Large scale RF shielding...

[Phil Hobbs]

Jeroen Belleman wrote:

On 2022-05-06 16:08, jlarkin@highlandsniptechnology.com wrote:
On Thu, 5 May 2022 22:08:06 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

John Larkin wrote:
On Thu, 5 May 2022 11:46:13 -0700, Don Y <blockedofcourse@foo.invalid
wrote:

Homes, here, tend to be reasonably opaque to RF.  OTA broadcasts
can only be received with a rooftop antenna (despite the fact
that it\'s only a few unobstructed miles to the transmitters).
Indoor FM reception is \"iffy\".  GPSs can\'t get a fix (I\'ve tried
2 handheld units, 2 dash-mount plus the one built into the car).
Even the two \"atomic\" clocks that I have spend all of their
time \"looking for signal\" (or so they claim).

And *everyone* steps outside to use their cell phones.  (OK,
maybe the neighborhood is a deadspot due to terrain -- despite
antennas being reasonably close by -- though I\'ve no way of
knowing who is \"operating\" each of them)

I.e., the \"problem\" isn\'t confined to our home.

This begs two *different* questions:
1.  How to punch holes in <whatever> is attenuating the signal
2.  How to identify the cause of the problem to be able to
      (willingly) *reproduce* it in other places

Most homes are masonry - 8-12\" thick walls.  Interior walls on
the perimeter are firred out with drywall coated with aluminum
foil (moisture barrier?).  All internal wiring is overhead, plumbing
in the slab.  Different types of roofing so I\'m unsure if there
is a common thread, there.

Ideally, there is a *cheap* way to get this sort of attenuation
that can be retrofitted to existing homes of different construction.

Must the the foil. What\'s strange is that it\'s really hard to build a
good EMI screen room.

It\'s the wallpaper effect--it won\'t stick when you\'re putting it up, and
won\'t come off when you\'re taking it down.

40 dB loss is a pretty crappy screen room, but will reliably make a mess
of cell phone communications.

(We built a test jig out of a big beefy 5x9-inch aluminum die cast box
whose lid attaches with a screw in each corner.  Turns out that the
RasPi inside communicates via wifi quite nicely.


One trick is to run a wire from outside (as a receive antenna) to
inside (as a radiator). I\'ve seen that done in tunnels.

Yup.  People have made passive VHF repeaters for amateur radio by
putting antennas on each side of a mountain and just wiring them
together with coax.

Cheers

Phil Hobbs

RF is hard to believe. My key fob will unlock my car from half a block
away. We get pictures back from Jupiter. Seems improbable.




It screams very loudly in a medium we cannot perceive. Imagine what
it would be like if we could hear RF.

Jeroen Belleman

[Fixed editing scars]

The main thing is the ease of getting huge intercepted areas with a
single pair of wires (i.e. one port), and a contributing thing is the
energy per photon.

The etendue (area*solid angle product) of a single electromagnetic mode is

E = lambda**2 / 2.

If you need more etendue than that, i.e. either a wider acceptance angle
or more intercepted area, you have to use either multiple ports or
incoherent detection. The SNR tradeoff involved in going to much
shorter wavelength is fairly heartbreaking.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Phil Hobbs]

Rich S wrote:

On Thursday, May 5, 2022 at 6:46:43 PM UTC, Don Y wrote:
Homes, here, tend to be reasonably opaque to RF. OTA broadcasts
can only be received with a rooftop antenna (despite the fact
that it\'s only a few unobstructed miles to the transmitters).
Indoor FM reception is \"iffy\". GPSs can\'t get a fix (I\'ve tried
2 handheld units, 2 dash-mount plus the one built into the car).
Even the two \"atomic\" clocks that I have spend all of their
time \"looking for signal\" (or so they claim).

And *everyone* steps outside to use their cell phones. (OK,
maybe the neighborhood is a deadspot due to terrain -- despite
antennas being reasonably close by -- though I\'ve no way of
knowing who is \"operating\" each of them)

I.e., the \"problem\" isn\'t confined to our home.

This begs two *different* questions:
1. How to punch holes in <whatever> is attenuating the signal
2. How to identify the cause of the problem to be able to
(willingly) *reproduce* it in other places

Most homes are masonry - 8-12\" thick walls. Interior walls on
the perimeter are firred out with drywall coated with aluminum
foil (moisture barrier?). All internal wiring is overhead, plumbing
in the slab. Different types of roofing so I\'m unsure if there
is a common thread, there.

