VSAT - VSAT Monitoring System

The physical RF link of VSAT stations, especially the quality of the MF-TDMA return link, is crucial for ensuring high quality satellite communication. An accurate aligned antenna minimizes interference and secures the best physical way of maximizing the Bit/Hz/Year ratio. The SIECAMS VSAT monitoring system allows terminal per terminal measurement of RF quality parameters dedicated to MF-TDMA traffic transmitted from VSAT satellite networks without service interruption.

Short Description

Benefits of VSAT monitoring

  • Automatic measurement of cross-polar isolation on terminal level
  • Alarm generation in case RF quality parameters are beyond requirements
  • Minimizing interference risk by detection and identification of cross-polar leakage on terminal level
  • Minimizing OPEX in an ACM network showing bad aligned antennas not utilizing the potential maximum physical transmission link rate (Bit/Hz/Year)
  • Permanent or on demand check of RF-link quality on terminal level without service interruption
  • Identification of “quick and dirty” installations

RF-check only at installation

Usually, the correct alignment of the antenna is only verified during the pre-transmission line-up phase when accessing the satellite for the very first time. The standard alignment method requires the installer to transmit a test signal (usually a CW signal), which is measured in terms of power and polarization discrimination by the satellite control centre.

Once the VSAT is in operational service, several occurrences (weather conditions, soil erosion, vandalism, construction work, hardware failure, etc.) may lead to antenna misalignment situations causing performance degradation and, even more important, potential interference due to cross-polarization leakage to services transmitting in the opposite polarization.

The challenge

Due to the nature of MF-TDMA traffic, it is a challenge for the service provider to identify misaligned terminal(s) in the network. One possibility is the "clearing the uplink" approach, which means to switch all terminals into CW mode and repeat the polarization discrimination and RF parameter measurement in a similar way as it is done during the line-up phase. But this is a time-consuming task and requires the interruption of operational services.

The Solution

The SIECAMS VSAT monitoring system overcomes these problems by permanently measuring the RF parameters such as polarization discrimination, uplink EIRP, C/N, Eb/N0, modulation type, symbol rate, BER, etc. of all operational terminals belonging to the network. This approach allows detecting and solving problems in a very early phase, even before it will become transparent to the customer and before it will cause significant interference to other services.

Project Partners


Siemens Communication, Media and Technology, Space - Erwin Greilinger


  • JOANNEUM RESEARCH Forschungsgesellschaft mbH - Michael Schmidt
  • University of Salzburg - Bernhard Collini-Nocker

Contact Address