Klaus Bibl

Ionospheric sounding in support of over‐the‐horizon radar

Precise coordinate registration for HF over-the-horizon (OTH) radar applications requires accurate knowledge of the ionospheric structure. In the mid-1980s Digisonde 256 systems were deployed in the American sector to provide this information from strategically located sites via telephone lines to the user. The mid-1990s saw the development of a new advanced system, the Digisonde portable sounder, or DPS, now being deployed in Australia in support of the Australian OTH radar system. A summary of the new features provided by the DPS is as follows: low radio frequency power (300 W); narrow transmission bandwidth; advanced automatic scaling; and control and data access via the Internet. The availability of real-time electron density profiles as function of time from a network of stations makes it possible to calculate the three-dimensional electron density distribution in the region of interest using Fourier transform techniques. The resulting density maps are the basis for the OTH radar coordinate registration. The DPS uses Doppler interferometry to determine the development of ionospheric irregularities.

Advancing Digisonde Technology: the DPS-4D

A new ionosonde, the Digisonde model DPS-4D, replaces the aging DPS-4. Faster computer hardware and operating systems together with digital transmitters/receivers provide unprecedented measurement flexibility, data precision, and signal processing gain. The novel features in this latest Digisonde are discussed and explained.

Practical method for routine analysis of the valley parameters between E- and F-region of the ionosphere

Abstract Measurement of the virtual height and the frequency of the minimum of the F-region extraordinary trace in digital and analog ionograms can provide a world-wide survey of the main parameters for the valley between E- and F-region ionization. The two added quantities establish also the starting point for the true height analysis of the F-region ionization.

Digital spacecraft ionosondes

Abstract In cooperation with RCA, Astro-Electronics Division, a digital spacecraft ionosonde has been developed and its prototype built by ULCAR. On-board use of the Direct Discrete Fourier Transform for signal-to-noise enhancement, suppression of unwanted echoes and the identification of echo properties permit several applications. In ionospheric topside satellites (>800 km above ground) the ionospheric profile over all parts of the earth will be measured with simple and new data compression techniques on board of the satellite. Digital data preprocessing overcomes the breakthrough of ground-based man-made interference and analyzes auroral and equatorial echoes. Because the ionosonde measures amplitude, phase, Doppler, range and polarization of a radio wave simultaneously, it will be a very useful tool for the Waves in Space Plasma program of the NASA Space Shuttle, especially for a mother-daughter configuration. With a synchronized transmitter on the ground, such a Digisonde in a low-flying satellite (100–400 km) can receive signals from ducted radio waves launched into the ionosphere near natural or artificial ionization depletion areas for the study of large distance radiowave propagation.

Electric and magnetic antennas as REAL transmission lines in plasma and the miracle of self-focusing of whistler mode propagation

When one considers the losses in an antenna impedance measurement of the Very-low Frequency RPI experiment in space mostly caused by local electrons and ions flowing into the antenna and the spacecraft, instead of radiation, because these losses were non-linear with voltage, and can explain the excellent recordings of multi-bounce whistler mode echoes as self-focused in spite of low power, the search for new antenna configurations is required if high-power transmission is necessary. Understanding the antenna in plasma as a real transmission line, leads to a magnetic-electric antenna, end-loaded with capacity.