the 60W light bulb misconception

"R. Mark Clayton" wrote:

> Later H2S had an oscilloscope display which rotated in sync with the
> transceiver dish with pulsed transmission (like modern radars). It was
> carried on bombers.

The official name for this type of display that we'd recognise today is
PPI.(plan position indicator).

I've seen some naval versions where the scanning coils rotate around the tube. I
gather this was the common way of doing it before the advent of computer storage
that could use ordinary raster scan display tubes.

Even so, I was involved in 1989 in developing a PPI display that used 'spiral
scanning' (using sine and cosine waveforms to drive the deflection coils)
because although it was microprocessor based, doing this avoided the need (and
computational overhead) to convert R, theta data into x, y.

Graham

---

› See More: the 60W light bulb misconception

"Eeyore" <[email protected]> wrote in
message news:[email protected]

[snip]

: : Microwaves are normally taken to begin at 1GHz btw not
: : 300MHz as you stated above. 300MHz would be UHF.

Some definitions here:

http://encyclopedia.thefreedictionar...adio+frequency
http://encyclopedia.thefreedictionary.com/microwave


Ivor

"Eeyore" <[email protected]> wrote in message
news:[email protected]...
>
>
> "R. Mark Clayton" wrote:
>
>> Later H2S had an oscilloscope display which rotated in sync with the
>> transceiver dish with pulsed transmission (like modern radars). It was
>> carried on bombers.
>
> The official name for this type of display that we'd recognise today is
> PPI.(plan position indicator).
>
> I've seen some naval versions where the scanning coils rotate around the
> tube. I
> gather this was the common way of doing it before the advent of computer
> storage
> that could use ordinary raster scan display tubes.
>
> Even so, I was involved in 1989 in developing a PPI display that used
> 'spiral
> scanning' (using sine and cosine waveforms to drive the deflection coils)
> because although it was microprocessor based, doing this avoided the need
> (and
> computational overhead) to convert R, theta data into x, y.

Oh come on al that is required is a sine and cos wave applied to the X & Y
plates (of an osciliscope) and a line scan (saw tooth) for the deflection -
all neatly analog. In fact the sine wave could be derived from the aerial
rotator and the cos by a simple delay, so the system would self
synchronising.

Having seen film of an H2S working over what is obviously The Wash, it is
fairly clear this is pretty much how it worked. The difficult bit was
compensating the gain of the return signal for the distance from the set so
that things close by are not to bright.

>
> Graham
>
>

"Alastair" <[email protected]> wrote in message
news:[email protected]...
> While the OP is clearly deranged, I've got to admit that this has turned
> into one of the more interesting and informative threads I've read for a
> long
> time, even if totally OT for uk.telecom.broadband!

Lenny thinks that broadband wi-fi is inherently dangerous...

"R. Mark Clayton" wrote:

> "Eeyore" wrote
> > "R. Mark Clayton" wrote:
> >
> >> Later H2S had an oscilloscope display which rotated in sync with the
> >> transceiver dish with pulsed transmission (like modern radars). It was
> >> carried on bombers.
> >
> > The official name for this type of display that we'd recognise today is
> > PPI.(plan position indicator).
> >
> > I've seen some naval versions where the scanning coils rotate around the
> > tube. I gather this was the common way of doing it before the advent of
> computer
> > storage that could use ordinary raster scan display tubes.
> >
> > Even so, I was involved in 1989 in developing a PPI display that used
> > 'spiral scanning' (using sine and cosine waveforms to drive the deflection
> coils)
> > because although it was microprocessor based, doing this avoided the need
> > (and computational overhead) to convert R, theta data into x, y.
>
> Oh come on al that is required is a sine and cos wave applied to the X & Y
> plates (of an osciliscope) and a line scan (saw tooth) for the deflection -
> all neatly analog. In fact the sine wave could be derived from the aerial
> rotator and the cos by a simple delay, so the system would self
> synchronising.

We're talking about a big bright daylight display tube that'll be be mounted on
the bridge, not an oscilloscope that you view under a hood.

I can tell you that there's more to it than you might imagine. In fact. that's
how the client company came to need some consultants to fix it. Yes, I do
electronics consultancy and I'm good at fixing 'runaways'.


> Having seen film of an H2S working over what is obviously The Wash, it is
> fairly clear this is pretty much how it worked. The difficult bit was
> compensating the gain of the return signal for the distance from the set so
> that things close by are not to bright.

Tell me about it ! I know a thing or two about that too. They didn't have very
good VCAs back then !

