Exactly!a timed emission of a given wavelegnth
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Exactly!a timed emission of a given wavelegnth
That's why low pulse-repetition rates are better for long range?
Because they send more pulses and ping the target more?
How does that occur?
A staggered system would be like slow, fast-fast-fast, slow, fast-fast-fast?
What's doppler ambiguity?
Because it would be overly complicated and cost an absurd amount of money to build?
So if there were slow speed targets you'd want to be switching routinely back and forth?
Which means the beam goes back & forth real fast and allows you to cover some space, particularly if the computer can store some data?
Encoded means that it can determine which pulse was sent at what time?Token said:For a simple, nonencoded pulse, search they are generally better.
UnderstoodYes, a higher PRF increases the average power of a return from a given target radar cross section at a given range. This means you can either track smaller targets or you are more sure to get a track on larger targets.
OkInstead of taking a page to try and explain it how about I point you at a page from that web site that fubar57 linked.
Radar Basics
UnderstoodI am talking about PRI (Pulse Repetition Interval, the reciprocal of PRF) or PRF staggers. These are the individual pulses the radar sends and their timing, pulse to pulse.
OkayA staggered system might do this: make a pulse, 2500 usec later make another pulse, 2250 usec later make a pulse, 2500 usec later another, 2250 usec later another. This 2500 / 2250 / 2500 / 2250 cycle repeats. This is called a two position 2250 / 2500 usec stagger.
UnderstoodOr have the radar do it automatically as part of its normal functions.
Okay
Is that bad?Zipper, you have a strange way to learn, asking the most detailed and involved questions in a way that only allows one word answers.
Good point...Much of the theory everyone knows but do not realise it. Low frequency waves travel further, that is why fog horns have a low note. High frequencies attenuate and reflect more readily which is why a police siren in a built up area seems to come from everywhere.
Hmmm...There is a limit to a waves reflection, a sea wave smashing a sea wall will send a wave back, it will pass a pole stuck in the beach with almost no ripples backwards. In ultrasonics the maximum detectable defect is one half of the wavelength used. There must be a similar ratio in RADAR because high frequency (centimetric) RADAR could detect a submarine conning tower whereas the lower frequency systems could only find a fully surfaced submarine.
Makes sense, in both cases they're both using the transmission of waves which bounce back and absorb to varying degrees.Fascinating for me how closely RADAR, in which I am a layman, follows ultrasonics which was my profession for many years.
Didn't know that the term was called a defectToken, the problem with ultrasonics and radiography is that they take a view from one angle, but used together they are complimentary and "almost" guarantee finding defects*. Using ultrasonics alone you must maximise the different angles and approaches to give a good result. In radar are systems linked to simultaneously compare results?
Ultrasonics generally uses multiples of 6dB because -6dB is a 50% reduction in signal on the screen (oscilloscope) any reason why RADAR uses 3dB
* I use defects as the commonly known word, actually ultrasonics just detects discontinuities, the specification and relevant code decide if it is in fact a "defect".
Is that bad?
Yes because knowledge is a pyramid you need a broad base to reach a significant height, delving into advanced electronics, filters and radio wave transmission before even mastering the basics is impossible. In physics you usually trade a positive for a negative, having a one word answer that gives the positive does not tell you the negative you just lost.
Good point...
I had a good teacher, C.J. Abrahams pioneer of the 20dB drop sizing technique in ultrasonic testing.
Ultrasonic Examination of Circumferential Butt Welds in Pressure Piping ~ Paperback ~ C.J. Abrahams
Hmmm..
What does Hmmmm. mean? The first part is a fact anyone that has stood on a beach can verify and the second is a fact any reader of anti submarine warfare knows. Your dicing of posts means my post makes no sense and I am not the first person to say this, neither is this the first time I myself have said it.
Makes sense, in both cases they're both using the transmission of waves which bounce back and absorb to varying degrees.
They both use waves and waves share properties but they are also different. Ultrasonic waves can be shear waves, compression waves, Rayleigh or Lamb waves. In certain circumstances they can change from one mode of propagation to another and you need to know how to spot it happening. RADAR also has similar effects at low altitude, everyone knows long wave radio hugs the earth at night, it is how I listened to Radio Luxembourg in the 1970s
4 types of ultrasonic waves
Didn't know that!
