A Conversation for Ask h2g2

Radios in tunnels

Post 41

Anonymouse

That's something else I am rather relieved to say I never did.. Compuserve or AOL or the like. I aquired internet access at the same time as the local BBS (which has since become the #1 and only long-lived ISP in the area... though '#1' isn't saying much ;-/ ... though RR has made it here now... at 4 times what I'm paying per month) did. smiley - biggrin

smiley - rose


Radios in tunnels

Post 42

Mistdancer-X-sporadically coherent

Can't remember the first site I visited...all of 18 months ago!!

But now my other half moans that I've taken over all the computers in the house (all 3) and that every time he boots up, all the browsers think it's me! Oh, and the My Docs folder is bigger than Windows!smiley - laugh
He's also amazed at how fast I've filled 60 Gb of hard drive space!!!

smiley - elf


Radios in tunnels

Post 43

Xanatic

60 giga? I didn't even know you could get them that big yet. But remember the time it takes to fill up the hardisk is inversely proportional to the size of it. The bigger the harddisk, the faster it goes.


Radios in tunnels

Post 44

Mistdancer-X-sporadically coherent

The 60 Gb is split between 3 computers....20Gb each! They're networked, so I can spread my stuff over them all, without leaving the comfort of my chair! smiley - winkeye

smiley - elf


Radios in tunnels

Post 45

Ollie Brennan

It's all about waveguides and cavities. The tunnel acts as a waveguide for the EM waves, it was in our lectures, but at the corner the waveguide is no longer straight so the EM waves interfere to obviously give a bit of a reception. The same concept also explains why you lose MW/LW reception going under (say) a bridge or something, but not FM waves which carry their information by modulating frequency which can be received in these cases. Amplitude modulation is affected. I've got loads of info about all this somewhere, but I can't be bothered to find it all.


Radios in tunnels

Post 46

Cakewalker

smiley - sadface not even for friendly fellow researchers? It's a subject close to our hearts - if you're a proper researcher you go through a great many tunnels.


Radios in tunnels

Post 47

Peregrin

smiley - erm I thought it was all to do with the evil radiowave-eating gremlins? Ah well, another childhood belief smashed.


Radios in tunnels

Post 48

Big Geordie

When I used to be a sailor (no jokes please) smiley - smiley We used to use hand held radios to keep in contact with control. These worked deep in the bowels of the ship. So the argument that radios don't work underground does'nt stand up. There is a possibility that at the corner the structural steelwork is closer together and is the same distance as the frequency of the signal that it is transmitted down the steel supports into the tunnel. The rest of the tunnel does not match the frequency so the signal does not travel to the receiver in the tunnel.

But I might be wrong, again smiley - sadface

There is probably a better explanation out there. there is plenty of egg heads in H2 maybe they can answer this one.


Radios in tunnels

Post 49

Anonymouse

They do make 60G drives now. My pop got one with his new machine -- right outta da box. Would make me jealous if it was a dell or custom (with a WD drive) instead of an HP Pavillion. smiley - winkeye

smiley - peacedovesmiley - rose


Radios in tunnels

Post 50

Rojo Habe (48-1+2-7)

...an unshielded coaxial cable??

Wouldn't that be, like, just a piece of wire?


Radios in tunnels

Post 51

Captain_SpankMunki [Keeper & Former ACE] Thanking <Diety of choice> for the joy of Goo.

LOL!

Liam. <- Who can't believe he used LOL.


Radios in tunnels

Post 52

Captain_SpankMunki [Keeper & Former ACE] Thanking <Diety of choice> for the joy of Goo.

Having spoken to someone in authority on the Blackwall tunnel project - namely my dad - I have made an important discovery regarding the original question. The corners of the Blackwall tunnel are where the vents are. It's clear air above you - with a little filtering and a couple of big fans.

Liam.


Radios in tunnels

Post 53

Researcher 224056

because radio waves are curved they have greater penetrance when you go round corners.


Radios in tunnels

Post 54

Whisky

smiley - erm Radio waves? Curved??? smiley - yikes


Radios in tunnels

Post 55

Wand'rin star

This brought back some happy memories. Why did you choose to revive it, 22056? If you put something in your space, lots of us could communicate with you. smiley - starsmiley - star


Radios in tunnels

Post 56

Captain_SpankMunki [Keeper & Former ACE] Thanking <Diety of choice> for the joy of Goo.

Yes, didn't you know Whisky? It curves up, then levels off and starts curving back down again. This is why some aerials have a curly bit at the bottom, for the penetrance - something to do with 5 people in a smiley - zen state no doubt.

Liam.


Radios in tunnels

Post 57

Potholer

*Please* let's not get into discussions on antenna design - at the best of times it's rather a black art, and most of the time it's much worse.


Radios in tunnels

Post 58

Captain_SpankMunki [Keeper & Former ACE] Thanking <Diety of choice> for the joy of Goo.

Antenna design is superb!

"Right so if I angle this bit at 34 degrees I get +24dB compared to 33 degrees." smiley - headhurts

Liam.


Key: Complain about this post

Write an Entry

"The Hitchhiker's Guide to the Galaxy is a wholly remarkable book. It has been compiled and recompiled many times and under many different editorships. It contains contributions from countless numbers of travellers and researchers."

Write an entry
Read more