Transmitters synchronization in distributed radio systems of aircrafts navigation and landing

Аuthors

Kishko D. V.

Moscow Aviation Institute (National Research University), 4, Volokolamskoe shosse, Moscow, А-80, GSP-3, 125993, Russia

e-mail: dvkishko@gmail.com

Abstract

The article shows the methods of synchronization transmitter devices in distributed radio systems. This systems primarily includes global navigation satellite system (GNSS), ground radio systems navigation (LORAN-C, OMEGA), pseudolite radio navigation system (Locata, DeckFinder), Multilateration system (MLAT). Correct work of those systems requires coherency of the signals which emitted by distributed transmitting devices- initial phases of emitted signals should be functionally interrelated. Process of synchronization provides a quasi-coherent emitting of the radio signal from phase center antennas of distributed transmitting devices. The synchronization algorithm is considered by the example pseudolite navigation systems. The considered pseudolite navigation system consists of two segments. The first one, which called system segment, includes a set of transmitter-receiver devices wich placed near the service area of the system and control and monitoring subsystem. The second one, which called user segment, are includes navigation equipment of the consumer of this system.

The considered algorithm belongs to the class of two way synchronization methods and doesn’t need calibration procedures for receiving and transmitting path of devices, but requires determination of distance between the phase centers of the antennas for each pair of devices.

The article showns that the synchronization accuracy depends on distances measurement errors between the phase centers of the antennas, and on the parameters measurement errors of radio signals from each device(pseudo-ranges and carrier phase). The standard deviation error of the synchronization transmitting devices is estimated at 0.01 ns, which comparable with accuracy of precise synchronization methods, such as TWSTFT (two way satellite time and frequency transfer). Synchronization of the transmitting devices is performed in the background during the main task operation system. This allows to reduce error noise of parameters measurements of radio signal by using filtering algorithms such as Kalman filter.

Keywords:

synchronization, time scale, distributed navigation system, pseudolite system, Locata

References

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