I am preparing for the RF course exam. I have an old question on hand that I am trying to solve. Please review my attempt.
A simple spectrum analyzer with superheterodyne receiver having 10.7 MHz intermediate frequency is given. It works well unless the analyzer is used to analyze a signal on 318.6 MHz by setting the analyzer to 318.6 MHz center frequency, 5 MHz span, and 10 kHz RBW. Before we switch on the desired transmitter, the analyzer detects a clear signal at the center frequency. Later, when we learn that there is a 340 MHz transmitter in the same antenna tower you immediately realize what happened.
1) Explain the "issue".
2) Improve the design of the spectrum analyzer that protects against this kind of problem.
Does the below arguments make sense to you? Thanks.
a) The adjacent channel interference generated by the carrier at 340 MHz frequency could be leaked to the spectrum analyzer receiver at 318.6 MHz.
b) The IF bandwidth of the receiver can be narrower in order to reject the adjacent channel interferences.