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External antennas for the Option GS3

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  • External antennas for the Option GS3

    We have several high gain antennas and cables/connectors here that could be used with the option gs3 for example: omnidirectional magnet mount or directional yagi . One caveat however is that they should only be used when absolutely needed. The option gs3 has pretty powerful integrated antennas that allow sufficient (RSS) received signal strength and EIRP (effective isotropic radiated power) to provide reliable communication in most situations. If your RSS is already good adding an external antenna will most likely not help and could in fact hurt the link reliability.

    There are instances where an external antenna is very critical. One of the classic examples is for vehicle use or where the Option gs3 has to be placed in a communication closet or in an area that would otherwise act as an RF shield. In this case the external antenna's primary benefit is not so much for its higher gain but for convenient antenna placement away from obstructions and where it can pick up a strong signal as well as have its radiation field not affected as much. This is also the case for buildings that have poor signal penetration. In this case a directional or omnidirectional cellular band antenna could be mounted external to the building and connection to the option gs3 using low loss coaxial cables. Also if your area doesn't have a good cellular reception then a roof mount directional yagi antenna oriented in direction of maximum received signal strength helps. You can find different styles of cellular band antennas here.

    If in doubt as to whether you need an external antenna or what external antenna style would be most suited for your application just ask. We will be happy to help.
    KF7RCQ

  • #2
    External antennas / amplifiers for the Option GS3

    Thuor,

    A few days ago I installed an Option GS3 on a yacht in Mexico for a Telcel customer. Same installation I've succesfully done in the US for AT&T customers. I have an unidentified gremlin (no internet connectivity) that has caused me much grief over the last few days. I'm hoping you can review & comment so I can resolve it.

    In your post above, you mention the following, "If your RSS is already good adding an external antenna will most likely not help and could in fact hurt the link reliability."

    Two questions for you.

    1. Could the amplifier & ext. antenna be comprimising the link reliabilty, therefore causing the internet connectivity issue?

    2.Since I have fair RSS at the dock but not while underway should I disconnect the external antenna while at the dock?

    Notes:
    1. Telcel usb aircard directly connected to laptop provides fast/reliable internet connectivity. Therefore, sim card and local GSM network coverage is good.

    Any comments/advice would be greatly apprectiated.

    I've emailed Option tech support to see if it is a firmware issue.

    Hardware Summary
    1. Cellular antenna (563-cw / digital antenna / 850/1900 - outdoor )
    2. Cellular Amplifier (DA4000 / digital antenna)
    3. Cell amplifier combiner ( DA-2190 / digital antenna

    4. Option Globe Surfer 3 (FW R1A67 shipped / upgraded to R2A72)
    5. Telcel Nokia CS10 USB aircard
    6. PC (windows 7 - ethernet connection)
    7. Laptop (windows 7 - wireless & ethernet)

    8. Fixed voice terminal with AT&T sim card (SX5E / Tellular)

    * The Tellular Option GS3 router & Tellular SX5E fixed voice terminal are connected to the cellular amplifier.

    See attached diagram.

    Thanks,

    Roo
    Attached Files

    Comment


    • #3
      1. Could the amplifier & ext. antenna be comprimising the link reliabilty, therefore causing the internet connectivity issue?
      This is possible but not likely. True if your amplifier/antenna were defective then this could clearly prevent any connectivity but we rarely find these antennas/amps to be completely DOA so this is usually the last thing we check. If you do have some signal it would be worthwhile to take them out of the loop and see if you are able to connect which would rule them out.

      2.Since I have fair RSS at the dock but not while underway should I disconnect the external antenna while at the dock?
      Again this is not necessary. Since this 563-cw antenna just has 9dBi of gain it is not likely to distort the communication. What we were referring above was when you already have a very strong signal then add a very power antenna which could potentially cause the signal to the input of the radios low-noise-amplifier to go above the dynamic range of the amplifier (which would result in clipping & distortion which would manifest itself as Bit-Error-Rates which in turn would cause low speed since the radio would try to adjust the modulation to prevent this ... note that this would not necessarily completely prevent the connection but rather either throttle the speed down or cause disconnections).

      Have you made sure to change your APN (Access Point Name) setting in the GS3? This is the carrier-dependent configurable network identifier used when the GS3 connects to a GSM carrier. I have seen that for a lot of cellular IP devices in the U.S it is usually not necessary to enter the APN so you don't need to do this with AT&T but you might with Telcel. You can get this info from the carrier or check out: http://www.flexispy.com/Mobile%20APN...use%20GPRS.htm

      The other common problem i have seen (and we have unfortunately inadvertently done this before ourselves) is to try to use an EMEA version of the GS3 with a NAM carrier. EMEA versions operate on 900/2100 but the NAM version is 850/1900 + AWS. Usually though how people catch this problem is that you might be able to connect on EDGE but not HSDPA. Does voice work on the GS3?
      KF7RCQ

      Comment


      • #4
        Thuor,

        I'm using the NAM Option Globe Surfer 3 indoors on the AT&T network and I'm getting mediocre reception at best. On average the the signal strength indicator reports "low" sometimes even poor. What antenna would you recommend?

