Radiophysical equipment for study of ionospheric plasma parameters and radiowave propagation

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Radiophysical equipment for study of ionospheric plasma parameters and radiowave propagation

The equipment consists of:

1. DPS-4D Digital Ionosonde designed to study the physics of the ionosphere and radio propagation, conducting regular observations of ionospheric parameters for research purposes and to improve predictions of radiowave propagation.

Basic features of DPS-4D digital Ionosonde

Ionosonde DPS-4D is one of the most modern and widespread tools of radio sounding of the ionosphere.

The composition of the DPS-4D

DPS-4D is composed of a main unit, monitor; 2 transmit antennas; 4 reception antennas with polarization keys; and battery backup unit. The main unit includes two computers, a transmitter, four receivers, and a signal processor. The appearance of the main unit DPS-4D is shown in fig. 1. The host computer controls the transmission and reception process, reads data from the signal processor output buffer, converts the data into the required format, the data recorded on the hard disk of the auxiliary computer. Auxiliary computer performs secondary processing of data, writes it to the hard drive, CD-ROM, transfers the data to the server through FTP-channel.

Fig. 1. DPS-4D appearance.

Key Features of Ionosonde DPS-4D

Ionosonde radiated power is only 300 watts (two 150 W transmitter each). However, with special signal processing methods can achieve a sufficiently high signal / noise ratio. 

Diversity Reception

DPS receiver system consists of 4 antennas: three antennas are located at the vertices of an equilateral triangle with a side of 60 m and other one is in the center of this triangle. Diversity reception allows to measure the vertical and azimuth angles of arrival of the wave reflected from the ionosphere. Registration  of arrival angles allows to separate vertical and non-vertical reflections. 

Methods of measurement of ionospheric plasma characteristics

Restoration of electron density profile is based on Ionograms processing. Processing consists of 2 parts:
Allocation of tracks, the construction of the altitude-frequency response h '(fn), corresponding to E, F1 and the F2-layer of the ionosphere. 

The measurement of the ionospheric plasma drift velocity

The algorithm is based on the measurement of characteristics of the signals reflected from the ionospheric irregularities.

Examples of ionograms:

Fig.2. Thule 00:15 UT 24 May 2008.

Fig.3.Moscow. 12:00 UT 11 April 2013.

  1. Flow Master Planar PIV System 

FlowMaster is an installation that allows to visualize and record the instantaneous distribution of the velocity field in a variety of optically transparent media (liquids, gases). Measurements are made using the method of Particle Image Velocimetry (PIV). This method is based on the fact that statistical methods give the most likely offset of visualizing particles in the area of interest and it can be used to restore kinematics of a flow. 

The setup consists of the following modules: 

  1. 1. The two-pulse solid-state Nd: YAG-laser with next characteristics: maximum energy of 400 mJ per pulse, the maximum frequency of operation of the laser 14.7 Hz, flash time 4 ns, the basic excitation frequency of 1064 nm. The laser is equipped with an optical system that allows to convert the light beam into a plane to illuminate the area of interest. The kit also includes 4 pairs of goggles.
  2. 2. PIV-camera. Its main feature is that it allows you to take two consecutive frames in increments of up to 100 ns, which allows the measurement of high-speed streams of up to 4 Mach numbers. Camera resolution is 1600x1200 pixels, images are black / white with A/D dynamic range 14-bit.
  3. 3. The synchronization unit enables you to synchronize image acquisition with a camera and a laser flash.

 

The laser with power supply

  

PIV-camera

  

Sync. Unit

To visualize flows in gaseous media aerosol of

bis (2-ethylhexyl) sebacate is used.

 Chemical formula: C26H50O4

Production rate: 1.4 ... 20 ∙ 108 # / s

   

For visualization of flows in liquids, the spherical hollow particles of borosilicate glass is used:
These particles have the following characteristics:

 

Density: 1.10 ± 0.05 g/cm3.
Average size: 9-13 mm; size distribution: 10% <5.4 microns 50% <11.9 microns 90% <19-21 microns.
Chemical properties: insoluble in water.

   

Web site of manufacturer: http://www.lavision.de/en/products/flowmaster/