Advanced Qualification · A-006 Receivers · A-006-005-007
Intermodulation interference is produced by:
- A the high-voltage stages in the final amplifier of an amplitude or frequency-modulated transmitter
- B the mixing of more than one signal in the first or second intermediate frequency amplifiers of a receiver
- C the mixing of two or more signals in the front-end of a superheterodyne receiver
- D the interaction of products from high-powered transmitters in the area
Correct answer: C — the mixing of two or more signals in the front-end of a superheterodyne receiver. From the official ISED question bank, verified word for word.
Why
Intermodulation happens when two or more strong signals enter the front end of a superheterodyne receiver and mix together in a non-linear circuit, creating new unwanted frequencies that sound like interference. The full explanation — and one for every question — is in Pro.
Practise this section
Receivers: superheterodyne design, selectivity, sensitivity, images, AGC and noise.