Using aircraft radio/frequency for ground?
AmaRobotDude
Posts: 14
Other than being illegal and possibly interferring with nearby radio controlled aircraft what other reasons are there for not using an aircraft freq for a land vehicle? I see alot of people online using them. I would prefer not to but I cannot find a ground unit that has more than 3 channels and has sticks instead of those wierd knobs.
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So many hobbies, So little time.......and money [noparse]:)[/noparse]
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So many hobbies, So little time.......and money [noparse]:)[/noparse]
Comments
I have used a single channel to "multiplex" information out to perform different functions, but it requires digging into the radio a little bit
to gain access to a channel.
Basically you send a specific pulse signal or width that denotes a "sync" pattern to the receiving end. I did something like a 1.5mS
width followed by a 1mS width as my Sync. The next width denoted the Function...
Function:
1.2mS = lights
1.3mS = horn
1.4mS = turn signal
...The last pulse width value in the "4pulse packet" contained a "data" value that could be a duration for the horn, which turn signal (left, right, hazard, etc.),
or just about anything else you needed.
Note:
Since this scheme requires sending 4 pulse packets, the response time is at best 80mS or 12.5Hz.... In other words, you don't want to do any real-time control
from this modified channel, but it's good for general purpose data transfer.
You can expand on this and increase the response time by using more than one channel, where one channel is dedicated to "Function" value ( Servo1, Servo2, Servo3, etc)
and the second channel contains the data value associated to the function.
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Beau Schwabe
IC Layout Engineer
Parallax, Inc.
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So many hobbies, So little time.......and money [noparse]:)[/noparse]
Many RC guys carry several different crystals so that they can change their operating frequency if someone in the area is already using a given frequency. I don't know if its still done this way but when you bought the crystals packaged for RC aircraft applications, you got a little, color-coded, nylon flag that you clipped onto your antenna so that the other people in the area could see which frequency you're using without having to walk up and ask you. I have a extra few crystals for my 4-channel Futaba that came with those flags (the transmitter itself came with a flag for the included-crystal).
If you aren't operating near an RC field I don't think you have to worry about anything.
If you're using a Stamp on the RC vehicle, you could get a lot of mileage out of a 2- or 4-channel transmitter by having the Stamp interpret the servo control signals coming out of the RC receiver. The positions of the control sticks will yield a different signal on the output of the RC receiver and if you programmed a Stamp to recognize the signals that correspond to various control stick positions then you could, in principal, control several discrete operations on the vehicle by having the Stamp "translate" the servo control signals into on/off states on it's I/O pins.
With a 4-channel transmitter/receiver, you could use 2-channels for conventional yaw (left/right) and throttle controls and 2-channels for other operations. If your Stamp can recognize four different control stick positions for each channel (you'd have to be able to reliably hit these positions with the control stick) and allowing for one neutral position on a control stick, you could control 6 operations with the spare 2-channels.
With 6-channels: 12 operations. With 8-channels: 18 operations.
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I wouldn't connect that if I were you...
Post Edited (aalegado) : 6/24/2006 8:06:46 PM GMT
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Chris Savage
Parallax Tech Support
csavage@parallax.com
Almost any modern day R/C Radio System can be supplied with either land or air crystal frequencies, as Chris mentioned. Just specify when you order the unit. That's the only difference in the units.
Regards,
Bruce Bates
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The USA has separate Air and Ground hobby frequencies and the idea is safety.
They actually try to market units that are not compatible to avoid problems.
After all, if you get hit in the head by an out-of-control R/C airplane or helicopter; the results might be quite serious.
Each country is different and Taiwan seems not to care, but you should really consider your immediate situation.
If it is a good flying day and people are running around in an open area just enjoying themselves - doublecheck for R/C activity and channel conflicts. Shut down if you appear to be on someone's flight channel. Then try and locate them and work out a plan.
I carry two sets of crystals so that I may switch to another frequency. This is considered polite protocol and if everyone does it; usually no one has to stop what they are doing. Traditionally colored-code flags on the transmitter's antenna give people a visible indication of the channel you are using and saves a lot of argument or frustration.· No one here has the colored flags.· I don't know why.
If you are at home on a rainy day, obviously no one is going to be flying R/C aircraft.
For the most part, there are less really good flying days in comparison and places that are good for flight are more limited too. I use my air R/C equipment for a walking robot and having many channels is quite useful.· I believe the limit is 8 due to the chip set involved.
