FS: WW II Magnetron GL-5J29 marked Classified, NOS

[Mat Nieuwenhoven]

On Fri, 30 Sep 2005 04:25:40 -0500, Hal Murray wrote:

<snip>

Yes, there is a fundamental range/velocity ambiguity, and the numbers
are interesting. I'm not smart enough to explain it, at least not
without a lot of work to refresh my memory.

Consider the extreme cases:
1) sharp pulse. You get back a pulse. You can clearly measure
the time delay. But what is the dopler shift?
2) a continous tone. You get back a shifted tone so you can
easily measure the dopler shift. But what is the time delay?

There's a way to have a broad pulse and still get high distance resolution.
You use a pulse that varies in frequency (sweeps in a controlled way during
the pulse, I think it was from low to high). On the receiver the IF stages
have a delay that varies with the frequency, so that the broad pulse gets
'compressed' timewise. Of course, any doppler info is lost.

Mat Nieuwenhoven

 

[Don Lancaster]

Mat Nieuwenhoven wrote:

On Fri, 30 Sep 2005 04:25:40 -0500, Hal Murray wrote:

snip

Yes, there is a fundamental range/velocity ambiguity, and the numbers
are interesting. I'm not smart enough to explain it, at least not
without a lot of work to refresh my memory.

Consider the extreme cases:
1) sharp pulse. You get back a pulse. You can clearly measure
the time delay. But what is the dopler shift?
2) a continous tone. You get back a shifted tone so you can
easily measure the dopler shift. But what is the time delay?


There's a way to have a broad pulse and still get high distance resolution.
You use a pulse that varies in frequency (sweeps in a controlled way during
the pulse, I think it was from low to high). On the receiver the IF stages
have a delay that varies with the frequency, so that the broad pulse gets
'compressed' timewise. Of course, any doppler info is lost.

Mat Nieuwenhoven


Called "chirp".

Bats invented it long time ago.

--
Many thanks,

Don Lancaster voice phone: (928)428-4073
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
rss: http://www.tinaja.com/whtnu.xml email: don@tinaja.com

Please visit my GURU's LAIR web site at http://www.tinaja.com

 

[Winfield Hill]

Tony Williams wrote...

Jim Adney wrote:
Reg Edwards wrote:

The receiver can't work properly unless it has a very wide
bandwith to accommodate a large proportion of it. Otherwise
radar echos from different distances become blurred and merge
with each other on the screen.

Am I missing something here? I don't see why a narrow band echo
wouldn't give a nice time delay signiture. Is this a Heisenberg
uncertainty principle thing, with f & t the variables?
(delta f) times (delta t) < h/2pi

http://www.doramusic.com/patents/579154.htm> might be
an interesting read. Patent first applied for in 1940.

Was an interesting read, what's the story behind the story?


--
Thanks,
- Win

 

[Robert Baer]

Don Lancaster wrote:

Mat Nieuwenhoven wrote:

On Fri, 30 Sep 2005 04:25:40 -0500, Hal Murray wrote:

snip

Yes, there is a fundamental range/velocity ambiguity, and the numbers
are interesting. I'm not smart enough to explain it, at least not
without a lot of work to refresh my memory.

Consider the extreme cases:
1) sharp pulse. You get back a pulse. You can clearly measure
the time delay. But what is the dopler shift?
2) a continous tone. You get back a shifted tone so you can
easily measure the dopler shift. But what is the time delay?



There's a way to have a broad pulse and still get high distance
resolution.
You use a pulse that varies in frequency (sweeps in a controlled way
during
the pulse, I think it was from low to high). On the receiver the IF
stages
have a delay that varies with the frequency, so that the broad pulse gets
'compressed' timewise. Of course, any doppler info is lost.

Mat Nieuwenhoven


Called "chirp".

Bats invented it long time ago.

...and they were wise to *not* patent the idea, and put it into public

domain; the other animals thought that was crazy, and so called them
"bats", and the name stuck.

 

[Tony Williams]

In article <dhv4b204db@drn.newsguy.com>,
Winfield Hill <Winfield_member@newsguy.com> wrote:

Tony Williams wrote...
http://www.doramusic.com/patents/579154.htm> might be
an interesting read. Patent first applied for in 1940.

Was an interesting read, what's the story behind the story?

The real interest (for me anyway) is the sense I get
when reading such documents on that site. These were
development engineers (like us), at the forefront of radar,
feeling their way through the problems for the first time.

The fundamental concepts, sums and circuit elements that
we now take for granted were being actively explored from
scratch at that time.

--
Tony Williams.