switching between 1900 and 800?

yamahammer · EVDO Newbie Joined: 13 Jul 2009 Posts: 8

Iv been reading here for a while and was getting ready to buy a grid antenna, but i have a problem. After going to field test mode on access manager i found my channel switches from 589 to 425 about every 15 seconds. This would mean im switching frequencies right? If im correct what does this mean for antenna buying? cant do it? or am i doing to need 2 lol? I live in an area where im pretty close to a alltell tower (about 1 mile) but there are several other towers within 4-5 miles.

yamahammer · EVDO Newbie Joined: 13 Jul 2009 Posts: 8

Anyone have any ideas? I would like to buy a grid soon but i cant until i figure this out. I have checked many times over the past few days and it still switches between 425 and 589 every few seconds.

3Gstore · EVDO Addict Joined: 19 Sep 2006 Posts: 3171

your best bet is a dual band directional like this one:

http://3gstore.com/dualbandyagi

yes, grids will have better gain, but there aren't any dual band grids that i know of.

yamahammer · EVDO Newbie Joined: 13 Jul 2009 Posts: 8

Hmm, i will get the Yagi if I have too, but I really wanted the grid since I do not have line of sight ( trees and hills ). I guess the reason for changing frequencies is that im picking up different cell towers? If i could figure out what frequency the close tower is could i get a grid for that frequency and just set it up that way? 1 Cell tower wouldnt be running 2 different frequencies right?

3Gstore · EVDO Addict Joined: 19 Sep 2006 Posts: 3171

not sure about alltel, but verizon has been known to have a tower running at one frequency and then switch to another under load.

yamahammer · EVDO Newbie Joined: 13 Jul 2009 Posts: 8

Well i have an update.. I drove up to the closest tower, which is alltell and my channel stuck at 589. I had a reading of ~ -60dBm, but my speeds were still pretty slow. Actually they were about the same maybe even worse than i get at home. So now i have no clue what to do. I guess this closest tower to me is a pile of crap. Now im thinking about trying to pick up on the signals from further away towers. I do have a question; all the towers within a 4m radius are pretty much due north, if i got the dual band yagi would it have a good chance of picking up signals from these other towers. From what i understand these yagi's have a wider range than the grids so would it be feasible to get the dual yagi and point it north towards these 3-4 towers and see what happens?

I guess one thing i should do first is drive up to these other towers and see what kind of speeds i get.

Wild Bill · Posted: Fri Jul 17, 2009 10:34 pm Post subject:

If you can do some testing while in field test mode you may be able to come to some conclusions from the comfort of your own home.

Can you see which frequency gives you better service? Check the signal strength and signal to noise ratio for each and see which is generally better. If you can, try to run some speed tests while you are connected at one frequency and then while connected to the other. Keep track of all your results and determine which signal gives you better service.

If you are dealing with two different towers/antennas I would think that you could go with a single band. If it is a single tower that is switching then that may be a different story. I, however, have no clue how you would determine which situation you are dealing with.

yamahammer · EVDO Newbie Joined: 13 Jul 2009 Posts: 8

well the channel changes so fast its impossible to do any testing. I just know when i start driving away from my house it sticks to the 800mhz band. Its only around my house it changes back and forth, which is weird because i get further away from all towers. It seems like the Altell tower is crap and i was just thinking about getting a 1900mhz grid and trying to lock into a more distant tower. I guess the other option would be to get the dual band yagi and pointing it at the altell tower and hope it picks up some signal from the better towers too?

Jim_in_VA · Posted: Mon Jul 20, 2009 7:42 pm Post subject:

what is your zip code?
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yamahammer · EVDO Newbie Joined: 13 Jul 2009 Posts: 8

25526

Jim_in_VA · Posted: Mon Jul 20, 2009 8:09 pm Post subject:

I'll get back to ya on what you need and whats around your area. Give me a day or so
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ChoP · EVDO User Joined: 13 Jul 2008 Posts: 54 Location: Alabama

The reason you are having the problem with channel switching is "Signal Fade", the modem is trying to lock the strongest signal for the channels available. When one fades, it looks for another by scanning for a stronger signal on other available channels. I had the same problem with a newer Alltel PRL 40050 and reverted back to 40042 and haven't unlocked since. Seems the PRL 40042 prefers Alltel towers much more. You can also try turning off mobile IP and see if it will stop channel scanning. As suggested do a little ride around homework and find the strongest and fastest connection for your location, you can then select the antenna that fits that frequency and I think your problem will be solved.

yamahammer · EVDO Newbie Joined: 13 Jul 2009 Posts: 8

OK i noticed something today. It only changes to 1900 when the connection is dormant. As long as im moving data it always stays on channel 589. Does this make sence or seem normal?