I have a circut that need checking

[stargate3216]

Ok, its a muiltiplexer w/ counter and clock that takes a 15 pin moniter input and compresses it into 1 line to be transmited. Also, does anyone know where I could find a small, compact, and cheap AM transmiter or schmatic for one? Also, smae requirments for a reciver

Sorry the picture is small, I had to take a screenshout

 

[jsolar]

Since you are showing 15 pin digital connector and not any sort of analog signals you do not have to time multiplex in the manner you are showing. You can transmit more than one bit per symbol. You should also be doing some sort of forward error correction. It is nearly free, as long as your requirements are low. What is your Bit Error Rate (BER) allowed after error correction and what is the sample frequency. This will tell you if your AM idea is adequate. Since you have a digital ckt. you may want to make a digital AM generator. By the way, why are you restricted to AM? Do you mean simple On-OFF (OO) keying or are you amenable to multi level coding? For the AM ckt. there are many HAM radio books. For the coding the book by Lin and Costello is good, if you have a strong math background; otherwise just stick with a short block code.

You did not ask abut or show how you were going to do your sync. How will you send the clock, lock it, and recover the symbol slicer and sync to the data so you will not get mixed up as to which time slot is which pin? That is a big practical matter. You might want to pick a standard protocol.
Best Regards,
John Solar

 

[stargate3216]

I plan to use on or off for 1 or 0. Also, what fz would the clock have to run at to stay ahead of the computer?

 

[stargate3216]

Oh ya. How to keep the clocks on both ends in syn. What I plan to do is have a second transmitter that transmites the clock signal to the reciver. There actually not be a second clock, is will just run off the signal. Speaking of which, how do I take the AM (after its though the diode) and make it digital unsted of like this:
/\/\/\/\____/\/\/\/\/\/\/\/\____
(10110)
into this:
______******_______________
|******|____|***************|____

The *s are place holders because the server doesn't like my illistration.

 

[stargate3216]

Also (I keep forgeting to put things) I haven't show the recevering circute. I'll post it tomorrow also with the other 2 (the 1 that will transmit the keybroad and mouse signals and the 1 that recives them.)

 

[jsolar]

Do mean that the 15 pin connector contains the analog video information from a computer monitor? You are talking BW that you will be able to achieve with your design. You would need the clock and sync on the same modulation line. The phase shift with the multi MHz BW you need is then critical. Or are you talking about something else? If you are talking about making all the wire cnnections to your PC remote, you may end up with severe latency problems. Do have your requirements defined? That is do you have bi-directinal requirements? Do you have an error rate that is acceptable to you? If you are using a USB mouse, then you are talking several MHz and a latency you could not afford.
What are your real requirements?
John Solar

 

[stargate3216]

I have to admit I don't know. The input comes from a standand computer monitor output, and I don't know if its A or D.

 

[jsolar]

A standard monitor output contains analog signals. There are concepts out there for extending them. Sometimes with using CAT5 wiring for controlled Z. Some add a transformer for Z matching. For your keyboard and mouse, you may be talking PS/2 or USB. Both are analog. There are USB RF solutions you can purchase. If your volumes are extremely high, you might be able to beat their prices, or OEM with them. PS/2, like USB or I2C has bidirectional latency equirements that can not be met by a long integration time required by a simple AM detector.

 

[itsmoked]

jsolar you said,

For your keyboard and mouse, you may be talking PS/2 or USB. Both are analog.

You probably ment *Both are digital*

 

[stargate3216]

So its a analog circute. Ok, then I have to redesign it, but at lest it will work. I have a big queston.
How do I make this:

http://img.villagephotos.com/p/2004-11/888495/analog2.JPG

Into this:

http://img.villagephotos.com/p/2004-11/888495/Analog1.JPG

I know I need a diode first, but what do I do after that?

 

[stargate3216]

Anyother thing: where an I get a 1-16 analog demuiltiplexer?

 

[stargate3216]

Also, would this AM transmitter work well transmitting out to 250 ft?

http://img.villagephotos.com/p/2004-11/888495/transmiter.JPG

 

[Skogsgurra]

Stargate,

Do you at all know what you are trying to do? Or how to achieve at least a little part of what you think you are going to do? Your postings are pointing in wildly different directions and I think that you should start from square one; that is mastering fundamentals like Ohms Law, simple basic circuits, quite a lot of signal math etcetera before you decide what you need/want to do. This will take you at least three years - more likely five years.

Asking a lot of questions here will not help you and those that are kind enough to try to help you will only get frustrated when they realise that you cannot benefit from what they say.

Gunnar Englund

http://www.gke.org

 

[jsolar]

itsmoked,
I did mean analog. USB drivers and Rx are done with analog, since there are rise time fall time, voltage range requirements and a PLL clock recovery involved. SInce PS2 also has current sense as part of it's desing (like USB), I would consider that analog.