Graham

On Mon, 6 Aug 2007 14:32:23 +0100, "R. Mark Clayton"
<[email protected]> wrote:

>
>Oh come on al that is required is a sine and cos wave applied to the X & Y
>plates (of an osciliscope) and a line scan (saw tooth) for the deflection -
>all neatly analog. In fact the sine wave could be derived from the aerial
>rotator and the cos by a simple delay, so the system would self
>synchronising.

A common configuration was to use electrostatic deflection for
rangefinders and, as Graham has said, electromagnetic for PPI
displays. A Selsyn was used to keep the radar head and display
rotating together. Apart from allowing bright displays it was a
simple and reliable system. Alignment usually simply meant
unclamping and rotating the servo half of the Selsyn assembly until
north was where it should be.

A lot of early radars were very mechanical had noises to suit as
various bits clattered away. The British Army Thunderbird missile
system even had a computer which required regular oiling. The
missile guidance commands were modified as missile range increased by
an analogue computer using several variable resistors which ran on
differently shaped cams to model fuel consumption, weight, speed etc
in the calculations).
--
Peter Parry.
http://www.wpp.ltd.uk/

Peter Parry wrote:

> "R. Mark Clayton" wrote:
> >
> >Oh come on al that is required is a sine and cos wave applied to the X & Y
> >plates (of an osciliscope) and a line scan (saw tooth) for the deflection -
> >all neatly analog. In fact the sine wave could be derived from the aerial
> >rotator and the cos by a simple delay, so the system would self
> >synchronising.
>
> A common configuration was to use electrostatic deflection for
> rangefinders and, as Graham has said, electromagnetic for PPI
> displays. A Selsyn was used to keep the radar head and display
> rotating together. Apart from allowing bright displays it was a
> simple and reliable system. Alignment usually simply meant
> unclamping and rotating the servo half of the Selsyn assembly until
> north was where it should be.
>
> A lot of early radars were very mechanical had noises to suit as
> various bits clattered away. The British Army Thunderbird missile
> system even had a computer which required regular oiling. The
> missile guidance commands were modified as missile range increased by
> an analogue computer using several variable resistors which ran on
> differently shaped cams to model fuel consumption, weight, speed etc
> in the calculations).#

Mechanical 'analogue computers' were very popular for a time. Mostly in gunnery
and especially in the Navy AIUI. The USAAF Norden bomb sight was another
example.

Graham

"Eeyore" <[email protected]> wrote in message
news:[email protected]...
>
>
> Peter Parry wrote:
>
>> "R. Mark Clayton" wrote:
>> >
>> >Oh come on al that is required is a sine and cos wave applied to the X &
>> >Y
>> >plates (of an osciliscope) and a line scan (saw tooth) for the
>> >deflection -
>> >all neatly analog. In fact the sine wave could be derived from the
>> >aerial
>> >rotator and the cos by a simple delay, so the system would self
>> >synchronising.
>>
>> A common configuration was to use electrostatic deflection for
>> rangefinders and, as Graham has said, electromagnetic for PPI
>> displays. A Selsyn was used to keep the radar head and display
>> rotating together. Apart from allowing bright displays it was a
>> simple and reliable system. Alignment usually simply meant
>> unclamping and rotating the servo half of the Selsyn assembly until
>> north was where it should be.
>>
>> A lot of early radars were very mechanical had noises to suit as
>> various bits clattered away. The British Army Thunderbird missile
>> system even had a computer which required regular oiling. The
>> missile guidance commands were modified as missile range increased by
>> an analogue computer using several variable resistors which ran on
>> differently shaped cams to model fuel consumption, weight, speed etc
>> in the calculations).#
>
> Mechanical 'analogue computers' were very popular for a time. Mostly in
> gunnery
> and especially in the Navy AIUI. The USAAF Norden bomb sight was another
> example.
>
> Graham

I remember learning to use an RAF (mechanical - manual) navigational
computer when I was in the air cadets in the late 'fifties. It was a
hand-held box, with an internal belt on rollers, if I remember correctly,
with an etched metal dial on the front. No electrical power required - just
turn the dial/knobs! Akin to a three-dimensional slide-rule.
ISTR that it calculated the aircraft's track compared with its heading, when
given the wind-speed and direction - or the other way round. It was a long
time ago and Alzheimer's is setting in fast ;-)

