Basic hospital communication system

I'm an undergraduate trying to figure out my final year project. I have in in mind a hospital communication system.. which connects the doctor,nurse and patients... it should also indicate in the nurse room the bed number and the ward the signal is coming from.. I intend to use a simple but intercom circuit that is based fully on transistors.. i.e RC coupled amplifier. Its kind of bulky.. when considering many wards and beds.. I need ideas on how to go about it or a better way to approach the project.:grin:

You'll need to decide several break-even points, as to which is easier (or more cost effective):

* Whether to (a) run wires to all beds, or (b) use radio waves.

* Whether to (a) install an led for every bed on the main panel (nurse's station), or (b) make a digital display showing the number of the bed and ward that is calling.

* Whether to (a) allow only one conversation at a time, or (b) permit simultaneous conversations.

* Whether to (a) have every bed alarm transmit its number to the main panel, or (b) give every bed alarm a direct connection to the main panel so it does not need to transmit its number.

* Whether to have microcontrollers involved, or whether in the main panel only or in all units, etc.

Thanks for your time and attention, using radio waves would have been preferable, but considering the cost, i will go for wires to all beds, also a digital display showing the number of bed and ward calling is preferable, it should also permit simultaneous conversations, microcontrollers will surely be involved so every bed alarm can transmit its number to the main panel. Thanks

One way would be to base the system on a telephone system (as you want use wires). A TDMF chip in every bed station could send a stream of tone pulses down the line when the "talk" button is pushed. A simple sequence controller, programmed with pins (so they can be replaced easily), can generate the code to give in essence a series of numbers. So a string of three numbers could address 999 beds. Its probabley wise to use one digit (0?) as a leading "blank" just to wake up the reception kit. So a 4 step controller would be better. At any reception station, the incoming number can be compared to a look up table and answered or ignored. You will have to consider what you do with mutiple calls (first one gets the line - remaining circuits are muted/disabled?)
Frank