通信工程代写 | MSc in Communications Engineering: Introduction to Communications

本次英国代写是通信工程基础introduction to communication的限时测试

放大器的电压增益为 20。假设输入和输出阻抗相同，它的功率增益是多少分贝？
放大器的输入信号为 10µV，阻抗为 50Ω，输出为 2W。 以 dB 为单位求其增益。
求出以下通信系统中的输出功率（以 dBW 和 nW 为单位）以及信噪比：
两个功率为 -10 dBW 的正弦波信号相加。 求信号总和的幂，假设：
正弦波具有相同的频率和相同的相位；
正弦波频率相同但相位相反；
正弦波具有不同的频率。

现在假设正弦波具有不同的频率，但具有功率：

-10 dBW 和 -15 dBW；
-10 dBW 和 -50 dBW。

1. An amplifier has a voltage gain of 20. What is its power gain in dB, assuming that the input and output impedance are the same?

2. An amplifier has an input signal of 10µV with an impedance of 50Ω, and an output of 2W. Find its gain in dB. 

3. Find the output power, in dBW and also in nW, and the signal to noise ratio in the following communication system:

4. Two sine wave signals of power -10 dBW are added together. Find the power of the sum of the signals assuming that :
   1. The sine waves have the same frequency and the same phase;
   2. The sine waves have the same frequency but opposite phase;
   3. The sine waves have different frequencies.

Now assume the sine waves have different frequencies, but have power:

1. -10 dBW and -15 dBW;
2. -10 dBW and -50 dBW.