Piloting a RC-plane with a PDA !

Hi,

Have a look here :

formatting link
The end of our beautiful designed transmitters (full of bells and wistles)? I think I'll quit RC-flying. Will never get used to that new stuff.

Oliver

Reply to
Olivier tx2tx
Loading thread data ...

I think the part you missed here may be the best part. Once these types of units are available, you may get 900mhz (or above) spread spectrum frequencies and we can finally get away from the restricted use frequency bands. These units are very selective and even can use encoding to specifically identify your transmitter as the only signal source. Very interesting times. Once the spread spectrum hurdle is breached, you will end up with a system that can talk in both directions passing control info to your plane and system status back to be displayed on the transmitter lcd screen. Imagine being able to readout airspeed, cylinder head temperature and battery condition while flying. No wait for the end of the flight to download the info or need a second system to monitor inflight. All in the same type package we are using today. Very cool stuff...

FredD

Reply to
RedFred1

Fred,

You among several others have talked spread spectrum as being the panacea for the R/C systems.

Would you please educate dumb old me as to exactly how this type of system would work. I need details as heretofore I have only read salesman like verbage. I could use engineering details.

Such as....

1) How many xmitters would be used? One that everyone shares or each has his own? 2) How is each pilots control identified? 3) What is the control latency time?

You get the idea.

Thanks,

Dan

Dan Thompson (AMA 32873, EAA 60974, WB4GUK, GROL) remove POST in address for email

Reply to
Dan Thompson

| It's the same way that your cell phone can share a frequency with | tens of thousands of other cell phone users yet still be able to | work without interference from all those other phones.

No, not really.

AFAIK, cell phones do not use spread spectrum. I think that what they do is more of a trunking thing -- they call the tower on a frequency, and the tower tells them to switch to another frequency ...

They're called `cell phones' because your phone only works within a small cell ... rather than having enough power to send your signal across the country or even across the city, it only has to go to the nearest tower. Otherwise we'd run out of spectrum, and would need much more powerful phones.

If you want to see how spread spectrum works, look at 802.11b devices. Many devices all work on the same channel, sharing the available bandwidth. This is by far your best analogy -- because it's not an analogy at all, but spread spectrum in action!

| We wouldn't have the problem of traveling into a "dead cell" like cell | phones do because we would remain in close proximity to our flying models... | or would we?

We have that problem now -- interference can cause zones where your signal is drowned out by other signals that aren't even on the same frequency. Spread spectrum isn't likely to fix that.

Spread spectrum isn't a panacea for interference issues. But what it will do is make it so you don't have to worry about what channel you're on and what channel the guy next to you is on. You just fly.

It would make the frequency board a thing of the past, and would remove the possiblity of you getting shot down by a fellow flier. But if there's a cell phone tower right next to your field and it drowns out your transmitter when your plane gets close, you'll probably still have problems with that.

| The possibilities are endless, and therefore the addition of federal | regulations to our activities would be endless as well.

Huh?

| > You among several others have talked spread spectrum as being the panacea | > for the R/C systems. | >

| > Would you please educate dumb old me as to exactly how this type of system | > would work. I need details as heretofore I have only read salesman like | > verbage. I could use engineering details. | >

| > Such as.... | > 1) How many xmitters would be used? | > One that everyone shares or each has his own?

Everybody would have their own. Just like they do now.

| > 2) How is each pilots control identified?

To be determined.

Each transmitter could have a unique code and a receiver set to respond only to that code. Or each receiver could have a unique address, and you put the address into your transmitter ...

You could also do some neat things like have the plane talk back to your transmitter, sending back telemetry or video pictures, but that's strictly optional -- the signal can be one-way and still spread spectrum.

| > 3) What is the control latency time?

To be determined. They could keep it pretty short, probably even better than PCM is. As more and more people started flying (or otherwise using the shared frequency band) in a given area, the latency would probably increase, though hopefully not by a signifigant degree.

Reply to
Doug McLaren

Like I said, "salesman like verbage" give me the details as I asked.

Dan

Dan Thompson (AMA 32873, EAA 60974, WB4GUK, GROL) remove POST in address for email

Reply to
Dan Thompson

That is VERY kewl....

Reply to
Joe D.

So, when I get to the field and some else is already using my code/address, I must then either wait or change my code/address. If I turn on my xmitter, does it interfere with the one that is already in use? Hummmm, how is that any different than it is now?

| > 3) What is the control latency time?

Should the latency time approach 100 to 200 milliseconds, and I expect it will, that would be bad. More traffic and error correction will alter the response time. What most here forget is that direct R/C as we do it is real time, not batch processing. Data communications can stand some correction and latency, R/C can't past a certain point. Dan Thompson (AMA 32873, EAA 60974, WB4GUK, GROL) remove POST in address for email

Reply to
Dan Thompson

In article , Dan Thompson wrote: | In article , snipped-for-privacy@frenzy.com | (Doug McLaren) writes: | | > > 2) How is each pilots control identified? | >

| >To be determined. | >

| >Each transmitter could have a unique code and a receiver set to | >respond only to that code. Or each receiver could have a unique | >address, and you put the address into your transmitter ... | | So, when I get to the field and some else is already using my | code/address, I must then either wait or change my code/address. If | I turn on my xmitter, does it interfere with the one that is already | in use? Hummmm, how is that any different than it is now?

I said unique, and I meant it -- as in every single transmitter or receiver has a unique address, not shared with any other device in existance.

Ethernet (and wireless ethernet) cards are already like this, and it works well.

| | > 3) What is the control latency time? | | >To be determined. They could keep it pretty short, probably even | >better than PCM is. As more and more people started flying (or | >otherwise using the shared frequency band) in a given area, the | >latency would probably increase, though hopefully not by a signifigant | >degree. | | Should the latency time approach 100 to 200 milliseconds, and I | expect it will, that would be bad.

Yes, it would (be bad.) It really depends on how much bandwidth is allocated to it. Hopefully enough bandwidth will be allocated to allow like 50 people flying at once with less than 50 ms latency. Ideally, this bandwidth would be dedicated to R/C use (and not shared with 802.11b or something else like cordless phones or microwave ovens) and only spread spectrum usage would be permitted on that band.

As I said, spread spectrum is not a magic bullet for interference problems. But done right, it could be almost perfect.

You could do all this now with pretty standard 2.4 ghz equipment. But the problem is that you're not allowed to use much power (unless you go under ham rules) so you won't get the range we're used to, and you are subject to interference from other 802.11b devices and other non spread-spectrum devices like cordless phones and microwaves.

(Spread spectrum will mostly ignore devices that aren't using it, but it will increase the error rate greatly, which will mean greater latency.)

| More traffic and error correction will alter the response time. What | most here forget is that direct R/C as we do it is real time, not | batch processing.

I don't think anybody is forgetting that here.

| Data communications can stand some correction and latency, R/C can't | past a certain point.

Well, they already do it to some degree with PCM. And yes, the latency does suffer, though it's still way faster than most can detect.

Reply to
Doug McLaren

No, that plane used standard radio equipment. Auto-pilot took it most of the way, with GPS tracking.

Kev

Reply to
Kevin M

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.