In article ,
says...

In message ,
Terry Casey writes
In article ,
says...

In message , Arny Krueger
writes

"Terry Casey" wrote in message
...


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.

Same lot, in the land of the concrete cows and a thousand roundabouts.
;o))

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.

Ah yes. That's certainly one of the reasons for using a weird reference
frequency. I recall that certain systems insisted that the four set-top
bypass channels had to be close to the standard off-air broadcast
channels, because some TV sets would not tune to anything but these.


They would have to be very unusual TV sets!

It was more likely to be, in the case of Westminster, that, when CATV
systems rarely went above 600MHz, there was nowhere else to put them,
coupled with the fact that the off-air channels were left clear, so it
was convenient utilise to this for the n + 2 arrangement by straddling
the otherwise blank off-air allocation.

A comb of 7.988636364MHz would allow E25, E27, E29 and E31 to be used
with +/-34kHz error (off-airs being 23, 26, 30 & 33)

Of course, this was all long before the Channel 5 debacle - I can't see
a way of interleaving 5 channels around Crystal Palace without involving
the allegedly taboo n + 5 scenario - although I've never seen a problem
with any set I used directly connected to a CATV network


But wasn't it at the same place which ingeniously used a not-quite-8MHz
comb reference which was actually derived from one of the UHF off-air
channels?

Well, dividing E26 by 64 or E30 by 68 would do the trick. I based my
comb frequency on E28, being the centre channel but an off-air lock
would certainly produce a very stable result, and the offsets would
still be reasonable - +58/-11kHz or +11/-58kHz, depending on choice of
off air channel.

As the headend equipment was largely supplied by the 'other'
company, I doubt if I would have been involved with tinkering with it
(although I'm pretty sure that I did swap one or two of the modulator
SAW filters because of the problems which arose when NICAM started).
Maybe 'my' comb generator was a replacement.

My involvement with the Westminster system was at the time of the DTV
roll-out (or possibly Broadband Internet, I can't remember which) which
coincided with the transfer of the system from BT to ntl, so I never saw
the BT headend but I did see the documentation related to it, complete
with frequency details.

--

Terry

In article ,
Bill Wright wrote:
Don't forget that the schools in the UK have many teachers who are
socialist and deny the true
history of the 20th century.

So there are no right wing teachers who deny the history of the 20th
century?

You must remember that a lot
of people in the UK are socialists, and they hate the US because that
country has demonstrated
that capitalism works.

All it has demonstrated is it works well for some. But doesn't work at all
well for many.

Tell you what, Bill. Go to a US health care website and get a quote to
cover you and yours.

There's also a lot of envy in the UK for the US, amongst those who are
given to envy. And that of course is the socialists.

Those given to envy will envy anything. Those in an average position in
the UK would be mad to envy the US. Unless they believe it's all like
Hollywood portrays it.

--
*I will always cherish the initial misconceptions I had about you

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Ian Jackson wrote:
If it could be used on a variety of voltages (120V, 200V - in Hong Kong,
220) and 230/240V), that meter could be extremely useful.

Quite. it serves no purpose in the UK since it couldn't resolve any likely
voltage variations - even for those so anal they wanted to know.

--
*Why do we say something is out of whack? What is a whack?

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
lid says...


That isn't the film I saw - the film even has sound! And it wasn't a
telerecording either.

It was shot at Alexandra Palace that night and is a fairly long shot
which makes the whole thing look even more haphazard. Until now, I
didn't realise that I'd heard part of the bulletin that wasn't
broadcast!


I've just checked the copy I made with my camera and it shows the start
of the re-run, then switches to that phantom phone call that appears in
the video clip. There is also some disturbance, as on the video clip,
pointing to at least part of it, at least, having originated from the
same source.

--

Terry

In message ,
Terry Casey writes
In article ,
says...




I recall that certain systems insisted that the four set-top
bypass channels had to be close to the standard off-air broadcast
channels, because some TV sets would not tune to anything but these.


They would have to be very unusual TV sets!

I don't know about 'unusual', but they were a problem. I think there
were only couple of budget brands which only tuned 'spot-on' to the UHF
channels (xxx.25MHz, in 8MHz steps). One might ask indeed "Why would you
need them to do otherwise?" Of course, even our cable set-top boxes
could normally only tune in 125kHz steps, but at least that got you to
within +/-63kHz of the correct frequency - and that was more than close
enough.

It was more likely to be, in the case of Westminster, that, when CATV
systems rarely went above 600MHz, there was nowhere else to put them,
coupled with the fact that the off-air channels were left clear, so it
was convenient utilise to this for the n + 2 arrangement by straddling
the otherwise blank off-air allocation.

A comb of 7.988636364MHz would allow E25, E27, E29 and E31 to be used
with +/-34kHz error (off-airs being 23, 26, 30 & 33)

Of course, this was all long before the Channel 5 debacle - I can't see
a way of interleaving 5 channels around Crystal Palace without involving
the allegedly taboo n + 5 scenario - although I've never seen a problem
with any set I used directly connected to a CATV network

Sets generally seemed to improve a lot in later years. I think that the
change of IF from 39.5MHz to the European 38.9MHz made quite a
difference to N+/- problems. What surprises me is how well some sets
could tolerate having direct inputs of 48+ channels (without them going
through the converter UHF bypass filtering). Certainly, in the olden
days, when faced with more than half a dozen channels, some sets tended
to sag a bit at the knees.

But, as you have said, there used to be so many embargoed channels on a
cable TV system - no adjacent, no N+/-5, no N+/-9, no sums or
differences (with single-ended amplifiers) etc. It's a wonder anyone was
able to get more than two or three channels!


