The Effect of Ionospheric Variability on the Accuracy of High Frequency Position Location

• Main Author: Heaps, Melvin G
• Format: Report
• Language: English
• Subjects: ACCURACY; COHERENCE; DATA ACQUISITION; HIGH FREQUENCY; IONOSONDES; IONOSPHERE; IONOSPHERIC DISTURBANCES; IONOSPHERIC PROPAGATION; LIMITATIONS; MONITORS; MULTIPLE OPERATION; PE61102A; POSITION FINDING; POSITION(LOCATION); RADIO WAVES; Radiofrequency Wave Propagation; SIZES(DIMENSIONS); SPATIAL DISTRIBUTION; STRUCTURES

The attainable accuracies in high frequency (HF) radio wave position location over ranges of several hundred kilometers are beset with errors of tens of kilometers due to constraints in three major areas: ionospheric variability and irregularity; system size limitations for easily fieldable systems; and sufficient data acquisition, processing, and interpretation. Of principal concern here is the area of ionospheric variability and irregularity. The temporal and spatial coherence of ionospheric structure has been considered with respect to its effect on the accuracy of HF position location. The findings show that medium and small-scale ionospheric structures most likely to affect HF position location accuracies have a spatial coherence on the order of 50 km and a temporal coherence on the order of 5 minutes. On this basis it is recommended that a multiple ionosonde net be used instead of a single ionosonde, such that an ionospheric sounding point is no more than 50 km from a potential radio wave reflection point, and that soundings be taken on the order of every 5 minutes or less.