Satellite Signal Loss at Night: Common Causes
It is a strange complaint: the picture is perfect all day, then every evening it drops out or pixelates. Satellite signal loss at night has a handful of recurring causes, and most of them are easy to fix.
Cause 1: Temperature-Driven LNB Drift
As the air cools, the LNB's local oscillator drifts. On a marginal install, the drift is enough to move transponders off-channel. Symptoms: signal fine in the afternoon, degrading after sunset.
Cause 2: Condensation in the LNB
Night cooling causes dew to form inside the LNB body. The water film absorbs signal. This usually resolves by morning.
Cause 3: Tree and Building Shadows
At night the sun is down, but the satellite arc is fixed. The real cause is often that as the satellite's apparent angle changes, a new obstruction — a chimney, a roof ridge, a newly grown tree — starts to bite at the lower elevation.
Cause 4: Congested Transponders at Peak Time
Some transponders broadcast at higher bitrates during prime time. A marginal signal that held up in the daytime may stutter in the evening when the video stream is denser.
Cause 5: Receiver Power Supply Failing
A weak receiver supply can provide enough LNB voltage when the set-top box is cold but sag once it has run for hours. Symptoms: dropout late evening, recovered after a reboot.
How to Diagnose
- Watch the signal quality meter from afternoon through evening.
- Does the dropout correlate with temperature or with the programme?
- Reboot the receiver at the first sign of trouble — if it recovers, suspect the receiver supply.
Fixes
- Peak the dish and add signal margin.
- Replace an aging LNB whose oscillator has drifted.
- Check the receiver's power supply.
- Clear new obstructions in the southern path.
Loss at night is usually a margin problem that only reveals itself when conditions change. Add a little extra signal headroom and the evenings stabilise.
