New Idea: Using Cell phones as TX and RX for RC, Why Not?

[jlagran Heli]

Hi...
I just got New Idea.

Why don't we just use GSM/CDMA Mobile Cell Phone as a Controller Device
to control our RC Plane/Heli?

So It will need 2 cell phone.
One as a TX, connected to 2stick, and buttons, and
One as RX connected to servos.
Nowadays cellphone are cheap (simple type), and light too.

Advantages:
1. Relatively Good connection
2. No frequency selection (No fight/argue about frequencies)
3. Noone jam us
4. Unlimited Channel(?)
5. No long antenna cable
6. Talk for 3 hours (depends on network, just like cell co. commercials)
7. Unlimited range (even for thousands miles, :D )

Disandvantages:
1. Need two CellPhone (or use yours and borrow your wife's)
2. Never late pay your cell bill.

mmm...
That look like a future of RC... :rolleyes:

How about that?
Any opinion?

JH

[Andy W]

Yikes!
If my model controls were as unreliable as my cell phone (and I've owned quite a few), I'd not feel safe even flying a foamie! :)
..a

[tve]

Hi...
I just got New Idea.

Why don't we just use GSM/CDMA Mobile Cell Phone as a Controller Device
to control our RC Plane/Heli?

So It will need 2 cell phone.
One as a TX, connected to 2stick, and buttons, and
One as RX connected to servos.
Nowadays cellphone are cheap (simple type), and light too.

Advantages:
1. Relatively Good connection
2. No frequency selection (No fight/argue about frequencies)
3. Noone jam us
4. Unlimited Channel(?)
5. No long antenna cable
6. Talk for 3 hours (depends on network, just like cell co. commercials)
7. Unlimited range (even for thousands miles, :D )

Disandvantages:
1. Need two CellPhone (or use yours and borrow your wife's)
2. Never late pay your cell bill.

mmm...
That look like a future of RC... :rolleyes:

How about that?
Any opinion?

JH


A similar, but probably better option would be to use spread spectrum modems. In the US, 902-928Mhz modems would be the best choice. Just about everywhere else would be 2.4-2.7 Ghz. Frequency hopping type would be the way to go... There are quite a few oem modules to choose from out there. The performance varies greatly. Usually directly related to cost. It would also be very easy to send back real-time altitude, gps, pitch, roll, etc....

[lazy-b]

I've been thinking about that also, I guess it will work on UAV, you can send way point and received telemetry information.

There already exist in the market a bluetooth controlled micro RC car, SONY-ERICSON, is selling that, a MICRO RC CAR controlled by Cellphone thru Bluetooth connection.....check there website....cost of the Bluetooth Micro RC car is USD 100.

[mwraight]

Why not? Simply Stated: "DROPPED CALL"! How would you like to be trying to place a call to your $2000 model plane as it screams towards the ground at trans-sonic speeds?

Since we're on zany ideas...why don't we all just pool our money and buy a satellite. We can upload R/C commands and beam them down to our planes. You could fly a plane on the other side of the world with enough satellite coverage? Or we can just wait until they get really good at making those new carbon nano tubes that work as light antennas and use light beams for control!

:)

[ZAGNUT]

even if you did get total reliability you would still have to deal with the delay between your input and the models response to it


dave

[vintage1]

Not with LEOS (low earth orbit atellites :D)

I would say its very likley we will see spread frequency radios in time using smething around 460Mhz or so, for model use.

Temporary loss of signal is an issue, but snce there is enough digital stuf in there already, it will probably just be a lockout as the plane flies through dead spots, rather than twitching etc.

[DesertDawg]

Okay - first, let's look at the theory and history behind mobile telephones. I'm going to use the U.S. model because it's what I was trained in; I'd bet the U.K. is very similar.......

Previously, the first truly "automated" mobile telephone system was known (in the US) as IMTS. Don't ask me the full name, I forget; but I think it stood for "Integrated Mobile Telephone System". Big honkin' 75-100 VHF radio stations on mountaintops, connected to telephone lines. Big, honkin' 40-75 watt VHF mobile radios in your car....the control head sat under the dash (or bolted to the floor); and a box about the size (and 5 times the weight) of a small suitcase lived in your car's trunk ("boot") carrying the actual TX/RX assembly; plus a 38" whip antenna mounted to the boot. Here, we had a maximum of 15 channels available; which meant you could talk for hours (if you had the checkbook) on one call while travelling quite some distance - if you could find an available channel!