Ideally, there is a *cheap* way to get this sort of attenuation
that can be retrofitted to existing homes of different construction.

uh, these homes lack windows?
Last I heard, glass is transparent for RF

IIRC some have ITO or tin oxide coatings on the inner pane for lower IR
emissivity. That can also be a reasonable RF shield.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Phil Allison]

John Larkin wrote:
===============

Homes, here, tend to be reasonably opaque to RF. OTA broadcasts
can only be received with a rooftop antenna (despite the fact
that it\'s only a few unobstructed miles to the transmitters).
Indoor FM reception is \"iffy\". GPSs can\'t get a fix (I\'ve tried
2 handheld units, 2 dash-mount plus the one built into the car).
Even the two \"atomic\" clocks that I have spend all of their
time \"looking for signal\" (or so they claim).

And *everyone* steps outside to use their cell phones. (OK,
maybe the neighborhood is a deadspot due to terrain -- despite
antennas being reasonably close by -- though I\'ve no way of
knowing who is \"operating\" each of them)

I.e., the \"problem\" isn\'t confined to our home.

This begs two *different* questions:
1. How to punch holes in <whatever> is attenuating the signal
2. How to identify the cause of the problem to be able to
(willingly) *reproduce* it in other places

Most homes are masonry - 8-12\" thick walls. Interior walls on
the perimeter are firred out with drywall coated with aluminum
foil (moisture barrier?). All internal wiring is overhead, plumbing
in the slab. Different types of roofing so I\'m unsure if there
is a common thread, there.

Ideally, there is a *cheap* way to get this sort of attenuation
that can be retrofitted to existing homes of different construction.


Must the the foil. What\'s strange is that it\'s really hard to build a
good EMI screen room.

One trick is to run a wire from outside (as a receive antenna) to
inside (as a radiator). I\'ve seen that done in tunnels.
===========================================

** Why is no-one here considering the safety issue of NO usable RF inside one\'s home ?
For a great many, that is not just inconvenient it is positively DANGEROUS.

The use of mobiles ( ie cell phones ) has taken over from old wired phones using twisted pair
and with modern broadband connections.
The ability to make emergency calls from within one\'s home is ESSENTIAL.

Faraday shielding residential properties needs to be made illegal.
==================================================

...... Phil

 

[Lasse Langwadt Christensen]

fredag den 6. maj 2022 kl. 04.08.18 UTC+2 skrev Phil Hobbs:

John Larkin wrote:
On Thu, 5 May 2022 11:46:13 -0700, Don Y <blocked...@foo.invalid
wrote:

Homes, here, tend to be reasonably opaque to RF. OTA broadcasts
can only be received with a rooftop antenna (despite the fact
that it\'s only a few unobstructed miles to the transmitters).
Indoor FM reception is \"iffy\". GPSs can\'t get a fix (I\'ve tried
2 handheld units, 2 dash-mount plus the one built into the car).
Even the two \"atomic\" clocks that I have spend all of their
time \"looking for signal\" (or so they claim).

And *everyone* steps outside to use their cell phones. (OK,
maybe the neighborhood is a deadspot due to terrain -- despite
antennas being reasonably close by -- though I\'ve no way of
knowing who is \"operating\" each of them)

I.e., the \"problem\" isn\'t confined to our home.

This begs two *different* questions:
1. How to punch holes in <whatever> is attenuating the signal
2. How to identify the cause of the problem to be able to
(willingly) *reproduce* it in other places

Most homes are masonry - 8-12\" thick walls. Interior walls on
the perimeter are firred out with drywall coated with aluminum
foil (moisture barrier?). All internal wiring is overhead, plumbing
in the slab. Different types of roofing so I\'m unsure if there
is a common thread, there.

Ideally, there is a *cheap* way to get this sort of attenuation
that can be retrofitted to existing homes of different construction.

Must the the foil. What\'s strange is that it\'s really hard to build a
good EMI screen room.
It\'s the wallpaper effect--it won\'t stick when you\'re putting it up, and
won\'t come off when you\'re taking it down.

40 dB loss is a pretty crappy screen room, but will reliably make a mess
of cell phone communications.

(We built a test jig out of a big beefy 5x9-inch aluminum die cast box
whose lid attaches with a screw in each corner. Turns out that the
RasPi inside communicates via wifi quite nicely.

we have used an old reefer container for setting up test in high temperatures
it is two layers of steel but a cellphone works just fine inside

 

[Don Y]

On 5/6/2022 1:40 PM, Phil Hobbs wrote:

Rich S wrote:

Ideally, there is a *cheap* way to get this sort of attenuation
that can be retrofitted to existing homes of different construction.

uh, these homes lack windows?
Last I heard, glass is transparent for RF

IIRC some have ITO or tin oxide coatings on the inner pane for lower IR
emissivity. That can also be a reasonable RF shield.

Exactly. We\'re not concerned with heat \"leaking out\" (like you\'d be
in northern climates) but, rather, leaking *in*. There\'s a different
kind of coating (process) prefered -- \"soft coat\" -- that deposits
a couple of fine layers of silver on the glass using magnetron sputtering
vapor deposition. \"Hard coat\" is fused with the glass during its
transition from liquid to \"solid\".

