Sierra Wireless DART 200 CDPD Modem - Manual (Page 93)

DART 200 CDPD Modem User’s Guide 7 Vehicle Installation Considerations
PN1197-00 Revision 1.0 7-3
In this situation, separate the antennas as far as possible and then run a
field test when the two-way radio is also being used. If the DART 200
works satisfactorily you do not have a problem, but if it does not filtering
is required. A bandpass filter on the two-way radio’s transmitter output
eliminates harmonics that can interfere with the cellular frequencies. A
band reject filter on the DART 200’s input, centered on the two-way
radio’s base frequency, provides signal attenuation at that frequency to
help prevent de-sensing the DART 200’s Radio Frequency (RF)
circuitry: either, or both can be required. The calculation to determine the
filtering usually requires an RF engineer.
If you do not have the option to field test, then the theoretical calculation
approach is your only option.