Telemetry reception – Fault isolation: no frames, or satellite may have gone silent
Fault description
One of these alerts is open:
No decoded frames for a period of time (caution after 12 hours, alarm after 24 hours by default).
Scheduled observations in a row produced no frames (alarm). The message may include the chance that the satellite has really gone quiet.
Frames arrive only when a volunteer station has heard the satellite and uploaded the recording. Gaps of several hours are normal. Most of these alerts are caused by the ground network, not the spacecraft.
Preliminary requirements
Required conditions
- An alert or symptom described above is present.
Required persons
1 × Operator. Estimated time: 10 to 30 minutes.
Support equipment
- A computer or phone with a web browser, on the same network as the server
- Terminal access to the server, for example over SSH, for steps on the server
Supplies
None
Spares
None
Safety conditions
None
Isolation procedure
Look at the other open alerts on the Console tab.
Is there also an alert that the server cannot reach SatNOGS, or that the API key is missing or rejected?
Yes go to Result ANo go to Step 2
Find the satellite's page on db.satnogs.org and look at its most recent frames.
Has any station uploaded frames for the satellite since the last frame shown in Downlink Desk?
Yes go to Step 3No go to Step 4
Select the Frames tab and look at the newest frames.
Are the new frames listed, but shown as unrecognised or not decoded?
Yes go to Result BNo go to Result C
Select the Passes & stations tab. Look at the stations that missed the satellite and their Hit rate (30 d).
Do the stations that missed usually hear the satellite (a high hit rate), and is the alert's stated chance of silence high?
Yes go to Result ENo go to Result D
Results
The cause is on the ground side: Downlink Desk is not collecting data. Go to SatNOGS link – Fault isolation: data is not being collected (DMC-DLD-A-10-10-00-00A-400A-A).
The satellite is transmitting, but its frames cannot be decoded. The satellite may have changed its telemetry format, or the frames may be other radio traffic. Write a log note with the time of the first undecoded frame. Report it to whoever maintains the server, so the decoder can be checked.
The frames exist on SatNOGS but have not been collected yet. Wait for the next fetch, which runs every 30 minutes by default. If you have access to the server, you can fetch now with cd ~/downlink-desk && .venv/bin/python -m downlink_desk.fetch --force. If the frames still do not appear, go to SatNOGS link – Fault isolation: data is not being collected (DMC-DLD-A-10-10-00-00A-400A-A).
The misses are most likely from stations that often miss the satellite, not a silent spacecraft. Acknowledge the alert. Write a log note naming the stations. If the alert will keep firing until the next good pass, shelve it for 6 hours with that reason. Check again after the next scheduled pass by a reliable station.
The satellite may have gone silent. Acknowledge the alert and leave it open. Write a log note with the time of the last decoded frame and the stations that missed. Check the space weather panel for a storm at that time, and check the satellite team's public channels for planned downtime. Downlink Desk is not the mission's own system: do not report the satellite as lost on the basis of this alert alone. Hand the alert over at the end of the shift.
Requirements after job completion
- The cause is found and recorded in the log, or the alert is handed over with notes.