# DBBC Plugin Overview

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The DBBC plugin implements the EDD backend for VLBI observations at Effelsberg using the
Digital Base Band Converter signal path. It receives wideband digitiser data, extracts narrow
subbands via GPU-accelerated digital down-conversion, packs the result into VDIF frames, and
delivers them to a disk recorder or sends them over the network for real-time correlation.

The plugin provides two **pipelines** controlled by the EDD Master Controller per
observation, and two **services** that run continuously to bridge external systems.
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## Pipelines

| Pipeline | Entry Point | Purpose |
|---|---|---|
| [DigitalDownConverter](ddc_processor/overview.md) | `edd_ddc_processor` | GPU digital down-conversion of packetizer data |
| [VDIFPacker](vdif_packer/overview.md) | `edd_vdif_packer` | VDIF frame packing and disk/network output |

## Services

| Service | Container | Purpose |
|---|---|---|
| [FieldSystemInterface](field_system_interface/overview.md) | `field_system_interface` | KATCP bridge between Field System and EDD |
| [jive5ab](jive5ab/overview.md) | `edd_jive5ab` | VLBI recorder, accepts UDP VDIF from VDIFPacker |

## Data Flow

```{mermaid}
graph LR
    packetizer["MPIFR Packetizer\n4 Gsps ADC"]
    ddc["DigitalDownConverter\npipeline"]
    vdif["VDIFPacker\npipeline"]
    disk["Disk"]
    jive["jive5ab\nservice"]
    fs["Field System\n(telescope control)"]
    fsi["FieldSystemInterface\nservice"]
    mc["EDD Master\nController"]

    packetizer -->|"SPEAD2\nMPIFR_EDD_Packetizer:2"| ddc
    ddc -->|"SPEAD2\nDigitalDownConverter:1"| vdif
    vdif --> disk
    vdif -->|"UDP VDIF"| jive
    fs <-->|"DBBC / Mark5 protocol"| fsi
    fsi <-->|"KATCP"| mc
    mc -->|"configure / start / stop"| ddc
    mc -->|"configure / start / stop"| vdif
```

## Docker Image

Both pipelines and the FieldSystemInterface run inside the `edd_dbbc` image. jive5ab runs in
its own `jive5ab` image. The images are built by GitLab CI from the Dockerfiles in
`roles/edd_dbbc/templates/` and `roles/jive5ab/templates/` respectively.