Classifier & Recognition

go2MONITOR Classifier & Recognition


Classifier

o2MONITOR offers different tools for automatic tuning and decoding of signals, a big advantages compared to other decoders where you are fixed to one work flow.

The tools used are:

  • Continuous narrow-band classifier (provided in the production channel)
  • Snapshot classifier, provided in the spectrum (spectrogram/FFT) display
  • Continuous wideband classification provided in the spectrum (spectrogram/FFT) display in Automatic Monitoring and Tasking  (Option) mode
  • Recognition (provided in the production channel)

Types of classification

Classifier Source Classification max. Span max. Signal Bandwidth Timeout
Narrowband Classifier Channel Continuous 100 kHz HF: 20 kHz
VUHF: 50 kHz
No
Snapshot Classifier RX-IQ stream, File Snapshot 1 MHz HF: 20 kHz
VUHF: 50 kHz
No
Wideband Classifier 1 MHz
AMT Option
RX-IQ stream, File Continuous HF: 1 MHz
VUFH: 1 MHz
HF: 20 kHz
VUHF: 50 kHz
3-5 sec
WCL 20 MHz Option
AMT Option
RX-IQ stream, File Continuous
Scanning
Stepping
HF: 2.4 MHz
VUFH: 20 MHz
HF: 20 kHz
VUHF: 50 kHz
3-5 sec

The classifier is an important component of non-cooperative communications monitoring in which a listener desires to intercept unknown signals.

  • The continuous classifier has a big advantage compared to some other classifiers as it tracks each emission from beginning to the end, measures continuously all emission parameters and delivers emission information updates in ~4s time intervals. Using the full signal history is essential to improve the quality of the results. Additionally you get also exact information about the start and end of the emission.
  • The narrowband classifier will only classify one signal in the production channel.
  • The snapshot classifier can classify the selected frequency range and presents you a filtered list of available stations in the selected spectrum. You can assign the signal to a production channel by using drag-and-drop or using the context menu. In the snapshot mode, only a 4s period from the continuous signal input is processed and emission info delivered.
  • The wideband classifier together with Automatic Monitoring and Tasking (AMT option) can:
    • Continuously classify the selected frequency range
    • Steps thru a frequency range and stores the result using the option "Automatic Monitoring and Tasking"
    • Scans thru a frequency range and stores the result using the option "Automatic Monitoring and Tasking". This mode requires receivers that can do independent scanning and only stop if the find a signal, advantage: faster than stepping.

Recognition & Decoding

In recognition mode, the production channel uses a configurable list of decoders and checks in parallel which one of these decoders is matching the received signal. If a usable decoder is found, then the signal is demodulated, decoded and the results are displayed in the result view.

Multiple decoder lists can be configured and modified. Depending on the task, the list can be configured with the required decoders.

During recognition and decoding the production channel is running in a continuous loop:

  1. Detection of the signal in a range predefined around the center frequency.
  2. Check of all decoders in the modem list
  3. If a match exists, the decoder starts and delivers output
  4. If the end of transmission is detected or the decoder is no longer able to decode the signal, the procedure starts at 1.
The advantages are:
  • No missing output if the protocol or modem will change during a transmission. Scenarios with ALE, then traffic in STANAG 4285 and later change to PACTOR-III require no operator interaction
  • No missing output if the frequency is changed inside the predefined range

Classification, Recognition & Decoding

During classification, recognition and decoding the production channel is running in a continuous loop:

  1. Classify the signal in the range predefined around the center frequency
  2. Detection of the signal.
  3. With the information (modulation, symbol-rate, shift etc,) of the classification, a dynamic modem list is prepared containing only the decoders that fulfill the criteria of the classifier result. Such a list is much shorter than a modem list containing all the decoders.
  4. Check of all decoders in the dynamic modem list
  5. If a usable decoder is found, then the signal is demodulated, decoded and the results are displayed in the result view. All this operations are buffered to avoid any loss of data
  6. If the end of transmission is detected or the decoder is no longer able to decode the signal or the classifier detects a new modulation , then the procedure starts at 1.

This setting requires less processing power, compared to recognition and decoding as the list of decoders is normally shorter.