4-Meter-Band Radar Station for Meteor Observations (M-3)
Abstract Generated abstract
The paper describes the M-3, a 4-meter wavelength radar station developed at Tomsk Polytechnic Institute for meteor observations under the International Geophysical Year program. It addresses limitations of standard Soviet meteor radars operating at 50 pulses per second, particularly reduced meteor detection and inadequate support for measurements such as velocity and polarization, by using a transmitter capable of 300 to 600 pulses per second and adjustable operation over a wider range. The article outlines the station’s main units, including transmitter, modulator, receiver, marker systems, photographic registration, operator controls, and automatic protection, and reports preliminary nighttime detection rates of 15 to 25 meteor reflections per hour on ordinary days.
Full Text
4-Meter Wavelength Radar Station for Meteor Observations (M-3)
F. I. PEREGUDOV
(Presented by the scientific seminar of the Radio Engineering Faculty)
For meteor observations under the IGY program in the USSR, standard radar installations with a pulse power of 100–120 kW, a carrier frequency of 72 MHz, and producing 50 transmissions per second are used [1]. Experience in operating such installations in Kazan and other observation points has demonstrated the possibility of carrying out typical radar observations of meteors with them. However, in the usual operating mode the maximum capabilities of an installation for the wavelength \(\lambda = 4\) m are not fully realized.
As shown by E. I. Fialko [2], at a repetition frequency \(F_i = 50\) pulses/sec there is a noticeable decrease in the number of detected meteors in comparison with \(F_i > 200 \div 300\) pulses/sec. The low repetition frequency does not permit the standard apparatus to measure meteor velocities, the polarization effect, etc.
At the Tomsk Polytechnic Institute named after S. M. Kirov, a simple radar station of the same range has been developed and constructed, but without the above-mentioned shortcomings.
The installation consists of (Fig. 1): a VHF generator, a modulator, a high-voltage rectifier, an autotransformer, a submodulator, brightness and amplitude markers, and a power-supply unit. Fail-safe operation is ensured by an automatic-control unit. Registration of meteor echoes is carried out with the aid of a photo attachment. From the operator’s console, control is performed of the operation of the photo attachment, counting of meteors during visual registration, and transmission of information to other radar stations (TPI-2, etc.). Starting of the submodulator and of the sweeps of the markers, as well as the application of scale marks, is performed either from the “TPI-2” synchronizing unit or from instrument 27I. The parameters of the installation are:
- Pulse power about 100 kW.
- Pulse duration \(2 \div 3\) μsec (rectangular pulse).
- Repetition frequency 300, 600 pulses/sec.
- Operating range up to 450 km.
- Calibration marks every 10 km.
In practice, the modulation circuit permits the transmitter to be triggered at any repetition frequency from 50 to 1000 pulses/sec. The M-3 installation
option, it can operate either with a weakly directional antenna or with a directional antenna of the “waveguide” type.
The external appearance of the “Meteor-3” radar station is shown in Figs. 2 and 3. The UHF generator is made according to a push-pull circuit with grounded anodes, using two GI-17 tubes. The high-frequency energy is fed to the antenna through an RK-3 type cable.
Fig. 1. Block diagram of the M-3 radar station.
Modulation of the generator is carried out by applying rectangular pulses with an amplitude of up to 8.5 kV from a pulse transformer to the tube anodes. The modulator is assembled according to a partial discharge-of-capacitance circuit using two GMI-83 tubes. At the modulator output there is a pulse transformer with a transformation ratio of 1:1, intended for changing the polarity of the modulating pulse.
Power for the modulator is supplied from a high-voltage rectifier assembled in a bridge circuit using V1-0.1/30 tubes. The high voltage of the rectifier is regulated by means of an autotransformer.
The entire transmitter is mounted in a separate cabinet, the left part of which is occupied by the modulator and the high-voltage rectifier, while the high-frequency generator is located on the right (Fig. 3).
Control of the modulator is performed by positive-polarity pulses of 700 V with a duration of 2–3 μsec, arriving from the premodulator unit. In the premodulator, under the action of triggering pulses arriving from the synchronizing device, modulating pulses are formed with a duration adjustable from 2 to 3 μsec. Pulses of the required duration are obtained by means of two 6N1P and 6P1P tubes and are then amplified on a GI-30 tube. The premodulator is mounted on a standard chassis. On the same chassis there is a stabilized 250 V rectifier.
The station receiver is made according to a superheterodyne circuit using 6Zh1P tubes. At its output there is a detector and a video-amplifier stage. The signal from the receiver is fed to the marker units.
The amplitude marker is used for visual observations of meteor echoes. The marker uses a 13LO-37 tube. The unit contains stages of the sweep expander, sawtooth generator, phase inverter, and the final stage of the video amplifier. The start pulses for the sweep generator and the scale marks come from the synchronizing unit of the TPI-2 station or from instrument 27I.
Fig. 2. Receiving-indicator cabinet.
Fig. 3. Transmitter cabinet.
The brightness marker is intended for photographic recording of echoes from meteors. Photography of the screen of the 13LO-37A tube is carried out with the aid of a photographic attachment. The circuit of the unit is similar to that of the amplitude marker, but the start of the sweep is delayed by 80 km in order to make better use of the tube screen. Power for the indicators is supplied from a separate power-supply unit.
The automatic-control unit ensures the normal sequence for switching on the station, and switches it off in the event of overload, short circuit, or failure of the door interlock. The automatic-control unit also houses instruments that measure the supply-line voltage and the voltage and current of the high-voltage rectifier. The automatic-control unit is located in the upper compartment of the station.
On the operator’s console there are a toggle switch and indicator for switching on the photographic attachment, as well as an end-of-film indicator. To facilitate recording the number of meteors during visual observations (with the amplitude marker), an electric echo counter is mounted on the console and is operated by pressing a button. During simultaneous photographic and visual recording of echoes, for perforation
film, check marks can be applied by means of the film-mark button. The control panel also has a transmitter-power indicator connected to the remote antenna.
The results of preliminary observations showed that on ordinary days the number of reflections during the night hours is 15–25 reflections per hour.
REFERENCES
- Meteor Observations, instructions, USSR Academy of Sciences Press, 1957.
- Fialko E. I. On the influence of wavelength on the effectiveness of the radar method of meteor investigation, Proceedings of the Siberian Physico-Technical Institute, vol. 37, Tomsk, 1959.