Hi vs. Lo Wing Cellfone Reception

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asicer

Touchdown! Greaser!
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asicer
Is it just me or is cellphone reception better in a high wing than a low wing? I haven't done any testing or analysis whatsoever so it very well could just be me, but I couldn't get any texts through from a DA40 that I thought went through fine from a C172 on a prior flight.
 
Cell phone reception is dicey in any configuration as the systems aren't designed to waste energy where they don't expect phones to be.
The low wing probably does provide some impediment as the cell towers are going to be below you (unless you're using a sat phone).
 
flyingron said:
the systems aren't designed to waste energy where they don't expect phones to be
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Someone told me the same thing recently. On a flight back from Livermore a few weeks ago we were over the LA area at 11,000 and I had no service on my phone, at all. I always assumed this stuff was line of site so I would have imagined to have full bars, but nope. Nada. I was told the towers focus their signals at lower altitudes? Very interesting...
 
Just flew 300 nm in a 152 @ around 4K and noted no bars every time I checked.
 
avongil said:
Just flew 300 nm in a 152 @ around 4K and noted no bars every time I checked.
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That's so strange to me. That's less than a mile from the ground and should have an unobstructed view to the cell towers. I never knew that signals could be focused so low, but obviously they can be because I'll go from full bars and service to zilch by the time I am at 3,000 ft.

Maybe a cell tower expert will chime in
 
I have better cell signal flying from KBJC to KCUT regardless of high wing or low wing than I do driving it.
 
I think the cell radiation pattern is only part of the story. I know at one time it was a problem to have more than 2 cells in contact at once. On the ground you're talking on one cell and as you travel along the next cell is also handling your call. As you lose the first cell you pick up another and work your way across the country. When you're over a couple thousand feet up in the air you've got contact with a much larger number of cells (if you have coverage) and they won't let you into the system. My phone works fine if I'm less than 2 thousand feet agl but higher up it gets iffy til it goes out altogether. Too many cells in contact.

Frank
 
I've never noticed any difference. Are you sure it's not the altitude you're flying at that's giving you reception issues?
 
Up to 6500 ft and near interstates I've always had good cell service.
 
tinerj said:
Up to 6500 ft and near interstates I've always had good cell service.
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I know someone who made a call from about 5,000' over Winslow, Arizona.
 
Its true.
To mitigate, I will do a quick barrel roll to collect my texts on longer flights.
 
BiffJ said:
I think the cell radiation pattern is only part of the story. I know at one time it was a problem to have more than 2 cells in contact at once. On the ground you're talking on one cell and as you travel along the next cell is also handling your call. As you lose the first cell you pick up another and work your way across the country. When you're over a couple thousand feet up in the air you've got contact with a much larger number of cells (if you have coverage) and they won't let you into the system. My phone works fine if I'm less than 2 thousand feet agl but higher up it gets iffy til it goes out altogether. Too many cells in contact.

Frank
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Not quite. What happened in the old ANALOG cell system is that the system was designed as the density of user's go up, that you can decrease the size of cell (The area surrounding one antenna) by decreasing power (the cell system tells the portables/mobiles to decrease power). This limits you from being heard in a lot of cells (two at once is NOT a problem). The problem is when you got some elevation on the system, you could be heard equally well by a whole BUNCH of cells and that persisted even after your mobile was commanded to the lowest possible power. It screwed up the frequency reuse and decreased the overall capacity of the system. It is for this reason that the section of the FCC rules covering this old AMPS technology banned airborne use.

This is less of an issue in the newer digital modulations which don't rely on a simple analog FM signal capture but a more complicated spread spectrum design.

The answer is mostly as I said, the base stations aren't designed to look up toward aircraft. The picture Rushie linked is a simplification. Even in the horizontal plane, many cells aren't omnidirectional. The system is designed (especially in urban areas and along highways and other busy locations) to narrowly focus where the cell is directing/detecting signals.
 
Now we got a thread going! Celebrity Telephonic Cage match!

In The North Corner - @denverpilot - Known the WWW over for long posts and telephony.
In The South East Corner - @flyingron - Equally capable of verbosity. Often with terms we have to google search for.

Play on, and enlighten us all!
 
Ravioli said:
Now we got a thread going! Celebrity Telephonic Cage match!

In The North Corner - @denverpilot - Known the WWW over for long posts and telephony.
In The South East Corner - @flyingron - Equally capable of verbosity. Often with terms we have to google search for.

Play on, and enlighten us all!
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Nope. I DGAF about trying to explain CDMA networks and handoffs again. It isn't all about the RF challenges. Your voice path still has to get back to the PSTN while you bounce around cell sites. Cross a controller boundary without a trunk a available to switch you to the other controller or do it too fast for the network to keep up, call drop.
 