And, windows only allow \"radiation\" in that is \"directed\" inward
(hence the reason sunlight is shaded out by \"wide\" overhangs).

Apparently it\'s much more effective (and comfortable) to step outside
to talk than to stand in front of the window (?)...

 

[Lasse Langwadt Christensen]

fredag den 6. maj 2022 kl. 22.40.45 UTC+2 skrev Phil Hobbs:

Rich S wrote:
On Thursday, May 5, 2022 at 6:46:43 PM UTC, Don Y wrote:
Homes, here, tend to be reasonably opaque to RF. OTA broadcasts
can only be received with a rooftop antenna (despite the fact
that it\'s only a few unobstructed miles to the transmitters).
Indoor FM reception is \"iffy\". GPSs can\'t get a fix (I\'ve tried
2 handheld units, 2 dash-mount plus the one built into the car).
Even the two \"atomic\" clocks that I have spend all of their
time \"looking for signal\" (or so they claim).

And *everyone* steps outside to use their cell phones. (OK,
maybe the neighborhood is a deadspot due to terrain -- despite
antennas being reasonably close by -- though I\'ve no way of
knowing who is \"operating\" each of them)

I.e., the \"problem\" isn\'t confined to our home.

This begs two *different* questions:
1. How to punch holes in <whatever> is attenuating the signal
2. How to identify the cause of the problem to be able to
(willingly) *reproduce* it in other places

Most homes are masonry - 8-12\" thick walls. Interior walls on
the perimeter are firred out with drywall coated with aluminum
foil (moisture barrier?). All internal wiring is overhead, plumbing
in the slab. Different types of roofing so I\'m unsure if there
is a common thread, there.

Ideally, there is a *cheap* way to get this sort of attenuation
that can be retrofitted to existing homes of different construction.

uh, these homes lack windows?
Last I heard, glass is transparent for RF


IIRC some have ITO or tin oxide coatings on the inner pane for lower IR
emissivity. That can also be a reasonable RF shield.
Cheers

afaiu some cars have the problem because the windows have a gold film between the layers for heating

 

[ke...@kjwdesigns.com]

On Friday, 6 May 2022 at 10:28:07 UTC-7, Don Y wrote:
....

Dunno. As I said elsewhere, *I* don\'t use cellular comms. The *cordless*
phones work everywhere in the house so we have no problem. But, friends
and neighbors seem to resort to \"stepping outside\" when they have to make
a call of any duration.

I suspect they must keep their phones located \"in a sweet spot\" indoors
lest they miss calls/texts (?). Or, resort to post-processing calls
by checking their voicemail (apparently, calls are intercepted thusly
in relatively short order... do they have to \"run\" to answer the phone
sited in that \"sweet spot\"? -- we have \"extensions\" throughout the house)
....

Most phones and carriers these days support WiFi Calling where phone calls and SMS messages are routed over the internet as an alternate to wireless. The phone will (fairly) seamlessly switch between using WiFi and cellular radio as the relative signal strengths change or wifi service is available.

The carriers still charge for time, even if they are using your own wifi.

kw

 

[Don Y]

On 5/6/2022 5:00 PM, ke...@kjwdesigns.com wrote:

On Friday, 6 May 2022 at 10:28:07 UTC-7, Don Y wrote: ...
Dunno. As I said elsewhere, *I* don\'t use cellular comms. The *cordless*
phones work everywhere in the house so we have no problem. But, friends
and neighbors seem to resort to \"stepping outside\" when they have to make
a call of any duration.

I suspect they must keep their phones located \"in a sweet spot\" indoors
lest they miss calls/texts (?). Or, resort to post-processing calls by
checking their voicemail (apparently, calls are intercepted thusly in
relatively short order... do they have to \"run\" to answer the phone sited
in that \"sweet spot\"? -- we have \"extensions\" throughout the house)
...

Most phones and carriers these days support WiFi Calling where phone calls
and SMS messages are routed over the internet as an alternate to wireless.
The phone will (fairly) seamlessly switch between using WiFi and cellular
radio as the relative signal strengths change or wifi service is available.

The carriers still charge for time, even if they are using your own wifi.

I have to assume that they either don\'t use this feature, don\'t know *how*
to use this feature *or* that it is unreliable, as well (?)

Speaking with a colleague two days ago and the call was dropped twice
over the course of 30 minutes. I\'m talking on copper wire so I doubt
it\'s on my end!

It seems that people now EXPECT calls to be unreliable whereas that
was far from the case with older technology (batteries dying, dead spots,
etc.)

I\'ll be doing a VoIP port, soon, so I\'ll see what quirks *that* has.