Then somebody came up with the idea of miniaturizing the whole system; including the coverage area of each base station. This last was quite simple; as with the miniaturization came a move to much higher UHF frequencies, nearly in the microwave spectrum. Two things came of this move to upper UHF: the ability to pack more channels into a given spectrum, and the limited ability to operate "line-of-sight", which means "If you don't stand a chance of seeing it, you can't talk to it!" . Therefore, cell phones on the ground are not subject to nearly as much "adjacent site interference" as cell phones at 200 meters AGL!

Now, why is it a bad idea to have two R/C clubs' flying fields within a couple of miles of each other? - And remember that cell sites are usually about that distance apart.
If your airplane (on Channel "1"), flying from Field "A" enters enters into the radiation pattern of my transmitter (also on Channel "1") over at Field "B"; what could happen????? Or if your cellphone receiving R/C signals from cell site "A" happens into the radiation pattern of my telephone conversation on cell site "B" (and on the same cell channel), well...............



Dawg

[air]

Now, why is it a bad idea to have two R/C clubs' flying fields within a couple of miles of each other? - And remember that cell sites are usually about that distance apart.
If your airplane (on Channel "1"), flying from Field "A" enters enters into the radiation pattern of my transmitter (also on Channel "1") over at Field "B"; what could happen????? Or if your cellphone receiving R/C signals from cell site "A" happens into the radiation pattern of my telephone conversation on cell site "B" (and on the same cell channel), well...............
Dawg

This isnt an issue. The channels dont overlap (much) between cells and the bsc will hand over a user from one base station to an other as you move between them. This is how you can move along in a car (on a call) and be transferred to the nearest base station as you go without (hopefully) dropping your call.
With a TDMA phone system each cell site has a certain amount of channesl which it can allocate to users in the area. Unless you flew into a saturated cell you would be transferred seamlessly. The BSC (Base Station Controller) wont allow two handsets to transmit on the same channel.

[jeffs555]

I think what DesertDawg is saying is that cell towers spacings are designed for phones on the ground. Adjacent cells don't overlap frequencies, but if you use a cellphone high in the air, the line of sight distance increases, and you are able to reach many cells which may use the same frequencies. This is probably not a problem for normal low altitude RC flying(but the uncertain reliability and delay would still be a problem). It would be a problem for high altitude remotely piloted vehicles. In the US, the FCC bans the use of cellphones in airplanes for this reason.

[Andy W]

(circling at only 2000' or so over Callaway, GA, in a full-scale sailplane, I was picking up a cell signal from AL. I knew, as the clock on my phone kept flipping over to central time)
..a

[Mr.RC-CAM]

I would never trust a cell phone to fly a model airplane. However, I think that eventually the video camera features will evolve into something that will be fun to use on an R/C model.

RC-CAM

[air]

I'd tend to agree with you, its wrong on so many levels!
However there are many desirable features of current phones from a radio access perspective (DSSS etc) which could greatly enhance RC, telemetry etc.

[Mr.RC-CAM]

With a cell modem and some other hardware, extensive model telemetry would be possible. But eventually a stock cellphone could offer some interesting fun too. Besides the video camera features, the GPS feature might work out as a lost model finder. There are other tricks you could do with them too.

RC-CAM

[tve]

Some modems like these would work very well for r/c. Range is NOT a problem (20 miles+ RF line of sight) unless you can't see the model. If thats the case, why fly it? If you use a frequency hopping spread spectrum modem, the channel dwell time is going to be important. It determines how often you can update your servos. These modems operate well with a 20 mS dwell time. I think this would be good enough. It would be superior in almost every way except one: cost. This will be the case for almost any spread spectrum modem. The fact is, it just costs more to make a reliable digital system. The benefits are great though...

No interference
No Jamming
2 way communications for telemetry
no glitches
etc, etc...
No, I don't work for this company :)
http://www.microhardcorp.com/products_oem_compactrf.htm

[Pete P.]

Somebody should try Bluetooth.....Might be fun :-) The class 2 has a range of 2 miles! Runs on 2.4GHZ, you can use WiFi antennas, too.

[Bill Harris]

> However, I think that eventually the video camera features will evolve into something that will be fun to use on an R/C model.

Or a "poor man's telemetry" system.

--Bill

[vpersiani]

Here in Japan you can buy some small car toys that you drive from your mobile phone!
If you are really interested I can try to find a link on this, but honestly I can't think of using that for anything more than cheap toys!

[Vampyre]

Well, I think that there has to be a much better way, the problem with cell phones is that it lags up to .5 sec, even on the same tower. Since I just got a radio hit and need to probond my E-Flight Ultimate back together, I think that anything with a better range would be a great benefit.

