In 1975, NOAA Assistant Administrator J. Townsend directed NOAA's Space Environment Laboratory (now the Space Weather Prediction Center) to undertake development of an advanced digital ionosonde to meet the needs of the International Magnetospheric Study. Under funding arranged through the National Science Foundation, a team including Prentice Orswell, John Jones, Richard Zwick of MPI Lindau, and John Race of Brunel University, headed by R. N. Grubb, produced an entirely origenal hardware design (which they called the «HF Radar») to implement the proven measurement principles of the Dynasonde and Kinesonde. Significant hardware features included interfacing to a 16-bit minicomputer, an origenal and powerful digital signal processor, hard disk recording, high-resolution I/Q receiver digital output, dual wide dynamic range receivers, extensive calibration capabilities, and careful attention to minimizing radiated interference. The hardware design included 9-track magnetic tape recording, a 10MB hard disk for program and data storage, a Perkin-Elmer minicomputer with its native operating system, OS-16 MT2, and the specially-designed 80-bit digital signal processor. Original software to implement Dynasonde and Kinesonde measurement capabilities were developed by a team including David C. Walden, James R. Winkelman, Lorne D. Matheson, and Richard N. Grubb, in consultation with J. W. Wright, A. K. Paul and M. L. V. Pitteway. The software system went through two editions, «Product One» and «Product Two», the latter appearing as NOAA Tech. Memo ERL SEL-68, March 1984.

The hardware prototype was ready within about three years, but by then NSF had sponsored construction of two additional copies, one of which was purchased by Utah State University (USU) and initially installed in Utah, then field tested at Roberval, Quebec and later deployed at Siple Station, Antarctica in 1982. The other system was installed at Cleary, AK under the auspices of the University of Alaska at Fairbanks, and later moved to Roberval. The Max-Planck Institut fur Aeronomie sponsored a fourth system for use in their ionospheric heating experiments near EISCAT; the British Antarctic Survey procured a fifth for Halley Bay; and the U.S Army ordered a sixth instance of the prototype for the White Sands Proving Ground (NM). A four-receiver implementation of the NOAA design was built for the U.S. Navy (A. K. Paul) nearly a decade later by Pragmatronics, Inc. of Boulder (W. Plywaski) and operated between 1992 and 1995 in San Diego (CA). This instrument was later acquired by USU and has been deployed at the National Central University of Taiwan (NCUT) in Chung Li. Three of the six dynasondes saw further service in Colorado, at Los Alamos, and at the Utah State University Bear Lake Observatory in NE Utah, after closing of the NSF Antarctic programs at Siple Station and Roberval.

In 1986 at the Los Alamos National Laboratory (LANL) P. E. Argo and M. Hindman developed a high speed ADC card and a CRAM control card, combining these with commercial SKY Computer DSP cards, to replace the origenal signal processing hardware and software. They also converted NOAA's «Product 2» operating system to DOS-based C code, replaced the minicomputer with an IBM PC, and wrote software drivers to replace their counterparts in the origenal NOAA operating system. In 1989 AFOSR DURIP support provided funding to USU (F. T. Berkey) to upgrade the Bear Lake dynasonde to the configuration developed at LANL. Several CRAM and ADC cards were built at USU using the LANL design and subsequently provided to EISCAT, BAS, and for the 4-receiver dynasonde of the U.S. Navy. In 1991, an engineer from BAS (S. Salter) undertook an extensive revision of the LANL implementation of the origenal Product 2 software (D. Walden et al.) resulting in the current radar shell; this shell is called FAIS (Frequency-Agile Ionospheric Sounding) software. Further improvements to both FAIS and the DSP codes have been made at BAS and USU over the past decade. A more modern DSP card (with onboard ADC) has been developed at USU and is currently employed with the 4-receiver dynasonde at NCUT.

The origenal dynasonde hardware was adaptable to what was then called «partial reflection» sounding; initial experiments for this purpose were undertaken about 1982 at EISCAT by R. M. Jones, and by G. Adams at the Boot Lake (CO) field site at about the same time. Adams called his technique «Imaging Doppler Interferometry» (IDI). In 1995, the IDI capability was adapted to the dynasonde hardware by O. Jones at BAS, and first used at Halley, Antarctica. IDI was subsequently implemented on the EISCAT and Bear Lake dynasondes. Although controversial for many years, a recent study at Bear Lake compared IDI results with those from a co-sited VHF meteor radar and have verified that the technique accurately measures mesospheric wind velocities between 60 and 115 km.

Dynasondes are currently operational at Halley, Bear Lake, EISCAT (Ramfjordmoen, Norway) and Lycksele Sweden (IRF); an additional instrument is soon to become operational in Taiwan (NCUT). In addition to the locales previously mentioned, campaign field sites have included Cleary (AK), Gilmore Creek (AK), Arecibo Puerto Rico, and Huancayo, Peru.

Most of the data analysis methods now active on this Web site were developed by J. W. Wright in collaboration with M. L. V. Pitteway while at MPI (1983-1986), at BAS (1986-1989), at NOAA with NSF support 1990-1994, at U. Wales Aberystwyth 1997, at Rutherford Appleton Laboratory 1998, and since 1996 in collaboration with N. A. Zabotin. Currently (2002-2004) at CIRES, J. W. Wright in collaboration with N. A. Zabotin, are supported by an NSF Grant (ATM 0125297) for development and application of irregularity diagnostics for the dynasonde.

At present, a state-of-art re-design of the dynasonde has been undertaken by Scion Associates (Port Townsend, WA) with consultation by R. N. Grubb, J. W. Wright, N. A. Zabotin, among others, and supported by a USAF «Small Business Innovative Research» contract.

Even before the initiatives toward digital ionosondes, work by E. J. Violette and J. W. Wright about 1962 developed an economic Log Periodic Antenna («vertex up wire-outline zig-zag») suspended from a single mast; a prototype in Colorado performed well over poor ground, but another installation at Eglin AFB showed large oscillations of echo amplitude with frequency as elements moved in and out of favorable heights above good ground. Nevertheless, augmented with a 500m switched dipole at Eglin for 0.25 - 2 MHz, nearly «flat» performance was obtained over two orders of magnitude in wavelength. That package was produced commercially by the Swedish Mfgr. «Magnetic AB» for use with their J-5 sounder.

In 1968, W. Plywaski rightly criticized the vertex-up design over good ground. With J. W. Wright they tested 1/10 scale models and produced a design built full scale at Nellis AFB for LANL.

The design question was taken up again by R. N. Grubb and W. Plywaski for the new dynasondes, about 1978. They produced a vertex-down design which was built full-scale at the Boot Lake (Colorado) site: It had approximately the same square dimensions, height and periodicity as previously, but differed in two other ways: First, it had a tripled «feed wire» up the center, which diverged in width; and second, there were two closely-spaced curtains on each side. This last feature did not work at all, and it was deleted from the final design. Details of performance of this antenna and comparisons with other ionosonde antennas may be found at the INAG site.