But wasn't it at the same place which ingeniously used a not-quite-8MHz
comb reference which was actually derived from one of the UHF off-air
channels?

Well, dividing E26 by 64 or E30 by 68 would do the trick. I based my
comb frequency on E28, being the centre channel but an off-air lock
would certainly produce a very stable result, and the offsets would
still be reasonable - +58/-11kHz or +11/-58kHz, depending on choice of
off air channel.

If this is what they did, they could have used either of those channels
from Crystal Palace. Next time I see him, I'll ask the man who will
almost certainly know (if I remember!).

As the headend equipment was largely supplied by the 'other'
company, I doubt if I would have been involved with tinkering with it
(although I'm pretty sure that I did swap one or two of the modulator
SAW filters because of the problems which arose when NICAM started).
Maybe 'my' comb generator was a replacement.

My involvement with the Westminster system was at the time of the DTV
roll-out (or possibly Broadband Internet, I can't remember which) which
coincided with the transfer of the system from BT to ntl, so I never saw
the BT headend but I did see the documentation related to it, complete
with frequency details.

I had little to do with the system in London (I think I only went there
once - underground, near Shepherds Bush IIRC). As I said, my involvement
was among the concrete cows and the roundabouts.
--
Ian

In message , "Dave Plowman (News)"
writes
In article ,
Ian Jackson wrote:
If it could be used on a variety of voltages (120V, 200V - in Hong Kong,
220) and 230/240V), that meter could be extremely useful.

Quite. it serves no purpose in the UK since it couldn't resolve any likely
voltage variations - even for those so anal they wanted to know.

But it could be useful if you had the need to operate some 120V
equipment using a step-down transformer (especially a variac).
--
Ian

In article ,
Ian Jackson wrote:
In message , "Dave Plowman (News)"
writes
In article ,
Ian Jackson wrote:
If it could be used on a variety of voltages (120V, 200V - in Hong Kong,
220) and 230/240V), that meter could be extremely useful.

Quite. it serves no purpose in the UK since it couldn't resolve any
likely voltage variations - even for those so anal they wanted to know.

But it could be useful if you had the need to operate some 120V
equipment using a step-down transformer (especially a variac).

I'd rather trust that to my Fluke than some dirt cheap tiny meter. I'll
bet the accuracy is horrendous. A mere gimmick for the gullible.

--
*Beware - animal lover - brakes for pussy*

Dave Plowman London SW
To e-mail, change noise into sound.

wrote in message
...

American wiring plus wooden houses... jeez.

All things considered it works very well, at a cost in copper.

My estimated death rate in the UK due to all fires was about 0.8 per
100,000 in the last year for which I have reports, and was (2006) and 0.96
in the US (2007)

I have not yet been able to get an exact comparison of death rate due to
structure fires in the same year but US homes are not the death traps that
seems to be suggested above.

US's death rate due to structure fires continues to be declining rapidly for
new buildings every year, of which we are still building quite a few. The UK
is also enjoying improvements in this area, but with slower rates of
improvement and probably lower rates of new construction. Both the UK and
the US show disappointing results for structures built in the 1950s and
1960s.

"Geoffrey S. Mendelson" wrote in message
...
Arny Krueger wrote:

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?

Given the lack of effectiveness of bomb sighting and delivery in those days,
you needed a lot of big bombers to do any strategic damage at all.

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.

I thought we were talking about Germany bombing the US.


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.

I now of no evidence that care taken during construction the shielding of
the bomb while being delivered was making the bombs that big and heavy. I'm
under the impression that most of the gains that were made in minaturizing
atomic bombs had to do with the design of the mechanism.

After all how much size or weight in shielding do you have on an A-Bomb that
you can fire with a mortar or a bazooka?

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

"Other potential delivery methods include artillery shells, mines such as
the Medium Atomic Demolition Munition and the (very odd) Blue Peacock, and
nuclear depth charges, and nuclear torpedoes. An atomic mortar was also
tested. Even an 'Atomic Bazooka' was designed to be used against large
formations of tanks."

More may be known about comparable Russian weapons because of the break down
of the Soviet military:

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

"These devices, "identified as RA-115s (or RA-115-01s for submersible
weapons)" weigh from fifty to sixty pounds."

While the active materials in an A-bomb are radioactive, they aren't all
that radioactive until they become a critical mass.

"Michael A. Terrell" wrote in message
...

Arny Krueger wrote:

"Michael A. Terrell" wrote in message
...

Arny Krueger wrote:

"Peter Larsen" wrote in message
k...
Ron wrote:

Surely you remember analogue TV Arny, it's when we had five
channels
of rubbish, now we have 900 channels and it's still rubbish

What's TV?

Something that can actually be enjoyable, useful and even a bit
educational,
managed well.

A capacious 2 channel DVR is a big help.

An internet ready BluRay is better. A lot of free TV via the
internet including classic movies, comedy and Sci-Fi.

We have the hardware for both. After experiencing a hands-on unfettered
comparison of the two for about a year, we kept the DVR and terminated
the
Internet service for the BluRay, but kept the stream of rental BD discs.


The BluRay was a one time investment of $80. Since I already have
broadband, there is no monthly fee. No need for a credit card, or trips
to one of the few remaining video stores, or to try to find something
worth watching in a 'Redbox'.

If you are obtaining current movies for just the cost of broadband, then you
are not paying the usual fees for viewing copyrighted materials. The
morality of that is up to you, but its not a fair comparison.

In the US the usual fee for obtaining a fairly current movie over broadband
is about $5 each. Netflix over broadband is more like $9 per month, but the
catalog is severely limited, both in terms of movies and also TV shows.

Redbox is the price/performance winner around here, and their nearest
machine is within easy driving or biking distance.