[Mr.RC-CAM]

Here in Japan you can buy some small car toys that you drive from your mobile phone!

I could be wrong, but I believe they use the bluetooth feature on phones so equipped. The range is limited. It is not the same thing as using the cellular network.

RC-CAM

[escudo]

In the US, once they got wind of this practice, the FCC would probably come down on the hobbyists like a ton of bricks. Modifying FCC approved radio equipment is not condoned. This includes attaching wires to button pads, changing the length of powersupply leads, changing antennae, modifying the case, etc.

Next, you'd get someone suing hobbyists claiming the cellphone equipped planes cause cancer as they fly overhead.

[tve]

Since this thread popped up again...

Check these modules out. High performance at a very very low cost (for what you are getting).
http://www.mouser.com/index.cfm?handler=data.getPcodes&pcode=AeroComm%2B900%2BMHz%2BWireless%2BTransceive r%2BModules&pcodenumber=81400
data sheet for 1 watt model with antenna $77US

http://www.aerocomm.com/Docs/Datasheet_AC4490.pdf

Aerocomm also makes some 2.4Ghz modules with the same footprint for those of you in countries that dont allow 902-928 Mhz licence free equipment.

You would need to make a simple controller to interface to it for r/c use.

I haven't tried them yet, but I'm planning on it....

[Grejen]

I've always wondered why the RC hobby hasn't started to switch to the radio phone technologies. Even with the 'old style' 900mhz phones the range would be sufficient for parkies and if you can have 10 or 20 phones in a high density housing complex why not RC planes. The electronics to take the signal to the servos instead of a voice signal can't be that much more costly to produce. 2.4Ghz digital radio phones are under $100.00. I understand the economies of scale on a 10,000 RC radio sets will be different from millions of telephones but the technology is already there.

Any DIY's out there ever tried hacking/converting a 2.4 phone? I'll bet you could sell kits.

[Mr.RC-CAM]

My opinion is that the UHF and microwave frequencies are not all that attractive for our R/C application (extreme mobile RF). Besides the congested spectrum in the license free areas, the RF's directional behavior invites a lot of multipathing and other signal integrity challenges. They are not as efficient, mW for mW, as the current VHF based R/C systems. So reliable range would be MUCH less unless the RF power was much higher.

Consider this: The typical cordless phone user can easily tolerate some signal integrity issues. They either learn to stop moving around when the signal gets goofy, or they ask the other end to repeat what they said. A fast moving R/C model, like a wing, can cover a lot of ground during the same short interference period -- which may be cause for a fresh pair of underware. For slow models, or ground vehicles, this would probably not be too bad an issue.

You can dress it up in a variety of ways, including spread spectrum, diversity antennas, and other magic. But, I would be very careful before I got really excited by microwave based R/C systems for model aircraft. Unless we were given a protected area in the RF spectrum, and could use higher power, I am not sure if it will be a wise technology for every R/C'er. But things may change to make it a winner in the future.

But on the plus side, the antennas would be amazingly short. :)

RC-CAM

[Grejen]

hmm.. seems there is much more to it than meets the eye. I've had a 900mhz phone for years with almost no signal issues at all. Guess thats not valid research eh?

[chaitanya]

i have a Nokia 6600 and i have installed a software - "psiloc Total irRemote" this one uses the phone's infrared port to control any device like TV, VCR, Car tape, etc. one has to choose the manufacturer from the in-built list which has about >50 manufacturers, then select the device and your phone really works as a remote!
I was wondering if we can use this remote to control airplanes.
the following webpage has a tiny robot controlled by TV remote so if we replace the robot with plane and tv remote with a 6600 (a tv remote will be cheaper ;) ) then we are done!!


http://home.megapass.co.kr/~cch8960/

Edit: heres the correct link if above dosen't work,
http://chanhak.com.ne.kr/robot.html/

[14U2NV]

And with Sprint's PCS to PCS plan, you'd have unlimited time to talk, umm, fly your model as long as it was also a Sprint PCS phone ;)


John

[Thecrazzyman]

http://www.mouser.com/index.cfm?handler=data.getPcodes&pcode=AeroComm%2B900%2BMHz%2BWireless%2BTransceive r%2BModules&pcodenumber=81400
verry intresting but im wondering how you hook thoes up. you can just expect it to make what ever you put in come out the other side. but that aside.

