Large electron density gradients in the ionosphere associated with the walls of the midlatitude trough produce tilted reflecting surfaces which lead to HF signals propagating over paths well displaced from the great circle. Measurements are presented of signals propagating over two paths along the midlatitude trough for which bearings deviations of up to 100° from the great-circle path, i.e. the expected direction of arrival, were frequently recorded. The times of occurrence and magnitude of these large deviations are consistent with the known features of the midlatitude ionospheric trough. Such large deviations of the measured bearing from the great-circle path, which far exceed the instrumental errors, have serious implications for the operation of position location systems operating within the HF band.
References
-
-
1)
-
B.W. Halcrow ,
J.S. Nisbet
.
A model of the F2 peak electron densities in the main trough region of the ionosphere.
Radio Science
,
5 ,
815 -
820
-
2)
-
W.D. Parkinson
.
(1983)
Introduction to geomagnetism.
-
3)
-
A.S. Rodger ,
M. Pinnock ,
C.S. Deehr ,
J.A. Holtet
.
(1980)
The variability and predictability of the main ionospheric trough, Exploration of the polar upper atmosphere.
-
4)
-
Warrington, E.M., Jones, T.B.: `Bearing determination and bearing quality indication from a goniometric HF DF system', Proceedings of the AGARD 50th symposium of the electromagnetic wave propagation panel on Radiolocation techniques, June 1992, London, p. 20.1–20.11.
-
5)
-
Dhanda, B.S., Warrington, E.M., Jones, T.B.: `Observations of Doppler spreading and FSK signalling errors on HF signals propagating over high latitude paths', Proceedings of AGARD specialists meeting on Digital communicationsystems: propagation effects, technical solutions, systems design, September 1995, Athens, p. 18/1–18/12.
-
6)
-
Lane, G., Rhoads, F.J., Deblasio, L.: `Voice of America coverage analysis program (VOACAP); A program guide', 01-93, 1993, (PB93-155174).
-
7)
-
K. Davies
.
(1990)
Ionospheric radio.
-
8)
-
R.J. Moffett ,
S. Quegan
.
The mid-latitude trough in the electron concentration of the ionosphericF-layer: a review of observations and modelling.
J. Atmos. Terr. Phys.
,
5 ,
315 -
343
http://iet.metastore.ingenta.com/content/journals/10.1049/ip-map_19970663
Related content
content/journals/10.1049/ip-map_19970663
pub_keyword,iet_inspecKeyword,pub_concept
6
6