VDIFPacker — Interfaces

Input Streams

The pipeline consumes one or more SPEAD2 multicast streams in DigitalDownConverter:1 format, one per subband channel. The stream descriptions are provided via input_data_streams.

Field	Value
Format	DigitalDownConverter:1
Bit depth	32 (float-32)
SPEAD2 item: timestamp	id 5632
SPEAD2 item: channel	id 5633
SPEAD2 item: polarization	id 5634
SPEAD2 item: data	id 5635

Output Format

VDIF:1

Field	Value
format	VDIF:1
description	The EDD VDIF stream 1
port	``
sample_rate	0
payload_size	8000
data_rate	500000

VDIF Frame Layout

VDIF frames are produced according to the VLBI Data Interchange Format standard. The payload size defaults to 8000 bytes. Each thread ID carries the channels assigned to it via thread_ids.

UDP Output

When output_type includes "network", the pipeline sends VDIF frames via UDP:

Parameter	Config key	Default
Destination IP	udp.dest_ip	127.0.0.1
Destination port	udp.dest_port	4991 (jive5ab default)
Bind IP	udp.bind_ip	0.0.0.0
Max rate	udp.max_rate	1.1 (relative to nominal)

POSIX Message Queue

Recording is gated by a POSIX message queue. The Field System Interface writes start/stop messages to this queue during an observation.

Parameter	Config key	Default
Queue name	mq_control	/vdif_control_message_server

KATCP Interface

Request	Description
?configure <json>	Load a new configuration
?capture-start	Begin data capture
?capture-stop	Stop data capture
?deconfigure	Release resources
?sensor-list	List available sensors
?sensor-value <name>	Query a sensor