Farwater-M4 (FM4) is a processor unit for the precession navigation. It is the part of the deformation monitoring system for the infrastructure and the mobile grounds. It receives crude measuring data (carrier code and phase) from GNSS/GLONASS/GPS/Galileo in the L1 band developed by FBU. It develops the parameters of the position and of the movement of the phase centers of the FBS antennas in the real time with precession accuracy. Up to 6 FBU can be connected to the FM4 via RS422 interface (standard). In case that one or more FBU can’t be connected to FM4 by the wire, one of the links listed above can be arranged. At least one FBU connected to the FM4 is used like a reference one (Base Station) and must be installed on the immovable surface. The rest ones must be attached to the points supposed to be watched. FM4 has 2 modes: – the main one (co-ordinates of the FBU’s are developed in RTK mode); – the parallel mode (dynamic filtering of the output data) allowing to achieve the best results in the accuracy depending on the dynamic of the monitored object. In the case when the movement of the watched points of the object is so slow that it can be described with the sequence of the static positions within the given time period, the special mode is envisaged. It is so called the mode of the quasi-static (static interval) measurement of the watched points positions. When this mode is used the accuracy of the measurement is maximal.

FM4 provides the following:

  • Receiving, decoding and developing of the measurement information from all connected units (carrier code and phase in the L1 band, GNSS);
  • Developing and sending to the external interface of the data on the space position and the movement of the phase centers of the antennas at the watched points relating the phase center of the FBU at the reference point. The data is produced in the real time with the precession accuracy;
  • Measuring of parameters of the watched points in the 3 modes simultaneously (real time, dynamic filtering, static interval);
  • Co-ordinates of the watched points in any custom co-ordinate system;
  • Automatic static monitoring system start-up, automatic setting of the custom co-ordinate system with FBU catching it up;
  • Special information to the external interface about the satellite situation in all the watching points, crude measuring GNSS data, data on the current mode of the system;
  • Remote diagnostic of the system, remote software up-grade.

Main Technical characteristics:

Number of interfaces for FBU (GNSS)

Up to 6

Accuracy of the superposition of the GNSS antenna phase center definition in the dynamic  filtering mode:



0,01 m

0,02 m

Accuracy of the superposition of the GNSS antenna phase centers definition in the dynamic filtering mode:




0,005 m

0,008 m

Accuracy of the superposition of the GNSS antenna phase centers definition in the quasi-static and post developing mode:- plane:

– altitude

0,003 m

0,005 m

Co-ordinate system

WGS-84 or customer’s

Power Supply

9-30  VDC

220  VAC

Power Consumption

 < 25 Wt

The frequency of the solution output

1 – 10 Hz

Link to the FBU

RS-422, Wi-Fi, УКВ

Output interface



300×226×76 mm


3 kg