 

[Martin Brown]

On 06/05/2022 17:31, Joe Gwinn wrote:

On Fri, 6 May 2022 10:46:00 +0100, Martin Brown
\'\'\'newspam\'\'\'@nonad.co.uk> wrote:


High end car theft gangs in Belgium did a pretty good job with lining a
largish HVG with supermarket grade aluminium foil and if memory serves
lead flashing seals on the opening joints. Good enough Faraday cage to
steal high end cars with notional satellite tracking on them anyway.

Cute. I assume that HVG is some kind of lorry.

Its a typo!
For HGV = heavy goods vehicle 44T tractor trailer combo.
US = big rig (but yours are max 64T?)

Where do they take the cars to? The tracking will start working once
delivered and out in the open, unless they are able to disable all
possibilities. So I\'m assuming that it is some place without
extradition.

They were very good at it. It was around y2k era. This isn\'t the right
link but gives the general idea. They were eventually caught...

https://www.expatica.com/be/uncategorized/car-theft-remains-high-in-belgium-83236/

A search with the most obvious search terms got me nowhere.

It was in the print media of the time (I was living in Belgium then).

--
Regards,
Martin Brown

 

[Martin Brown]

On 06/05/2022 21:40, Phil Hobbs wrote:

Rich S wrote:
On Thursday, May 5, 2022 at 6:46:43 PM UTC, Don Y wrote:

Most homes are masonry - 8-12\" thick walls. Interior walls on
the perimeter are firred out with drywall coated with aluminum
foil (moisture barrier?). All internal wiring is overhead, plumbing
in the slab. Different types of roofing so I\'m unsure if there
is a common thread, there.

Ideally, there is a *cheap* way to get this sort of attenuation
that can be retrofitted to existing homes of different construction.

uh, these homes lack windows?
Last I heard, glass is transparent for RF

IIRC some have ITO or tin oxide coatings on the inner pane for lower IR
emissivity.  That can also be a reasonable RF shield.

Although it does and mine are low emissivity there seems to be very
little attenuation at any of FM, DAB, Wifi or mobile phone frequencies.
I guess it is thin enough that most wavelengths are unaffected.

The stuff we had on the computer room windows for radio telescope
control had woven copper mesh inside grounded at every edge and an
airlock of two doors with all the fittings between the computer suite
and the outside world. Its attenuation was good up to 32GHz which was as
high as we could go. Door seals caused trouble from time to time.

The computer sitting in the innermost really good windowless Faraday
cage to protect IF stages and correlators from its interference. That
was a cost no object lined with 1/16\" copper sheet - it looked fabulous!
(shame that the door was normally kept shut so no-one got to see it)

--
Regards,
Martin Brown

 

[rbowman]

On 05/07/2022 02:12 AM, Martin Brown wrote:

On 06/05/2022 17:31, Joe Gwinn wrote:
On Fri, 6 May 2022 10:46:00 +0100, Martin Brown
\'\'\'newspam\'\'\'@nonad.co.uk> wrote:


High end car theft gangs in Belgium did a pretty good job with lining a
largish HVG with supermarket grade aluminium foil and if memory serves
lead flashing seals on the opening joints. Good enough Faraday cage to
steal high end cars with notional satellite tracking on them anyway.

Cute. I assume that HVG is some kind of lorry.

Its a typo!
For HGV = heavy goods vehicle 44T tractor trailer combo.
US = big rig (but yours are max 64T?)

80,000 pounds, to avoid the ton ambiguity. Some states will license
105,000 for intrastate traffic.

 

[Martin Brown]

On 07/05/2022 17:23, rbowman wrote:

On 05/07/2022 02:12 AM, Martin Brown wrote:
On 06/05/2022 17:31, Joe Gwinn wrote:
On Fri, 6 May 2022 10:46:00 +0100, Martin Brown
\'\'\'newspam\'\'\'@nonad.co.uk> wrote:


High end car theft gangs in Belgium did a pretty good job with lining a
largish HVG with supermarket grade aluminium foil and if memory serves
lead flashing seals on the opening joints. Good enough Faraday cage to
steal high end cars with notional satellite tracking on them anyway.

Cute.  I assume that HVG is some kind of lorry.

Its a typo!
For HGV = heavy goods vehicle 44T tractor trailer combo.
US  = big rig (but yours are max 64T?)

80,000 pounds, to avoid the ton ambiguity. Some states will license
105,000 for intrastate traffic.

It is only really a problem in the US where short tons are used to
defraud the buyer of 10% of what they paid for. An Imperial or British
ton and a metric Ton are close enough for most practical purposes.

US short measure sharp practice gets you problems like the Gimli glider.

--
Regards,
Martin Brown

 

[Mike Monett]

Martin Brown <\'\'\'newspam\'\'\'@nonad.co.uk> wrote:

[...]

