Implementation of the Cityfix receiver concept

Cityfix is an integrated navigation system, which combines Differential GNSS and MW-radio transmissions. During outages or poor performance of the DGNSS the Cityfix system measures the carrier wave phases of the MW-radio transmitters to determine a displacement from the last accurate DGNSS position. This paper describes the implementation of the...

Positioning & Control of the Cityfix System

Position determination systems based on differential satellite systems can achieve a very high accuracy. The Eurofix system for example, can determine positions with an accuracy of 5 metres for 95 percent of the time. A problem that arises when using these differential satellite systems, is the bad reception quality of the satellite signals in...

EUROFIX Regional Area Augmentation System: Reducing spatial decorrelation with Extended DGPS

Eurofix is an integrated navigation system, which combines Differential GNSS and Loran-C. The Loran-C system is used to transmit messages which contain differential corrections for GNSS by additional modulation of the transmitted signals. It has been shown that reliable data transmission with Loran-C stations up to 1,000 km distance is feasible....

Soft-Decision Decoding on the Eurofix Datalink

In Eurofix, Differential GNSS information is transmitted by modulating Loran-C or Chayka pulses. The applied modulation is a form of Pulse Position Modulation. To protect the transmitted DGNSS information against errors, Forward Error Correction codes are applied. The Loran-C or Chayka pulses are transmitted in groups of 8 pulses and 6 of them...

Reducing frequency offset within a EUROFIX receiver using asynchronous uniform sampled LORAN-C pulses

EUROFIX is a new proposed system in which the LORAN-C navigation system is altered slightly to transmit DGPS data. This system is tested at the Telecommunications and Traffic Control Systems Group by using an atomic clock for precision timing measurements. Within the EUROFIX project an investigation is conducted to see if groundwaves as well as...

Eurofix : Ternary modulation and error control coding

The Eurofix navigation system is intended to overcome the problems of the GPS satellite navigation system by broadcasting corrections for this system using existing LORAN-C transmitters. By modulating the pulses transmitted by the LORAN-C stations, a low speed digital communication channel becomes available. This datalink must fulfill a number...

Design and Testing of an Advanced Eurofix Demodulator

In the Eurofix system, DGPS corrections are transmitted using an already existing infrastructure: the Loran-C system. Primarily, this provides a cost-effective way to supply coverage for DGPS-corrections over a large area. Secondly, the use of the Loran-C navigation system in combination with normal GPS will yield a combined system with improved...

Modulation Schemes for the Eurofix Datalink

In the Eurofix system DGPS corrections are transmitted using the Loran-C signal as a datalink by time shifting the Loran-C pulses. The performance of the datalink, however, is bounded by restrictions of both the Loran-C system and the DGPS system. First, the normal Loran-C performance should not degrade noticeably due to the extra data...

Analysis of the Eurofix Data Link

After the introduction of the Eurofix concept for transmission of Differential GPS data via Loran-C signals by additional phase modulation, the consequences of this modulation for conventional (non-Eurofix) users is discussed. In what follows, various modulation schemes will be introduced and the properties of these schemes will be described.