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3G iPad Data Reception in the Air

dpansier

Well Known Member
I developed an external aircraft antenna intended for data transmission, the antenna designed to be used with a Wilson mobile wireless signal amplifier, the type used in construction vehicles, over the road trucks and boats. (Wilson model 801212, available on eBay for about $260) The Wilson unit wirelessly connects with the iPad 3G and similar devices.

The aircraft Data antenna is similar in size and shape to the Transponder antenna I now offer on my webpage.

The installation in the aircraft requires mounting the external Data antenna, attaching the amplifier box (12VDC at 3 amps), and placing the internal antenna within 3 feet of the 3G device. A few other items are required such as a short section of RG-400 with a BNC male connector on each end, and a BNC Female to FME Female adapter.

My intent of developing this was to supply inflight weather data to the iPad3G / ForeFlight, beyond that, it does not take much thought to see the potential of other data uses for the system, email, text message, flight data, MiWi Hotspots, Etc.
With the iPad accessory market exploding , small wireless keyboards, voice recognition software and the like are available that offer iPad interface flexibility only limited by imagination.

The complete unit is undergoing testing in a RV and so far, the results have been very positive. Testing has taken place up to 10,500' AGL and the iPad / ForeFlight is being supplied with constant data updates to Radar, METARS, TAF's, etc.

This development is experimental in nature and by no means has the system been completely tested in all flight conditions, testing will continue to determine the limitations.
 
Sounds like a product that will have a pretty good market waiting for it.

Any more details, photos, price etc??
 
Sounds like a product that will have a pretty good market waiting for it.

Any more details, photos, price etc??

I guess I should chime in here. I am doing the testing for Don. I mounted Don's antenna on the belly of my RV-6. I removed my tracker antenna for the new antenna and borrowed the tracker's RG-400 coax.

The Wilson amp uses a power supply that plugs into a cig lighter outlet. The RF output of the amp goes to an "inside" antenna that should be positioned near the cellular data receiver: in this case, my 1st generation iPad. The amp has three green lights on it: the first indicates that it is powered on, the second indicates that there is throughput of the lower frequency cellular signal and the third light indicates throughput of the higher frequency cellular signal. So, if you have 3 green lights, everything is working properly.

So far I am impressed with this setup. Like many of you, I have experimented with the 3g data on my iPad below a couple of thousand feet and found it to be adequate but intermittent. So I was quite impressed when I was receiving data today at 9,500 feet. On a previous flight, I was receiving data up to 6,500.

I would emphasize that I have a long way to go before I can have a definitive opinion about this system, but initial results are very promising. I am getting 5 bars (the maximum) at 9,500 feet along with the AT&T logo and then the 3G and the hourglass indicating that it is receiving data. Occasionally, I get an "E" instead of the "3G" which I guess indicates an older technology network than the 3G. It does lose lock quite a bit: one minute you'll have 5 bars, and then nothing. But the data appears seamless to me. Even though there are a lot of interruptions, the data seems to continually update. I tried getting the weather at KSFO, for example, while at 9,500 and had no problem getting the entire SFO package, including NOTAMS, winds aloft, METAR and TAF. It comes in very quick.

On my last flight, I was playing around with the radar map and although it received data fine, it appears the bit rate is not high enough to enable the loop function. So what you get is the last 5-minute snapshot of the radar return and it updates approximately every 5 minutes. Of course it is time stamped so you know how old the data is.

I can easily envision flying along on a cross country and being able to look ahead at the weather without any problems--at least this has been my impression so far, but I want to use the system quite a bit more to see just how reliable it is going to be.

I will update my findings as I go along and post some pictures in my next entry. My hope is that this will be another use for the iPad in the cockpit: already it has proven to be very useful to me as an EFB.
 
Thanks for your reporting your findings Pat, I apologize for my error in the maximum test altitude, looks like I was 1000' off.


More information on the components that make up the system.

Wilson amplifier is readily available on eBay, occasionally a used Wilson amplifier will show up but they sell for nearly the price of a new unit.
The Wilson Model 801212 sells new for $250 to $260.

