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VSAT NMS(Network Management System) Tutorial


Refer VSAT tutorial covering following sub topics:
RF Terminology   Satellite Terminology  Access types  SCPC  MCPC  RF Transceiver  C band RFT  Microstrip  RF upconverter design   Power Amplifier  what is modulation  satellite Modem  Link Budget 


This tutorial on VSAT NMS describes NMS (Network Management System) used for monitoring and control of Hub Station and VSAT subsystems. This is for star configuration of VSATs based satellite applications.

As shown in figure, there are two main parts of NMS, viz. local NMS and Remote NMS. Local NMS monitor and control (M&C) subsystems at respective locations i.e. either at Hub station or at VSAT. Remote NMS at Hub station takes care of M&C of remote VSATs.

NMS (Network Management System) for VSAT

Usually at Hub station following subsystems will be available.

1. Satellite Modems and modem switch over unit
2. Up converters and Up converter switch over unit
3. Down converter and Down converter switch over unit
4. LNA and LNA switch over unit
5. HPA and HPA switch over unit
6. MUX with switch over unit
7. NMS controller Unit
8. NMS GUI software running in PC

Usually at VSAT following subsystems will be available.

1. MUX 2. MODEM 3. RF ODU 4. LNA 5.PA 6. NMS controller

Switch over unit helps switch from one active unit to hot standby unit in case of fault/failure in active working unit.

NMS controller at Hub and VSAT consists of microcontroller hardware and software logic and will interface with respective subsystems as mentioned. All the subsystems manufacturer usually build protocol in the firmware of the device so that the device can be remotely monitored and controlled.

NMS GUI software at Hub station interface with NMS controller at Hub. Following are the NMS protocols used at VSAT and Hub station.

NMS Protocol at VSAT/Hub

VSAT NMS Protocol

As shown in the figure NMS protocol consists of following fields.

Station Address- It is the VSAT address.
Unit Address- It is the subsystem address, i.e. MUX/Modem/RF ODU/SSPA/LNA. For example 0x65 is used for ODU, 0x01 for Modem and 0x6a for MUX.
Single query/block query- segregates between single query or block query
Command/Query- This field indicates whether the packet is indicates command to set some parameters or query for obtaining some parameter of the unit address (subsystem address). There are different fields defined at this place to indicate different functions, for example 0xcc for query, 0xaa for command and 0xbb for response from remote etc.
Data Size- size of the data fields.
Data 1 and data 2 - Data fields carried in the packet.
Checksum helps in error detection and is usually equal to 256- (sum of all previous bytes in the message).

VSAT system useful References

Refer our page on RF Link Budget which covers basics of RF link budget and friis equation.
Example calculation of VSAT-1(2.4 meter) to Ku band satellite to VSAT-2(2.4 meter) star system RF Link Budget, Download Excel sheet
Refer our Page on LNB basics and manufacturers.
Refer our page on RF LNA manufacturers.
Refer our page on VSAT subsystem equipment Providers.
Antenna diversity types  SCPC   MCPC   Set Top Box  Receiver sensitivity versus receiver selectivity  VSAT NMS protocol  Satellite Ground Station  RF measurements   waveguide basics   GPS Basics   SCADA system basics  

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