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Antenna help

Discussion in 'General Electronics Discussion' started by jackorocko, Dec 31, 2011.

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  1. jackorocko

    jackorocko

    1,284
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    Apr 4, 2010
    Davenn, I think this is probably a good one for you to answer, but I will take anyone's advice. :D

    I have one of these Network Extenders, femtocell, devices from verizon. Recently my neighbor informed me that he was gonna cancel his landline and internet to get a pre-paid cell since he gets at the very least a weak signal. Well this weak signal he is referring to is my femtocell device. This really annoys me, I don't pay my bills so that others can stop paying theirs.

    So my idea to fix this little situation was to try and weaken the signal or limit it's range to only my house. So far I tried a piece of metal in front of the device, it worked, but it also blocked the gps signal and the device shutdown. (needs gps to work) So then I decided to go ahead and remove the antenna, results where magnificent. I barely get a signal in my house, but it is enough for me to receive text and that is all I care about. But now I have severely limited my usage outside of my house. Which is not fair to me since I have a huge backyard with a detached garage that I would like to receive calls in.

    So here is my question, say I wanted to keep the device in the same spot but want to move my antenna to the far side of my house, would using a cable from the device to the antenna create a lot of losses? Also, what type of antenna is required for these cell phones, is it possible to buy a pre-made directional antenna to keep my sponge of a neighbor off my femtocell?

    I will post pics later, but the device and antenna both have that common screw terminal that you see on things like routers.
     
  2. OLIVE2222

    OLIVE2222

    690
    25
    Oct 2, 2011
    Hi jackorocko,

    An attenuator can probably do the job (being reversed sma you probably need an adapter too)
    I let you the floor Davenn :)

    Olivier
     
  3. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    I have a different approach, but it may not help you.

    My femtocell allows me to select up to 12 (I think) numbers which it will connect to.

    In my case the call gets routed over the internet, so I really am paying bills to carry the data.

    From the GPS thing, it sounds like you have a very similar device. Do Verizon not give you access to the ability to limit the devices it will connect to?

    Mine is one of these.
     
  4. jackorocko

    jackorocko

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    Apr 4, 2010
    Well in the states where I am from every femtocell device needs to have 911 access and everyone has to be able to access it. So verizon won't let you select certain devices, they only let you select certain devices for priority. So in other words, if all the channels are used up and I have priority and I make a call, it will drop another caller to give me access to one of the 6 channels.

    Mine works over the internet to which is why I am so ****ed off about it. I am close to just getting rid of my cell all together.
     
  5. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,448
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    Jan 21, 2010
    Interesting. Does your femtocell have to provide 911 calls to everyone, or all calls to everyone?

    I'm not certain whether my device provides emergency call access to everyone, but I doubt it as people who are not registered to see it simply can't connect. But it's something to try...

    In any case, my device warns me that I may not get emergency call access as it depends on my internet connection.

    In your case, does state legislation require that (say) AT&T's cell towers provide access to Verizon customers? Or is this provision only for the little guy?

    I can't imagine your neighbour would use too much bandwidth. The onlt hassle is if he has an "unlimited" data connection on his mobile service.

    In my case the femtocell provides 3G internet access that comes through *MY* internet connection, yet I am charged by the phone provider for using it! Needless to say I don't use 3G data whilst at home.

    My device seems to open an encrypted tunnel after it initialises, and closes all other open ports, so there's no hope of looking at the network activity to see if you can snoop the packets and see who's calling. I imagine the same thing is true of your device.
     
  6. jackorocko

    jackorocko

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    Apr 4, 2010
    verizon is cdma based wireless technology, where att and others like the small guys are gsm 1900. So no I don't believe they will work on each others network. But, with that said I think all cell phone companies need to provide 911 service on any cell phone with or without service on any wireless technology.

    I looked up ATT femtocell and those devices you can create an access list and it is totally secure, so this is nothing but more verizon wireless bs. I am getting to really hate this company. My device also works like yours in that it creates an encrypted tunnel to the verizon network, vpn. Trust me I already tried to packet sniff and distinguish something I could filter, but no luck.
     
  7. jackorocko

    jackorocko

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    Apr 4, 2010
    Seems to me that a simple firmware update would allow for access list and then reserve one channel for 911 emergency calls. But from reading everything over the internet verizon does not want to do this and I think it is pretty shady. Who are they to tell me who I can and can't share my money with. It is my money that pays the internet bill after all. I don't care if I use all my bandwidth 24/7 or not, it is mine to either use or waste. I will be calling verizon tomorrow and get the full scoop. Then in another four months I will switch to prepay and a year after that when my other line contract is up I will just switch carriers all together.
     
  8. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    It's standard behaviour that all cells provide any phone with emergency call access. Try using your phone without a sim for example. It may actually display a message telling you that calls to 112 are still permitted.

    (See http://en.wikipedia.org/wiki/Emergency_telephone_number#Emergency_numbers_and_mobile_telephones)

    Interestingly, the Verizin page describing this product tells me that it requires a verizon internet connection and does not mention the bandwidth usage.

    My device allows for *any* broadband provider, but I don't own the box. They charge me $20 per month for access, but forthat I get unlimited free local, national and cell calls from the primary device when used over the femtocell. I also get a $15 per month credit because I was an early adopter -- and believe me it was a very dodgy device in the beginning... The documentation tells me how much bandwidth (internet) I should expect it to use.

