RSSI drops and connection lost during mid-day

wvbills

Verizon service 4.5 miles away NLOS - Yagi Antenna - USB727 - Cradlepoint CTR 350 - PC.

RSSI has been running around -77 since installation last November. Rock solid connections.

Since Friday, from mid morning to early evening the RSSI down to -81 to -90 and, of course the connection drops. There are also periods when I have a connection and I can ping various sites - but I can't make an http browser connection.

Trees have leafed out so I have ordered a grid antenna to try to solve problem - but the trees have the same leaves on them early morning and evening so I'm not absolutely convinced it's a tree leaf issue.

Any thoughts?

Why would I be able to ping a site but not make an http connection? How is that related to RSSI?

Wondering if there's an issue with the tower. Could tower overload cause a drop in RSSI?

By the way - what's the Verizon Tech support phone number? Is it worth calling them or are they useless?

Thanks
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WVBill

Virginia_Bill · EVDO Newbie Joined: 28 Mar 2008 Posts: 2

How is your antenna mounted?

I have never used your particular antenna but Yagis in general are very directional, hence pointing is quite critical. If it is mounted on something that flexes due to a change in heat, that could throw the pointing off just enough during the heat of the day to cause the described problem.

If you don't get the same symptom on cloudy, rainy or cooler days, that would indicate something along the lines above.

You might also want to try repointing the antenna slightly during problem-times to see if that helps.

Best of luck.

Bill

wvbills · Posted: Mon Jun 08, 2009 6:24 am Post subject:

Thanks for replying, Bill

Antenna is mounted on a 10' piece of 1 1/4" EMT conduit attached to the railing of my deck. It's solid.

I have the antenna pointed at the tower based on a visible landmark on a Google Earth line between my house and the tower.

It was actually quite rainy on Friday when I first saw this happen (I was working from home so it was an opportunity to observe the situation continuously). I thought initially it was the rain but the problem continued Saturday and Sunday when it was completely clear and quite warm.

Saturday, I swung the antenna 4 5degrees either side of the line to the tower - in small increments, waiting a minute or two between each move and there was little signal change until I was about 30 degrees off the original angle in either direction when the signal dropped to -100

Maybe the leaves fluttering in the breeze decreases the signal (?).
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WVBill

Virginia_Bill · EVDO Newbie Joined: 28 Mar 2008 Posts: 2

Do you have a laptop so you could drive over toward the tower during an outage period and see if you can get a good connection there?

It isn't inconceivable that the problem is with the tower/telco equipment and if you can get a good connection (or not) closer to the tower it should indicate pretty conclusively where the problem lies.

Also, do you by any chance have a neighbor that uses the same tower with whom you could compare notes?

As you said earlier, the leaves are still the same 24 hours per day, so I doubt the problem is with the foliage...

Bill

n6gn · Posted: Mon Jun 08, 2009 7:34 am Post subject:

wvbills · Posted: Wed Jun 10, 2009 4:07 am Post subject: Grid antenna saves the day!

Success!!

My new grid antenna from L-com arrived yesterday. When I got home, I assembled it (15 minutes max), went outside and replaced the yagi with the grid. Same pole, same location, same pointing direction. Like I said, I'd been getting in the upper -80s RSSI. With the grid, the RSSI went up to -76 to -78 !! Back to a rock solid connection. I tweaked the pointing angle a bit Just to check my aim and see if I could get any more but that's the max I can get.

I'm a "grid convert"!

By the way, all my RSSI readings are what's reported by my Cradlepoint CTR 350. Throughout this whole deal, I tried several times to plug the USB727 directly into both my laptop and my PC and it would never connect and the diagnostic screen would register nothing. Never did get around to driving closer to the tower, though.
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WVBill

n6gn · Posted: Wed Jun 10, 2009 6:51 am Post subject:

Glad it worked so well for you. By the numbers your previous yagi was not very good, hardly better than a properly operating omni. As I have detailed before, even at 850, the difference between a well designed yagi and a 3' grid should be less than 8 dB or so. That you saw more improvement is an indictment of the yagi. Unfortunately a lot of antennas get sold as "X dB gain" that actually perform pretty far from X.

n6gn