Microtronix Spectrum Analysis software plays an audio file through the Artificial Mouth or one of the telephone interfaces (POTS, Handset, IP, ISDN, etc...), and analyzes the received signal at the artificial ear or another telephone interface. Using FFT analysis, the frequency response of the signal path is determined.

This feature can be used to measure the frequency response and loudness rating of the Send, Receive, or Sidetone signal path of a telephone. Spectrum Analysis can also be applied to other measurements such as weighted terminal coupling loss (TCLw).

The test signal used by the Spectrum Test is played from a WAV file on the hard disk of the Test System. Using appropriate sound files, it is possible to perform tests using a wide range of different signals including noise, voice and artificial voice.

Testing with signals that simulate the conditions of actual use is important for certain types of telephones. For example, a telephone that utilizes digital signal processing to implement an echo canceller or high compression codec may respond differently to voice-like signals than it does to sine waves.

The Microtronix Products that support the Spectrum Analysis Option include the following:

• Telephone Acoustic Tester (TAT)
• IP-II Phone Test System
• Wireline Phone Test System (WPTS)
• IP Acoustic Tester (IPAT)

Features of Spectrum Analysis

• The software can pre-equalize the audio to compensate for the frequency response of the
  artificial mouth. Residual error after the equalization process is taken into account during
  analysis.

• The output amplitude of the stimulus signal can be set based on either RMS or the Active   Speech Level algorithm defined in ITU P.56

• The play file can be converted between the different sample rates supported by the test  
  system. For example a 32 kHz file can be converted to 8 kHz to be played through a
  narrow band IP protocol stack.