    I wonder if your internet is either "unmetered" or if bandwidth used by this device is unmetered? In either case, it would compensate for allowing others to use the device. If neither, I would be having some serious thoughts about the device.

    I do note that apparantly you need to be closer to the device to register on it than you need to be to use it. This *may* allow you to attenuate the power enough to prevent others from connecting, but not restrict your range too drastically. But there are a lot of weasil words in that section...
     
  9. jackorocko

    jackorocko

    1,284
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    Apr 4, 2010
    Well let me assure you that is a line of bs. The device requires any broadband internet connection. I don't have verizon broadband. But I bought the device outright for $250 from them.

    The limit at which you can connect is well, at best, unreliable.

    Last night I unplugged my device and walked over to his place with my cell phone and sure enough ever since I pulled my antenna off his booster picked up my other neighbors femtocell. I live in a very small town, houses are close together but the town is rural, most every house has a femtocell. But instead of choosing to do what he did I decided to invest in my service. That is why I am clearly annoyed by this. By his booster alone the area in front of my house is now covered where their used to be zero signal. That is why I am rather happy to just move mine and try and attenuate the signal.

    This should not be a big deal I know, but it is principal and that ass hat wouldn't do anything for free so why should I provide him with anything free? Trust me, there is more to this story that doesn't deserve to be printed here.
     
  10. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    I wonder if you can add an external antenna, one with nulls that can be pointed toward him.

    He'll probably still get some reflected signal though. Maybe a combination of this and attenuation?

    Can you add an external antenna? If not, is the internal antenna "hackable"
     
  11. jackorocko

    jackorocko

    1,284
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    Apr 4, 2010
    please explain more in detail. An external antenna on my device or just an external antenna that is separate from my device that would essentially jam his signal?

    I looked it up, you are saying that if I attenuate the signal and use another antenna (phasing) providing nulls I can prevent overshoot? Which essentially helps keep the signal close to the source. Now how does one go about that?
     
    Last edited: Jan 1, 2012
  12. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    A simple antenna like a dipole has a radiation pattern like a doughnut (imagine signal strength is like how much you eat through to get to the centre of the hole -- much more on the sides than from top/bottom). If you have an antenna like this you can point one of the nulls toward your neighbour and he will see a much reduced signal (beware that it's not always this easy).

    You need to determine if your device has (a) an external antenna connection or (b) an easily unplugged internal antenna.

    Alternativly, this might be interesting.
     
  13. jackorocko

    jackorocko

    1,284
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    Apr 4, 2010
    Yes, I just unscrewed it. Same type of external antenna you find on wifi routers. Verizon phones are cdma technology, which is incompatible with gsm phones. So as of right now I am stuck with this device as much as I don't like it.

    I believe they call it, like oliver stated, a SMA connector. Pretty standard for all the antennas I have seen. Picture sucks, but maybe it will give you an idea.
     

    Attached Files:

    Last edited: Jan 1, 2012
  14. OLIVE2222

    OLIVE2222

    690
    25
    Oct 2, 2011
    Hi,


    If you try the antenna solution here what's sma and reverse sma looks like.

    http://wificablepro.com/wp-content/...nnectors-Understanding_WiFi_Polarity_CR21.jpg

    and a common type of SMA attenuator (here 3dB)

    http://www.minicircuits.com/pdfs/VAT-3+.pdf

    or at mouser

    http://www.mouser.com/Crystek/_/N-1yzt1dh?Keyword=sma+attenuator&FS=True

    You can also try a very small gain less antenna.

    Maybe you can also access to the picocell menu and reduce the maximum output power.
    But in this case the caveat is that you will have a somewhat unbalanced link.

    Olivier
     
  15. jackorocko

    jackorocko

    1,284
    1
    Apr 4, 2010
    If I knew how, it would have been my first option. Those attenuators a not cheap either. $20 bucks?

    I actually called verizon and they are gonna honor the warranty on the device. Supposedly like steve says and I read in the manual. The RHK distance is fifteen feet, supposedly this is how verizon secures their femtocells.

    Well I disputed this claim, because I know for a fact that my phone locks on to the femtocell device well before I am fifteen feet away. Because of this, they will honor the warranty and send me a brand new one straight from the factory. I am not really sure how this is gonna help, but if they want to send me a new unit for free I have to accept.
     
  16. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,448
    2,809
    Jan 21, 2010
    As I read the manual, it seemed to say that the RHK distance would vary. I suspect that in areas with poorer signal strength it would be larger. In areas with zero signal strength it could be *huge*.

    I share your scepticism.

    I'm pretty sure the only real difference could be firmware. My unit downloads firmware changes automatically, and apparently there were *many* during the initial phase-in of the device.

    I think Verizon just want to use these things to improve their image by making their network seem better than it is (thus allowing anyone to connect) rather than just improving your experience.
     
  17. jackorocko

    jackorocko

    1,284
    1
    Apr 4, 2010
    Exactly what my first impression was. Instead of thinking about me (my money) they are are more worried about improving their own network to increase further sales. Well at least someone agrees with me, whether that makes a difference, only time can tell.

    I did happen to read a thread on howards hardware forum about verizons femtocell. One person stated that they thought verizon could do a firmware update and change the RHK distance. I wonder if this is the case with me, they just aren't willing to tell me that. I might have to inquire about that when I call nicholas back at verizon to verify the device is working.
     
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