USDA, ARS, Northern Plains Area, 1201 Oakridge Drive, Suite 150, Fort Collins, CO 80525

70 -- DIFFERENTIAL GLOBAL POSITIONING SYSTEM Sol RFQ 27-82HW-95. Due 090195. Contact Point, write to Lee Shea, Purchasing Agent. Turn key Differential Global Positioning System (DGPS) shall be 100% compatible with existing Ashtech Ranger M12 System. Existing receivers will be used as remote units only in the post-processing operation mode. The system shall work with existing system without any type of data conversion to the Ashtech Ranger data prior to post-processing, as wellas the post-processing computer software. The DGPS (base and remote) shall be all-in-view dedicated 12-channel receivers capable of continuously tracking 12 satellites simultaneously on 12 separate and parallel channels. Loss of lock on one channel shall have no impact on the other channels. Both receivers shall be C/A code and have L1 carrier phase to achieve centimeter level position accuracy in the static operation mode via differential post-processing using the post-processing software. The new system shall have real-time differential capability; in this operating mode, position accuracies shall be less than 1 m (sub-meter). For real-time differential positions, one independent measurement shall be determined per second with no interpolation or extrapolation from previous solutions. When operating in the real-time, the base receiver as well as the remote receiver shall store the raw data for post-processing, if so desired, to improve position accuracies. System shall use existing Maxon SM-3010-H VHF transceivers for the radio data link when the system is used to obtain real-time differential position. (226)

Loren Data Corp. http://www.ld.com (SYN# 0530 19950815\70-0007.SOL)