Yes you did, you just didn't think about it. A photograph is a different type of test, in the visual range of the spectrum but also in two not three dimensions. Having two eyes instead of just one doesn't double our capability in sight it multiplies it by many thousands of percent.
A conversation here should be some sort of resource, there are some real experts here, I am not one, but I do know what I know on some subjects. Zipper turns every discussion into gibberish no one can follow.I put him on ignore long ago but then I missed all the intelligent posts so now I skim over the trash to get to the good stuff
I didn't intend to make the post uninteligeable...Now, slice and dice my posts again and I will put you on ignore, I am not spending any more time cutting and pasting to make sense of your posts, and anyone reading this must go back to the previous post to make sense, it is a pain in the butt.
Token did a pretty good job and I've learned quite a lot, actually.pbehn said:Yes because knowledge is a pyramid you need a broad base to reach a significant height, delving into advanced electronics, filters and radio wave transmission before even mastering the basics is impossible. In physics you usually trade a positive for a negative, having a one word answer that gives the positive does not tell you the negative you just lost.
I found it fascinatingWhat does Hmmmm. mean? The first part is a fact anyone that has stood on a beach can verify and the second is a fact any reader of anti submarine warfare knows.
You didn't because you have not learned about attenuation or reflection, you have learned just enough to use some words and quote out of context.Token did a pretty good job and I've learned quite a lot, actually.
I found it fascinating
I am not sorting this jibberish out any more especially since you are editing it.Is that bad?
Good point...
Hmmm...
Makes sense, in both cases they're both using the transmission of waves which bounce back and absorb to varying degrees.
Didn't know that the term was called a defect
I did compared to what I knew before: As for making jibberish, I was under the impression your objection was that I quoted out of sequence, not that I responded line by line.You didn't because you have not learned about attenuation or reflection, you have learned just enough to use some words and quote out of context.
I'll read the stuff Fubar57 wrote and the other links, but I'm not entirely sure where else I'd find much, unless you would prefer I just sent Token some PM's?XBe02Drvr said:Zipper, come back when you've done your homework! You need to learn a little on your own so you can carry on an informed intelligent discussion instead of this incessant "picking everybody's brains". We know you can do it; you did it on SAC history and bombing tactics, and there you actually talked sense. Instead of collecting disconnected factoids, try to build a coherent body of knowledge about whatever topic you're pursuing at the moment.
GOOD GOD MAN!! There are people on here who've trained and studied and worked a lifetime to acquire their knowledge and experience. So far they've been amazingly patient with you, but do you think they'll have the time and inclination to spoon-feed your kindergarten lessons forever? You need to put in a little effort on your own behalf. There's a world of information out there on the internet, in libraries and bookstores, and potentially on your own bookshelf. Go get it.I did compared to what I knew before: As for making jibberish, I was under the impression your objection was that I quoted out of sequence, not that I responded line by line.
I'll read the stuff Fubar57 wrote and the other links, but I'm not entirely sure where else I'd find much, unless you would prefer I just sent Token some PM's?
BTW: As for the limited experience, that is one reason why I would be inclined to pick the brains of those more knowledgeable than myself.
Fascinating for me how closely RADAR, in which I am a layman, follows ultrasonics which was my profession for many years. Token, the problem with ultrasonics and radiography is that they take a view from one angle, but used together they are complimentary and "almost" guarantee finding defects*. Using ultrasonics alone you must maximise the different angles and approaches to give a good result. In radar are systems linked to simultaneously compare results?
Ultrasonics generally uses multiples of 6dB because -6dB is a 50% reduction in signal on the screen (oscilloscope) any reason why RADAR uses 3dB
Low frequency waves travel further, that is why fog horns have a low note. High frequencies attenuate and reflect more readily which is why a police siren in a built up area seems to come from everywhere. There is a limit to a waves reflection, a sea wave smashing a sea wall will send a wave back, it will pass a pole stuck in the beach with almost no ripples backwards. In ultrasonics the maximum detectable defect is one half of the wavelength used. There must be a similar ratio in RADAR because high frequency (centimetric) RADAR could detect a submarine conning tower whereas the lower frequency systems could only find a fully surfaced submarine.
I was struggling with the words when I wrote it to avoid confusion but didn't manage it. Submarine commanders realised they were visible to RADAR while fully surfaced, they then went to being partially submerged, just the conning tower above water. With centimetric RADAR just the conning tower could be detected.Note that in WW II even the 3 GHz radars could not detect periscopes on the surface.
T!