Re: Audio Precision System One Dual Domani Measuirement Systems

[[email protected]]

Are you really that stupid, or do you just play a fool on Usenet?
The US National Electrical Code is online. It goes into great detail
about what can and can not be done. Read it, and see if you can learn
anything.

Ahem... the posting to which you reply to deals with UK ring
circuits.
Frankly, anyone who recommmends the practice of wiring as employed in
the US, is having a laugh.
American wiring plus wooden houses... jeez.

 

[Geoffrey S. Mendelson]

Not a bomber - it would have been the A10 rocket.

No, it was a "stealth" airplane.

According to the show, the troops found an experimental stealth airplane
in a hangar in France in the spring of 1945. It had crashed durng a test
flight in February, killing the pilot, but had been restored.

The airplane and parts (possibly for others) were broght back to the US and
stored in a warehouse. Airplane technicains were allowed to
come in and take measurments for a short time.

They then went back to their factory and built a model of it which was used
to test it for it's ability to be detected by 1945 vintage radar. It was
good enough that had it flown, it would not have been detected until
20 miles off the coast of England or the US.

The film also re-enacted a meeting between the head of the Luftwaffe and
the designers of the airplane (which was reliably documented) that they were
told to produce a stealth bomber which could reach New York from (occupied)
France.

At the time of the meeting, it was expected that Germany would have an
atomic bomb in time for a 1946 flight.

<http://news.nationalgeographic.com/news/2009/06/090625-hitlers-stealth-fighter-plane.html>


Geoff.

 

[David Looser]

I refer you to the photo I posted a link to elsewhere.

You seem to think that your photos prove something, they do not beyond what
colours were used in one Spanish installation. If you want to know what the
harmonised colours actually are go and read the documents!

David.

 

[Mike Tomlinson]

You seem to think that your photos prove something,

Yes, they prove that the installation was done with brown/black/black.
You seemed to have difficulty believing me, which is why I posted a
photo.

You said in an earlier post "I guess the installers simply didn't have
any grey cable" which means you thought the cables were single,
individual cables. I merely pointed out that they were not, but were in
in an armoured outer jacket.

I'm fine that the harmonised colours are brown/black/grey, just saying
that I know of installations - note the plural - where they are not.

Take a chill pill, ffs.

 

[Terry Casey]

US analog TV's improved greatly and were generally happy with adjacent
channels for maybe the last 20 years of their lives.

http://www.jneuhaus.com/fccindex/cablech.html

shows cable channels on 6-7 MHz intervals. Adjacent numbered channels were
used all the time.

A couple of questions regarding that list:

Why is the HRC channel spacing offset[1] by 300Hz - 6.0003MHz instead of
6MHz?

Why are the IRC channels offset from broadcast channels (where they
exist) by 12.5kHz?

[1] UK cable systems mostly use HRC at 8MHz spacing but this is
sometimes varied by a carefully calculated amount so that one block of
UHF channels coincides almost exactly with the broadcast frequencies.
This is done on systems with a by-pass facility to allow a few channels
- usually the local off-airs - to be fed directly to the TV giving the
subscriber direct access from the TV without needing an aerial.

Obviously this block of channels has to be chosen so as not to conflict
with local transmitters, so the offset will vary from system to system
and can't be fixed as in the US table

 

[Terry Casey]

[1] UK cable systems mostly use HRC at 8MHz spacing but this is
sometimes varied by a carefully calculated amount so that one block of
UHF channels coincides almost exactly with the broadcast frequencies.
This is done on systems with a by-pass facility to allow a few channels
- usually the local off-airs - to be fed directly to the TV giving the
subscriber direct access from the TV without needing an aerial.

Obviously this block of channels has to be chosen so as not to conflict
with local transmitters, so the offset will vary from system to system
and can't be fixed as in the US table

In case it isn't clear, I should have pointed out that normal cable
reception is via a set top box and, of course, I was referring to
analogue systems ...