Regardless of who might be at fault; try to keep your own aircraft under control.
Sometimes that means not flying because someone else is messing up.
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"If you want more fiber, eat the package.· Not enough?· Eat the manual."········
Post Edited (Kramer) : 6/25/2006 12:37:24 PM GMT
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So many hobbies, So little time.......and money [noparse]:)[/noparse]
When you arrive you take the peg that matches the frequency of your Xtals and clip it onto your transmitter antenna. The flags that came with the xtals are never used. (flags or pegs can go missing and well... pegs are cheaper to replace)
(If 'your' frequncy has already been 'pegged out' you need to either switch to another set of xtals, or locate who took that peg, and either hope that he has other xtals, or that he's willing to let you use the frequency some of the time. Being a friendly bunch, it's usually no big problem. )
Also, when they have a large meet or organised event, they set up signs warning people NOT to bring toy walkie-talkies or other transmitters. They also set out buckets with the crushed remains of such items. And yes, those were found being operated in the area, 'confiscated' and crushed.
The reason toy walkie-talkies are banned is that they usually operate on the 27MHz band, and there are still RC-plane enthusiasts using that band.(I'm one of them, unfortunately. )
Seasoned RC enthusiasts switches on their receivers BEFORE the transmitter, so that they can spot if anyone has 'pegged out' the wrong frequency or are using banned equipment...
My preferred RC-sailplane is a Carl Coldberg 'Gentle Lady' which is a sedate thermal model, and you wouldn't think that it could do much damage, but the nosecone is of hard balsa, and can easily punch through the windshield on a car...
(Or a couple of ribs in a chest)
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Thanks.
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So many hobbies, So little time.......and money [noparse]:)[/noparse]
Doing it right will cost you absolutely nothing, so why not do it right? If you do it wrong, you may inadvertantly take someone else's radio controlled device and cause it to crash. What's the fun in that?
You are correct though, it won't be a problem for YOU, unless the "other guy" is bigger than you are!
Regards,
Bruce Bates
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A six or seven channel radio retuned for ground is 300$ to 400$. I already have a six channel air radio. There is no chance of interferring with someones plane because I am at least 3 miles away from the nearest flying spot and in the city.
I also have a 2 channel ground radio I might end up using because I can contol the other remote devices another way.
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So many hobbies, So little time.......and money [noparse]:)[/noparse]
Gadgetman... is your sailplane the 3 or 6 meter?
I'v the 6 meter, a futaba 8 channel transciever and a home made launcher, and it's awesome!
Last summer I made the second longest flight on our field, 4 hours and 35 minutes.
I had to land; the battery timer started beeping, so before it went into failsafe I dropped in for a 3 foot stall and rollout. That was spot on as well.
I missed the longest time by less then 20 minutes; had I reclabrated the timer for the new batteries in the reciver... Oh well, maybe this year...
More On Topic:
Using products from here : http://www.glolab.com/index.html you can make your own digital many channel reciever.
Using the encoder, a stamp (or something else on the other side ... like a propellrer or sx), take the 16 bits of data and create
255 channels of 8 bit data (or some other combination of the 16 bits of incomming data).
Feed this incomming data into your survo controller (Beau and I designed a 144 servo controller using a propeller) and you have LOTS of controll.
Using a SAFE frequency that doesn't bother anything AND... using their encoder chip, makes it almost impossible to recieve interference from others on the same frequency
Nots:
Fact: For direct servo controll via parallex's servo controller you would need 12 bits for data, leaving 4 bits for addressing.
This is very simular to the 16 channel digital recievers you see on the market now.
Theory:
You could multiplex encoders on the transmitter side (the reciever side wouldnt really matter). Just xmit the first 16 bits of data on encoder 1, switch to encoder 2 and xmit the next 16 bits of data there, switching back and fouth. The only way this will work is the servo controller must preserve the previous value until a new value is sent. The servo controllers do this, as well as it's a simple programming chore in any controller. So, with a moderate investment in hardware, you can get a reliable, 16 bits of address space with 16 bits of data. The basis of this idea is mostly visible on this page: http://www.glolab.com/encdec/gl/gl116.html
I do know there's a time domain issue where the amount of data being sent exceeds the limits of bandwidth. I haven't done any math on it yet, but I'll get there.
