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3G External antennas / amplifiers/ TelCel in Baja California

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  • 3G External antennas / amplifiers/ TelCel in Baja California

    I'm one of these old guys that their kids have dragged out of the stone age and am trying to keep up with technology.

    My situation is that I'm living in northern Baja California, Mexico, about 100 miles below the border from San Diego, California. Its an extremely rural place on the pacific coast but recently the Mexican cell phone company (Tel Cel) put up a cell tower on a hill about 3 miles away from my house. From the roof top of my cement house, with cement roof, I can see the tower about three miles away.

    I signed up with Tel Cel for a data plan (and hoped to Skype with my loved ones at home) and got their only Modem (Internet stick) available.

    It is a Nokia CS-10. After 100's of speed tests from inside my house, outside my house, and points in between (including right up to the base of the tower), I've determined the only way I can use it inside my house is with an external antenna, roof mounted, and with 30' of cable.

    The data signal is weak & erratic. (My Iphone gets 5 bars on the roof and only 1 to 2 inside the house.) Best download speed on my Hp G72 laptop, with the Nokia CS-10 (even at the tower) is .23Mg/S and best upload is .08Mg/S. I can get these same speeds outside my house or on the roof, but inclement weather conditions can be extreme.

    On a good day, outside, I can skype uninterrupted, for 45 minutes to an hour. Other times in the same day, its impossible to keep the connection up. It drops, but comes right back.

    I understand there's no way to improve the towers signal, i'm only trying to find a way to have the same reception inside my house, as outside.

    My Iphone has much better reception and transmission inside (and outside) the house, than my HP laptop with the Nokia CS-10. Tel Cel uses 850 MHz / 2100 Mhz.

    Two Questions:

    - Does your company sell (or know if anyone else does) a more sophisticated Internet stick that may improve performance of my system?

    - I would like to purchase a roof top antenna and need at least 30' of cable so I can have "line-of-sight reception" inside my house and out of the elements. How would that interface with Tel Cel's Nokia system? (I can find no external or internal ports on the Nokia dongle to plug in external antenna.

    I'd appreciate any leads. Thanks,
    Calvin

  • #2
    - Does your company sell (or know if anyone else does) a more sophisticated Internet stick that may improve performance of my system?
    Not sure this would help you. While it's true that some USB modems might perform better than others this difference is usually very marginal to make much of a difference in a situation similar to what you describe. You are limited primarily by a low signal strength and a minor performance differences in USB modems is unlikely to help overcome this.

    One reason that you might want to consider replacing that USB Stick however would be to switch to one that has an external antenna port so that you can hook it up to a high gain outdoor antenna to improve indoor signal strength. For example the Sierra Wireless USB308 Aircard modem is unlocked and can work with a Telcel sim card.

    - I would like to purchase a roof top antenna and need at least 30' of cable so I can have "line-of-sight reception" inside my house and out of the elements. How would that interface with Tel Cel's Nokia system? (I can find no external or internal ports on the Nokia dongle to plug in external antenna.
    The problem with devices that don't have external antenna ports is that the only way to hook up an external antenna is using an inefficient inductive coupler device such as: http://www.rfwel.com/shop/Universal-...ta-Modems.html
    This device introduces too much attenuation due to imperfect coupling and as such the performance is much worse than using a direct-attachment pigtail available for devices that have external antenna ports.

    So to summarize given your scenario you have 3 options:

    1. Get new modem with external antenna port e.g USB308. Then add external antenna as follows:
      1. Get pigtail to attach modem to coaxial cable.
      2. Get low loss LMR-400 cable of appropriate length. Select N-Male/N-Male ends.
      3. Select cellular band antenna. For example:

        - 9dBi omni-directional multiband cellular antenna. Since this is omni-directional you dont have to orient to tower.
        - directional wideband cellular antenna. This is directional so you need to orient it to direction of maximum received signal strength. Really what you do is hook up everything then sweep the antenna looking for a sweet spot.
      4. Optional but STRONGLY recommended is a coax lightning protection device. It is EXTREMELY dangerous to roof-mount an antenna (pretty much a very good electricity conductor) then run coaxial cable to the interior of the house to your modem without a lightning discharge device. You could use a short coaxial jumper cable to hook up the ligtning protection.

    2. Stay with current modem and replace the pigtail above with a passive coupler. This is NOT recommended due to the coupling losses.
    3. Stay with current modem and use a cellular repeater such as: http://www.rfwel.com/shop/Wilson-Ele...er-800MHz.html (please confirm that Telcel is using 850MHz for 3G in this market). You would need an indoor dome antenna such as: https://www.rfwel.com/shop/Multi-Ban...e-Antenna.html to hook up to the amplifier. The advantage of this solution is that you could multiple devices concurrently such as phones or internet cards but they have to be within range of the dome antenna.

    Last edited by thuor; 03-15-2011, 07:55 PM.
    KF7RCQ

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    • #3
      Greetings, I see on your main website that you have a list of recommended USB/PCMICI/Express modems for Telcel. Is this a generic list of modems for GSM carriers in general or is it something your tech department has tested and feels comfortable with? I read in old posts online from 2009, that Telcel uses a 850MHz band that a US phone or modem may not work with, something to do with data being on the lower band and voice on the 1900MHz band? I am looking for a modem that has an antenna jack that works with the GSM carriers AT&T & T-Mobile in the US, Telcel & Movistar in Mexico, Tigo and Claro in Guatemala and as far south as you have information for. Do you have a recommended universal modem that will give reasonable performance and has an external ANTENNA JACK? Thanks!

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