long distance communication
Matt Battle
Posts: 172
Hey guys-
How would one communicate between a computer and a robot long distance? like 1000, 5000 feet - 5, 10 miles.
Thanks,
Matt
How would one communicate between a computer and a robot long distance? like 1000, 5000 feet - 5, 10 miles.
Thanks,
Matt
Comments
For getting started, have a look at the Parallax Surelinks which will get you out to 500 to 1000 feet, in my experience.
For longer range, look at Maxstream 100 mW which I've used at 6 km ( 4 miles). For really long distance, the MAXstream 1 Watt units can get you out 20 miles or more with proper site lines and antennas.
If you're running your robot where there is Wi-Fi coverage, using a wireless receiver with the Parallax PINK module may be an option if you can live with the response time of the Internet.
Cheers
At the risk of being corrected, I believe the entire SureLink series of RF products has been discontinued from the Parallax offerings. The next comments I make are purely my own, and MAY NOT represent reality, but I seem to remember some comments to this effect.
As I remember, Parallax will be offering (under their own brand name) some longer range RF products, but I can't remember the projected announcement date. Their present involvement with the announcment of, and the presentation of, the Propeller product may well have pushed this back some. So too the recent loss of some of their long term employees, may also have put this project on "hold" for a bit.
PLEASE don't take this as gospel, unless confirmed by Parallax!
Regards,
Bruce Bates
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Edit : I should add that the thing that really makes this simple... If you purchase the dev kit, it comes with two radios and the Dev boards. Leave one radio in a Dev board and connect to computer. Connect second radio to stamp = instant communication, with no need to worry about dealing with RS232 issues, as the Dev. board connected to the computer takes care of all that.
We are using some MaxStream 9XSTREAMs (900mhz, 100mW) at the moment, as we will be launching a CanSat package about 2 miles straight (we hope!) up...but these modules can supposedly achieve 20 miles LOS with the right antenna. Maxstream also gives a 25% educational discount for the OEM modules, as well as 50% off the development kits.
Great product , and it works exactly how the data sheet claims :
"No configuration is necessary for out-of-box RF operation.
Simply feed data into one module, then the data is sent out
the other end of the wireless link."
Of course, advanced programming is possible through extensive AT commands, if you need it done.
Alohas
Post Edited (Robert@HCC) : 7/31/2006 1:09:51 PM GMT
update: I found the link to the MaxStream website.
Matt
Post Edited (Matt Battle) : 7/31/2006 1:53:17 PM GMT
Long distance comm's depends on lots of variables. Distance, frequency being used, power radiated, sensitivity of the receiver, how much money have you got, and on and on.
In your posts you've gone from 100 feet to ten miles and now around the globe. Which is it? One solution is not going to cover all bases.
As a WAG, if I was going around the world, I'd use the phone system with a low-power transceiver near the robot. The robot could be controlled wirelessly while near the tranceiver which would hook to the phone system with an auto-answer modem. At home base another modem would connect to the controller. Use Skype-out and the call is free, in North America anyway.
Cherers
Thanks for your informative responses. They are much appreciated.
That is what exactly what I want to do. I want to start out short distance, around my house, front and backyard. Then move up to a couple of thousand feet to a mile and use a webcam to interact with environment and also be able to send commands to the robot. Then down the road from that send a robot across the ocean and be able to receive data from the robot/boat on various things (wind, temp, power, etc, etc). Yea I know you are laughing at the last one. But that is my plan for the next couple of years.
Matt
Once you get into transmission and reception by radio that is more than a few 100 meters, there are a lot of regulations to comply with. And if you want to go international, a ham license in a must.
A lot of this has been developed over many many years. Try the ARRL or Amature Radio Relay League. Both short wave and satallite communication are global. Alternatively you could use Iridium satallite phone communications to relay to a home phone and by pass the Ham Radio approach. Buy you won't have the support of a global fellowship and you will be paying bucks for each and every phone call.
