Dealing With Uplink Overpower or Dirty Carrier

Uplink Overpower or Dirty Carrier From Your Network

Objective: Stop one of your terminals from over-driving the transponder and creating ASI, XPI, or intermod products.

Typical Symptoms

Satellite operator reports:

• Overpowered carrier at [freq], your network ID

On your spectrum view:

• Carrier looks wider or distorted versus nominal mask
• Neighbour carriers show raised noise floor or visible intermod spur lines

Often triggered by:

• Misconfigured output power
• PA in compression
• Multiple carriers on one PA without enough back-off

Immediate Actions (0-15 Min)

• Mute or sharply back-off the suspected carrier
• If multiple terminals share the same transponder:
  • Use Carrier ID or terminal IDs where available to identify the offending remote

Investigation (15-120 Min)

Step 1: Confirm configuration

Check:

• Assigned EIRP or power back-off versus link budget
• Modem output level, upconverter gain, and PA drive settings

Step 2: PA linearity

Run a local output power sweep or intermod or 1 dB compression test where possible to verify the PA is not being over-driven.

Step 3: Cabling and combining

Inspect:

• IF or L-band cabling for poor terminations or wrong connections
• Any multiplexers or combiners that might be feeding unexpected signals back into the uplink chain, causing forwarding interference

Mitigation and Recovery

Restore uplink with:

• Proper power calibration (under sat-operator supervision for shared transponders)
• Correct back-off for multi-carrier PAs

If PA hardware fault is suspected:

• Swap to a known-good PA and re-verify mask and EIRP with the satellite operator

Prevention

Enforce mandatory power-up procedures:

• No transmission until sat-operator gives go-ahead on power and mask

Keep a power and EIRP history per site:

• Deviations from the baseline should trigger automatic alerts

Periodically test PA linearity and document 1 dB compression points for typical operating conditions.