It is only really a problem in the US where short tons are used to
defraud the buyer of 10% of what they paid for. An Imperial or British
ton and a metric Ton are close enough for most practical purposes.

Some background courtesy google:

What are the different types of tons?

The three types are all a measure of mass(weight) the short ton aka US ton
is 2,000/lbs. the long ton aka British ton is 2240 lbs. the third ton is
the metric ton which is, equal to 1000 kilograms, or approximately 2204
pounds.

What is a short ton vs ton?

United States. In the United States, a short ton is usually known simply as
a \"ton\", without distinguishing it from the tonne (1,000 kilograms or
2,204.62262 pounds), known there as the \"metric ton\", or the long ton also
known as the \"imperial ton\" (2,240 pounds or 1,016.0469088 kilograms).

Why is it called a short ton?

In the U.S. there are 100 pounds in the hundredweight, and in Britain there
are 112 pounds in the hundredweight. This causes the actual weight of the
ton to differ between countries. To distinguish between the two tons, the
smaller U.S. ton is called short, while the larger British ton is called
long.

What is the meaning of hundredweight?

A hundredweight (abbreviated as CWT) is a standard unit of weight or mass
used in certain commodities markets. It also may be used to price smaller
shipments of goods. In North America, a hundredweight is equal to 100
pounds; in the United Kingdom, a hundredweight is 112 pounds.

Why is it called a hundredweight?

In England in around 1300, different \"hundreds\" (centum in Medieval Latin)
were defined. The Weights and Measures Act 1835 formally established the
present imperial hundredweight of 112 lb. The United States and Canada came
to use the term \"hundredweight\" to refer to a unit of 100 lb.

What is the difference between a long and short ton?

ton, unit of weight in the avoirdupois system equal to 2,000 pounds (907.18
kg) in the United States (the short ton) and 2,240 pounds (1,016.05 kg) in
Britain (the long ton). The metric ton used in most other countries is
1,000 kg, equivalent to 2,204.6 pounds avoirdupois.

What is the British ton?

\"The ton\" was Britain\'s high society during the late Regency and the reign
of George IV, and later. The word means, in this context, \"manners\" or
\"style\" and is pronounced as in French.



--
MRM

 

[server]

On Sun, 8 May 2022 09:48:01 +0100, Martin Brown
<\'\'\'newspam\'\'\'@nonad.co.uk> wrote:

On 07/05/2022 17:23, rbowman wrote:
On 05/07/2022 02:12 AM, Martin Brown wrote:
On 06/05/2022 17:31, Joe Gwinn wrote:
On Fri, 6 May 2022 10:46:00 +0100, Martin Brown
\'\'\'newspam\'\'\'@nonad.co.uk> wrote:


High end car theft gangs in Belgium did a pretty good job with lining a
largish HVG with supermarket grade aluminium foil and if memory serves
lead flashing seals on the opening joints. Good enough Faraday cage to
steal high end cars with notional satellite tracking on them anyway.

Cute.  I assume that HVG is some kind of lorry.

Its a typo!
For HGV = heavy goods vehicle 44T tractor trailer combo.
US  = big rig (but yours are max 64T?)

80,000 pounds, to avoid the ton ambiguity. Some states will license
105,000 for intrastate traffic.

It is only really a problem in the US where short tons are used to
defraud the buyer of 10% of what they paid for.

But we pay 10% less!


An Imperial or British

ton and a metric Ton are close enough for most practical purposes.

US short measure sharp practice gets you problems like the Gimli glider.

The Glider was carrying 45% of its required fuel, not 90%.



--

Anybody can count to one.

- Robert Widlar

 

[Jeroen Belleman]

On 2022-05-08 13:05, Mike Monett wrote:

Martin Brown <\'\'\'newspam\'\'\'@nonad.co.uk> wrote:

[...]

It is only really a problem in the US where short tons are used to
defraud the buyer of 10% of what they paid for. An Imperial or British
ton and a metric Ton are close enough for most practical purposes.

Some background courtesy google:

What are the different types of tons?

The three types are all a measure of mass(weight) the short ton aka US ton
is 2,000/lbs. the long ton aka British ton is 2240 lbs. the third ton is
the metric ton which is, equal to 1000 kilograms, or approximately 2204
pounds.

What is a short ton vs ton?

United States. In the United States, a short ton is usually known simply as
a \"ton\", without distinguishing it from the tonne (1,000 kilograms or
2,204.62262 pounds), known there as the \"metric ton\", or the long ton also
known as the \"imperial ton\" (2,240 pounds or 1,016.0469088 kilograms).

Why is it called a short ton?

In the U.S. there are 100 pounds in the hundredweight, and in Britain there
are 112 pounds in the hundredweight. This causes the actual weight of the
ton to differ between countries. To distinguish between the two tons, the
smaller U.S. ton is called short, while the larger British ton is called
long.