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"If you want more fiber, eat the package.· Not enough?· Eat the manual."········
It’s been awhile, how you been? My knowledge in amateur radio is very limited and hopefully by the end of the day it will increase by a little. I don’t remember if you told me or not but do you have your Ham Radio license? What are the steps to getting one? This is something I will most likely be using for my big robot/boat project in the future so any info will be appreciated. Thanks
-Matt
Here is one excellent place to start looking into geting a radio amateur's license in the United States:
http://www.arrl.org/
Regards,
Bruce Bates
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Thanks for the link. It looks like all I need to ace the Technician class test is to read a couple of books that ARRL recommends unless there are some other ones you recommend? I will wait about an hour or so before I order them just in case you have better suggestions. Thanks
-Matt
Check with the largest library you have near you BEFORE you buy ANYTHING! As my dear grandmother used to say "Why buy a cow when milk's so cheap!"
Regards,
Bruce Bates
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I just checked with my university and the local public library branches and no luck with those two books (most likely because they are to new. Are there any books that you have found in your local library that you recommend?
-Matt
P.S. 100th post :-D
To be truthful, I am not a radio amateur, although I've thought about getting my license for about 50 YEARS! It just seems I never set aside the appropriate time for doing it.
I can't recommend any particular books, but let me pass on a important "clue". There is a cadre of radio amatuers known as "Elmers", and they THRIVE on helping new folks get into the hobby. If you know ANY radio amateur, ask him/her if he/she knows of a local "Elmer". Let me ASSURE you, you'll be in FAT CITY! I can all but GUARANTEE IT!
Regards,
Bruce Bates
P.S. 1515th post :-)
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Be alert to the fact that the Technician license question pool, and hence any books written to that pool, changed in Jun 2006; so be careful of buying the older version of the Technician license guide--you will learn still accurate information, but it will not "match" the test you would be taking.
Daniel KB3MUN
Some study guides present the question, give you the correct answer, and tell you why the answer is correct, but don't really give lessons on the theory.
The ARRL guides that I have seen will present the material, then give the questions & answers at the end. If you get a wrong answer, go back and re-read the theory section.
In my teens I really wanted to become one and studied the exam material, but being a city boy in the 1960s, my Dad didn't want the neighbors complaining about my transmissions interferring with their newly bought color TVs. He was quite right. The other problem was where to put a 1/4 wave 20 meter or 40 meter antenna in a typical San Franciscon neighborhood. Again, the neighbors were afraid that I might start an electrical fire on our roof and void their fire insurance. Or at least cause everyone to pay a lot more insurance premiums.
I guess I was a bit of a holy terror, but everyone was quite nice about it.
The older ARRL books may actually be better. LSI has caused less and less teaching of the fundamentals of radio contruction. Now you just buy an IC and assemble a board. PLLs and VCOs have eliminated the need to build your own capacitors or coils. Maybe you just by a whole unit. The Morse Code requirement is no longer a must and you can get into talking to people right away.
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"If you want more fiber, eat the package.· Not enough?· Eat the manual."········
You can purchase the Tech study guide from the ARRL web site. Most ham RC control is done in the 6m band, the transceiver units sold by Parallax in fact fall in the 70cm ham band, they must get away with that because of the low power of the units. BUT as a ham you would be able to hack those to a higher power say 5 watts if you wish and get a much larger range. 5 watts is what most hand held ham radio units run at. I have my Extra class Ham license, the above mentioned about the Morse Code is correct for the Tech license, if you wish to go higher though ie. General or Extra class then a 5 wpm Morse Code is still required, though the FCC has been talking about dropping that requirement for all classes. The best part of being a Ham though with what you are wanting to do, it is legal for you to tamper and hack FCC certified radio equipment such as the Parallax Transceiver kits. Normally all that is required, when doing telecommand of a unit within the ham band is that your call sign is displayed at the unit ie PC doing or giving the commands. Try looking in your local area, to see if any Ham clubs exsist, they will have a VE team that do local testing, and normally even have the study guides you could purchase from them.
Patrick
Post Edited (KE5EBS) : 8/2/2006 12:47:56 PM GMT
·
Sorry about not responding and what not in the last day and a half.· my internet connection was messed up.· I have thought of some goal(s) to accomplish·for the next 3 to 4 years.· Tell me if they seem reasonable to accomplish and makes sense to do in this order.