The Ultra Wide Band Data Antenna physically looks like the Delta Pop Transponder Antenna but the internal components are different to allow a low VSWR over a very wide frequency range. The mounting hole pattern is the same as the Transponder Antenna as they share a common base design.
The price for the UWB Data Antenna is $89.95 plus shipping.

Pat mentioned he will post some pictures of his installation soon.
 
Pat mentioned he will post some pictures of his installation soon.

Here are the pictures of the installation.

Don's antenna is the rearmost. It is actually the same size as the transponder antenna on the right.

IMG_2741.jpg


I have the amp just sitting on the floor for now, but it can easily be velcroed to the forward side of the wing spar. The ON/OFF switch for the amp is on the cig lighter plug and has a red LED in the switch to indicate when the switch is on. There are also three green LED lights on the unit, barely visible here.

IMG_2754.jpg


This the interior antenna. It comes with velcro attachment tape. I have it just sitting on the right arm rest for now with a piece of painter's tape until I decide the best place to mount it. You can also see the cig lighter plug/switch just above the red fuel selector on the center console.

IMG_2757.jpg
 
Is there any update on the testing? This looks like a great alternative to the XM WX Receiver and Barron Mobile link system that is about $1,200 plus the monthly XM WX Data packages which start at $35.00 per month.

I have been using ForeFlight for about 18 months which I really like. I just dont have good reception at higher altitudes or over less populated regions. That is not an issue for the maps, just weather data.

I have been using the Pilot My-Cast 30 day free trial. It has some nice features but still prefer FF. WingX Pro7 has some nice features too. For me the inflight radar/weather is my focus.

Thanks for all the information.
 
The testing reports I'm receiving continue to be very positive. Several additional members of VAF will be equipped and flying by this week Friday so I will have performance results from a wide area of the US.
 
As an ex-AT&T network engineer that had to deal with making a cell phone system work, while hoping someone didn't rain down watts of RF from the sky down into my network, I have to ask:

How do you feel about the legality of using a cellular phone in the air? The FCC is pretty clear that this is illegal, and the FAA supports this in AC 91.21-1A.

The FCC rule is not there because a cell phone might interfere with the airplane, it's there because an airborne transmitter spreads out the RF over such a wide area that it reduces the usability of the network for everyone significantly. You're hurting the network for every single person that is below you.

Read this if you need more information why this happens. It's even worse when you are using an amplifier that is increasing your power output:
http://en.wikipedia.org/wiki/Mobile_phones_on_aircraft#Cell_tower_channel_re-use
 
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it reduces the usability of the network for everyone significantly. You're hurting the network for every single person that is below you.
Jordan,

Is this still true today? I know it was when the network was originally set up, but I was under the impression that today the network is intelligent enough to localize you to the central towers that you're closest to, and reject your signals from towers that are further away.

In Canada we have no such law against use of cell phones in the air, and I was under the (possibly mistaken) impression that this was because the networks quickly advanced to solve this issue before our lawmakers could get their hands on it... :) I regularly make use of my 3G signal while airborne, usually to call up google maps.
 
It's still true today. There's no way for a tower to "reject" your signal. The cell system is based on the fact that you actually are MUCH closer to one tower than another, and your cell phone backs off the power so it just reaches that close tower. Thus all the towers far away don't even hear you because they are all MUCH farther away than the closest tower.

Even with that, you have to be careful. We used to have to watch out for hills 10 miles away from the cell tower since they could be higher than you and a tower there could be stronger in your location than one just a mile away but blocked by trees. Designing a working cell phone system is not just putting up towers and having it all work.

When you're in the air, you can be equally close to many towers, so your signal interferes with them.

RF can't be rejected from a source you don't want. Every transmitter in the world on the same frequency increases the signal to noise for every receiver in the universe. If you could reject signals you didn't want without any side effects, we could put every signal in the world on the same frequency, and your 3G phone would have unlimited bandwidth even if every subscriber in your town was in your house at the same time.
 
