RECV Monitoring and Logging

Overview

RECV implements monitoring points related to the external interface between PST and the Correlator Beamformer (CBF) as described in the CBF to PSR Interface Control Document.

Monitoring Points

Monitoring data that are computed by RECV are published by the PST Beam TANGO device. The attributes are described in detail in PST TANGO Monitoring Attributes and they span metrics covering valid and invalid data received from the CBF. Each of these metrics include a count (bytes or packets) and the current rate of that count in the previous monitoring period (1 second). Monitored attributes have the following definition with respect to CBF-PSR packets

  • Received An expected packet was received in good order

  • Dropped An expected packet was not received, the reason for the the loss is not known

  • Ignored The packet was valid, but the packet precedes the scan start time and so is ignored

  • Malformed The packet’s magic word field did not equal 0xBEADFEED

  • Misordered A packet was substantially out of order, meaning the sequence number field was more than 2*N different to the current PSN. The value of N is configured on a per band process where

    • Low: 16

    • Mid.Band[1|2]: 1024

    • Mid.Band[3|4|5]: 512

  • Misdirected The packet is valid, but did not match the configuration of PST, violating

    • The CBF/PSR packet Beam Number does not match the timing_beam_id in the PST Scan Configuration JSON; or

    • The CBF/PSR packet Scan ID does not match the scan_id provided to PST in the Scan command; or

    • The CBF/PST packet channel number does not match the channels numbers computed by PST after the Configure Scan has been applied. These are computed by PST using the centre_frequency and total_bandwidth fields in the PST Scan Configuration JSON, and then reported back to CSP-LMC via the PST channelBlockConfiguration TANGO attribute.

  • Checksum Failed The number of packets that did not pass the hardware checksum, indicating a corruption in the transport layer or invalid encoding by the CBF. Note: not currently inspected.

  • Timestamp Sync The number of packets with a timestamp that is inconsistent with the packet sequence number. Note: not currently inspected.

  • Sequence Number Sync The packet sequence number is inconsistent with the configured data rate and elapsed time, reported as a Misordered (packet arrives too late) or Dropped (packet arrives too early) packet.

Logging

RECV generates real-time logging during a scan, where the data capture performance is printed, with a 1 second cadence, to standard output in the following format:

RX      DR      Ignore   Misdir   Malform  Misor    Drop     Sleeps
8.192   0.000   0        0        0        0        0        0
8.191   0.000   0        0        0        0        0        0
8.192   0.000   0        0        0        0        0        0

The columns in this output map to attributes reported above:

Column

Description

RX

Current data receive rate in Gigabits per second

DR

Current data drop rate in Gigabits per second

Ignore

Number of ignored packets in the current scan

Misdir

Number of misdirected packets in the current scan

Malform

Number of malformed packets in the current scan

Drop

Number of dropped packets in the current scan

Sleeps

Number of busy-wait sleeps in the current scan, not currently used