40 OEM4 Family Installation and Operation User Manual Rev 12Chapter 3 Installation and Set UpOnce the external oscillator has been installed, the EXTERNALCLOCK command must be issued todefine the clock model (e.g. cesium, rubidium or ovenized crystal). If the input clock rate is 5 MHz,the EXTERNALCLOCK command must be issued to change the 10 MHz default rate. For moreinformation on this command, please refer to Volume 2 of this manual.3.3.5 External Antenna LNA Power (OEM4-G2 Only)For the OEM4-G2 it is possible to supply power to the LNA of an active antenna either from theantenna port of the GPSCard itself or from an external source. The internal antenna power supply ofthe GPSCards can produce +4.50 to +5.25 VDC at up to 100 mA. This meets the needs of any ofNovAtel’s dual-frequency GPS antennas, so, in most cases, an additional LNA power supply is notrequired.If a different antenna is used whose LNA requires voltage capacity beyond what the receiver canproduce, then the external LNA power option must be utilized. This simply requires setting a voltagesupply between +12 and +30 VDC, 100 mA maximum, and connecting it to pin 40 of the 40-pinconnector on the OEM4-G2. See Appendix A for more details.In either case, the LNA power is fed to the antenna through the same coaxial cable used for the RFsignals. The internal LNA power source should be disabled using the ANTENNAPOWER command.Refer to Volume 2 of this manual for more information on this command.External LNA power is not possible with an OEM4-G2L, a FlexPak or ProPak receiver.CAUTIONNo warranty is made that the receiver will meet its performance specifications if a non-NovAtelantenna is used.3.3.6 Mounting Bracket (ProPak-G2 and ProPak-LB Only)Along with the ProPak enclosures, mounting kits have been provided to facilitate mounting thereceivers to a surface. This section provides information on how to mount the receivers.The mounting kits are not designed for use in high-dynamics or high-vibration environments.Contact NovAtel Customer Service if your application requires the ProPak to be mounted in thesetypes of environments.3.3.6.1 ProPak-G2 and ProPak-LBTo install the mounting bracket provided with the ProPak-G2 and ProPak-LB, refer to the instructionsprovided with the mounting kit. Figure 12 and Figure 13 are included to provide the dimensioninformation for the bracket.
