Specgram Filter

The foglamp-filter-specgram is a filter that generates spectrogram images from incoming signal data based on defined configuration.

Specgram filters are added in the same way as any other filters.

  • Click on the Applications add icon for your service or task.

  • Select the specgram plugin from the list of available plugins.

  • Name your specgram filter instance

  • Click Next and you will be presented with the configuration page as in the image below. Configure as required.

  • Enable the filter and click Done to activate it


  • Enabled: Whether this filter is to be enabled

  • Log level: Logging level for debug/error information

  • Asset from which vibration data is read: Asset name containing the signal data to create spectrograms for

  • Output asset indicating small shoot discharge length: The asset name under which small shoot discharge width and timing is reported

  • Comma separated TS and Data channel(s): comma separated list of columns for timestamp (mandatory) and data channels to be processed

  • Sampling rate (per sec): The sampling rate of the incoming signal data

  • Forward data: Whether to forward original vibration data down the filter chain

  • Vibration data evaluation interval: Time interval after which to generate spectrogram images

  • Delete spectrogram images older than these many days: Number of days after which older spectrogram images may be discarded

  • Destination directory: Destination directory to store spectrogram images organized into date-wise directories

  • Data stream filtering: Whether to filter the data stream based on subsequent config parameter values: “Periodic event UTC timestamp” & “Event repetition time” or the data stream is already filtered. “Filter data stream” option would typically be required when using this filter on the south service that ingresses vibration data into Foglamp. And “Pre-filtered data stream” would be used in the conditional forwarding case where data has already been filtered and only interesting data has been forwarded using a notification service instance that might be using notify-north delivery plugin. So in latter case, spectrogram filter would process all incoming data and won’t use the values of “Periodic event UTC timestamp” & “Event repetition time” config params.

  • Periodic event UTC timestamp: UTC Timestamp (potentially in the past) when a periodic event of interest happened/would happen (e.g. a small shoot event)

  • Event repetition time: The time after which the desired event repeats (e.g. small shoot frequency i.e. 31 mins)

  • Pre event time: The amount of time to consider for collection before the desired event [eg., 1min]

  • Event duration: The duration for desired event [eg., 1min]

  • Post event time: The amount of time to consider for collection after the desired event [eg., 1min]