 

[Terry Casey]

No, it was a "stealth" airplane.

According to the show, the troops found an experimental stealth airplane
in a hangar in France in the spring of 1945. It had crashed durng a test
flight in February, killing the pilot, but had been restored.

The airplane and parts (possibly for others) were broght back to the US and
stored in a warehouse. Airplane technicains were allowed to
come in and take measurments for a short time.

They then went back to their factory and built a model of it which was used
to test it for it's ability to be detected by 1945 vintage radar. It was
good enough that had it flown, it would not have been detected until
20 miles off the coast of England or the US.

The film also re-enacted a meeting between the head of the Luftwaffe and
the designers of the airplane (which was reliably documented) that they were
told to produce a stealth bomber which could reach New York from (occupied)
France.

At the time of the meeting, it was expected that Germany would have an
atomic bomb in time for a 1946 flight.

<http://news.nationalgeographic.com/news/2009/06/090625-hitlers-stealth-fighter-plane.html>

Very interesting link. Thank you.

 

[Terry Casey]

No, there was also a super bomber based on conventional technology:

http://en.wikipedia.org/wiki/Amerika_Bomber

"The most promising proposals were based on conventional principles of
aircraft design and would have yielded aircraft very similar in
configuration and capability to the Allied heavy bombers of the day..."

Which conflicts with the idea of a stealth bomber ...

 

[David Looser]

The version of events I described is the one that has been quoted for
over 40 years but I only became aware of that bulletin a couple of
months ago ...

Was it a recording you saw - or a film made at the time?

What I actually saw was a DVD, copied from a video tape. My understanding is
that someone at Kingswood Warren decided to record this "first programme"
off-air, but that the tape then lay forgotten for many years until it was
rediscovered a few years ago. I also understand that the DVD I saw was a
direct copy from the original off-air tape. It's clear from the picture
quality that this was a video-tape recording, not a film telerecording.

It was rather a pathetic attempt which should be filed in the "it would
have been better if they hadn't bothered" category.

I don't know what the viewers (if there were any left!) made of it at
the time but, when I saw the film it generated some laughter - possibly
out of pity - from some of the audience.

I entirely agree. Its the most appallingly amateurish thing imaginable. I
particularly like the fact that there is total silence for the first minute
or so and then, at the end of the bulletin, the newsreader says that the
bulletin will be repeated in one minute's time as "I gather nobody could
hear me". So the loss of sound was at the transmitting end. I guess the BBC
were too embarrassed to admit that this news bulletin was actually broadcast
and were quite happy to have the myth that BBC2 only started the next day
gain currency!

David.

 

[David Looser]

Yes, they prove that the installation was done with brown/black/black.
You seemed to have difficulty believing me, which is why I posted a
photo.

I never for one second doubted that you had seen installations done in
brown, black, black. So there was no need to post photos to prove that you
had.

All I said was that the harmonised colours are, and always have been, brown,
black, grey. A fact which you have seemed reluctant to accept.

I'm fine that the harmonised colours are brown/black/grey, just saying
that I know of installations - note the plural - where they are not.

Its entirely possible that brown, black, black was in use in parts of Europe
before the EU-wide harmonised colours were introduced. But they've never
been used here.

Take a chill pill, ffs.You too

David.

 

[Geoffrey S. Mendelson]

One point - this Nazi development (never a practical tool of war) was a
fighter not a bomber. Even in more modern times developing a stealth bomber
was far more difficult and there was a delay of many years between the
first stealth fighter and the first stealth bomber.

How big a bomber and how unpractical a tool of war is a fighter sized
airplane that can't be seen until you are 20 miles off the coast and it's
carrying an atomic bomb?

The distance from the coast to London is 92 miles so it needs to go 112
miles to drop the bomb directly on London. If it was travelling 100 mph,
that would take enough time for it to be noticed and if a fighter got lucky,
it would be shot down visually.

