I MIGRATED THIS DISCUSSION FROM WIRELESS - THIS EXPLAINS THE FOCUS OF THE FIRST PAGE
THIS IS the BEST (imo) Telemetry module out there currently !!!
This is a radio module that's small, fast, inexpensive, powerful, US legal 900mhz (and others). It has adjustable power output, spread spectrum frequency hopping, encryption, and TONNNNSS of other features. Also, at only $70 a pop (from digikey.com), they are Very easy on the wallet! especially compared to the digi xtend radio that is near $200 per. ouch!
I have three of RFM's DNT900 radios, and am working on Arduino programming to set-up and control them. I am working with the friendly tech at RFM who supports their products, and we are discussing a few more details about the needs of the radio. I intend to post more as I get farther along, and create a code block that people can copy-paste into their program to utilize this fantastic radio.
It has been a month, and I have just recently set up the architecture and got communication between two radios. I have them set to 200kb/s RF over air, allowing for up to 1watt of transmission power.
Still to go - i need to set up radio access lists, add 128 bit encryption, and adjust baud rate.
oh, and clean up the code! messy
After many months of doing nothing, I got a bug and started working on this again
Prototype is at the board shop - parts are ordered!!
CHECK IT OUT!!!! :-D
^^ ^^ ^^^ ^^^ ^^^ ^^^
I have been dabbling in a little board design / layout. Currently, I have two piggyback boards made up. They plug in atop an arduino Mega.
One acts as the basestation
This has a DNT900 radio, a Maxim chip to allow for a special type of controller (more info later), 5volt (3 amp) and 3.3 volt power supplies. The 5volt PS has an input range from 7-40 volts, and replaces the arduino 5v ps. This allows for a single power supply to power all components, and be able to provide current in excess of the peak requirements of the radio and the controllers power bus. It also has a plug for status LED's if desired. It is the same size as the mega board. There's still room on the board for future additions
The other acts as the Remote.
This piggy-back module includes the remote DNT900 radio, plugs for 10 servos, plugs for status LED's, and external power plugs. It also has pin connections for Remzibi OSD, and CHRobotics Extended Kalman filtered CHR-6dm 9dof. I am extremely impressed with these two devices. Integrating them gives us filtered XYZ positional data, GPS information, on screen display, 3.3 power supply. I have also added a SCP1000 for barometric and temperature readings.
This board requires twin 5volt supplies, and a 12v. - I am trying to fit them into the PCB, but its tough. Also, switching buck controllers are noisy - so i need to make sure they wont interfere with other electronics.
- one 5v will power the board, sensors, radio, and video transmission radio.
- the other 5v is dedicated to powering the servos. They share a common ground - arduino will be able to switch on/off to save power if you are landed
- a 12v power supply will also be added for the camera - arduino will be able to switch on/off to save power
- power input will accept between 12 volts and 40 volts, for a variety of battery setups!
http://www.happykillmore.com/Software/Faq.asp << REMZIBI OSD
http://www.chrobotics.com/index.php?main_page=product_info&prod... << CHRobotics
OK so its been a while since ive updated - but ive been working on a few other secret ideas for this muhahaha
so far so good - should be a really new approach that no one on these forums has taken!
That aside - radios are 100% operational. Full variables for data, and parsing on both sides. Therefore you can spit control data at it, and it prints it on the other side... at the same time the remote can be sending flight data and the base station can be monitoring stats.
I'm going back into my cave now... lots to do with school etc, but i will continue progress on this project! hopefully get it all stuck to a PCB one day - which would mate to a mega, or something similar!
I just switched to Elec. Engineering at the U of I !! ...agh, my true calling!
This is quite cool.
As of this morning...
I now have authentication lists based on the units MAC addresses, and 128 bit AES encryption enabled.
an exclusive & secure connection that hops frequencies, and is spread spectrum - very nice indeed! that means it will be very tough to sniff and interfere with your wireless control. It will also be more resilient to the environment around it
At the lowest power level (1mW), I was able to transmit from the far south basement corner to the far upper north corner of the 2nd floor. Pretty good i think - especially considering the duct work, walls, and floors separating the radios. I'm also using a crappy, made-in-china, throw-away, 1/4 wave-lenth antenna on both units. The baud is currently set to 115200 b/s.
Next on the list...
- construction of a semi-directional antenna
- reading back stats from the radio such as signal delay, and adjusting the power level accordingly
does anyone know of an efficient way to parse hex words? im newbie