What is the meaning of hundredweight?

A hundredweight (abbreviated as CWT) is a standard unit of weight or mass
used in certain commodities markets. It also may be used to price smaller
shipments of goods. In North America, a hundredweight is equal to 100
pounds; in the United Kingdom, a hundredweight is 112 pounds.

Why is it called a hundredweight?

In England in around 1300, different \"hundreds\" (centum in Medieval Latin)
were defined. The Weights and Measures Act 1835 formally established the
present imperial hundredweight of 112 lb. The United States and Canada came
to use the term \"hundredweight\" to refer to a unit of 100 lb.

What is the difference between a long and short ton?

ton, unit of weight in the avoirdupois system equal to 2,000 pounds (907.18
kg) in the United States (the short ton) and 2,240 pounds (1,016.05 kg) in
Britain (the long ton). The metric ton used in most other countries is
1,000 kg, equivalent to 2,204.6 pounds avoirdupois.

What is the British ton?

\"The ton\" was Britain\'s high society during the late Regency and the reign
of George IV, and later. The word means, in this context, \"manners\" or
\"style\" and is pronounced as in French.

That\'s an excellent argument in favour of metrication.

Jeroen Belleman

 

[rbowman]

On 05/08/2022 02:48 AM, Martin Brown wrote:

On 07/05/2022 17:23, rbowman wrote:
On 05/07/2022 02:12 AM, Martin Brown wrote:
On 06/05/2022 17:31, Joe Gwinn wrote:
On Fri, 6 May 2022 10:46:00 +0100, Martin Brown
\'\'\'newspam\'\'\'@nonad.co.uk> wrote:


High end car theft gangs in Belgium did a pretty good job with
lining a
largish HVG with supermarket grade aluminium foil and if memory serves
lead flashing seals on the opening joints. Good enough Faraday cage to
steal high end cars with notional satellite tracking on them anyway.

Cute. I assume that HVG is some kind of lorry.

Its a typo!
For HGV = heavy goods vehicle 44T tractor trailer combo.
US = big rig (but yours are max 64T?)

80,000 pounds, to avoid the ton ambiguity. Some states will license
105,000 for intrastate traffic.

It is only really a problem in the US where short tons are used to
defraud the buyer of 10% of what they paid for. An Imperial or British
ton and a metric Ton are close enough for most practical purposes.

US short measure sharp practice gets you problems like the Gimli glider.

A ton is defined as 20 hundredweights but a British hundredweight is 112
pounds for some obscure reason going back to stones, another strange
unit of measurement. Why there are 8 stones in a hundredweight also
escapes me. Actually Canada uses short tons.

They did use the imperial gallon so I always thought I was getting a
bargain when buying gasoline in Canada. After going to the liter and the
loonie (Canadian dollar) falling to .75 USD, I gave up trying to figure
out how badly I was getting screwed. The US uses the Queen Anne\'s gallon
and wasn\'t about to adopt the Imperial system in 1826. We also retained
the Winchester bushel. I can\'t find a citation but it wouldn\'t surprise
me if a hundredweight was 100 pounds before 1826 too.

Anyway the Gimli Glider was the end result of many more problems than a
simple conversion. It wasn\'t a high point for Air Canada. Boeing
certainly didn\'t help. I once worked for a firm that did fuel
measurement and management systems. We didn\'t assume the engines would
be running to keep the system powered up. Admittedly the systems
primarily went into military aircraft where a little wear and tear is
expected, but still...

 

[server]

On Sun, 8 May 2022 10:37:17 -0600, rbowman <bowman@montana.com> wrote:

On 05/08/2022 02:48 AM, Martin Brown wrote:
On 07/05/2022 17:23, rbowman wrote:
On 05/07/2022 02:12 AM, Martin Brown wrote:
On 06/05/2022 17:31, Joe Gwinn wrote:
On Fri, 6 May 2022 10:46:00 +0100, Martin Brown
\'\'\'newspam\'\'\'@nonad.co.uk> wrote:


High end car theft gangs in Belgium did a pretty good job with
lining a
largish HVG with supermarket grade aluminium foil and if memory serves
lead flashing seals on the opening joints. Good enough Faraday cage to
steal high end cars with notional satellite tracking on them anyway.

Cute. I assume that HVG is some kind of lorry.

Its a typo!
For HGV = heavy goods vehicle 44T tractor trailer combo.
US = big rig (but yours are max 64T?)

80,000 pounds, to avoid the ton ambiguity. Some states will license
105,000 for intrastate traffic.

It is only really a problem in the US where short tons are used to
defraud the buyer of 10% of what they paid for. An Imperial or British
ton and a metric Ton are close enough for most practical purposes.

US short measure sharp practice gets you problems like the Gimli glider.


