SurfBeam Modem Lock Test



Use the Modem Lock Test to determine if the satellite modem can lock onto the signal across the satellite to the gateway.

Important: While a Modem Lock determines if the modem and the gateway are communicating, the modem connection can still be poor. Use the Poor Performing Modem Matrix to resolve poor communication link issues.

This Job Aid covers:

Unprovisioned Modem Lock

Possible Results

Tools Required

Required Escalation Data

Test Details

This Job Aid supports all Technician audiences.

Unprovisioned Modem Lock:

If modem replacement occurs during the repair process, the replacement modem is an un-provisioned modem. Complete the un-provisioned modem lock process before starting the modem swap provisioning process. Use the Antenna Pointing Aid (APA) and the Viasat Attenuation Pads in the Coax RX path during un-provisioned modem lock for two reasons:

  • Because the modem can communicate with every beam frequency offered by the satellite, the APA and Attenuators force the modem to ignore all frequencies not outside the beam where the customer site is located.
  • Because the Network Multi-rate Frequency management software allows sets of modems to communicate on different frequencies within the beam depending on environmental factors, the APA and Attenuators force the modem to use the correct frequency for the local area within the beam.


Power down modem

Disconnect Ethernet cable

If this is a replacement modem, add the APA and Attenuators to the Coax RX cable path.

Power up modem

Observe Modem Lock process

Possible Results

There are two possible outcomes for this test:

    • Modem Lock OK
    • Validate internet access with Internet Access Test
    • Modem Lock Failed
    • Evaluate failure with Modem Short-Cable Test

Test Details

Validate that the appropriate pre-tests are complete as detailed on the Trouble Isolation Check Sheet.

Disconnect the AC power plug from the power source to power down the modem.

Connect the Transmit and Receive COAX cables (along with the APA and Attenuators if this is a Replacement Modem) to the appropriate connectors on the back of the modem.

Disconnect the Ethernet cable from the modem.

Reconnect the modem AC power cable to the power source.

Observe the modem LED activity.


  • If Modem Lock occurs, the test is PASSED.
  • If Modem Lock does not occur, the test is FAILED.

Use the results of this test to determine the next step based on the checklist.