SU1187282A1 - Device for transmission of reference signal in radiointerferometer - Google Patents

Description

The invention relates to radio direction finding and can be used to transmit a reference signal to the peripheral points of the radio interferometer.

The purpose of the invention is to increase the temporal stability of the signal during transmission.

The drawing shows a structural electrical circuit of the proposed device.

The device contains a transmitting part that includes an optical carrier oscillator 1, a reference oscillator 2, a first Modulator 3, an optical carrier registration block 4, a distribution block 5, a second modulator 6, a phase multiplier 7 and (A-1) times and a phase multiplier 8 in A times and receiving parts, each of which includes an amplifier 9, a photodetector 10. and a reference signal filter 11.

The device works as follows.

The angular change of the radiation pattern of the radio interferometer, and, consequently, the error in determining the coordinates, is determined by the formula

~ δίρ-'λο ' ⁽¹⁾

2 "·’ ·

where & C is the angular change in the radiation pattern of the radio interferometer, due to the fluctuation of the phase 8c> of the reference signal at the peripheral points;

Ά _ο is the wavelength of the reference signal;

Ό is the geometric distance between the points of the radio interferometer.

The fluctuations of the phase are due to fluctuations of the electrical lengths (the geometric length multiplied by the refractive index of the communication line) of the communication lines caused by changes in temperature, pressure, humidity of atmospheric air.

The phase shift on one of the optical carriers between the central and peripheral points where the receiving part is located is recorded as

1 (1 ^],

(2)

ten

15

20

25

thirty

35

where P is the frequency of the reference signal;

£ - distance between points;

C is the speed of light;

111-group indicator

air refraction;

- function depending only on the wavelength I of light;

P and T - pressure and air temperature.

The phase shift C> ₂ on the second carrier:

From (2) and (3) follows

£ __

t ‘pp

(3)

Measuring ^ can be determined

the value of y is responsible for the fluctuations of the electrical length, and correct the phase shift caused by the atmosphere:

A h, -H _g ) = —l—

40, Phase run C> ₀ =

no longer

. . ^r ° c depends on atmospheric conditions

Denote

45

50

(five)

which depends on the choice of two optical carriers (for Ά, = 0.63 μm and. Ά ₂ = 0.44 μm, A = 20, for

= 0.63 μm and = 0.37 μm,

Ά = 9).

The signal from the output of the reference oscillator 2 is multiplied in multipliers 8 and 7 in A and A (A-1) times, after which the signal multiplied by (A-1) times modulates the first optical carrier in the first modulator 3, and multiplied by A times modulates second optical carrier in the second mod1187282

6, after which the modulated carriers are combined in block 4 of the alignment of optical carriers and enter the distribution block, from where they are sent to the peripheral 5 points. At each peripheral point, the signal is received and amplified by the amplifier 9, fed to the photodetector 10, and then to the filter 11 of the reference signal, highlighting the reference signal (differential signal on two optical carriers, which is then mixed with the signal received by the antenna of the radio interferometer and the phase 15 of the reference and the received antenna signals determine the coordinates of the objects (with phase) /. 2ΐΡ0 independent of atmospheric conditions on

20

the distribution path between the points of the radio interferometer. This follows from relations (4) and (5),

_."BUT

. 25

Since for optical carrier waves = 0.63 μm, Ά ₂ = 0.44 μm, the value of A = 20, in the device

phase multipliers are applied 20 and 19 times. The short-term accuracy (for 0.5-1 h) of the proposed device, as well as the known one, depends on the magnitude and accuracy of measurement and the separation of the phase difference of the reference signal of two optical carriers, and is determined from (5) as follows:

where b φ ₀ - the accuracy of maintaining the phase of the reference signal;

8 (φ, accuracy of measurement of the phase difference of the reference signal on two optical carriers.

For δ (4 <4> _g ) ⁼ ° » ¹ ° and A = 20,

= 2. When using two

optical carrier 0.63 μm and = 0.37 μm, A = 9, therefore

Ηφ ₀ = 9 °. The long-term stability of the maintenance phase of the proposed device for 12-17 hours of operation is 2, which is sufficient for conducting a session of observations on the radio interferometer for 12-17 hours without operator intervention.

Claims (2)

TRANSMISSION DEVICE * A REFERENCE SIGNAL IN A RADIO INTERFEROMETER, containing a transmission part located at a central point and including a reference oscillator., The first modulator, whose input is connected to the output of an optical carrier oscillator, and distribution block, receiving parts located at peripheral points and including The amplifier and photodetector, which are connected by the fact that, in order to increase the temporal stability of the signal during transmission, the second modulator, a phase multiplier, is introduced A times, multiplied the phases (A – 1) times and the optical registration unit the outputs of the first and second modulators are connected to the inputs of the block combining optical carriers, the output of which is connected to the input of the distributor dividing unit, the output of the optical carrier generator is connected to the input of the second modulator, the output of the reference oscillator The phase multiplier is (A-1) times and the phase multiplier is A times connected respectively to the control inputs of the first and second modulators, and a filter of the reference signal is inserted into each receiving part, the input of which is connected to the photodetector output, and the output is output reception part. yes, 5 Μ οι) _- 1187282 2 1187282