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It makes perfect sense that you wouldn't want to site a tower on a hill where it can communicate across a larger radius, because the area of a circle (and the number of phones within it) increases with the square of radius. No doubt you could quickly overwhelm the capacity of a single tower.

It doesn't seem like the same logic should apply to an airborne cell phone however. Yes your signal might go to hundreds of towers, but its just one extra signal going to a tower that normally handles what, 1000 signals? (just making up a number). At any given time I'd be surprised if there were more than a few dozen private airplanes aloft over a given city. I don't see how this could overwhelm the network. However, maybe there's more to the problem?

My read of AC 91.21-1A is that the use of portable electronic devices is pretty much left to the discretion of the operator. However airborne use of cell phones is cleaerly illegal according to the FCC: http://www.fcc.gov/guides/wireless-devices-airplanes
 
Jordan, question for you.

For those of us who are not interested in using a cell phone in flight, but only in receiving data-----weather in my case, would the system in the first post be in violation of the regs you site?
 
Mike,
There is no way to only receive on a cell phone or 3G connection.

The connection you have requires constant communication both ways, so the cell tower knows that you are there, if you got the data it sent, etc.

Even more, with data, there's no way for the system to know what data you want without you requesting it, so you have to transmit to them to ask for it. Since this isn't a specialized weather transmission station, but a generic internet connection, the data looks like this:

Phone: I want a bit of weather data
Network: Here you go
Phone: Ok thanks. Got it. Send more
Network: Here you go
... repeat forever

Anytime you are receiving data on phone or any other cellular device, you're transmitting just as much as if you were on a normal phone call. This is why using data drains batteries so quickly.
 
Jordan,

Does this mean we have to use XM if we want to have weather on a system like Fore Flight? Are there other options you know of? Would a satellite phone be an alternative?

I am enjoying the education.

Jim
 
Let's review the regulations:

"The use of cell phones aboard airborne planes is banned by the FCC in 47 C.F.R. ? 22.925: The use of cellular telephones while the aircraft is airborne is prohibited by FCC rules. The use of cellular telephones while the aircraft is on the ground is subject to FAA regulations. The FCC ban applies to phones that use the 800 MHz spectrum. Personal Communications Services (PCS) phones that use the 1900 MHz spectrum are governed under FCC 47CFR24 and their use in aircraft is not restricted by the FCC whether on the ground or in flight."

What I get from this is the FCC prohibits the use of wireless devices operating in the 800 MHZ spectrum once the wheels leave the ground.

Equipment Spec's:
The iPad 3G has the ability to operate on several frequencies, 850 MHZ, 1900 MHZ, and 2100 MHZ.
The Wilson device has the same multi frequency capability basically repeating the iPad 3G operating frequency.


Carrier Coverage and Frequency:
As as an example AT&T published the following map.
(Not sure of the publication date)

Where AT&T uses 1900 MHz Coverage:

22fbqs.gif


Based in this information I find it difficult to make a blanket statement that the FCC regs prohibit the airborne use of the iPad 3G device.
What am I missing?
 
dpansier,

The point is that the iPad 3G uses the same signal. It's an iphone without the ability to talk. If the FCC wanted to pursue a case against you, the burden of proof (and significant legal defense) is going to be on you to defend. The term "cellular phone" can encompass more devices than just what common sense would term as a "phone." i.e. any device that transmits/recieves data over a cellular network. That said, cellular is really an archaic term since "cell" phones really haven't existed in the true definition in years.

Personally, I've jailbroken my iPhone, tethered it to a wi-fi only iPad, and get data that way. Used it to download plates, SIDS, STARS, etc on the fly. (No pun intended).
 
Jordan,

Does this mean we have to use XM if we want to have weather on a system like Fore Flight? Are there other options you know of? Would a satellite phone be an alternative?

I am enjoying the education.

Jim


Take a look at Navworx. You will soon be able to use wifi on the Navworx to transmit data to to Foreflight.
 
Following the rules

First, this is important enough that the military also has the same ban, absolutely no cell phone use in the aircraft. I will be honest, we have done it once or twice (turn phone on, quick text, get reply, turn off) when a mission critical question comes up and no comms with base (we don't have onboard wx for example).