        Comment


        • #5
          Whether an antenna will help pretty much depends on whether you have a decent outdoor signal to begin with. If you do then you could use something like this: http://www.rfwel.com/shop/9dBi-Multi...r-Antenna.html (850/1900MHz omni-directional) or http://www.rfwel.com/shop/Yagi-806-9...r-Antenna.html (850MHz directional) or http://www.rfwel.com/shop/Yagi-1800-...S-Antenna.html (1900MHz directional). You can figure out if you are using 850 or 1900MHz in your area from customer service or by looking at the diagnostics page.

          You would hook this up to a low-loss cable of appropriate length e.g. LMR-400 N-Male/N-Male cable.

          Then attach it to an Option Globesurfer III pigtail using an N-Female/FME-Female adapter.

          If you will be mounting any of these on the roof we STRONGLY recommend you add a lightning surge device and you can use a 2-foot jumper cable to hook this up.

          If your outdoor signal is weak you could use a cellular amplifier such as: http://www.rfwel.com/signal_improvem...ers.php#direct with any of the antennas linked above.
          KF7RCQ

          Comment


          • #6
            Originally posted by thuor View Post
            Whether an antenna will help pretty much depends on whether you have a decent outdoor signal to begin with. If you do then you could use something like this: http://www.rfwel.com/shop/9dBi-Multi...r-Antenna.html (850/1900MHz omni-directional) or http://www.rfwel.com/shop/Yagi-806-9...r-Antenna.html (850MHz directional) or http://www.rfwel.com/shop/Yagi-1800-...S-Antenna.html (1900MHz directional). You can figure out if you are using 850 or 1900MHz in your area from customer service or by looking at the diagnostics page.

            You would hook this up to a low-loss cable of appropriate length e.g. LMR-400 N-Male/N-Male cable.

            Then attach it to an Option Globesurfer III pigtail using an N-Female/FME-Female adapter.

            If you will be mounting any of these on the roof we STRONGLY recommend you add a lightning surge device and you can use a 2-foot jumper cable to hook this up.

            If your outdoor signal is weak you could use a cellular amplifier such as: http://www.rfwel.com/signal_improvem...ers.php#direct with any of the antennas linked above.

            Thanks for the input, can I use any of those antenna indoors? Where I live it wouldn't be possible to place one outdoors. Would it be possible to buy an amplified indoor antenna? I bought a cheap antenna from China off eBay and it sucked. It even seemed to make the signal worse. I get a pretty good signal with my cell phone, usually 4 or 5 bars but the gs3 signal is pretty weak.

            Comment


            • #7
              Yes you can use it indoors but of course doesn't have as much of an effect as compared with it being outdoors. When using just an antenna you are just trying to bring the strong outdoor signal indoors to overcome the shielding effect of the buildings walls.

              But if your cellphone is also from AT&T thus using the same frequency band and you are seeing good data performance on it, then the fact that it has a decent signal suggests that the GS3 placement might be what is causing the poor performance (but be sure you are comparing apples-to-apples i.e. that the cellphone also is using the same cellular data protocol that the GS3 is using). If relocating doesn't resolve it, it would suggest that an indoor antenna conveniently placed might give you the same performance. Have you ever seen good RSSI on the GS3 by relocating it? This would help rule out other issues and also give you an idea on where to properly place an external antenna.
              KF7RCQ

              Comment


              • #8
                Originally posted by thuor View Post
                Yes you can use it indoors but of course doesn't have as much of an effect as compared with it being outdoors. When using just an antenna you are just trying to bring the strong outdoor signal indoors to overcome the shielding effect of the buildings walls.

                But if your cellphone is also from AT&T thus using the same frequency band and you are seeing good data performance on it, then the fact that it has a decent signal suggests that the GS3 placement might be what is causing the poor performance (but be sure you are comparing apples-to-apples i.e. that the cellphone also is using the same cellular data protocol that the GS3 is using). If relocating doesn't resolve it, it would suggest that an indoor antenna conveniently placed might give you the same performance. Have you ever seen good RSSI on the GS3 by relocating it? This would help rule out other issues and also give you an idea on where to properly place an external antenna.

                I moved the gs3 from the desk to the window sill (a little less than a meter) and changed the orientation from laying flat to standing. Now the the signal fluctuates from low (-93 dBm) to Good (-87 dBm), before it varied from poor to low.

                Comment

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