32 nd International Loran Association November 3-7, 2003 Predicting Differential Loran-C Performance in Boston Harbor Erik Johannessen Andre Grebnev Wouter Pelgrum

32 nd International Loran Association November 3-7, 2003 Context Supports on-going LORIPP/LORAPP evaluations and analyses Specifically part of a program to prototype Integrated GPS/Loran for Harbor Entrance and Approach Program Participants

32 nd International Loran Association November 3-7, 2003 HEA Receiver Program Scope Prototype Integrated Receivers  Receiver/Integration Specification  Antenna Design  Cost Study  5 Deliverable Evaluation Units Measurement Campaign  On-the-Water Data Collection  Reference Station Measurements  Demonstration Documentation

32 nd International Loran Association November 3-7, 2003 Reelektronika develops miniature integrated GPS/Loran-C receiver as OEM product for NELS (Northwest European Loran System) Credit Card 85 x 54 mm Front End & ADC 77 x 47 mm Signal Processor 77 x 51 mm Prototype Integrated Receivers

32 nd International Loran Association November 3-7, 2003 Prototype Integrated Receivers (cont’d) Replace MF Beacon Engine with Loran/GPS/WAAS Modify H-Field Beacon Antenna To H-Field Loran

32 nd International Loran Association November 3-7, 2003 Measurement Campaign Overview Envisioned as three steps leading to set up capable of formal demo in DC area First step local to Megapulse resource availability Temporal and spatial decorrelation measured, also local effects Differential measurements by tightly time coupling a reference and rover Method applicable to all modes Stored raw sample data permits comparison of multiple envelope and carrier tracking points

32 nd International Loran Association November 3-7, 2003 Experimental Set-up – Step 1 Reference Station at MegapulseRover Receiving Equipment Suite

32 nd International Loran Association November 3-7, 2003

32 nd International Loran Association November 3-7, 2003

32 nd International Loran Association November 3-7, 2003

32 nd International Loran Association November 3-7, 2003 A lovely day for a sail?

32 nd International Loran Association November 3-7, 2003

32 nd International Loran Association November 3-7, 2003

32 nd International Loran Association November 3-7, 2003

32 nd International Loran Association November 3-7, 2003 Reference Station Data Measurement Date : June 20, ET Recorded at Megapulse –(Nan, Sen, Crb, CB shown) 5 sec independent samplesNon-moving average of 12 samples

32 nd International Loran Association November 3-7, 2003 Reference Station Data (cont’d) Note: discrete steps of 20 ns - LPAs or Other?? Nantucket – last 3.5 hoursCaribou – 7 hours, 10nsec/div

32 nd International Loran Association November 3-7, 2003 Reference Station Data (cont’d) Scatter plot created using 7 TOAs, 5 sec integrated/independent Repeatability of 7 hour set: 6.5m, 95% and 8.6m, 99% Slight offset from mean due to ASF variation

32 nd International Loran Association November 3-7, 2003 Reference Station Data (cont’d) Mean of 1 st minute used to compensate next twelve 5 sec samples Repeatability improves slightly: 6.1m, 95% and 8.2m, 99%

32 nd International Loran Association November 3-7, 2003 Reference Station Data (cont’d) Mean of ten minutes used to compensate next 120 samples Repeatability: 6.2m, 95% and 8.4m, 99%

32 nd International Loran Association November 3-7, 2003 Rover Receiver Results/Issues Antenna related  Phase error with orientation  Include cable and attenuators as part of antenna Receiver related  Data grabber worked very well  Need to lose some weight Vessel related  Alternator noise

32 nd International Loran Association November 3-7, 2003 Measurements-Step 2 Currently completing analysis of Step 1 Rover Results Antenna related issues addressed via hardware upgrade and compensation in software Ship Shape gone to FLA for winter, will need alternate vessel Alternatively, SiTex resources in Tampa Expect to be on water again early December

32 nd International Loran Association November 3-7, 2003 Summary Reference station and Rover data collection systems useful for post processing High update rate of differential correction did not significantly improve position fix Vessel related issues need resolution Measurement campaign has been critical input to integrated receiver design