Second, for those who think this is only a thing of the past "old" technology and network, please research the light squared problems with GPS. Strong ground station signal disrupting relatively weak satellite signal. This is a problem many of us are aware of and can get behind because we want our GPS and don't want it jammed (I have taken part in jamming tests from light squared and believe me, your GPS reception goes very quickly downhill as you fly towards the ground station). This is the exact same thing (from a signal strength perspective) to the above stated 3G reception...just reversed.

It sounds like a great idea, but the benefit (cost and simplicity) for the individual makes many problems for the group.
 
idea??

Actually, now that I think about it, and hams out there? Could there be a way to use the legal spectrum available to amateur radio operators to ship that data on another freq? APRS is a data packet, etc. I have been flying a LONG way from home (VERY long) and used our onboard HF system, called a ham in Florida who did a radio patch with the phone and let me talk to my parents while flying on deployment in "bad" areas of the world...There has got to be some other way to transmit similar data??
 
LAMPSGuy:

We've traveled over 2/3 of the world via sailboat while using amateur radio's Winlink service for both email and weather data downloading. Some pilots doing long hauls rely on Winlink or Sailmail (a commercial alternative to Winlink using the same equipment & technology...or used with Inmarsat, or Iridium) for both email and limited (small scale, large area) wx info. However, Pactor speeds are very slow and the wx data suitable for those speeds is therefore very broad in scope. Forget practical, useful graphics altogether.

(From the Sailmail intro page: "Depending on propagation, the quality of your radio (especially grounding system) installation, the type of equipment used, and the distance from the station, members are able to send and receive internet email at a rate varying from 10 to 500 characters per second using Pactor-III. These rates approximately compare to sending and receiving text on a PC using a modem of between 110 and 4800 baud (remember those days?). sailmail.com )

The silver lining is 'saildocs', an email-based document-retrieval system for the delivery of text-based Internet documents. Meaning: If the wx info you want is available as a web page, you can order that webpage via saildocs, which works as a text stripper converting all the HTML (if any) into text and forwarding it via this slow-speed, Pactor III mode.

Bottom line: This is a time intensive process, which is OK for a slow boat at sea but not for a/c flights. It requires a significant set of hardware (cost & install quality), and would not bring nearly the comprehensive wx data many are accustomed to having in their cockpits these days.

BTW we've enjoyed ham voice comms with our son, even while he's been flying a SH-60B, while we and he "were deployed" outside CONUS and you're right - for a purpose like that, ham radio is a fun comms tool to have onboard.

Jack
 
quick test

just lay your iphone next to your Bose Headset switch and let the fun begin..
Mine ALWAYS produces static and interference in the headset unless it's in airplane mode.
 
Equipment Spec's:
The iPad 3G has the ability to operate on several frequencies, 850 MHZ, 1900 MHZ, and 2100 MHZ.

Based in this information I find it difficult to make a blanket statement that the FCC regs prohibit the airborne use of the iPad 3G device.
What am I missing?

I came to the same conclusion when I looked into this a couple of years ago. As long as your device is not using the 800Mhz band, it is not illegal to use in the airplane according to the FCC regs. Note that the device might indeed present the same interference/overloading issues that others have pointed out even if using 1900Mhz, but it is not illegal according to the current regulations. However, if the interference/overloading issues start to have a noticeable effect due to lots of pilots using this, my prediction is that they will simply update the regs to ban it... :)

-Dj
 
I located an interesting study performed in 2002 by several students at the University of Colorado, Boulder regarding the use of GSM in aircraft.

Of interest to the forum discussion here is the "Legal Constraints" section on page 2 and "Conclusions and Recommendations" on page 11.

https://drachma.colorado.edu/dspace...1/gsm+applications+for+airborne+platforms.pdf

Although the study comes to the conclusion that voice communication may not be reliable, they do indicate that data can be an effective means to pass information.
 
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I have not done any further testing on this project but at least 30 VAF members are using the system and most which to remain below the radar.
 
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