Installing a Directional Antenna

A directional antenna can enforce the GSM/GPRS signal for an iMETOS which is more than 7 or 15 km away from the nearest antenna of the GSM provider. Pessl Instruments can deliver Yagi directional antennas (en.wikipedia.org/wiki/Yagi_antenna). A directional antenna can only increase the the signal strength if it is optional directed to the nearest antenna with a free line of sight. To be able to find this position you can use external devices connected to the antenna showing you the available signal strength or you can use the modem of the iMETOS. To use the iMETOS modem you have to connect the modem with the serial link cable for iMETOS to your PC. For more information on this and on the jumper settings of the serial link card please refer to Using the RS 232 Interface Card
If you connected the modem to an terminal program on your notebook the modem LED should start to blink and the modem should answer the "at you type on your notebook keyboard by "OK". ("" indicates a carriage return on your keyboard and the carriage return linefeed action on the screen of your terminal program.) The command for testing the signal strength is "at+csq". The modem will answer with "+csq: a,b". Where a is the level of the receiving signal and b is the level  for RX (sending). This will be 0 or 99 because there is no existing connection to test for it. For this reason we can only use the TX (receiving) level to set the antenna. Values for the a value will range from 0 to 31. A value of 99 is indicating an error.
Possible values for "a"
0 -113dBm or lower
1 -111dBm
2...30 -109dBm to -53dBm
31 -51dBm or higher
99 unknown or not readable

Please test and change position until you reach the best possible signal quality.




Created by heiner. Last Modification: Thursday 09 of February, 2012 12:15:13 GMT by Lena.