TTMER2: Call Paths Testing - "In-circuit" measurements on ISDN and VOIP network elements

Control questions

You must give an answer to 5 questions at the beginning of the laboratory exercise. One wrong answer will make the mark given to the measuring with one grade worse. Two or more wrong answers will result a supplementary measuring!

  1. How to model an analogue channel?
  2. Give the definitions of the network-characteristic functions used also in the measuring practice!
  3. What is the criterion of the distortionless signal transmission in the frequency domain?
  4. Enumerate the distortions of a not exactly linear channel!
  5. Give the characteristics of a narrowband noise measuring signal!
  6. What kind of measures are executed on a PCM telecommunication channel for the determination of quality of the channel?
  7. What does MTTS mean?
  8. How large is the absolute enhancement of the +3,5 dBr of input, and -3,5 dBr of output connection level channel?
  9. Input connection level of a -7 dB nominal enhancement channel +3,3 dBr, and its output connection level is -3,4 dBr. How large is the difference of the enhancement from the nominal value? Is this kind of difference allowed?
  10. What influence is upon the relative connection levels, if we raise the attenuation of channel units at the sides of the transmitter and the receiver?
  11. What is the auxiliary signal? What is the purpose of the auxiliary signal at the measurement of the basic noise?
  12. What are dBu, dBm, dBm0, dBm0p, dBr? Where can the dBm0, and the dBr be derived?
  13. Give the principle of the enhancement measure. With what kind of variable parameters and measuring signals can the measurement be executed?
  14. How can the measure of drive of a channel be determined from a linearity measurement?
  15. Give the principle of the quantizing distortion measurement!
  16. What is the psophometer?
  17. A measure must be executed with a signal levelled at -10 dBm0. Measuring signal must be fed into at a point levelled on +3,5 dBr/600 ohms. Signal level can be set in dBu. How large is the value of level set on the generator?
  18. We give a sinusoid signal at the level of -25 dBm0 to the input of a channel with connection level of +3,5 dBr/600 ohms. Level of the second harmonic of the signal at the output point of -3,5 dBr/600 ohms is -68,5 dBm. How large is the second harmonic attenuation of distortion?
  19. We give a signal with a level of -10 dBm0 to the input of the channel with connection level of +3,5 dBr/600 ohms. How large is the level of the received signal in dBm0 at the output of the channel which has a connection level of -3,5 dBr/600 ohms?
  20. How can we examine the correctness of the operation of channel filters?
  21. How Hz-s of sinusoid signal can be resulted by a sinusoid signal of 8500 Hz-s given to the input of the PCM speech channel from the signal lapstreak?
  22. What does hybrid mean? Give the principle of operation of the hybrid!
  23. How can you measure the hybrid closing attenuation of an analogue interface of an exchange?
  24. What are MSS and MSSN? How many MSS are located in the MSSN of the laboratory?
  25. What is Media Gateway?
  26. Draw the hardware block scheme of a Media Gateway implemented in MSS!
  27. Review the main functions of the Media Gateway!
  28. Review some procedures used for the handling of the voice channels in VoIP!