Stargate is correct. This is a very ambitious project. You must be doing this for a hobby, a learnign experience, or for school. Is so, taking on one small part of this might be a good place to start. If you just want to learn some electronics and are not involved in a formal education, there is the HAM radio community around the world and in many contries, the equivalent of a Radio Shack store/books.
Best Regards,
John Solar

 

[stargate3216]

1.I know a lot about electronics, its just that I make stupid mistates when I work fast, and I don't take certian things into account (like that monitor outputs are analog). What I am trying to build is a transmitter that takes a moniter ouput from my computer and transmits it to a moniter in a remote location. The reciver would take the signal and imput it is a moniter. There would be a transmitter of that end that would take the keybroad and mouse signals and tranmit them back to my computer. Basically a wireless workstation.

2.The orginial circute is the transmitter from the computer.

3.Then, I started working on the reciver. Then post with the really bad drawings of the sign wave and the analog wave were about that. How do you take the sign wave and make it into an analog wave?

4.Now, I don't know where to find a analog 1 to 16 bit demuiltiplexer. That was another queston.

5.Some responses asked how I planed to keep the multiplexer and demultiplexer in synic. I will do this by transmitting the output from the clock over a seporate transmitter (from the one that send the data). The reciver will used this signal. Again, that goes back to #3.

6.Both transmitters and both reciveres are going to be the same. The mouse only takes up 5 or 6 lines, as does the keybroad.

7.Forgive my spelling.

8.What is the Voltage requirements for the keyboard and mouse? (the moniter pluges into the wall, so its not a problem).

There it is, all layed out and explained in one post (for once). If I forgot something important (which I probably did), please tell me.

 

[jsolar]

Much clearer. Still, this is very ambitious for a digital person.

Of the 15 pins, only 5 of them do anything useful for your transmitter. So, you only have to transmit 5 signal. Those are your 3 colors, and horizontal and vertical sync. The color is impedance controlled and in the MHz bandwidth range. That will preclude you from transmitting RF without a license unless you are ISM. The TDMA switching you propose may not be the best or the simplest. You could consider matrixing the 3 colors into I/Q phase and amplitude. This may better control your phase shifting (time shifting) of the colors. But this is standard practice and nothing new. You do not have to treat all 5 signal equally in your TDMA scheme. You might want to send the sync's over digitally.

You mentioned sending the clock over a side channel. This will not solve your sync problem. At best you will have a phase locked clock, which is good, but not good enough. There are several good books on communication sync and slicers, many from Europe.

The analog mux you are asking about is quite simple and perhaps the easiest part of your system. Hittite (spelling) is one low switch vendor with the BW you want. However, this mux will drive your A/D cost very high. It is much simpler to A/D each line and digitally mux them. Eight bits each at 5 MHz is 40 Mbit per second for the color.

This might help on the 15 pins:

http://www.epanorama.net/documents/pc/monitors.html

There are many good books on the USB protocol. You might try Jan Axelson first.

http://www.lvr.com/

USB is bidirectional and is PC centric. The PC will poll your keyboard and mouse. If you use PS/2 for both you will eliminate the large overhead cost of USB.

Still PS/2 is a bi-directional serial protocol.

http://www.computer-engineering.org/ps2protocol/

You not only have to send the signal, but send or know who is doing the talking at each moment. This will be tricky in your scheme.

Power needed:
< 300 mA keyboard, mouse even less. Can be powered through your USB connection.

Is this a hobby or a learning exercise? It is much cheaper to purchase these large system solutions. I would recommend learning how to do each technology on a small project. Then when you master each one, you can approach a large project. You could read the back issues of Circuit Cellar Inc. to get good ideas on each of these topics.

Best Regards,
John Solar

 

[stargate3216]

Accually I'm doing it because I want a laptop but can't get one with the right stuff so I thought I would build a WiFi-like thing and hook it up to my computer and buy a laptop case, moniter, keyboard, and mouse, and put one side in it.

About just the 5 pins. how do I know what 5 pin I need and why is there 15 when they only need 5?

 

[stargate3216]

No more thing relating to the moniter. What size output do I need for the A/D converter? Will 8-bit work?

 

[stargate3216]

And also: do you have a website that saids what leads on the keyboard and mouse are gnd and outputs?

 

[jsolar]

WiFi is no where near enough bandwidth.

I mentioned previously that 8 bits was enough.
I gave you a web site reference previously that gives you which 5 pins are for the 3 color and 2 sync lines, which are grounds, and which are inputs to the PC and which are open.

I gave you a web site link previously that gives the PS/2 ground and signal information and a web site reference to a book that has the USB information.

WiFi does not have the BW, the latency nor the QOS (Quality of Service) for your application.
If you do not have enough money for 30 laptops and a few workstations you do not have the money for the custom HW for this project.