Displaying FFT Analysis with xy Graph

Grafana InfluxDB
1

  • What Grafana version and what operating system are you using?
    I’m working with Grafana V9.4.7 on Windows 10

  • What are you trying to achieve?
    I want to display a FFT Analysis with Grafana. The Analysis is done within a python script. I transfer the results with MQTT to InfluxDB.

  • How are you trying to achieve it?
    I tried to transfer the data in different formats:

  1. Two different topics for the frequency and the magnitude. I can display the values in grafana with mqtt_consumer.
  2. One topic for both values in the following format: FFT = {“frequency”: 0.0, “magnitude”: 1.9435151515151514}. Grafana tells me “No data”
  3. One topic for both values in the following format: FFT = [62.5, 0.0026666666666664805]. Grafana tells me “No data”

This is my query: SELECT mean(“value”) FROM “mqtt_consumer” WHERE (“topic” = ‘SENS/Measurements/MPU/FFT’) AND $timeFilter GROUP BY time($__interval) fill(null)

  • What happened?
    The connection should be not the problem because I can receive the same topics for the first case. But I can’t display them with a table or a xy graph.

  • What did you expect to happen?
    I expected in the second case, that I can see a table in this format:
    | Timestamp | Frequency | Magnitude |

  • Can you copy/paste the configuration(s) that you are having problems with?
    This is my query and also most likely my only configuration: SELECT mean(“value”) FROM “mqtt_consumer” WHERE (“topic” = ‘SENS/Measurements/MPU/FFT’) AND $timeFilter GROUP BY time($__interval) fill(null)
    There are no more configurations with the xy Graph because I already can’t display the data with a table.

  • Did you receive any errors in the Grafana UI or in related logs? If so, please tell us exactly what they were.
    No, I don’t receive any error messages.

  • Did you follow any online instructions? If so, what is the URL?
    I’m really new to Grafana and have some issues with finding easy documentation for me as a beginner for this exact subject. Hopefully the community can help me. Please tell me if any important information is missing. Thank you very much!

2

Welcome @marianutz

is the data in value column literally either

FFT = {“frequency”: 0.0, “magnitude”: 1.9435151515151514}

or

FFT = [62.5, 0.0026666666666664805]

3

Hi @yosiasz

Thank you for your reply!

the MQTT Broker receives both formats at the moment. (The exact topics are …/MPU/FFT and …/test/FFT.) But I can see none of them in Grafana in coumns.