how to drive remote speaker & mic ?

[bulerias1]

Hi,
i have to design a main board,that has to drive voice chanell (coming from phone) to remote speaker and Mic for up to 100meter.the solution must be cheap as possible.
does anyone knows how to do that?
what kind of driver should be used?
simplex or duplex tx\rx?
what about feedback?
any help will be highly appriciated...
bulerias

 

[djalli]

with wire or wireless?

 

[radiohead]

Wired is the cheapest solution. As telephone requires duplex you will need two twisted pairs, on for RX and one for TX (telephone cable will do). It is possible to multiplex RX and TX on one twisted pair but that would only add to your cost. Drive TX differentially and receive RX differentially. This is to block interfering signals that appear on your cables as common mode signal.

A good solution can be to use a ADSL driver/receiver pair, like the MAX4363. Perhaps the chip is a little overspecified to this purpose, but it's good and cheap, so what do you need more? If the ADSL driver/receiver gain is not enough, you can add some gain stages on the main board.

It's jsut an idea!

 

[bulerias1]

thanks guys.
the point is to do it very low cost.so of course wireless is not an option.
you can look on my problem like this:
i have a voice source (chip with recordered messages),and i need to
spread this voice on wires ,up to couple of dozens of meters.

the adsl driver seems to be overdesign solution.we're talking here about
0 - 4Khz Bandwidth.

so it seems that i have to work tx\rx separatly,differential...
what else do i need?
thanks,for your help
bulerias