Campbell Scientific LoggerNet Datalogger Support Software - Manual (Page 474)

Section 14. Troubleshooting Guide
between –95 and –115 dBm which is below the power limit for good data
transmission.
Similarly, if a 10 dBm attenuation pad is inserted in the link and the radio
subsequently will not detect the signal, the actual signal power is between –105
and –115 dBm. In this case, the signal power is far below the power limit.
Attenuation Pads
(10 - 20 dB)
Radio
Programmable
Scanner
To test the power being received by a radio over an RF link, disconnect the
radio from the antenna and insert the programmable scanner as shown in the
figure above. Program the scanner to the radio frequency and adjust the
squelch control until ambient RF noise is just cut out. This level will normally
be around –110 to –115 dBm. The scanner is now ready to conduct the test.
If you are using a data radio that does not have a transmit button
built in, you can easily build a push to transmit button from the
documentation of the radio/RF modem interface connector. There
will be one pin that when pulled high or pulled low will initiate
radio communication. See the radio documentation to identify this
pin. Connect a momentary push-button to either raise or ground
that pin. Always make sure that the antenna is connected to
the radio before attempting to transmit. Serious damage to the
radio can occur if transmitting without an antenna.
First, test the sub-link of the base station to the first repeater or field station.
Initially treat the base station as the transmitting station and the first field or
repeater station as the receiving station. Disconnect the radio’s multicolored
cable from the RF modem. To start the test, have the person at the base station
initiate a radio transmission. When the radio transmission is received, if
squelch is broken, you will hear it on the speaker of the scanner. If you don’t
hear the radio transmission, the signal is getting lost in the ambient noise and
NOTE
14-12