Wifi and 3G signals can influence each other - when the same antenna is used for both - if there is no good filtering before the LNA of the receiver (when Wifi transmits during 3G/4G reception).
(for technical details, see this link: radio-electronics.com/info/r … ocking.php)
So do the Sierra Wireless 4G modules (MC73xx) have appropriate filtering against WiFi signals?
There is no filtering mechanism against Wi-Fi signal… but if the module is placed near the Wi-Fi receiver then there is a chance that the signal may interfere the 3G signal.
this is all time a Stupid idea.
3G Use 800Mhz/ 900Mhz/ 1800Mhz
Not for a train, when the antenna is expensive (±200€) and the installation costs are high.
So we use a combi-antenna, and also a diplexer with +50dB filter. This should be ok for the desensitisation.