The problems of a beginner
First, let's say that I have the following problem because of
the robot car, I am building. I ain't got much
time left and I really need your help !
(erikyyy at erikyyy dot de) Please send me some mail, if you have any suggestions !
OK. I have a Computer that stands in the edge of a room, another computer is driving around on some
kind of car. The maximum distance is 80 meters (radius, not diameter). Each computer carries the same
kind of equipment for communicating. (it is shown below). I want to have IP traffic. I use
Linux 2.0.29 on a 386DX computer
MY PROBLEMS:
- I ain't got no antennas. (I'd like to have some primitive self-made things that are limitated to
80 meters... (How do I build them ???)
- I absolutely don't know how to configure linux for this radio IP stuff. (My knowledge is limitated
to ethernets and telephone modem based IP networks)
OK, now WHAT have I bought ??? (Everything shown here exists twice). The parts should work together
because they were sold in a set.
This is the CB radio thing. (Technical specification follows)
The following pictures show the radio modem (Technical specification follows)
The manual says to do the following: (The open end of the modem shall directly be plugged into the
computers serial interface)
Technical documentation of the CB radio thing (copied from it's manual)
RECEIVER
Channels .................................................. 40 FM
Frequency coverage ......................... 26.965 to 27.405 MHz
Sensitivity .................. 0.001 mV or better for 20 dB SINAD
Adjacent Channel Rejection .... 60 dB at 10 KHz; 70 dB for 20 KHz
Intermediate Frequency ........ 1st IF=10.695 Mhz; 2nd IF=455 KHz
Audio Output Power ................................ 4.5 watts max
Frequency Response -6dB ............................. 450-2500 Hz
Cross Modulation ................................. 60dB or better
Squelch ......................... Adjustable from 0.0012mV to 1mV
TRANSMITTER
Frequency coverage ......................... 26.965 to 27.405 MHz
Output .............................................. 4 watts max
Type of modulation ........................................... FM
Max Deviation ........................................ +- 1.8 KHz
Spurious Radiation .............................. 62 dB or better
Frequency Tolerance .......................... better than 0.002%
Antenna Impendance ....................................... 50 Ohm
Current Drain (13.8V) .................................. 1.3 Amps
Dimensions ........................................ 124x38x190 mm
Weight .................................................. 800 Gr.
PUBLIC ADRESS
Output power (RL4 Ohm) ................................. 4.5W max
10% THD Output (RL4 Ohm) .................................. 3.5 W
Microphone sensitivity for 4W PA ... 12mV (at 1 KHz) output power
Frequency response (-6dB) ........................ 450 Hz-2500 Hz
Power requirements ........ 12-16V DC positive or negative ground
"Technical documentation" of the radio modem (no manual exists)
The catalogue sais that this thing is a radio modem of 1200 baud.
it also sais, that it does the "AX.25" protocoll, and multiconnect-mode.
a file on the disc sais:
Usage of the RS 232. (Caution ! Unusual usage !!)
Signal 25pin 9pin
DTR - 20 - 4 - Transmitting data
RTS - 4 - 7 - PTT
CTS - 5 - 8 - Receiving data
GND - 7 - 5 - Ground
PLEASE help me !!!! I can't even start to play around myself, because I ain't got some antennas !
So The Thing of maximal priority is the building of 2 antennas that do a maximum of 80 meters !
