OEM638 Technical Specifications
Appendix E
OEM6 Family Installation and Operation User Manual Rev 12
189
NovAtel and the OEM638 development team have put significant effort into mitigating RF interference on the
GNSS card itself. However, if an emission (fundamental or harmonic) from equipment co-located with the
GNSS receiver or antenna falls into one of these bands, there are a few things that integrators can do to
ensure good system performance:
•
Place radio transmitters and their associated antennas at least one meter from the GNSS antenna
and OEM638 card (for example, a cellular radio antenna).
•
Provision for RF shielding over all high-speed digital logic circuitry (even if the design meets the
required emissions regulations). A CPU operating at 400 MHz will produce an emission at 1200 MHz
(3
rd
harmonic) and another at 1600 MHz (4
th
harmonic)—the emissions may be strong enough to
affect the GNSS system’s performance as both signals are very close to (or inside of) the GNSS
reserved spectrum. Similar provisions should be made for any RF circuitry near the GNSS receiver
or antenna.
•
Run the OEM638 coaxial RF cable away from high speed digital logic, other radio sections and high
current nets (as in switching power supplies).
