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Author Topic: Help finding and long range communication device  (Read 2407 times)

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Offline bldavisTopic starter

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Help finding and long range communication device
« on: December 03, 2008, 05:02:14 AM »
 ??? i have a problem, I am comming close to the completion of the control system for my guided rocket, but I have an issue! I need to know if there is a schematics for a long range serial modm that is not going to weigh or cost too much. I want to be able to locate the rocket if there is a guidance problem and want a real time connection or very short delay to transmit location data back to a remote location, line of sight could work but not preferred. also i would like a platform that could support the data to moniter the system and deploy recovery devices if there is a system failure. I have looked and I have not turned up anything that I think that will be useful or usable. so I thought that I would ask! I was looking at HF transievers, but the range is log i think, is there a circuit schematic that would be able to amplify the signal to extend the range? i thought that might be an option but i have not had the time to fully explore it, any suggestions?  :'(
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Offline Admin

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Re: Help finding and long range communication device
« Reply #1 on: December 04, 2008, 10:17:57 PM »
Whats your desired range and baud rate?

Offline bldavisTopic starter

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Re: Help finding and long range communication device
« Reply #2 on: December 06, 2008, 08:40:18 PM »
I don't know what this desired baud rate would be right now i am only trying to send location data to include altitude, i would like to add some other infomation such as G's and maybe speed. However, the most important thing is location from a GPS unit - and they range in baud, this is my insurance policy for recovery of my rocket, 5 miles would be the longest distance, but i would like to learn from this to use in my UAV which will have a Line of sight connection and less than 20 miles, i have found the following for use in the UAV - but i don't know what to calculate or how to calculate the range if there are obsticales in the path of the wave - any insight on this?

any way to ball park the figure?

here's the linke to the chip that i think that i'll be attempting to use unless you can lead me in a more correct direction!

http://www.digi.com/products/wireless/point-multipoint/xstream-modulespecs.jsp

also if possible i would like to find a more cost effective chip - thanks for the replay and the information
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Re: Help finding and long range communication device
« Reply #3 on: December 13, 2008, 08:22:21 AM »
The only solution I can think of: GPS enabled cell phone launched inside the rocket.

You write a program for it to SMS you it's GPS coordinates at a set point in time.

You won't find any transmitter that you can fit in a rocket to give you 5 miles of range with obstacles blocking transmission . . . to my knowledge . . .

Offline bldavisTopic starter

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Re: Help finding and long range communication device
« Reply #4 on: December 29, 2008, 10:08:58 PM »
thanks fo the reply and sorry for the delay, i have been working on this issue but i still have the same problem, i have also thought about this "Phone or GPS launch and there will be a GPS unit in a later unit but here is my issue, while this will work in the "city" or where ever i can reach a signal tower but there are several launches a year that are out of range of cell towers, and while most of them don't have anything in the path of the rocket there are those where situations that there is some sort of obstical in the way..... Did you get the oppertunity to look at the xstream? they state 40 mile range what do you suppose that the range would be with a something in the way? plus....sms texting and service is an additional change that I really don't want to take on for a toy project! Thanks once again for all of the assistance!
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Offline dunk

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Re: Help finding and long range communication device
« Reply #5 on: December 30, 2008, 06:05:11 AM »
Quote
they state 40 mile range what do you suppose that the range would be with a something in the way?
the XStream website states """Indoor/Urban range: Up to 1500 ft (450 m)""" so that would be your worst case scenario.

i presume the non LOS issues arise when your launch site is out of sight of the bunker where you sit?
what about using several of these modules to relay the signal to the launch site?
look at some of the XBee mesh modules for this as i *think* they can be used as repeaters with little extra work.

lower frequencies will stand up to objects in the way better than high frequencies but at a cost of lower datarates.
search DigiKey for low frequency RF modules.

the only other thing i can think of is build a directional antenna to improve range. obviously you would need to track the rocket with the antenna.
i know there are lots of instructions for 2.4GHz directional antenna on the internet from people trying to improve WiFi range but at 900MHz you might need to buy a book on the subject.

the only other option i can think of is getting yourself a Ham radio licence so you are not bound by maximum power levels (or be a rebel and ignore the restrictions) and look into adding an RF amplifier to an existing RF module.


dunk.

Offline airman00

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Re: Help finding and long range communication device
« Reply #6 on: December 30, 2008, 06:16:15 PM »
didn't want to stretch into two topics , but I guess I'll have to
and look into adding an RF amplifier to an existing RF module.
Can you provide any more details about an RF amplifier? Will it work on ANY RF module?
Check out the Roboduino, Arduino-compatible board!


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Offline madchimp

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Re: Help finding and long range communication device
« Reply #7 on: December 30, 2008, 09:25:24 PM »
how big is your rocket and how much do you want to spend?  ;)
https://buy.garmin.com/shop/shop.do?cID=209&pID=8576#featureTab
It looks like you might be able to fit that into a larger rocket especially if you remove the case. Of course without modification it's only a tracking solution but it will point you right to your rocket.

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Re: Help finding and long range communication device
« Reply #8 on: January 09, 2009, 04:39:23 AM »
Quote
the only other option i can think of is getting yourself a Ham radio licence so you are not bound by maximum power levels (or be a rebel and ignore the restrictions) and look into adding an RF amplifier to an existing RF module.
I got a license, but never actually needed it.

There is a provision that says you can use strong signals on the condition that they are short lived, not malevolent, and doesn't interfere with emergency services. An experiment is perfectly ok, but a full product for sale wouldn't be.

Basically, your project is experimental and can fit within this provision.

 


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