Chapter 2 SPAN InstallationOEM7 SPAN Installation and Operation User Manual v4 30A conversion is required between the MMCX, MMBX or MCX connector on the OEM7receiver card and the female TNC connector on NovAtel’s GNSS antennas.NovAtel recommends using high quality coaxial cables because an impedancemismatch is possible when using lower quality cables and this produces reflectionsin the cable that increases signal loss. Although other high quality antenna cablescan be used, the performance specifications of the OEM7 receivers are warrantedonly when used with NovAtel supplied accessories.2.1.3 Mounting the GNSS AntennaThe OEM7 receiver is designed to operate with any NovAtel GNSS antenna.When installing the antenna:l Choose an antenna location with a clear view of the sky so each satellite above the horizoncan be tracked without obstruction. For more information on RF signal propagation and mul-tipath, refer to the NovAtel application note APN-008 Discussions on RF Signal Propagationand Multipath at www.novatel.com/support/.l Mount the antenna on a secure, stable structure capable of safe operation in the specificenvironment.l Ensure the antenna cannot move due to dynamics.Antenna LNA PowerNovAtel antennas and coaxial cables meet receiver RF input gain requirements. NovAtel coaxialcables are designed to introduce no more than 10 dB loss and NovAtel antennas are equippedwith built-in LNAs that provide 29 dB of gain to the satellite signal received.The power to the antenna LNA is provided through the receiver’s RF port center conductor.OEM7 receivers provide +5 VDC ±5% at a maximum of 200 mA.Antenna supply over current protection limits the LNA power.If a short circuit or other problem causes an overload of the current supplied to theantenna, the receiver hardware shuts down the power supplied to the antenna. Torestore power, power cycle the receiver. The Receiver Status word, available in theRXSTATUS log (see OEM7 Commands and Logs Reference Manual), provides moreinformation about the cause of the problem.2.1.4 Mount the IMUMount the IMU in a fixed location where the distance from the IMU to the GNSS antenna phasecenter is constant. Ensure that the orientation with respect to the vehicle and antenna is also con-stant.For attitude output to be meaningful, the IMU should be mounted such that the positive Z-axismarked on the IMU enclosure points up and the Y-axis points forward through the front of thevehicle, in the direction of track. If the IMU is not mounted in this orientation, a rotational offsetmust applied. See Rotational Offsets on page 75 for more information.