Again, this is only theory, and is subject to reality; I can only imagin what I could controll with 65535 addresses of 16 bit data.
I am waiting on SHMBO's permission to invest, at which point, I will be creating such a device, working out any thing I may have missed.
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Just tossing my two bits worth into the bit bucket
KK
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Only one encoder/decoder pair is needed.
There xmit/reciever set's max transfer rate is 4800 bits per second, 150 32 bit transfer per second.
Next, you don't want only 1 update per second, so that needs to get divided by the number of updates per second you want. (I'd suggest no less then 4 per second)
4 Updates per second = 37 complete 32 bit transfers. Subtract for overhead (ie building the incomming data stream, decoding and using the incoming data stream)
Overhead is hard to determin due to the vast number of ways (both hard and software) of doing things.
On the upside, I'd guess the max number of 16 bit digital channels is 32 (leaves the time periods of 5 complet transfers for over head.)
Now, if 4 updates per second is too much, and you need more channels, you can do 2 updates per second and double your channels.
Logic and instinct (with expierence) tells me not to go lower then 4 updates per second.
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Just tossing my two bits worth into the bit bucket
KK
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There are many places to buy ground-tuned multi-stick radios and they are becomming more common.
The Robot Marketplace (www.robotmarketplace.com) sells quite a few ground frequency radios of varying prices.
(Except after one of my landings, when the outer panels usually break off... Lucky that I enjoy building planes... Should probably buy a couple of the wing kits soon... )
Edit: fixed link....
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Don't visit my new website...
Post Edited (Gadgetman) : 7/21/2006 9:40:50 PM GMT
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Propeller + Hardware - extra bits for the bit bucket =· 1 Coffeeless KaosKidd
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I've only ever seen the 2 meter models, such as mine, or the motorized 'Sophisticated Lady', which also have a 2 metre wingspan.
And if there really exist a 6 meter version, where can I get it?
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Don't visit my new website...
Lets see... dating myself here... Father and I built it between 6th & 7th grade... that makes it the summer of '77 when it was built.
I'll ask my father if it was a kit or if he upscaled it. I don't know / remember. It was fun building it, that's for sure.
The wing is in three parts that fit, along with the fusalage, into the carrier. The radio set is a "black box", 8 channel.
I had to repair one of the wing sections about 2 years ago (my last crash requiring repairs); hand making each rib and spear from scratch along the way.
The new launching system should be done by the time I return home... with a little luck, I'll get a good flight in on end of august meet.
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Propeller + Hardware - extra bits for the bit bucket =· 1 Coffeeless KaosKidd
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My dad informed me it was not a Gentle Lady, but something like it. He purchased upscalled plans from someone on base, and we built it from there.
It's a stunning image of one, slightly different in the saddle and wing ends. I thogut it was. Anyway...
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Propeller + Hardware - extra bits for the bit bucket =· 1 Coffeeless KaosKidd
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I sometimes want a bigger plane, too...
(Not that I have room to store it, or time to fly it... )
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Don't visit my new website...
I have both RC airplanes and RC trucks and use interchangable controllers for both. If you live in corn fields no one will care in the slightest. If you live in the city then it depends on whats where.
I fly my airplanes and run my trucks at a small airfield that gets very little airtraffic. Yes, you can safely and effeciently use what ever you want for an rc controller.
RC Flying clubs frown rather strongly on using any airborn controllers for ground vehicles and vice versa. On the other hand there is a significant number of people like myself who don't really care about clubs because A) there aren't any around or
My point is do what works, use common sense and go for it. I strongly stress commong sense. If you are using an RC control like is used for indoor electric airplanes or vehicles that run around a gymnasium you have absolutly nothing to worry about because the signals seldom if ever go farther then 50 or 100 yards - more like 50 or 100 feet.
If you are using a contorller for a gas powere vehicle they have an effective range of about 1/4 mile. Thats about 300 or 400 yards out. My trucks start to get weak signal reception much closer then that but my airplanes will go about that far and return. (boy it sucks when there out of range and you have to chase them down.) If you suspect you are in range then checking other frequiencies is wise simply to keep the peace. Again, use common sense, lots of it and often.
Is it easiest to get a controller with interchangable crystals and swap out a few - you betchya. Do you have the money for it? Thats a different question. Do people care what you use for a controller - not one bit - unless you tell them.