Advanced Qualification · A-006 Receivers · A-006-003-009
Why are very low noise figures relatively unimportant for a high frequency receiver?
- ARegardless of the front end, the succeeding stages when used on HF are very noisy
- BExternal HF noise, man-made and natural, are higher than the internal noise generated by the receiver
- CIonospheric distortion of the received signal creates high noise levels
- DThe use of SSB and CW on the HF bands overcomes the noise
Correct answer: B — External HF noise, man-made and natural, are higher than the internal noise generated by the receiver. From the official ISED question bank, verified word for word.
Why
On the high frequency bands, the static from lightning, power lines, and other human activity is so loud that it completely drowns out the quiet hiss a receiver makes inside itself. The full explanation — and one for every question — is in Pro.
Practise this section
Receivers is section A-006 of the Advanced exam: Receivers: superheterodyne design, selectivity, sensitivity, images, AGC and noise.
Drill A-006 — free, no account