Hmmmm. I have pics of the schematic here somewhere.
It took me MONTHS to find the information. Apparently
it is illegal to modify phones (FCC), but I don't see why
more people don't use cordless phones ($0.50 at a
thrift store) for wireless data transformer.
I will look for the schematic.
You have your PC's modem connected to the cordless
phone base-station. Your robot needs a modem (has to
to de-modulate the signal), and this modem needs
to connect to the cordless handset.
This involves cutting open the phone, cutting the
ground and signal wires from the earpiece and
microphone, soldering leads to those spots, and
routing them to the small circuit you have to build.
The circuit is powered by a 9-volt battery, and
has a standard RJ ??11?? phone cord coming from
it. You plug this into the modem on your robot.
until I find the schematic, you'll need to find:
2 "telephone" transformers. I don't know what
the specs are, but transformers from:
will work. They are small, about 3/4" by
2 pots, 2 transformers, 9 volt, and a telephone
cord is all you need.
The circuit takes the MIC and EAR signals
from the handset and combines them
into one signal line.
The pots are used to tune the circuit. You
leave the earpiece on while you
are tuning, and you can tune out the static.
This setup is very sensitive to noise from
electric motors. I do not know how to
eliminate the noise. Seperate power
supply didn't seem to help.
But it is cheap, and easy.