UM150 & Omni External Antenna Troubleshooting

reggie14 · EVDO User Joined: 09 Aug 2008 Posts: 29

I'm having problems getting a decent signal with an Alltel UM150 modem. Using just the internal antenna I get signals strengths all over the place- sometimes as low at -85db, up to about -105db. I think it bounces from tower to tower looking for a stronger signal. The closest evdo tower is 3.8 miles away, but there are trees in the way. The rest are close to 10 miles away.

After talking with the 3gstore people, I bought the omni directional external antenna and mounted it on my house. I was hoping it would drop me to about -80db, and keep me there somewhat consistently. But, I'm having a really hard time telling if it's working at all.

Even plugged into the external antenna I'm still seeing RSSI numbers all over the place. I've seen it as low as -80db, but it's almost always in the -90-100db range. I thought it might be the adapter tip, and 3Gstore sent me a new adapter, but that didn't help. I thought it might be the modem, so I replaced that with the same results. I haven't asked 3gstore to replace the antenna yet because it seems so unlikely that the antenna could be screwed up.

What kind of gain should I expect from the omni directional trucker antenna compared to the internal antenna on the UM150? What kind of troubleshooting should I try?

Jim_in_VA · Posted: Sat Aug 09, 2008 4:02 pm Post subject:

In your Connection Manager menu do you see a setting for "HDR Only"?
If so put it in that mode. If the selection is grayed-out you need to disconnect first. Try that step.
_________________
evdo-tips.com

JoeCHecht · EVDO Junkie Joined: 05 Jan 2008 Posts: 401

reggie14 · EVDO User Joined: 09 Aug 2008 Posts: 29

JoeCHecht · EVDO Junkie Joined: 05 Jan 2008 Posts: 401

Alex · Posted: Mon Aug 11, 2008 12:00 pm Post subject:

Joe is right about lightning arrestors... they should always be installed as a safety precaution.

However, it is my opinion that if 3Gstore were to "promote it" to his satisfaction, the majority of our customers are more likely to perceive it as "pushy sales" rather than "concern for safety".

Every time that I've brought up our lightning surge protector in a conversation before a customer has, the customer has responded with something like -- "does this do anything for reception? is it really necessary?" -- and naturally I've had to answer that it does nothing to improve performance and is merely a safety precaution.

Those conversations made me feel like a moronic chain-store electronics clerk who just asked a customer buying a ToasterOver if they wanted the extended warranty option. That discomfort leads me to stop bringing it up in conversation, but prepared to agree with any customer who asks if they should buy one.

This is worth repeating: Joe is right about lightning arrestors, regardless of how it makes me feel personally.

For that reason, rather than "push" the idea on customers, I'll suggest that our sales team start recommending the forum post he did above, to every customer who buys an externally mounted antenna.

For simplicity sake, I've created a 'shortcut' to it:

http://3gstore.com/lightning

I must also add that use of a lightning surge protectors does not positively guarantee your house will not catch on fire as a result of a lightning strike, nor does it guarantee against damage to signal amplifiers, repeaters or cellular equipment that are downstream from the lightning surge protector.

JoeCHecht · EVDO Junkie Joined: 05 Jan 2008 Posts: 401

NefariousCoal · Posted: Mon Aug 11, 2008 7:06 pm Post subject:

Reggie:

I also have a UM150 from Alltel. I don't use a Wilson antenna, though I tried one before, but I do have an external hooked up that I normally get an extra 4-6 dBm out of.

I've noticed that if your signal get a short fade out, your RSSI will jump all over the place, even if the bars looked good at the time. I was having that problem often enough before getting an external antenna but that fixed it - for awhile....

I noticed a few days ago that the signal to my local, and only, Alltel tower had dropped by about 4 -5 dBm. It wasn't a problem with my external antenna or UM150 but seems as if Alltel has gimped the EVDO signal here. Hopefully that's not the case in your area.

reggie14 · EVDO User Joined: 09 Aug 2008 Posts: 29

Thanks, everyone. I spent some more time troubleshooting the antenna. It turns out, where I had the antenna placed it didn't do any better than the internal antenna on the UM150. It was mounted about half way up the side of the house since I don't currently have enough cable to get it near the roof. It turns out it does much better on a post a few feet away from the house compared to mounted next to the house. Just moving it those few feet dropped RSSI numbers by about 8db.

It's not an ideal setup right now, but it seems to be working a little better. I think no matter what we do for antenna placement we'll always be in a fringe area. Even though it's just 3.8 miles away, there are a lot of trees between us and the tower. So, I don't think Alltel is gimping the signal (though, my Sprint phone went from getting great coverage to no coverage over the course of the last year, so they must have done something). Allegedly Alltel will be upgrading a tower that is only 2 miles away, with significantly fewer trees in the way, in a month or two. If that ever happens I think we'll have much better luck with this thing.

Right now this is for my mother's house. My sisters and I decided to get her this so we wouldn't have to put up with 28.8kbps dial-up when we visit. But so far it's been a pretty big disappointment and I think we'd all rather eat the ETF before dumping any more money in this thing, if it comes to that.

WVHillbilly · EVDO Newbie Joined: 29 Mar 2008 Posts: 7

This thread caught my attention on a drive by through the forums. In regard to the lightning arrestors I'd like to mention that an ungrounded arrestor is useless. Catching lightning without a groundwire to the arrestor is like catching a bee in a bottle- there's no where for it to go. However the groundwire has to be sufficiently sized to handle the voltages coming from the strike. From the photo picture I'd say that the Wilson arrestor should have at least a 10 gauge copper wire connecting to the ground screw. A 12 gauge maybe. The bigger the better. Physical Wire sizes are inverse to their gauge number. Run the wire directly to a copper clad grounding rod driven firmly into the ground at least into soil that is moist year round i.e. more than 4' preferably 6'+. That thing has to momentarily handle the equivalent of a surge capable of lighting a small community. I do not recommend connecting it to your home's internal wiring as through an adapter into the third leg of an electrical outlet. Surge arrestors that do this are just siphoning off the remnants of a surge that has gone through several layers of voltage reductions before reaching them or your equipment. Besides who wants a bolt of lightning cruising through their home's wiring your antenna surge is coming directly from the sky not a power pole 3 miles away.

WVHillbilly · EVDO Newbie Joined: 29 Mar 2008 Posts: 7

At what point does elevating an antenna above/around ground obstacles reach a point of diminishing returns via signal loss though the required long cable runs?

Alex · Posted: Fri Sep 05, 2008 3:02 pm Post subject: Re: How high is too high

WVHillbilly · EVDO Newbie Joined: 29 Mar 2008 Posts: 7

On the antenna vs obstruction question: I was getting no where with the verizon 727 modem as my workstation is in a basement surrounded by dirt up to 21" down from the top of the foundation. I opted for the Wilson Omni trucker and rigged up a bracket to attach the omni to the side of my house. I'll be 5' off the ground at the top of the antenna or optionally just under the front porch roof if mounted on the front side. I have to use some of the antenna's RG58 cord to get into the house and then to the PC so height is limited using just the antenna lead. In the meantime I injured my lower spine and have been home bound since May so the antenna is not mounted outside. I laid the omni on a shelf that is above ground level but still behind the 10" foundation and let the top portion hang out into the basement. I can now get RSSI's of 79, 81, 83 with downloads of 994,817, 1148, 440, 1468, 1100 kbps after following the tweaking instructions elsewhere within these forums. If the antenna gets this kind of reception inside a basement will outside height, trees, yard buildings, etc., be a reception concern. Also does this antenna pose a radiation hazard if used indoors or relatively close to a person?