So bloody typical. Experiencing the wonders of flight that humans could only dream of for millennia and you're busy looking at your phone. Phe.

Had a headset for awhile that would receive Bluetooth from the phone. Only time I could get out a call was on approach to land. Fortunately, it was the only time I wanted to (tell my ride to get going to pick us up).
 
steingar said:
So bloody typical. Experiencing the wonders of flight that humans could only dream of for millennia and you're busy looking at your phone. Phe.
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Bah. "Siri, send a text to aunt Kathy ".
 
This is all very interesting. My phone goes nuts getting new messages from a lack of service as soon as I land!
 
No argument here. Nothing contradictory between me and denverpilot. Both issues contribute to the fact that the system doesn't work well at altitude because it wasn't designed to. SMS works slightly better at altitude (probably because of what DP said) but even that doesn't work well. I can tell because every time I start a descent into my home fields my phone starts dumping backed up texts at me right about 1500 AGL.
 
flyingron said:
The answer is mostly as I said, the base stations aren't designed to look up toward aircraft. The picture Rushie linked is a simplification. Even in the horizontal plane, many cells aren't omnidirectional. The system is designed (especially in urban areas and along highways and other busy locations) to narrowly focus where the cell is directing/detecting signals.
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It's called leakage. I've got a buddy who contracts out to Verizon and that's all he does is go around and tune cell sites. If you're getting reception in your airplane, consider yourself lucky. The towers (most anyways) have a somewhat narrow and intense RX/TX band that they try to stay in for the most optimal signal.
 
SixPapaCharlie said:
Its true.
To mitigate, I will do a quick barrel roll to collect my texts on longer flights.
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Doesn't everything fall out through that wide open "fighter cockpit" canopy when you do that?
 
They just have directional antennas. This isn't rocket science.

Think of a MagLite... shine it at a wall. Now twist the cap and focus it... the spot where it's focused gets brighter. That's all a directional antenna does to RF.

Some "light" still leaks other directions (you can see the flashlight is on, if you look at it from above). But the majority of the "signal" is where the bright spot on the wall is.

Since it's essentially just like optics, you can also SEE a tiny point of light shined back at the MagLight from the wall, if you could stick your eyeball behind the lens in the MagLite. "Gain" is a two-way thing in RF, for the most part.

And if someone shined a light at the MagLite from above, it would be weak or not visible in the focused optic of the MagLite if your eyeball were inside of it.

It's really rare unless a site is being "re-engineered" that anyone is going up the tower and re-aiming any of the sector antennas, or changing where they point at, and cover. That's done back at the office by an RF engineer.
 
denverpilot said:
They just have directional antennas. This isn't rocket science...It's really rare unless a site is being "re-engineered" that anyone is going up the tower and re-aiming any of the sector antennas, or changing where they point at, and cover. That's done back at the office by an RF engineer.
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An "RF engineer". Sounds like they would be loads of fun at a party. :rolleyes:
 
GRG55 said:
An "RF engineer". Sounds like they would be loads of fun at a party. :rolleyes:
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When they like go out shooting, ride UTV's, blow s**t up, and have a collection of hot rods that Jay Leno would be envious of... yes, they can be pretty fun people to hang out with. ;)
 
azblackbird said:
When they like go out shooting, ride UTV's, like to blow s**t up, and have a collection of hot rods that Jay Leno would be envious of... yes, they can be pretty fun people to hang out with. ;)
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You are mixing "RF engineer" with "Rednecks With Paychecks"
Close, but not the same at all. In fact the latter are likely to keep the former employed given what they might use for target practice. :D
 
GRG55 said:
You are mixing "RF engineer" with "Rednecks With Paychecks"
Close, but not the same at all. In fact the latter are likely to keep the former employed given what they might use for target practice. :D
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He's the Redneck that employs the engineers. He has a crew of 30 or so. Funnest part of his job (at least to me anyways) is taking one of his Sno-Cats and hitting one of the more hard to reach cell towers high up in the hills during the winter time. Those things are a blast to drive!
 
denverpilot said:
It's really rare unless a site is being "re-engineered" that anyone is going up the tower and re-aiming any of the sector antennas, or changing where they point at, and cover. That's done back at the office by an RF engineer.
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Really? So they re-aim antennas from the office? :lol:
 
topgun260 said:
Really? So they re-aim antennas from the office? :lol:
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LOL no. The field engineers don't move the antennas without there being an engineering change order first. The post about "tuning" the sites is BS. The field folks go look for busted things not operating as designed, they don't design the RF coverage in the field.

Most of these companies use contractors like the "redneck who employs the engineers" for site management. All they do is read the design doc and implement it. The carrier's engineer determines where they want the signal pattern to go.
 
That works for me. The earlier post sounded like they would move the antennas from the office. Thanks for clarifying.
 
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