·
1. Short distance communication (1 to· 100 feet)
·
Goals (6 months to 1 year)
1. Two-way communication between home base and “robot” (i.e. send and receive data).
2. Interact with the environment (i.e. collision detection: “bumpers”, sonar or IR, “tilt”
3. Basic Stamp Programming(C, C++, or C#)
4.
5.
·
2. Medium to long distance communication (1,000 to 10-15 miles) (improving on the first set of goals)
·
Goals (1 to 2 years)
1. Receive video
2. Receive live data from sensors (i.e. GPS, speed, direction, battery, temp, etc, etc)
3. Control “robot” from base (i.e. joystick)
4.
5.
·
3. Very long distance communication (50 miles to “as far as I can go”[noparse];)[/noparse] (improving on the last two set of goals)
·
Goals (2 to 3 years)
1. Satellite communication
2. Testing autonomous functions (i.e. course correction, speed correction, switching between power modes, satellite following antenna, etc, etc)
3.
4.
5.
·
I might add or remove tasks from goals. This is why I left some numbers.· If you have any suggestions or questions please post them.
·
·
Hey KE5EBS,
·
Are you telling me even at the tech level I can do a lot of hacking and what not?· Wow, that is awesome.· I always thought you had to go through like a million classes.· 20+ cert. before you can do anything.
·
Thanks everybody,
Matt
That is what I am saying, you can as a Tech hack until your heart is content, provided you stay within your band limits which for the most part is VHF/UHF only. You are limited to the amount of wattage you can put out on a radio as a Tech but it is way more then you will ever use on a Boe-Bot
Good Luck
You were talking about how HF can reach overseas with the right power; does that include the use of Repeaters? I am asking because I wouldn’t mind using satellites to communicate with my robot/boat. It would be a challenge and a great learning experience but at the same time a lot more work to do so. What is your opinion on this? Thanks
Regards,
Matt
P.S. I am taking it that KE5EBS is your call sign
oh and yes KE5EBS is my call sign
Wow, you’re telling me that with a HF rig with say 100w output and a directional antenna, I can communicate with my robot/boat that is crossing the Atlantic Ocean (Please don’t laugh anybody, I want to do this one day)? That is not bad.
Regards,
Matt
One thing that you want to consider is to maintain a good understanding of the FCC regulations for the Amateur Service. There is a lot that you can do, but you can't do "just anything."
If you browse around the ARRL website, you'll find plenty of books on RF theory, design, FCC regs, etc. Also, it is worth joining the ARRL, since you will have access to their articles, and will receive QST magazine as a benefit.
Other stes that you might want to look at:
AMSAT (The Radio Amateur Satellite Corporation): www.amsat.org
TAPR (Tuscon Amateur Packet Radio): www.tapr.org
AMSAT deals with amateur satellites, TAPR does a lot of work with GPS tracking & reporting.
Kevin,
Thanks for your opinion about using HF and the antenna size. Also thanks for the links to the other sites. I did a little browsing on AMSAT site but didn’t know about TAPR. I will take a gander at them both.
Regards,
Matt
VHF and above has its' considerations, too, but it would probably be easier to implement.
Please correct me if I'm wrong here, but VHF has that awful line-of-sight limitation, doesn't it?
I am not a ham, but I've used commercial frequencies in business and pleasure environments. I've used both HF and VHF (marine use only) and although the HF would "punch" anywhere you needed it too, the VHF set·was such a quiet, and easily squelchable (new word!) radio that it was a sheer pleasure to use.
With the AM-HF set, if there was "weather" anywhere around, you had to keep your ear to the speaker to make sure you didn't lose any content. I can only presume that translates, in data transmission terms, to a need for data integrity checking - which isn't a bad idea regardless of the RF·format.
Regards,
Bruce Bates
With the VHF and above, as long as you have enough power and a clear enough line of sight, it shouldn't be a problen to communicate.
I know that people have worked (contacted) the International Space Station & Space Shuttle with as little as 5-watts on 2 meters. I've made an approximately 40-mile contact into a repeater from a dorm rooftop with 2-watts on 2 meters.