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IDU vs ODU | difference between IDU and ODU in VSAT

This page compares IDU vs ODU and mentions difference between IDU and ODU used in VSAT. IDU stands for Indoor Unit and ODU stands for Outdoor Unit. Refer VSAT basics before understanding IDU and ODU as these are terms associated with VSAT (Very Small Aperture Terminal).

VSAT system is used to provide remote connectivity with satellite to avail voice and data services. It helps in making voice calls and data calls for remote users where other means of communication is difficult to install.

VSAT connects with the satellite using various frequency bands as per the need. Typically it includes C band, Ku band etc.

IDU-Indoor Unit

Typically VSAT system components are categorized into IDU and ODU. The components or subsystems of a VSAT which are located inside the office or home premises fall under IDU. As mentioned IDU stands for Indoor Unit.

IDU consists of MUX/DEMUX, Satellite modem (modulator-demodulator), EDU (Encryption decryption Unit) and subscriber interfacing part. Following are the functions of each of these subsystems.
• MUX/DEMUX: It is used to provide multiplexing of voice channels and data channels at the transmit end while demultiplexing at the receive end.
• Satellite Modem: It consists of modulator at transmit end and demodulator at receive end. Modulator does modulation of baseband information (voice/data) at IF (either 70+/-18 MHz or 140+/-18 MHz). Modulator generated modulated IF frequency. Demodulator does the reverse operation i.e. demodulation of modulated IF to retrieve baseband information.
• Baseband interface: This is voice and data connectivity. Usually voice can be a subscriber line or exchange connection with 2W E&M or 4W E&M etc. configurations.


ODU-Outdoor Unit

The components or subsystems of a VSAT which are located outside the office or home premises fall under ODU. As mentioned ODU stands for Outdoor Unit.

ODU cosists of RF upconverter/downconverter, RF Power Amplifier, OMT, LNA and Antenna.
Following are the functions of each of these subsystems.
• RF upconverter/downconverter: The Up converter converts modulated IF to modulated RF as per band i.e. C band or Ku band etc. The down converter does the reverse i.e. converts modulated RF to modulated IF.
• RF Power Amplifier: This module provides amplification to the signal output of the RF up converter before transmission via RF antenna.
• LNA: This module provides low noise amplification to the received signal from the satellite.
• OMT: It stands for Ortho-Mode Transducer. It helps in segregating both transmit and receive frequency signals. Refer OMT basics>> for more information.

Satellite and VSAT Related Links

Satellite tutorial   Satellite tutorial   About satellite   Bands   Parts   Orbits   Services   Types   capacity allocations   network configurations   Applications   Remote sensing   VSAT basics   VSAT tutorial   VSAT NMS protocol

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