ive been thinking of using cellphones for radio tx and rx. i was thinking what if you made a relay setup with a mic. so when it hears. say 2600hz it triggers this relay. so then by just pushing the right buttons would send the right sound down the line out the speaker on the plane then controlling it. i was going to use this for a diffrent thing im bulding and still might as it is a cheep way to get good coverage. the other problem i can think of is cell sites dont shoot the signal up its mostly faced down and out to get best ground coverage. but i think for a heli or a car it would work as you should not be that high. well thanks for your time and sorry for the grammor and spelling its cold and im in a hury. its 52f in my room. so my digits dont work to well

[Rudy F]

Namdio.net

[Chamkeeper]

In the US, once they got wind of this practice, the FCC would probably come down on the hobbyists like a ton of bricks. Modifying FCC approved radio equipment is not condoned. This includes attaching wires to button pads, changing the length of powersupply leads, changing antennae, modifying the case, etc.

UNLESS, you have a proper licence, such as an amateur licence, and you have permission to operate in the frequecies etc of the equipment you are modifying.

The BIG cell companies bought the rights to use 2.4-2.7 Ghz a few years ago. They are in a whizzing contest with the FCC trying to get the freqs released for use in cell phones/personal devices etc.

If you think 900Mhz or 2.4 Ghz that cordless phones work on then why not use the 27Mhz or 47Mhz that the old phones use??? Heck why not use your CB radio?

[tve]

Besides the congested spectrum in the license free areas, the RF's directional behavior invites a lot of multipathing and other signal integrity challenges.
I agree that higher frequencies do have mutli-path issues, but this would not be a problem for outdoor r/c use. For indoor use, I don't think you could make a well designed system NOT work because of the ranges involved. I just don't see how multi-path would be an issue for r/c use unless you tend to fly your model behind buildings and trees that are miles away...


They are not as efficient, mW for mW, as the current VHF based R/C systems. So reliable range would be MUCH less unless the RF power was much higher.
This is true, but the point is that you CAN use much higher power levels. For r/c use, even a mere 100mW transmitter would be more than enough to fly the model as far as the eye could see it if it is a good design.


Consider this: The typical cordless phone user can easily tolerate some signal integrity issues. They either learn to stop moving around when the signal gets goofy, or they ask the other end to repeat what they said.

Typical cordless phones with poor range are hardly a good example of what could be done at these frequencies. They are typically very low power, fixed frequency or direct sequence spread spectrum. Frequency hopping spread spectrum would be a good way to go. I have state-wide systems using 902-928 Mhz frequency hopping spread spectrum. Some of the hops are up to 50 miles hilltop to hilltop. This is with 1 watt transmit power.


You can dress it up in a variety of ways, including spread spectrum, diversity antennas, and other magic. But, I would be very careful before I got really excited by microwave based R/C systems for model aircraft.

I understand being careful, but in this case, the only reason I can see not to use the 902-928Mhz, 2.4-2.7 Ghz bands for r/c use is cost. A good spread spectrum transceiver costs more than most r/c'ers are going to want to pay.

I predict you will start to see more and more of these type of systems for r/c use as prices drop.

Mr.RC-CAM, not trying to be negative about your post. Just trying to share my thoughs/experience on these frequencies.

When you say 900Mhz, most people instantly think: cordless phones and tend to compare quality of link, range, etc with other 900Mhz systems. This just isn't the way it is. You can do a lot of neat things with UHF. The military and commercial sectors use these frequencies for all kinds of in-flight applications. I think it fits r/c use perfectly (other than cost).

Regards,
tve

[Mr.RC-CAM]

tve, I have had my share of experiences with wireless video and wireless data products. The issues I mentioned are based on what I have seen in todays consumer technology. For example, multipathing is a real issue in outdoor apps. Little things like a cyclone fence or a row of cars at the field will create an RF burden.

I agree that eventually microwave spread spectrum based R/C may be practical for model aircraft use. I'm just not going to rush out and buy the first generation products.

RC-CAM

[flieslikeabeagle]

This is a fascinating thread. Earlier today I was reading a thread about Berg receivers and their ability to reduce RC "hits", and that got me thinking a little about the RC transmitters of today.