A ton is defined as 20 hundredweights but a British hundredweight is 112
pounds for some obscure reason going back to stones, another strange
unit of measurement. Why there are 8 stones in a hundredweight also
escapes me. Actually Canada uses short tons.

They did use the imperial gallon so I always thought I was getting a
bargain when buying gasoline in Canada. After going to the liter and the
loonie (Canadian dollar) falling to .75 USD, I gave up trying to figure
out how badly I was getting screwed. The US uses the Queen Anne\'s gallon
and wasn\'t about to adopt the Imperial system in 1826. We also retained
the Winchester bushel. I can\'t find a citation but it wouldn\'t surprise
me if a hundredweight was 100 pounds before 1826 too.

Anyway the Gimli Glider was the end result of many more problems than a
simple conversion. It wasn\'t a high point for Air Canada. Boeing
certainly didn\'t help. I once worked for a firm that did fuel
measurement and management systems. We didn\'t assume the engines would
be running to keep the system powered up. Admittedly the systems
primarily went into military aircraft where a little wear and tear is
expected, but still...

This is one of my designs, or at least the hardware part is:

http://www.highlandtechnology.com/DSS/P330DS.shtml

Fuel volume measurement is tricky with a funny-shaped tank in a
tiltable vehicle.

Did you work for Simmonds?



--

Anybody can count to one.

- Robert Widlar

 

[rbowman]

On 05/08/2022 08:44 AM, Jeroen Belleman wrote:

On 2022-05-08 13:05, Mike Monett wrote:
Martin Brown <\'\'\'newspam\'\'\'@nonad.co.uk> wrote:

[...]

It is only really a problem in the US where short tons are used to
defraud the buyer of 10% of what they paid for. An Imperial or British
ton and a metric Ton are close enough for most practical purposes.

Some background courtesy google:

What are the different types of tons?

The three types are all a measure of mass(weight) the short ton aka US
ton
is 2,000/lbs. the long ton aka British ton is 2240 lbs. the third ton is
the metric ton which is, equal to 1000 kilograms, or approximately 2204
pounds.

What is a short ton vs ton?

United States. In the United States, a short ton is usually known
simply as
a \"ton\", without distinguishing it from the tonne (1,000 kilograms or
2,204.62262 pounds), known there as the \"metric ton\", or the long ton
also
known as the \"imperial ton\" (2,240 pounds or 1,016.0469088 kilograms).

Why is it called a short ton?

In the U.S. there are 100 pounds in the hundredweight, and in Britain
there
are 112 pounds in the hundredweight. This causes the actual weight of the
ton to differ between countries. To distinguish between the two tons, the
smaller U.S. ton is called short, while the larger British ton is called
long.

What is the meaning of hundredweight?

A hundredweight (abbreviated as CWT) is a standard unit of weight or mass
used in certain commodities markets. It also may be used to price smaller
shipments of goods. In North America, a hundredweight is equal to 100
pounds; in the United Kingdom, a hundredweight is 112 pounds.

Why is it called a hundredweight?

In England in around 1300, different \"hundreds\" (centum in Medieval
Latin)
were defined. The Weights and Measures Act 1835 formally established the
present imperial hundredweight of 112 lb. The United States and Canada
came
to use the term \"hundredweight\" to refer to a unit of 100 lb.

What is the difference between a long and short ton?

ton, unit of weight in the avoirdupois system equal to 2,000 pounds
(907.18
kg) in the United States (the short ton) and 2,240 pounds (1,016.05
kg) in
Britain (the long ton). The metric ton used in most other countries is
1,000 kg, equivalent to 2,204.6 pounds avoirdupois.

What is the British ton?

\"The ton\" was Britain\'s high society during the late Regency and the
reign
of George IV, and later. The word means, in this context, \"manners\" or
\"style\" and is pronounced as in French.

That\'s an excellent argument in favour of metrication.

Jeroen Belleman

I\'ll drink to that... I have two US vehicles, a F150 pickup and a
Harley bike. Both are mostly SAE (inch) fasteners, except when they
aren\'t so I need wrenches in both sizes. I believe newer vehicles are
all metric. With the Toyota and two Suzuki bikes I know they\'ll be
metric. Thankfully I haven\'t had to deal with Whitworth in decades.

The US has been talking about metrication for decades but the
legislation has only been a suggestion not a mandate. The only
wholehearted adopters were the liquor bottlers. A \'fifth\' (of a gallon)
was a customary size and was 757ml. Seems trivial to go to 750ml but
those milliliters add up.