According to the Wikipedia page its top speed was 977 kmh, so it could
go from first contact to ground zero in 11 minutes. Not a lot of time to
find and stop it.

The cargo load of the airplane was about 2000 pounds, about 1/5 of the size
of the Hiroshima and Nagasaki (fat man and little boy) bombs, but that does
not mean that someone could of built an atomic bomb that would fit the weight
critera if one did not care to survive the construction of the bomb and the
flight.

Geoff.

 

[Geoffrey S. Mendelson]

Right. It wasn't jet powered, either. The jet engines of the day had service
lives measured in integer hours, which means that a flight from Europe to
the US would be pretty much guaranteed to fail. Fuel economy was miserable
as well.

According to the wikipedia entry (quoted in an earlier post), it had the
speed to make it from Paris to New York in about 6-7 hours.

The jet engines would not of gotten you to New York and back, but it would
of gotten an atomic bomb to New York, which is what was intended.

Geoff.

 

[Ian Jackson]

A couple of questions regarding that list:

Why is the HRC channel spacing offset[1] by 300Hz - 6.0003MHz instead of
6MHz?

I don't know.

I recall once specially tweaking a UK 8MHz HRC harmonic comb generator
(to which all of the TV channels were locked). It was a little above (or
was it below?) 8MHz. There was a reason for this, but at the moment, I
can't remember what it was. However, I have a feeling the reason was a
bit of a red herring. I also remember tweaking another so that one of
UHF cable channels was carefully offset from a local off-air in order to
minimise the visibility of interference patterning (essentially the same
fix as discussed below).

If memory sserves, two transmitters that are interferring just a little,
produce nasty herringbones if they are running at the same frequency, but
move them apart a tad, and the artifacts are far less objectionable.

That is almost certainly the reason. Running IRC channels exactly on
frequency can result in unacceptable beat patterns of 0.75 and 1.25MHz
(at least, it did on one European system I was involved with). Moving
all 65 channels HF by 25kHz worked wonders. [This is close to the 5/3 x
15.625kHz offset broadcasters use for off-air 625-line TV.] 12.5kHz will
probably also be a good offset.

[1] UK cable systems mostly use HRC at 8MHz spacing but this is
sometimes varied by a carefully calculated amount so that one block of
UHF channels coincides almost exactly with the broadcast frequencies.
This is done on systems with a by-pass facility to allow a few channels
- usually the local off-airs - to be fed directly to the TV giving the
subscriber direct access from the TV without needing an aerial.

Obviously this block of channels has to be chosen so as not to conflict
with local transmitters, so the offset will vary from system to system

US cable systems ran on some of the same channels as local broadcasters.

These days, UK cable TV systems don't seem to avoid clashing with (or,
at least, partially overlapping) the off-air TV channels (which are all
UHF). Obviously, to prevent interference problems caused by
ingress/egress, sufficient attention has to be paid to the RF-tightness
of the network.

 

[David Looser]

According to the wikipedia entry (quoted in an earlier post), it had the
speed to make it from Paris to New York in about 6-7 hours.

The jet engines would not of gotten you to New York and back, but it would
of gotten an atomic bomb to New York, which is what was intended.

All this is pure speculation. The "flying wing" jet fighter flew test
flights, but crashed killing it's pilot. It was a second copy (that never
flew) that was "liberated" to the USA after the war. None of the other
designs for an "Amerika Bomber" made it off the drawing board. How long
would it have taken to develop any design to the point that it could make
the trans-Atlantic flight? How long would it have taken the Nazis to develop
an atomic bomb, bearing in mind that Germany had ceased all work leading to
one back in '42?


David.

 

[Don Pearce]

Sigh. America was supplying AKA: LENDING planes and other war
materials to help Europe clean up their mess, long before Japan attacked
Pearl Harbor. Is the school system really that bad where you grew up?

