# VDIFPacker — Troubleshooting

## No data written to disk

**Cause**: Recording has not been started via the message queue, or `output_type` does not
include `"disk"`.

**Resolution**: Check that `mq_control` matches the queue name used by the Field System
Interface. Verify `output_type` in the active configuration via `?sensor-value current-config`.

---

## UDP frames not received by jive5ab

**Cause**: `udp.dest_ip` does not point to the jive5ab host, or jive5ab is not listening on
`udp.dest_port`.

**Resolution**: Confirm `udp.dest_ip` and `udp.dest_port` in the configuration. On the
jive5ab host verify the service is running and listening:
```bash
ss -ulnp | grep 4991
```

---

## `recording-state` stuck at `recording` after observation ends

**Cause**: The Field System Interface did not send a stop message to the POSIX queue, or the
queue name is mismatched.

**Resolution**: Check that `mq_control` in the vdif_packer config matches
`mq_control_name` in the Field System Interface config. Restart the pipeline to clear the
queue.

---

## High heap drop rate

**Cause**: The `vdif_packer` binary cannot keep up with the input data rate, or the DADA
ring buffer is too small.

**Resolution**: Check CPU pinning and reduce `nfft` or `naccumulate` to lower processing
load. Verify that no other process is competing for the input NIC.

---

## `vdif-channel-mean` sensor shows unexpected values

**Cause**: The DDC output levels are outside the expected range (e.g., due to ADC clipping
or incorrect attenuation).

**Resolution**: Check the DBBC attenuator settings via the Field System Interface. Adjust
`digitizer_threshold` if automatic level control is enabled.

---

## Log locations

| Log | Location |
|---|---|
| Container stdout | `docker logs vdif_packer` |
| vdif_packer binary output | included in container stdout |
| Signal level monitoring | Grafana → visualizations panel |
| Waterfall spectrogram | Grafana → waterfall panel |