 

[rbowman]

On 05/08/2022 08:27 AM, jlarkin@highlandsniptechnology.com wrote:

On Sun, 8 May 2022 09:48:01 +0100, Martin Brown
\'\'\'newspam\'\'\'@nonad.co.uk> wrote:

On 07/05/2022 17:23, rbowman wrote:
On 05/07/2022 02:12 AM, Martin Brown wrote:
On 06/05/2022 17:31, Joe Gwinn wrote:
On Fri, 6 May 2022 10:46:00 +0100, Martin Brown
\'\'\'newspam\'\'\'@nonad.co.uk> wrote:


High end car theft gangs in Belgium did a pretty good job with lining a
largish HVG with supermarket grade aluminium foil and if memory serves
lead flashing seals on the opening joints. Good enough Faraday cage to
steal high end cars with notional satellite tracking on them anyway.

Cute. I assume that HVG is some kind of lorry.

Its a typo!
For HGV = heavy goods vehicle 44T tractor trailer combo.
US = big rig (but yours are max 64T?)

80,000 pounds, to avoid the ton ambiguity. Some states will license
105,000 for intrastate traffic.

It is only really a problem in the US where short tons are used to
defraud the buyer of 10% of what they paid for.

But we pay 10% less!

In an era where a 5lb sack of sugar becomes 4lbs in hopes nobody
notices, I really don\'t think a short ton was meant to defraud. Before
Canada went metric everyone (except the completely clueless) knew what
you were getting on either side of the border when you bought a gallon
of gasoline.

 

[rbowman]

On 05/08/2022 11:45 AM, jlarkin@highlandsniptechnology.com wrote:

On Sun, 8 May 2022 10:37:17 -0600, rbowman <bowman@montana.com> wrote:

On 05/08/2022 02:48 AM, Martin Brown wrote:
On 07/05/2022 17:23, rbowman wrote:
On 05/07/2022 02:12 AM, Martin Brown wrote:
On 06/05/2022 17:31, Joe Gwinn wrote:
On Fri, 6 May 2022 10:46:00 +0100, Martin Brown
\'\'\'newspam\'\'\'@nonad.co.uk> wrote:


High end car theft gangs in Belgium did a pretty good job with
lining a
largish HVG with supermarket grade aluminium foil and if memory serves
lead flashing seals on the opening joints. Good enough Faraday cage to
steal high end cars with notional satellite tracking on them anyway.

Cute. I assume that HVG is some kind of lorry.

Its a typo!
For HGV = heavy goods vehicle 44T tractor trailer combo.
US = big rig (but yours are max 64T?)

80,000 pounds, to avoid the ton ambiguity. Some states will license
105,000 for intrastate traffic.

It is only really a problem in the US where short tons are used to
defraud the buyer of 10% of what they paid for. An Imperial or British
ton and a metric Ton are close enough for most practical purposes.

US short measure sharp practice gets you problems like the Gimli glider.


A ton is defined as 20 hundredweights but a British hundredweight is 112
pounds for some obscure reason going back to stones, another strange
unit of measurement. Why there are 8 stones in a hundredweight also
escapes me. Actually Canada uses short tons.

They did use the imperial gallon so I always thought I was getting a
bargain when buying gasoline in Canada. After going to the liter and the
loonie (Canadian dollar) falling to .75 USD, I gave up trying to figure
out how badly I was getting screwed. The US uses the Queen Anne\'s gallon
and wasn\'t about to adopt the Imperial system in 1826. We also retained
the Winchester bushel. I can\'t find a citation but it wouldn\'t surprise
me if a hundredweight was 100 pounds before 1826 too.

Anyway the Gimli Glider was the end result of many more problems than a
simple conversion. It wasn\'t a high point for Air Canada. Boeing
certainly didn\'t help. I once worked for a firm that did fuel
measurement and management systems. We didn\'t assume the engines would
be running to keep the system powered up. Admittedly the systems
primarily went into military aircraft where a little wear and tear is
expected, but still...



This is one of my designs, or at least the hardware part is:

http://www.highlandtechnology.com/DSS/P330DS.shtml

Fuel volume measurement is tricky with a funny-shaped tank in a
tiltable vehicle.

Did you work for Simmonds?

Yes, briefly. That was my first and last brush with DoD projects. It
didn\'t help that it was in the middle of the walker debacle and DISCO
put everything on hold as far as clearances went. I\'d been hired to work
on the test kit software but when there\'s nothing to test...

The upside was I had plenty of spare time to go down to Middlebury and
learn how to fly. The FBO was run by an ag pilot whose family had
originally built the strip for their spraying operation. It was
interesting to say the least. He had a couple of elderly Larks, one of
which added pumping up the brakes to the usual final approach protocol.

I was moonlighting for another employee who had a side project going. He
contacted me almost a year later about some tax paperwork. I asked if
he\'d written any code yet. The answer was no, they were still haggling
over the design document. I can fully understand why projects like the
F-35 have problems.

I\'d taken a contract at GE Ft. Wayne to develop a copier power supply
testing system and it was very refreshing to actually make progress.