I hope you are not imagining that America did that from anything other
than good, solid self-interst.

d

 

[David Looser]

Lend-lease was hardly decisive in the 1939-1941 period. The planes that
denied Goering air-superiority over Britain were all British designed and
built and flown overwhelmingly by British pilots (with some from
Czechoslovakia and Poland).

I hope you are not imagining that America did that from anything other
than good, solid self-interst.

And its worth pointing out that the country that did far more than any other
to defeat Nazi Germany was the Soviet Union. Once Hitler made the fatal
mistake of invading the USSR he sealed the fate of his regime. The most
probable outcome had the US not entered the European [1] war would have been
Soviet hegemony over most of Europe, rather than just the Eastern part. The
implications of that for the post-war balance of power are obvious.

[1] The US didn't have the luxury of deciding whether or not to enter the
Pacific war, unless, of course, it chose to cease to have any presence in
the Pacific region.

David.

 

[David Looser]

They were a dollar. This isn't the same as what I saw, but it will
give you some idea:
<http://i00.i.aliimg.com/photo/v0/255041326/DZ_909A_6_way_power_outlet_with.jpg>
since the meter was next to the power switch and cord.

Right. You started all this by refering to European sockets which had to be
installed in equipment racks. So I naturally assumed that you were talking
about UK specific installation sockets being sold in flea markets in the US.

But now I realise that you are talking about plug-in extention sockets, and
I notice from the photo that that one has "universal" sockets that will
accept US and a variety of European plugs as well as UK ones. Personally I
wouldn't touch one of those with a barge-pole. Those sort of "universal"
sockets rarely make good contact whilst the meter is clearly for show, it
would tell you nothing useful. I'm sure it would not be legal to sell those
here as the sockets appear not to have shutters, which probably explains why
I've not seen one.

David.

 

[Ian Jackson]

Do you know that the channel combiners in a CATV head end
were wired in odd and even banks, on separate groups to prevent IMD
caused in the passive mixing?

It might have depended on whose combiners you were using.

I hadn't heard about this so, one day (it must have been back in the
80s), I decided to do a quick test to see if it was true. To be honest,
I don't think I saw much difference whichever way I grouped the
channels. From what I remember, with the modulators putting each out
60dBmV, all the intermod products were at least 85dB down, and were
rather difficult to measure quickly. Such low levels of intermod would
have had a negligible impact on the overall system performance.

 

[Terry Casey]

[1] UK cable systems mostly use HRC at 8MHz spacing but this is
sometimes varied by a carefully calculated amount so that one block of
UHF channels coincides almost exactly with the broadcast frequencies.
This is done on systems with a by-pass facility to allow a few channels
- usually the local off-airs - to be fed directly to the TV giving the
subscriber direct access from the TV without needing an aerial.

Obviously this block of channels has to be chosen so as not to conflict
with local transmitters, so the offset will vary from system to system
and can't be fixed as in the US table

In case it isn't clear, I should have pointed out that normal cable
reception is via a set top box and, of course, I was referring to
analogue systems ...

The advent of TV sets that could tune the cable channels all by themselves
was a game changer.

They are used on the continental cable systems but never have been in
the UK. Possibly because there is much more encrypted subscription
content?

 

[Terry Casey]

A couple of questions regarding that list:

Why is the HRC channel spacing offset[1] by 300Hz - 6.0003MHz instead of
6MHz?

I don't know.

I recall once specially tweaking a UK 8MHz HRC harmonic comb generator
(to which all of the TV channels were locked). It was a little above (or
was it below?) 8MHz. There was a reason for this, but at the moment, I
can't remember what it was.

One system where this was done was the old BT Westminster system -
probably very useful in an area where I would expect a lot of off-air
reception problems.

I don't know what offset they used but, as an example, if you alter the
comb to 7.990963855MHz, channel E45 is bang on (663.25MHz) so, if you
centred the five off-airs around this using E41, E43, E45, E47 and E49,
the worst case error will be +/-36kHz from the nominal frequency.