George

"George Weston" <[email protected]> wrote in message
news:[email protected]...
>
> "Eeyore" <[email protected]> wrote in message
> news:[email protected]...
>>
>>
>> Peter Parry wrote:
>>
>>> "R. Mark Clayton" wrote:
>>> >
>>> >Oh come on al that is required is a sine and cos wave applied to the X
>>> >& Y
>>> >plates (of an osciliscope) and a line scan (saw tooth) for the
>>> >deflection -
>>> >all neatly analog. In fact the sine wave could be derived from the
>>> >aerial
>>> >rotator and the cos by a simple delay, so the system would self
>>> >synchronising.
>>>
>>> A common configuration was to use electrostatic deflection for
>>> rangefinders and, as Graham has said, electromagnetic for PPI
>>> displays. A Selsyn was used to keep the radar head and display
>>> rotating together. Apart from allowing bright displays it was a
>>> simple and reliable system. Alignment usually simply meant
>>> unclamping and rotating the servo half of the Selsyn assembly until
>>> north was where it should be.
>>>
>>> A lot of early radars were very mechanical had noises to suit as
>>> various bits clattered away. The British Army Thunderbird missile
>>> system even had a computer which required regular oiling. The
>>> missile guidance commands were modified as missile range increased by
>>> an analogue computer using several variable resistors which ran on
>>> differently shaped cams to model fuel consumption, weight, speed etc
>>> in the calculations).#
>>
>> Mechanical 'analogue computers' were very popular for a time. Mostly in
>> gunnery
>> and especially in the Navy AIUI. The USAAF Norden bomb sight was another
>> example.
>>
>> Graham
>
> I remember learning to use an RAF (mechanical - manual) navigational
> computer when I was in the air cadets in the late 'fifties. It was a
> hand-held box, with an internal belt on rollers, if I remember correctly,
> with an etched metal dial on the front. No electrical power required -
> just turn the dial/knobs! Akin to a three-dimensional slide-rule.
> ISTR that it calculated the aircraft's track compared with its heading,
> when given the wind-speed and direction - or the other way round. It was a
> long time ago and Alzheimer's is setting in fast ;-)
>
> George

Bad form to reply to one's own posts but I just found one of these on eBay.
http://tinyurl.com/2t37zb

George

Peter Parry wrote:
>
> The Type 85 didn't just produce prodigious peak powers but kW of
> average power - and not a Magnetron in sight - it used Klystrons
> (albeit very very big ones - not many valves are man sized!).

Was it *ever* run at full power though?

--
Old Codger
e-mail use reply to field

What matters in politics is not what happens, but what you can make
people believe has happened. [Janet Daley 27/8/2003]

Mortimer wrote:
> "Eeyore" <[email protected]> wrote in message
> news:[email protected]...
>>
>> Mortimer wrote:
>>
>>> "Eeyore" wrote
>>>
>>> It was (I think) Chain Home: Danby Beacon in the North York Moors,
>>> anyway.
>> http://maps.google.com/?ie=UTF8&ll=5...&t=k&z=18&om=1
>>
>> You can only make out the roads that were left behind now.
>
> Yes. I went up there when I was on holiday in the area and found the site,
> identified by a noticeboard beside the road. There's virtually nothing
> identifiable now, just a few cracked concrete slabs hidden among the
> heather, than may have been the floor of a building with a basement below
> it.
>
> I wish I'd listened more closely to the stories he told me about the work
> they did. I remember him telling me about the time he went into Whitby on
> his day off and phoned my grandma from a phone box and was rather alarmed to
> hear the talkback from the radar station to the central plotting site when
> he picked up the phone due to a crossed line!

There was a CH site at GT Bentley in Essex. Towards the end of the war
local rumours were that the ARP wardens climed to the top of the masts
from where they could hear the planes taking off in Germany.


--
Old Codger
e-mail use reply to field

What matters in politics is not what happens, but what you can make
people believe has happened. [Janet Daley 27/8/2003]

Eeyore wrote:
>
> tony h wrote:
>
>> "Eeyore" wrote
>>> Peter Parry wrote:
>>>
>>>> Amazing how none of these mysterious "clusters" of variegated
>>>> ailments never occurred around them or in people working on them.
>>> Naval radars can apparently cook seagulls in flight.
>> any evidence of this, or purely anecdotal?
>
> I've heard it claimed in the electronics groups. It was alleged that they could
> 'shoot down' birds with their radar beams.

I find that difficult to believe unless the bird if flying close to the
centre of the beam, in a circle and in sync with the rotating antenna.
I suppose it *might* work if the bird was hovering and the radar beam
was stationary with the bird at the centre.


