Communication Engineering MCQs | Page - 4

 the repeated symbols are called as chips.

 slow frequency hopping is several modulation per frequency hop.

 fast frequency hopping is several frequency hops per modulation.

 in frequency hopping technique hop duration is shorter than the symbol duration.

 frequency division multiple access (fdma) assigns individual channels to individual users. each user is allocated a unique frequency band or channel. these channels are assigned on demand to users who request service.

 if an fdma channel is not in use, it sits idle and cannot be used by other users to increase or share capacity. it is essentially a wasted resource.

 the bandwidth of fdma channels is relatively narrow as each channel supports only one circuit per carrier. that is, fdma is usually implemented in narrow band systems.

 fdma systems have higher cell site system costs as compared to tdma systems. it is due to single channel per carrier design, and the need to use costly bandpass filters to eliminate spurious radiation at the base station.

 intermodulation (im) frequency is undesired rf radiation which can interfere with other channels in the fdma systems. the nonlinearities cause signal spreading in the frequency domain and generate im frequency.

 the first us analog cellular system, the advanced mobile phone system (amps) is based on fdma/fdd. a single user occupies a single channel while the call is in progress.