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A. D. Akchyurin, R. G. Minullin, V. I. Nazarenko, O. N. Sherstyukov, A. L. Sapaev and E. Yu. Zykov

Physics Faculty, Kazan State University, RUSSIA


Development and manufacture of different types of ionospheric stations was started at Kazan University in 1977. In 1979 an analog ionospheric station (a mobile station) was made. Several cycles of measurements for investigating sporadic E layer peculiarities were made with the station.

Subsequently, a series of digital ionospheric systems, called "Cyclon", were started in 1983 utilising the radio receiving apparatus P-399, A ("Katran") and a computer, "Electronica D3-28". Further development of the ionosonde is continuing. At present, the seventh ionosonde model, Cyclon-7, and the tenth model, Cyclon-10, have been developed and produced with the following characteristics:

Sounding frequency band

1-32 MHz

Pulse width

50-200 mks

Pulse repetition rate

10-100 Hz

Pulse power

5-10 kW

Pulses per frequency


Receiver bandwidth

30 kHz

Receiver dynamic range

60 dB

Digitisation levels quantity of amplitude


Range increment

2,5 km

Range samples


Quantity of sounding frequencies

1-500 kHz

Minimum recording time of ionogram

2 s

The Cyclon-10 has a higher power output than the Cyclon-7.

The ionospheric complexes Cyclon-7 and Cyclon-10 were developed by Kazan University and are intended for digitally recording three dimensional ionograms (range, frequency, amplitude) from vertical, oblique and backscatter soundings of the ionosphere and to then calculate the electron density profile.

The complexes comprise a pulse transmitter, receiver, IBM compatible PC "Iskra-1030" and equipment for keeping and locking the time standard. A Pascal program controls the operation of the complex and allows automatic processing of ionograms and interactive modes, to determine and store the ionospheric parameters as well as calculate the electron density profile and determine the monthly average values of the ionospheric parameters. The ionograms and ionospheric parameters are displayed and stored, using international standards, on paper and floppy disks.

Both Cyclons can be applied in static and mobile situations for scientific research and in ionospheric networks. Both ionosondes are intended for operation in a regional network as a central and also as an outlying ionosonde. Ionosondes "Cyclon-7" and "Cyclon-10" can both handle vertical and oblique soundings and are equipped to maintain a time standard. Both ionosondes take records of ionospheric parameters (critical frequency, virtual height) in the international standard form, and also the frequency and virtual height of every reflection point for any ionospheric layer.

As already mentioned, Cyclon-7 and Cyclon-10 may be to used for scientific investigations. It is possible to study any ionospheric layer or some regions of reflected traces. Frequency steps of 1 kHz can be used. The ionosondes can be used to study energy characteristics of reflected signals. Every reflected pulse can be displayed on the screen as an amplitude-time realisation where pulse distortion due to multi-ray interference is evident.

The Cyclon-7 and Cyclon-10 ionosondes are designed for making detailed investigations of the Es-layer and the characteristics just mentioned support this when analysing Es-layer reflections. It is possible to analyse multiple Es-layer reflections in both frequency and amplitude, to investigate the amplitude-time dynamics of Es-layer reflections, to watch the Es-cloud generation and destruction, to observe the rate of amplitude-frequency variation of Es-layer and so on. The Cyclon-10 ionosonde, unlike the Cyclon-7, has increased radiated power for detailed research of weak Es-layers that are not always seen successfully with ordinary ionosondes.

Cyclon-7 was used to make over-all tests in three measuring cycles: June 1992 in Kazan, September - November 1992 in Moscow region. The tests have shown agreement between the calculated and real engineering characteristic of ionosonde. Cyclon-7 was used to make around-the-clock tests at different seasons in a mobile version. These tests were carried out successfully and confirmed the normal operation of the ionosonde in different unfavourable climatic conditions. The comparison of data obtained with the Cyclon-7 and those from the institute ionosonde, a distance of about 50 km away, were good. The critical frequency errors for ionospheric layers were no more 0.2 MHz in most cases. Routine operations were tested using Cyclon-10 during June 1993 at the experimental range in Kazan.

Thus, the over-all tests of Cyclon-7 have shown satisfactory, normal operation and good accuracy agreement with characteristics obtained with a network ionosonde. Consequently, Cyclon-7 may be used successfully in regional ionospheric networks as well as for scientific research on small-scale irregularities.

By using the Cyclon-7 and Cyclon-10 ionosondes, we plan to test the principles of a regional ionospheric network described above. One of the ionosondes will be used as a central location and the others as outlying ionosondes, thus creating one arm of a regional ionospheric network. Using two ionosondes it will be possible to work out all regimes of ionosonde co-operation as well as support a regional ionospheric network.

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