This question appears in Mumbai University > Satellite Communication and Network subject

Marks: 5 M

Year: May 2015

AM to PM conversion

• Due to the non-linear amplification characteristics of the amplifier, an intermodulation product will occur when inputting multiple signals, thereby generating interference in each signal
• In addition, as the electrical length of the travelling wave tube operating in the non-linear region varies with input signal power, if amplitude modulation (AM) is present in the input signal, phase modulation (PM) will appear in the output signal. This phenomenon is called AM-PM conversion ins satellite communication, and it also gives rise to an intermodulation product.

AM-PM Conversion

• When the envelope variation is due to baseband modulation, the AM to PM of the non-linear power amplifier may cause the modulated information to be coupled into the carrier as a form of intelligible cross talk.