving apertures to obtain correspondingly high resolution along the track." is also false. The large apertures are "required" only if one desires to detect that low-frequency information--it certainly isn't "necessary" to retrieve that information just because UWB SAR happens to provide the information while narrow-band SAR does not! Fleem (talk) 11:56, 9 May 2008 (UTC)
thread_title:  UWB SAR 

message: Much nonsense here:
"The equivalence of these two methods can be seen by recognizing that multiplication of sinusoids can be done by summing phases which are complex-number exponents of e, the base of natural logarithms."
This makes not one whit of sense because a phase is merely a number, and summing phases yields nothing but another number. Multiplication of sinusoids has nothing to do with "summing phases" or (adding up) any other kind of a number. Also, phases are real numbers, and they do not have anything to do with "complex-number exponents of e", which are generally complex numbers themselves. Furthermore, this article is nonsense without any diagrams that show what is going on, and also nonsense without any equations. Trying to explain or describe synthetic aperture radar entirely in words is a fool's errand. The fact that "e" is the base of natural logarithms needs to be taken as a given. The reader should be assumed to know what Euler's identity states.98.67.110.231 (talk) 03:07, 29 July 2012 (UTC)
thread_title:  Much nonsense here 

message: It seems to me that the "authors" of this article have compiled layer and layer of jargon on top of unnecessary complexity, without adding a single thing to the article's readability.  I am continually amazed at how dumb some "smart" people can be.  And if it's not dumb - then it's worse than that:  it's arrogance.  The vast majority of technical articles here are not written to explain how something works, but rather to demonstrate how much the author knows and how magnificently that author can obfuscate the obvious.  — Preceding unsigned comment added by 98.194.39.86 (talk) 03:20, 6 April 2013 (UTC)
replies: text: The history sections looks OK, but the technical material is very questionable.  The "Algorithm" section is either a very eccentric formulation of SAR, or it's a joke or vandalism by someone.  It needs to be entirely replaced.  DonPMitchell (talk) 19:04, 2 February 2016 (UTC)
replies: text:  Yes, the Algorithm section is certainly a strange way of looking at SAR. I'll spend some time this weekend re-writing it with a more standard approach. Mysticdan (talk) 21:44, 2 February 2016 (UTC)

text: Just to reanimate this discussion: I have attempted to fix the "Algorithm" section. I've been aware for some time that it is nonsense and I've finally got around to replacing it with something short, sourced and I believe more accurate. Theoh (talk) 22:06, 14 January 2023 (UTC)
thread_title:  Extreme nonsense here 

message: This article is in need of help, and there is only so much I can do – but YOU can help! Here are some suggestions if you want to improve this article:
* Include some informative images. Look for images in Wikipedia/Commons, e.g. here.
* The text is much much too long and much too "winding" – the information should be presented much shorter and much more concise. Wikipedia is an encyclopaedia, after all.
* Links to other relevant articles should be added.
* Better structure
A suggestion for a structure would be:
* Applications: For what is SAR used, with examples
* Technology: Some details how SAR works, the different types of SAR, differences to other radar technologies, and so on
* History: How it started, how it was developed over time, and so on.
A final suggestion: Feel free to delete any of those long and winding passages of text currently present, and replace them with new and concise text of your own.
Tony Mach (talk) 13:33, 12 June 2014 (UTC)
replies: text:  Google translate does a pretty good job with that figure:  Top: Equivalent phased-array antenna  Middle: Synthetic aperture length  Description: The distance to the target is different between the positions of the platform. If the target is on the central axis of the real aperture, the distance is less than if the real antenna must squint toward the target. This expresses itself in a phase difference Δφ. For a sharp picture, the phase difference between the position C and the other positions must be corrected in the image processing software.  — Preceding unsigned comment added by Mysticdan (talk • contribs) 17:11, 11 November 2015 (UTC)
replies: text:  The English version is available. However, it would be better to create this file in SVG format with international labeling. --c.w. (talk) 18:36, 24 January 2023 (UTC)
thread_title:  This article needs your help 

message: It is absolutely necessary to provide a picture for the section "Image appearance". This is an extremely important section, but without pictures, it is too hard to understand.
Statisticastatistico (talk) 20:42, 16 May 2016 (UTC)
thread_title:  Please: a picture for the "image appearance" section 

message: This edit by  again re-introduces copy and pasted text to this article. This needs to stop. Just because it's published by NATO does not make it public domain. I am left to assume that large chunks of that text is also a copyvio. ie. "3D SAR Tomography, also known as 3D SAR focusing or 3D SAR imaging, represents a very recent improvement of SAR interferometry that allows obtaining additional information from multi-baseline SAR dataset by overcoming the limitation of available techniques" is a direct copy paste from Tomographic SAR. --Dual Freq (talk) 22:10, 15 November 2016 (UTC)
replies: text: A good place to start would be remove the material you copied from the article. --Dual Freq (talk) 23:28, 15 November 2016 (UTC)
thread_title:  Copy paste copyvios 

message: There is some information on MDA website that seem to suggest far better imagery was already achieved in 1957.
See the "Did you know?" section on this page?
Can this image be verified to be attributable to MDA?
Can the date be verified - if so - it will certainly be worth showcasing that result here on the wikipedia page
http://www.mdaus.com/intelligence,-surveillance-and-reconnaissance/synthetic-aperture-radar-(sar)
An aerial SAR image (on the left) taken in 1957 of a Volkswagen Beetle compared to an aerial photograph (picture on the right) illustrates the power of SAR applications from the earliest applications  — Preceding unsigned comment added by 146.64.81.115 (talk) 13:33, 26 January 2017 (UTC)
thread_title:  Comment on History Section 

message: Hi editors, what would you think about adding :File:Hoover Dam 50 cm Resolution Synthetic Aperture Radar Image.jpg to the Image appearance section? Right now, the article has outdated SAR imagery and does not have any recent examples of high-resolution SAR imagery. This 50 cm high resolution image of the Hoover Dam shows an example of modern SAR imagery and adds context to current capabilities. Let me know what you think! I work for Umbra, the company that took the image, so I wanted to see if someone would add it on my behalf. We're not looking for any credit or PR—we'd like to help keep the article up-to-date. If you have a suggestion for a different image(s), I'm open to providing it.
@Graeme Bartlett, pinging you since we've talked about images in case you would like to take a look.
Thanks in advance for your help! NT at Umbra (talk) 16:05, 13 July 2023 (UTC)
thread_title:  Adding an image