Radio-modem control

[JamesNichols]

I'm building hardware to send and receive radio waves that contain information. It's like wifi. My question here is that I need to see some guides to know how to send the information throught the device. I mean, the code and the theory about sending and receiving information throught the device.

[Doogle]

What sort of device (ie Make and Model) ?

[JamesNichols]

I'm building the device, I haven't bought the hardware. Some references like books, websites or advices from members of this forum will be useful.

[CVMichael]

Post the schematic of what you have until now.

To send the radio it's obviously analog, but do you have anything to convert analog to digital and the other way around ? or are you using transceivers ?
Are microcontrollers involved in your design ?

You need to give us more info to help you.

[JamesNichols]

here you have the specifications:
http://freenrg.info/Physics/Scalar_V...ransmitter.htm

I want to connect the transmitter to the RS232 port to send information and to receive the information I want to use an AM receiver. So, the AM receiver will be connected to the usb port. I make this combination since I don't know how to make an antenna to receive and send information (bidirectional).

[CVMichael]

Hi JamesNichols,

That design is really bad for sending digital data, let me explain why?
The signal is a 600Hz tone. In order to detect that tone you probably need about 10 pulses (of the 600) to know if you got a "bit", so this means 600/10 equals 60 bits per second. Now you have to send the data in packets, each packet has a header of a few bits. Depends on your design, but lets say it takes 10 bits for the header, so you are left with 50 bits of data. That is 50 bits per second!!!

Now here are the other problems:
That is only the transmitter, now you need something that receives the signal an understand that signal. I am not very good with analog stuff, but I think you need some kind of filter to make the 600HZ signal into 1's an 0's bits. Then something else (like a microcontroller) to take those 60 bits (including header) and convert them to the signal (bytes) that goes to your RS232.
Also, you have to do the same thing for the transmitter. You have to take the data (bytes) from the RS232 and convert those to the 60 bits (header + data), and that is done with a microcontroller also.

I don't know what is your programming & electronics level, but (based on your question) I think this is too advanced for you.

To make it easier I suggest you buy 2 transceivers modules, here are some that might work for you: http://www.robotshop.com/ca/general-...telemetry.html
I got this one: http://www.robotshop.com/ca/active-r...-module-3.html
This connects directly to your computer, and then you just have to make a program connect to the COMM port and start sending or receiving data.

Since your question is more about electronics than programming, I suggest you post your question here:
http://forum.allaboutcircuits.com/index.php

[JamesNichols]

Thank you very much CVMichael for the useful answer.
I was looking a way to send data from a car to a home computer. I was planning to send some data like kilometer made in a day, amount of charge remaining in the battery, etc... to a computer at home that is able to connect to the internet and send the information to a database. But this is about electronics, of course.

This connects directly to your computer, and then you just have to make a program connect to the COMM port and start sending or receiving data.

Have you any example in VB6 to see how it's done? as you know I have a beginner level in electronics and programming, but I learn fast. Can it be done with this:
http://www.thaiio.com/prog-cgi/0002_serial.htm ?

[CVMichael]

Did you find out how to read all that info from the car yet? Like how to read the odometer?
This is the only thing useful I could find: http://www.randomwisdom.com/2007/10/...icrocontroller

The code in link you posted is made for "Interfacing for HardwareS systems" (whatever that is...), but it is a good starting point to understand how the COMM control works.

First do all the electronics, find out how to read the data, how to send the data (probably with a microcontroller and transceiver), and the receiver (in your home).

You are still FAR away from doing any programming for the computer...

The most difficult part (I think), it will be to send the data through the wireless connection. For that the only way I can think of is to use microcontroller(s), because you need to convert that information, for example the analog reading from the battery (the battery voltage), the odometer (I have no idea how to read that, and what kind of signal it is), or other things you want to read. A microcontroller has many inputs and outputs, (a few analog, and most digital, depends on the microcontroller).

And by the way, if you have to use microcontrollers, then you have to do the programming (for the microcontroller) in lower level programming. The most common programming languages for microcontrollers are: ASM, C, Basic, and Pascal.
I program microcontrollers in C... more precisely, I use mikroC, this is their website: http://www.mikroe.com/ and this is their forum: http://www.mikroe.com/forum/

That was about the programming language, then you have to choose what type of microcontroller you want to do this in. Your choices are: PIC, Arduino or AVR (there are others, but these are the popular ones). I use PIC...

What I can quickly tell about the differences between PIC and Arduino (I don't know about AVR), is the the PIC compilers (in general) are expensive, while Arduino is FREE. PIC is for more advanced users, Arduino is for beginners. But this does not mean you have to start with Arduino first and then switch to PIC. I started to directly with PIC, for example, and when I tried Arduino, I did not like it...

Anyways, everything I told you, you have to research MUCH MORE !!!!

Post on the electronics forum, probably they will help you decide what ways to go, and maybe you can do it without microcontrollers, but from what you said until now, I think that is the only way...

[Doogle]

You may be interested in looking at the Microchip web site, especially here http://www.microchipdirect.com/Produ...words=DV164102

[JamesNichols]

thanks to all, I will start with more simple circuit and program.

[dbasnett]

See this device

http://www.matrixmultimedia.com/prod...433&PHPSESSID=

Matrix makes a system that uses a building blocks approach to designing systems. I currently am designing a RS232 trainer that uses the EB006 as a base and allows the user to add relays, keypads, light detecting resistors, and simple switches. The even make boards that support CAN and LIN. As I am in the US I buy their products from

http://microcontrollershop.com/default.php?cPath=165