--
Old Codger
e-mail use reply to field

What matters in politics is not what happens, but what you can make
people believe has happened. [Janet Daley 27/8/2003]

dennis@home wrote:
> "tony h" <[email protected]> wrote in message
> news:[email protected]...
>> "Eeyore" <[email protected]> wrote in message
>> news:[email protected]...
>>>
>>> Peter Parry wrote:
>>>
>>>> Amazing how none of these mysterious "clusters" of variegated
>>>> ailments never occurred around them or in people working on them.
>>> Naval radars can apparently cook seagulls in flight.
>>>
>>> Graham
>>>
>> any evidence of this, or purely anecdotal?
>
> I once worked with an ex-army type who said they would unhook the rotation
> gear on their dish and cook wood pigeons from the trees when they fancied a
> change to the army rations. They certainly have enough power to do it but I
> am not sure you can stop the rotation on most radars which would have been
> about when he was in the army.

I am sure the rotation could always be stopped. However, once 'ealth
and safety got in the loop one would have to also overcome some
interlocks to keep the radiation going.

--
Old Codger
e-mail use reply to field

What matters in politics is not what happens, but what you can make
people believe has happened. [Janet Daley 27/8/2003]

In message <[email protected]>, George Weston
<[email protected]> writes
>
>"Eeyore" <[email protected]> wrote in message
>news:[email protected]...
>>
>>
>> Peter Parry wrote:
>>
>>> "R. Mark Clayton" wrote:
>>> >
>>> >Oh come on al that is required is a sine and cos wave applied to the X &
>>> >Y
>>> >plates (of an osciliscope) and a line scan (saw tooth) for the
>>> >deflection -
>>> >all neatly analog. In fact the sine wave could be derived from the
>>> >aerial
>>> >rotator and the cos by a simple delay, so the system would self
>>> >synchronising.
>>>
>>> A common configuration was to use electrostatic deflection for
>>> rangefinders and, as Graham has said, electromagnetic for PPI
>>> displays. A Selsyn was used to keep the radar head and display
>>> rotating together. Apart from allowing bright displays it was a
>>> simple and reliable system. Alignment usually simply meant
>>> unclamping and rotating the servo half of the Selsyn assembly until
>>> north was where it should be.
>>>
>>> A lot of early radars were very mechanical had noises to suit as
>>> various bits clattered away. The British Army Thunderbird missile
>>> system even had a computer which required regular oiling. The
>>> missile guidance commands were modified as missile range increased by
>>> an analogue computer using several variable resistors which ran on
>>> differently shaped cams to model fuel consumption, weight, speed etc
>>> in the calculations).#
>>
>> Mechanical 'analogue computers' were very popular for a time. Mostly in
>> gunnery
>> and especially in the Navy AIUI. The USAAF Norden bomb sight was another
>> example.
>>
>> Graham
>
>I remember learning to use an RAF (mechanical - manual) navigational
>computer when I was in the air cadets in the late 'fifties. It was a
>hand-held box, with an internal belt on rollers, if I remember correctly,
>with an etched metal dial on the front. No electrical power required - just
>turn the dial/knobs! Akin to a three-dimensional slide-rule.
>ISTR that it calculated the aircraft's track compared with its heading, when
>given the wind-speed and direction - or the other way round. It was a long
>time ago and Alzheimer's is setting in fast ;-)

I've got one of those somewhere!

Modern versions are still sold.

Mike
--
M.J.Powell

In message <[email protected]>, Old Codger
<[email protected]> writes
>Eeyore wrote:
>> tony h wrote:
>>
>>> "Eeyore" wrote
>>>> Peter Parry wrote:
>>>>
>>>>> Amazing how none of these mysterious "clusters" of variegated
>>>>> ailments never occurred around them or in people working on them.
>>>> Naval radars can apparently cook seagulls in flight.
>>> any evidence of this, or purely anecdotal?
>> I've heard it claimed in the electronics groups. It was alleged that
>>they could
>> 'shoot down' birds with their radar beams.
>
>I find that difficult to believe unless the bird if flying close to the
>centre of the beam, in a circle and in sync with the rotating antenna.
>I suppose it *might* work if the bird was hovering and the radar beam
>was stationary with the bird at the centre.

My boss at Marconis, Dr. Eastwood, wrote the only book on a subject,
'Radar Ornithology'.

It took me nearly 20 years to find a copy.

Mike
--
M.J.Powell