Integration and Testing of a Wide-Band Airport Pseudolite
The paper provides initial results of a series of flight tests conducted using the LAAS Test Prototype/Airport Pseudolite system.
The FAA's Local Area Augmentation System (LAAS)
The Federal Aviation Administration (FAA) is developing the Local Area Augmentation System (LAAS) as a public use local area differential GPS system. The LAAS is required to support all categories of precision approach navigation. The purpose of this paper is to summarize the FAA's LAAS technical activities and programme plans. First, the complementary roles of the Wide Area Augmentation System (WAAS) and LAAS are summarized. Then technical activities are discussed, including requirements, system architecture, and flight tests. The paper concludes with a summary of the FAA's plans for LAAS, including the planned schedule of major programme activities.
The Use of Pseudo‐Satellites for Improving GPS Performance
The NAVSTAR Global Positioning System has proven itself to be extremely
accurate under tests of normal operations conducted at the Yuma proving ground. During the same tests of several years ago, a special technique called Differential GPS was also evaluated and shown to have even more startling accuracies. The basic concept of Differential GPS is to have a local receiving station continuously calibrate the remaining bias in the GPS signal and transmit it to the local users. This allows aircraft, ships or land vehicles to refine their estimate of position to the last meter or two.
One technique for transmitting such a correction is to use a GPS-like transmitter itself. The exact form of the signal used may be quite significant to operations and accuracy enhancement. The “pseudo-lite” or GPS ground transmitter also provides powerful geometric leverage for the total navigation solution. A pseudo-lite will be called a PL in this paper.
This paper will address the geometric problems encountered by the current GPS satellite constellation. Simulation results will show the value of PLs to deal with both poor satellite geometry and potential satellite outages (in the event of failure).
Quantitative examples of the performance improvements are included.
This paper will also outline potential design alternatives for the PLs.