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Strona: Performance Graphs
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Backup and Restore Creating Portal Templates Home Performance Graphs Setting Up a WiFi Connection Using the ADS B Receiver Image
2 Performance Graphs
Jacob Wall edytuje tę stronę 2016-09-04 16:55:11 -05:00
Spis treści

The goal of this wiki is to help users understand and interpret their graphs.

How are the graphs made?

  • collectd - a system statistics collection daemon
  • rrdtool - A high performance data logging and graphing system for time series data

Where is the configuration file for the graphs?

/home/pi/adsb-receiver/build/portal/graphs/make-collectd-graphs.sh

What graphs are available?

A lot! Let's break them out into ADS-B related and systems related graphs.

ADS-B Graphs

ADS-B Message Rate

ADS-B Message Rate

  • Messages Received - Your SDR is receiving ADS-B messages that are 112 bits in length. There is a trade-off between taking more messages per aircraft in a defined time frame or having more aircraft seen but less frequent updates. The blue lines represent the number of messages per second your SDR → dump1090/978 decoded, as an average of the sample time frame.

  • Min/Max - I believe this is where most people would get confused when looking at this graph. When collectd creates the graphs, using the rrd data located at /var/lib/collectd/rrd/ it graphs the lines as an average of all samples. So, there are plenty of data points that are not graphed on a line. A yellow filled area represented, during that time frame, the minimum and maximum messages per second that was received.

  • 7 Day Average - The average of the last seven days of messages received from your receiver.

  • Messages > -3dBFS/Hr (RHS) - The count of messages received that had a strong signal. dBFS is decibels relative to full scale. So, if you have a dBFS of 0 then you have attained the maximum that your device can handle. With cables, etc you will never hit 0 dBFS.

  • Positions/Hr (RHS) - How many of the messages received had position reports, or, using MLAT able to get a position.

ADS-B Aircraft Seen / Tracked

ADS-B Aircraft Seen

  • Aircraft Seen / Tracked The number of aircraft that were seen that may or may not have position reports.
  • W/ Positions - Aircraft reported with positions
  • W/o Positions - Aircraft reported without positions
  • mlat - Aircraft reports that were MLAT only.

ADS-B Tracks Seen

ADS-B Tracks

The number of ADS-B reports of messages, that pertain to a single aircraft. If there was only one message then it is denoted in red.

ADS-B Max Range

ADS-B Range

The maximum range of which your receiver was able to pick up an aircraft. The red line is the maximum distance your receiver could pick up an aircraft in the defined time frame.

ADS-B Signal Level

ADS-B Signal

Mean Level - The mean level of signal strength. The higher the number, the better (i.e. -20 is better than -23.2 in this example).

Peak Level - The best signal strength you were able to attain during that defined period of time graphed. The closer to 0 that number is, the better.

Noise - Wikipedia defines noise as a general term for unwanted (and, in general, unknown) modifications that a signal may suffer during capture, storage, transmission, processing, or conversion.

ADS-B Message Rate

ADS-B Message Rate

  • Messages Received - Your SDR is receiving ADS-B messages that are 112 bits in length. There is a trade-off between taking more messages per aircraft in a defined time frame or having more aircraft seen but less frequent updates. The blue lines represent the number of

  • Messages > -3dBFS/Hr (RHS) - The count of messages received that had a strong signal. dBFS is decibels relative to full scale. So, if you have a dBFS of 0 then you have attained the maximum that your device can handle. With cables, etc you will never hit 0 dBFS, but -3 dBFS is a good benchmark to try and hit (i.e. with a filter).

  • Positions/Hr (RHS) - How many of the messages received had position reports, or, using MLAT able to get a position.

ADS-B Message Rate / Aircraft

ADS-B Aircraft Message Rate

  • Messages / Aircraft - The average number of messages received by an aircraft, during that period. =SUM(Messages)/SUM(Aircraft)

  • Aircraft Seen / Tracked - The number of aircraft seen or tracked by your ADS-B receiver.

ADS-B CPU Utilization

ADS-B CPU Utilization

  • USB - How much of the CPU usage is attributed to the SDR that plugs into the USB port of your raspberrypi.

  • Other - Other uses of CPU beyond that of the USB and demodulator.

  • Demodulator - dump1090 and dump978 are both demodulators. So, essentially, how much of the CPU usage was attributed to dump1090/dump978.