The technology we are using for RC today is *old*, developed in the days of simple analog circuits, when 72 MHz was a challengingly high frequency. The old technology causes a high amount of inefficiency and limitiations. For instance, RC bandwidth: the fastest concert pianists reportedly play around 12 to 14 notes per second. Assuming a similarly improbably fast-fingered RC pilot, using both hands, and consequently sending out data on four channels, it would seem the bandwidth requirement is perhaps 14 notes/sec x 4 channels x 8 bits/channel - for a total of under 1000 bits/sec. (I suspect the real requirement is far less). Yet each RC channel in the USA is 20 kHz wide...talk about wasted bandwidth. The last generation of dial-up phone modems (V .92/ V.44) have the ability to squeeze 56 Kb/sec of data through phone lines with only a 3kHz bandwidth. Thats 56 times more data, squeezed through a pipeline 3 times narrower - or an improvement of about 170 times! If RC Tx/Rx used some of the compression technology in those modems, we could fit hunderds of RC channels into the existing bandwidth, allowing more flyers with less interference.

Then there's the issue of the low (50 Hz) frame rate. Today I hooked up some microservos to an Rx to test the linkages for a parkflyer I'm building, and I realized most of the noise and vibration from the servos comes from the low frame rate. Buzzzz! Again, thats because dumb analog Rx's put out signals at the same rate as they are transmitted, so if the Tx puts out 50 frames/sec, that's all the servos get. With a digital Rx, it would be easy to interpolate/extrapolate pulse widths based on the ones received from the Tx, and put out much higher pulse frame rates to the servos, reducing buzz and vibration.

Another issue that comes to mind - the question of interference, again. I know a little about the Ethernet networking that connects most of our computers today, and one of the clever tricks that Ethernet uses is something called a MAC address: essentially, a unique digital ID number for every Ethernet network card in the entire world, that allows your computer (and the routers it connects to) to pick out only the data from the one computer you want, among all the millions of Ethernet devices on the internet. What if every RC transmitter had a similar digital ID number, that it encoded and transmitted periodically along with the control data from the Tx joysticks? You would program your receivers to receive signals only from that particular Tx, and this would go a long way towards eliminating hits from other Tx's on the same channel. Add the best feature of Ethernet - packet switching - where a stream of data is broken into tiny little packets which are reassembled at the receiving end - and two-way comunication to allow for re-requesting any missed data packets - and you'd have an RC link that is as reliable as an Ethernet connection, despite the storm of data from all the other computers on the same network.

Spread-spectrum communication was mentioned earlier on this thread, and is complimentary to everything I've suggested. In fact, modern wireless computer networking has most of the technology needed to jump RC technology forward to the present.

Like our present TV technology, RC technology is antiquated - designed decades ago, in the Jurassic era of electronics, which evolves at an astonishing pace. TV technology is about to leap several decades at a single shot, with the imminent arrival of digital TV. RC technology is waiting for someone to come along and kick it a few decades forward, to new levels of reliability, efficiency, and precision. Lets hope it happens before the FCC sells our current bandwidth to some large corporation with deep pockets.

-Flieslikeabeagle

[Mr.RC-CAM]

Yet each RC channel in the USA is 20 kHz wide
In the USA, the R/C channels are 10Khz apart. Hobby users are not allowed to use the commercial channels that exist in between ours. There is some guard band to allow for component tolerance and most of the work is done in less than a +/- 2Khz spread. This is the nearly the same bandwidth used by legacy telco modems.

RC-CAM

[flieslikeabeagle]

RC-CAM, thanks for the correction, but I think even +/- 2 KHz is far more than needed if modern modulation and data compression tricks are used. V .92/ V .44 modems pack 56 kb/sec into something like a 3 kHz or 5 KHz bandwidth...we only have to deal with maybe 1 Kb/sec at the most, fifty six times less data rate (and that's probably a very generous estimate, given that visual feedback from the model planes movements are needed for the pilot to input changes, making it very unlikely that 14 movements/sec of the pilots fingers will ever occur in RC flying...not to mention, that rate is only achieved when multiple fingers are playing music sequentially, unlike RC, where the same pair of fingers are used for all the movements). If the same modem technology was used, even with a full 1 kb/sec data stream, that should correspond to only about 54 Hz of bandwidth!

-Flieslikeabeagle

[Miami Mike]

If we were to advance to a more modern radio control system, I doubt it could happen on the same channels we already use. The transition would be too chaotic. What we need is a new band assignment, probably at a much higher frequency. Unfortunately, we probably don't have the lobbying power to ever get it.

[flieslikeabeagle]

Mike, I suspect you're right. I think in the year 2004, money has come to be the deciding factor behind this sort of decision - and commercial interests have a lot more of it than us RC hobbyists.

I understand that amateur radio (ham radio) is facing a similiar situation - except they may be worse off, as there appears to be a declining number of ham radio operators, while the electric flight/parkflyer boom seems to be increasing the number of RC pilots.

-Flieslikeabeagle