Sunday Mirror - Sunday 28 May 1939

Dog Saved Two Miles of Digging
EVERY dog has his day, but never has a dog had such a day as Rex, Home
Office trained Labrador.
By smelling what he thought was hundreds of cats, Rex saved the Post
Office two miles of digging.
The cat and dog idea was a brainwave. This is how it happened.
Sixteen miles of underground cables are connected to the new Post Office
" anti-sunspot" transatlantic radio-telephone receiving station being
built at Cooling Marshes, near Rochester, Kent.
One day it was noticed that the air in the maintain a high electrical insulation, was leaking through a number of minute punctures.
Station Out of Action
The leakages put the cable, and consequently the station, out of action
and might have caused serious damage by permitting the infiltration of
water into the cable.
Mr. H. S. Lloyd, who trains dogs for the Home Office, was summoned.
He brought Rex with him, and a gas that smelt strongly of " eats "—that
is how the Post Office put it—was introduced into the air pumped into
the cable.
Rex was brilliant. They led him over the path of the cable. Every time
he smelt cats he set about digging furiously. He found fourteen leaks.

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JMB99 <[email protected]> wrote:

New technique?

[...]

Diversity reception. A bank of identical receivers with their AGC lines linked, whichever receives the strongest carrier suppresses the others. Originally the P.O. and Bell Systems did it with relays and semi-manual control, but the linked AGC system was used throughout WWII and well
into the 1960s.

The receivers could be connected to aerials with wide geographical
spacing, in which case the receivers were situated near the aerials and
the AGC lines were linked by landline. Alternatively, the receivers
were co-located but identical transmissions were sent simultaneously in different wavebands, so the multipath fading effects were different for
each one.

Double-diversity needed four receivers: two different wavelengths and
two spaced aerials - I believe that was what the Bell/GPO system used.


--
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

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On 12/11/2023 10:07, JMB99 wrote:

New technique?

Edinburgh Evening News - Wednesday 14 September 1938

POST OFFICE ACTS SUN-SPOT THREAT TO RADIO SPECIAL STATION AND NEW TECHNIQUE

Refers to Cooling Marshes - a friend's father worked there.

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On 12/11/2023 11:30, Liz Tuddenham wrote:

JMB99 <[email protected]> wrote:

New technique?

[...]

Diversity reception. A bank of identical receivers with their AGC lines linked, whichever receives the strongest carrier suppresses the others.

There is a HE report on it.

Cooling Radio Station, Hoo Peninsula, Kent: An Archaeological
Investigation of a Short-Wave Receiving Station

Report Number:
110/2010
Series:
Research Department Reports
Pages:
73

It used MUSA then MEDUSA

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JMB99 <[email protected]> wrote:

On 12/11/2023 11:30, Liz Tuddenham wrote:

JMB99 <[email protected]> wrote:

New technique?

[...]

Diversity reception. A bank of identical receivers with their AGC lines linked, whichever receives the strongest carrier suppresses the others.

There is a HE report on it.

Cooling Radio Station, Hoo Peninsula, Kent: An Archaeological
Investigation of a Short-Wave Receiving Station

Report Number:
110/2010
Series:
Research Department Reports
Pages:
73

It used MUSA then MEDUSA

Thanks for that - so it was MUSA, not diversity..


I seem to remember reading about the American end of that system in
either the Bell Labs Record or the Bell System Technical Journal. There
were some interesting comments about the differences between Bell and
the G.P.O. in the attitudes they held towards their customers. Bell
wanted to reduce inconvenience to callers by providing a good
person-to-person service, even if it meant more apparatus - whereas the
G.P.O. wanted to optimise the use of minimal appartus even if it meant inconveniencing their customers.


--
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

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