My first attempt at Design - HELP NEEDED!

[electroniks]

Ok, here it is, my first attempt! Although it may be a little too much for a beginner but if I can accomplish this I am way ahead...

So... I decided that I want to build a 1 byte interval transmitter and receiver.
I thought about it for a while and I think this is a very good attempt at learning many things at the same time.

Description:
- I want to transmit 1 Byte of data (hard coded (for now!)) each 10 seconds.
- I want to receive that 1 byte of data and read it via the parallel port of the computer.

My basic diagram is as follows: (any suggestions?)

Transmitter:
0/7-(hard coded bits)---[MUX]--[TIMER]--[D/A]---[Transmitter]--[antenna]

Receiver:


[antenna]----[Receiver]----[A/D]-----[DEMUX]--0/7 lines--[PC PARALLEL PORT]

I know how to interface to the computer so I don't need any help on that for now.
I just want to if my design is logical and/or if I am missing any major components.
Also, I want the range to be less than 10 meters but I don't want to use a standard like 802.11b or anything like that.
Which standard (or if any) should I think about and what frequency (more importantly)
The goal is to keep it simple and functional and learn something from it!

I need lots of help on this so please be gentle on the criticisms though very much appreciated.

I just found out that we have Orcad 10.5 available at my workplace, so I installed it and played with it a bit. Does anyone have experience with that and how can I use it for this project?

Thank you very much.

 

[Nigel Goodwin]

I suggest you try looking at how RF comms is done, or even telephone comms, give particular thought to why you have a modem to connect through!.

I also suggest you look at micro-controllers, try my tutorials which do pretty well exactly what you need!. I would also suggest STRONGLY that you use licence free radio modules.

 

[electroniks]

I suggest you try looking at how RF comms is done, or even telephone comms, give particular thought to why you have a modem to connect through!.

I also suggest you look at micro-controllers, try my tutorials which do pretty well exactly what you need!. I would also suggest STRONGLY that you use licence free radio modules.

I know how modems work. I don't want it to be that complicated, i mean I;m not worrying about quality of service right now so I don't need any hand-shacking, byte encoding, encapsulating, checksums,... and all that stuff.

I just want to be able to transmit a byte over some interval and then receive it, it don't matter if the quality is bad and full of noise or even partially received, my goal here is mainly learning the steps in design.

I rather not get into the micro-controllers since I'm not doing the complex byte encoding stuff.

What I appreciate is a feedback about the little diagram that I had or some help on how to make it work or some help on how to use Orcad tools to build this thing and analyze it. Of course your related experiences would be much much appreciated.

Thank you.

 

[Nigel Goodwin]

I know how modems work. I don't want it to be that complicated, i mean I;m not worrying about quality of service right now so I don't need any hand-shacking, byte encoding, encapsulating, checksums,... and all that stuff.

All the terms you mentioned aren't anything to do with a 'modem' (MODulator/DEModulator) as such, but are facilities often built in the same box for telephone purposes.

I just want to be able to transmit a byte over some interval and then receive it, it don't matter if the quality is bad and full of noise or even partially received, my goal here is mainly learning the steps in design.

A modem is a device to send digital data over an audio path, such as phone lines, radio, IR etc. You can't just bung an analogue DC voltage down a phone line (and even less so an RF link).

I rather not get into the micro-controllers since I'm not doing the complex byte encoding stuff.

No 'complex byte encoding stuff' required, you're not trying to build a 56Kbaud phone modem. If you don't use micro-controllers you're seriously increasing the difficulty and complexity.

What I appreciate is a feedback about the little diagram that I had or some help on how to make it work or some help on how to use Orcad tools to build this thing and analyze it. Of course your related experiences would be much much appreciated.

Harsh, but! - start again, the scheme as drawn isn't workable.

 

[motion]

I think you missed a samll item in your block diagram.

Transmitter:
0/7-(hard coded bits)---[MUX]--[TIMER]--[D/A]---[Modulator]---[Transmitter]--[antenna]

Receiver:
[antenna]----[Receiver]----[Demodulator]----[A/D]-----[DEMUX]--0/7 lines--[PC PARALLEL PORT]

 

[akg]

My basic diagram is as follows: (any suggestions?)

Transmitter:
0/7-(hard coded bits)---[MUX]--[TIMER]--[D/A]---[Transmitter]--[antenna]

Receiver:


[antenna]----[Receiver]----[A/D]-----[DEMUX]--0/7 lines--[PC PARALLEL PORT]

but how will u synchronize the Tx and Rx (ur not transmitting the clock) . so my suggestion - replace the dac with a tone generator which generates two tones for 1 and 0 , and the adc with tone detector (lm567) (or filter + addln things) . Remember the will speed of transmission will be very low, but i think u'll get what U want .