VSAT Terminal Commissioning: What to Check Before You Go Live

Published by Bravosatcom · VSAT Engineering Series

Commissioning a VSAT terminal is the process of configuring the modem, verifying the satellite link, and confirming that the terminal meets the operator’s performance specifications before it is handed over for service. A systematic commissioning procedure saves significant troubleshooting time later and ensures the link will perform as designed throughout its operational life. This guide covers what to check, in what order, and what the acceptance criteria should be.

The Four Phases of VSAT Commissioning

VSAT terminal commissioning phases checklist pre-installation physical modem acceptance — Figure 1 — VSAT commissioning consists of four phases. Each phase must be completed and verified before proceeding to the next. Never begin the TX test without NOC clearance.

Modem Configuration: Key Parameters

Before the modem can acquire the satellite, it must be configured with parameters provided by the satellite operator or network operations centre (NOC). These parameters are site-specific and must not be estimated or copied from another installation. Request a commissioning parameter sheet from the operator before arriving on site.

VSAT modem commissioning parameters receive transmit frequency symbol rate — Figure 2 — Key modem commissioning parameters split by receive and transmit. All transmit parameters must be obtained from the satellite operator NOC — never estimated.

The TX Test: Working with the NOC

The transmit test is the most critical step in commissioning and must never be done without the NOC standing by on a communication channel (phone or email). The procedure:

Confirm with the NOC that they are ready to observe your carrier on their monitoring system.
Set the modem to transmit a CW (continuous wave, unmodulated) carrier at a power level 10–20 dB below the calculated operating level.
The NOC confirms they see the carrier on their spectrum display and reports the measured frequency offset and power level.
Adjust modem output power and frequency offset per NOC instructions until within specification.
Switch to modulated transmission at the operating power level. The NOC confirms the carrier is clean, on-frequency, and within EIRP limits.
The modem registers on the network. Proceed to acceptance testing.

Acceptance Testing Criteria

VSAT commissioning acceptance test pass fail criteria Eb/No BER throughput latency — Figure 3 — Acceptance test criteria for VSAT commissioning. Document all results at commissioning to establish a performance baseline for future troubleshooting.

Common Commissioning Problems and Solutions

The most frequent issues during VSAT commissioning are:

No Rx lock: Check IFL cable connections (BUC and LNB ends), verify LNB power supply voltage at the modem’s LNB supply output, confirm antenna polarisation and pointing, verify modem Rx frequency matches operator parameters.
Low Eb/No: Re-peak the antenna, inspect IFL cable connectors for moisture or poor crimp, verify LNB noise figure (compare to spec), check for nearby interference sources (adjacent satellite, terrestrial microwave).
NOC cannot see TX carrier: Verify modem is set to transmit, check BUC power supply voltage, check waveguide or connector between BUC and feed, verify TX frequency in modem config matches NOC parameter sheet.
High latency (>700ms RTT): Normal GEO latency is 550–650 ms. Higher values indicate IP network buffering or TCP optimiser misconfiguration at the hub. Report to the NOC — this is not an RF issue.

Frequently Asked Questions

How long does VSAT commissioning typically take?

For an experienced engineer with all parameters ready and the NOC on standby, a single fixed VSAT terminal can be commissioned in 2–4 hours including physical installation and modem configuration. If the physical installation is pre-done and the engineer is commissioning only (modem config, TX test, acceptance), 1–2 hours is typical. Complex sites with multiple feeds, redundant systems, or integration with enterprise networks take longer.

Can commissioning be done remotely?

The physical pointing must be done on-site. Modem configuration and TX test coordination can be done remotely if the modem has remote access and someone on-site can physically adjust the antenna per phone instructions. Most network operators support remote commissioning for operators who know the equipment. The NOC handles the TX test verification remotely as standard practice regardless of who is on-site.