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Thread: Sending internet around the Aerial circuit

  1. #21
    Moderator toscal's Avatar
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    Quote Originally Posted by TimH View Post

    Old-skool networking was on coax but 50-ohm (IIRC). Aerial cable is likely to be 75-ohm Maybe some products would still work...


    Tim.
    The aphelion stuff is designed to work with normal aerial cable so 75 ohms.
    I remember the old 50 ohm network stuff too. Never had enough of those dam termination plugs.

    One problem may be with the ISP. They may not like it that you are using one DSL line for multiple users.
    Which countries are the flats in. You may find that one solution in one country won't work in another. The way buildings are built in Spain especially the older ones means that Wifi signals don't travel that well. They have a rebar ring beam top and bottom, in each room, that is tied together with vertical rebars at the corners and its usually also tied to earth as well. So its almost like a basic Faraday cage.
    Most aerials that come with access points are rubbish, I would change the aerial for a better one. They are not that expensive. I did this in my house and the signal is reasonable in the bedroom and kitchen now. Couldn't get anything before.
    IF YOU CAN'T FIX IT WITH A HAMMER, YOU'VE GOT AN ELECTRICAL PROBLEM.
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  2. #22
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    Yeah, Bingo Toscal. This test building is in spain.

  3. #23
    Automated Home Guru jpdw's Avatar
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    A bit OT now, but to answer some specific questions...

    Quote Originally Posted by michaeldon View Post
    Thanks Jon,
    Just wondering. You say cisco is no good for repeating? Who is good and what's the difference?
    How many times can you repeat a wifi signal before you get significant degradation?
    Doing multiple hops over WLAN will always cause degradation due to a couple of factors - delay going through each AP and interference. In any 802.11g deployment in the US & EU you can only get 3 APs on channels that dont overlap to some degree. In the EU we can, with a tiny bit over overlap squeeze 4: 1,5, 9 & 13. Having any overlapping APs and they will cause a level of interference & degredation. Enough to bother you? depends on what you're doing. A little bit of web surfing maybe no real issue but video er...ouch. You get the idea.


    Quote Originally Posted by TimH View Post
    I think the point was that you'd normally select different channels for adjacent access points to avoid interference. Configuring all access points for the same channel means the signals bleed over each other and your overall range is significantly reduced.
    Tim.
    Tims right, and here's where multiple hops will add to your interference woes as you're using channels to hop out to the APs. Which reduces any remaining unused ones. Worse, it means your link from ADSL to laptop is now subject to interference-caused retries on more than 1 wireless hop. So there is 2x or 3x the chance of retries ... which cause delays, missed data packets etc,. Again, how annoying this is will depend on what you're doing.
    There are actually 2 vendors in the world that do work on a single channel but thats a differnet story and aimed at enterprises anyway... but for everyone else including Cisco, this is a no-no

    Quote Originally Posted by michaeldon View Post
    Regarding the tenants, we have control over all the flats so we can get in and out when we want to but I would have trouble with the building owner running ugly cables in the stairwell or drilling through walls and windows.
    Out-of-the-box idea: I know somewhere where the APs are mounted in the garden outside, pointing inwards ! Maybe/may not be an option.
    Jon

  4. #24
    Moderator toscal's Avatar
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    Whereabouts, I'm near Alicante.
    If you use repeaters rather than APs don't you halve the bandwidth available. I have never had much success with repeaters.
    Last edited by toscal; 26th January 2010 at 10:22 AM.
    IF YOU CAN'T FIX IT WITH A HAMMER, YOU'VE GOT AN ELECTRICAL PROBLEM.
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  5. #25
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    We have places in Madrid but this building is in Barcelona.

    I wasn't aware that APs and repeaters were different gear. Pardon my ignorance. I think now we us APs configured to repeat the signal.

  6. #26
    Automated Home Legend TimH's Avatar
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    Quote Originally Posted by TimH

    Old-skool networking was on coax but 50-ohm (IIRC). Aerial cable is likely to be 75-ohm Maybe some products would still work...
    Quote Originally Posted by toscal View Post
    The aphelion stuff is designed to work with normal aerial cable so 75 ohms.
    I remember the old 50 ohm network stuff too. Never had enough of those dam termination plugs.
    Agreed
    I was wondering whether you'd get anything useful out of 50-ohm network switches attached to 75-ohm cable.

    You'd certainly get better performance out of kit *designed* to work with aerial coax though

    Cheers,

    Tim.

  7. #27
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    What do you think about something like this Tim?

    Is a high output wifi a possibility? Or will it just have problems getting signal from the laptop users?

    http://www.google.com/products/catal...698&sa=title#p

  8. #28
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    Another solution is to use leaky cable. I think its actually called Leaky Feeder Cable and can be thought of much like a hose pipe that is full of holes. The cable basically leaks WiFi signals. Its used in tunnels to maintain radio signal coverage.
    Its now not that expensive its about 8 pounds a meter,but looks like it could be a what not to install as its about the thickness of a small pipe, diameter is 2.7cm. The way you set it up is you have an access point in the corridor and instead of the antenna you use this cable and run it the length of the corridor.
    A decent hi power access point costs about 80 to 90 pounds these have dual antennas that both send and receive, so you would put it in the middle of the corridor and then run 2 lengths of leaky cable.
    Its also used quite a bit in hotels.
    I can get you more info if you want.
    Is the building a new one or an old one, and does it have false ceiling or is it that suspended plaster type called Escayola
    Last edited by toscal; 29th January 2010 at 11:14 PM.
    IF YOU CAN'T FIX IT WITH A HAMMER, YOU'VE GOT AN ELECTRICAL PROBLEM.
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  9. #29
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    Hi Toscal

    Thanks for the info. I have never been to the building. I would need to find out.

    The main point of my exercise was to work out how to use existing cabling in buildings to provide an internet solution. (ie low man-hour cost and no drilling or causing need for repaint when we leave the contract).

    Re-cabling might be an option in some cases, and in other cases not, however your option sounds good for small buildings where we are in the process of negotiating a new contract. If you have info, please let me know. Thanks


  10. #30
    Automated Home Legend TimH's Avatar
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    Quote Originally Posted by michaeldon View Post
    What do you think about something like this Tim?

    Is a high output wifi a possibility? Or will it just have problems getting signal from the laptop users?

    http://www.google.com/products/catal...698&sa=title#p
    The unit looks "ok", but I’m wary of “recommending” products without knowing too much about the building layout. If signals from the communal corridor won’t reach the lounge then coming in through the window from outside could be a possibility, depending on access, number of floors, number of properties to be covered etc.

    I wonder whether the newer 802.11 “n” products are any better than the previous “g” ones – ISTR “n” claimed greater speed and range?

    Toscal’s “leaky cable” was also suggested to me previously by a wireless equipment vendor I was working with on a work project. We had hazardous area issues (it was a hydrogen plant) and there weren’t many (if any) suitably-rated access points available. Their suggestion was to have a survey carried out to determine the best routing etc. but I imagine you could gather a reasonable amount of basic info from the ‘net re: max range etc. However, I would’ve thought that an active device (i.e. an access point) would have better range than a passive cable, but I’m happy to be proved wrong

    The other thought that struck me was the possibility of providing a “local” adsl service – i.e. giving each household their own router linked back via the existing phone line to a mini-exchange on-site before being connected into the telephone company's network. I’m not sure the costs would pan out for a small development, and the local phone co. may not be too happy either…

    How good is 3G coverage? Could you offer a deal whereby they rent a USB modem for the duration of their stay? PAYG services are available in the UK for £2 per day, or from around £15/month for a contract.

    HTH,

    Tim.

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