Signal Display Metrics Generator

This processor takes in the Full Visibilities, and outputs them based on which metrics this processor is looking at, and the associated Flow entries.

Configuration

Configuring this processor is in 2 parts, first there are CLI parameters that are given, and then there are also ConfigDB Flow entries that are also used.

ENV Variables

Some environment variables can be used to configure the processor.

Value	Default	Required	Comment
SDP_KAFKA_HOST	None	No	This variable will only get fetched if the Config DB has been disabled.
SDP_PB_ID	pb-unknown	Yes	This specifies which processing block to look at, without this variable other items will not be configured, for example flow entries. It isn’t needed when using --use-random-ids.
SDP_EB_ID	eb-unknown	No	This will get overridden with the Config DB entry (if found)
SDP_SUBARRAY_ID	01	No	This will get overridden with the Config DB entry (if found)

Command Line Options

Value	Default	Required	Comment
--use-random-ids	False	No	If set the IDs will be randomized, and no Config DB data will be used.
--ignore-config-db	False	No	Never try connect to the Config DB (use defaults or ENV values for everything.)
--disable-kafka	False	No	Send no data to Kafka if set.
--metrics	stats	Yes	Set the comma-separated list of metrics this processor should care about. Besides metric names, the other options are stats, and all.

Flow Entries

The expected flow entries should look like the following:

{
    "data_model": "MetricPayload",
    "sink": {
        "format": "msgpack_numpy",
        "host": "ska-sdp-kafka:9092",
        "kind": "data-queue",
        "topics": "metrics-amplitude-01"
    },
    "sources": [
        {
            "function": "SignalDisplayMetrics",
            "parameters": {
                "metric_type": "amplitude",
                "nchan_avg": 50,
                "additional_windows": 5,
                "rounding_sensitivity": 5
            },
            "uri": "metrics://signal-display/01/amplitude/low_res"
        }
    ]
}

These flow entries should only be configured from ska-sdp-scripts/vis-receive.

Flow Entry State

The state of a flow entry is used to configure high-resolution sections of the metric data.

A state entry should resemble the following:

{
    "windows": [
        {
            "start": 1000000,
            "end": 2000000,
            "channels_averaged": 1
        }
    ]
}

Note that len(state["windows"]) should be less than or equal to flow["sources"][0]["parameters"]["additional_windows"].

Note that the state can also be None, and the windows key can be missing.

Metrics Available

The metrics that the processor can currently generate are listed below, with a short description. For a better description refer to the full documentation on the Signal Display Documentation:

Stats

These are general stats regarding the current receive process. Currently you can get:

• The last known state of this receiver (most of the time this will be receiving).

• The amount of payloads received (these can be aggregated).

• The amount of time slices received (multiple of these can be received per payload).

• The amount of seconds between this payload, and the previous payload (includes processing time).

Graphable Metrics

The following metrics are available for graphing and the documentation is available in the Signal Display Documentation:

• Spectrum

• Polarization vs Phase

• Polarization vs Amplitude

• Lag Plot

• Band Averaged Cross Correlation Power

• UV Coverage

• Phase variance as a function of uv/baseline distance

• Amplitude variance as a function of uv/baseline distance

The structure of these metrics are available in Signal Display Metrics.