Simulator to test integrated GPS/eLoran receivers, implementing all of the existing Loran-Ĭ/eLoran specifications and fully capable of supporting a wide variety of potential changes to In response to this clear need, Alion Science and Technology has recently developed a signal These include the employment of additional secondary factors,īoth E-field and H-field antennas, and the data carrying capability provided by the Loran Data ![]() Implementations as well as be adaptable to changes in the system itself and the developing An effective eLoran simulator should support the current Loran-C/eLoran Synchronized for the test locations and receiver trajectories of interest (similar to existing GPS To do so under a variety of signalĬonditions requires a signal simulator that generates both eLoran and GPS signals, It handles the loss of one or the other of the signals). Using GPS or eLoran separately as well as the algorithms for integrating the two (including how Receiver performance under the expected signal-in-space situations this includes performance As these are beingĭeveloped, a critical need of both manufacturers and system evaluators is the ability to assess These devices are typically single box, integrated GPS-eLoran receivers. This paper, as a follow-up of prior work by these authors, investigates and tests possible changes to the 9th pulse Loran Data Channel's modulation set and Loran's phase codes and examines what improvements the changes could provide.Īs Loran-C transitions to eLoran, commercial manufacturers are developing eLoran receivers. Part of this testing time also allowed for on-air implementation of potential changes to the eLoran signal. During the summer and fall of 2008, these authors have tested a new transmitter for eLoran, installed temporarily at the Loran Support Unit, in order to determine whether it meets both the existing Loran signal specification and the envisioned eLoran specification. As part of the move to eLoran, it is time to evaluate the impact of potential changes and embed those of value into the new system. Over this history there have been examinations of how changes to the system might improve or extend performance, but these basics are unchanged. ![]() The specifications of the Loran-C system have remained static over the past 50 years: a teardrop shaped pulse, 8 pulses in a group (9 for Master), a set of Group Repetition Intervals, a two group Phase Code Interval with fixed Master and Secondary phase codes, etc. implementing a form of code division multiplexing)? Could different stations have different phase codes (e.g. Two important issues considered are: 1) The codes themselves - could redesigned phase codes still provide sufficient sky wave protection, yet yield improved cross rate interference rejection? 2) The allocation of the codes - currently, all secondaries share a common phase code (master signals have a different code). ![]() ![]() The goal in this paper is to open up the discussion of phase code selection. The phase codes now in use allow for cancellation of sky wave interference (beyond 1 msec delay, that is) and for discrimination between master and secondary stations, an important consideration for legacy Loran receiver technology. (The term "phase code" refers to a multiplier of plusmn1 on the envelope of each individual Loran pulse the sequence of signs repeats every two groups or "phase code interval.") Currently, all master signals use one specific phase code and all secondary signals use another. This paper investigates possible changes to the Loran phase codes, and the potential improvements that such changes could provide.
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