D. F. Kitrosser

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.

Internet access to ionosondes

Abstract Connecting ionosondes to the Internet gives easy access to real-time information on ionospheric conditions. Some of the ionosonde sites provide just the ionogram displays, others give in addition the scaled ionospheric characteristics directly usable for frequency management and HF channel assessment. Some sounders also store days or months of station data, which makes it possible remotely to evaluate the time history of geophysical events. The Internet link is also a convenient means for remote system maintenance and control. The paper addresses various aspects of the Internet ionosonde scenario, including data base support, WWW publishing, user interface, security, and data format. A list of Internet accessible ionosonde stations is provided with a brief description.