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BrianG · 04.15.2009, 09:42 PM

Before you can ask that question, one should ask what the differences between the various types are.

AM:
AM stands for Amplitude Modulation. The control (throttle, steering, etc) signals are superimposed onto a carrier wave (radio frequency) such that the amplitude of the radio signal varies in proportion to those control signals. This works fine, except it is vary susceptible to noise. Noise (RF interference, power line induction, etc) affects the tops and bottoms of the radio waves. Unfortunately, this is where the signal is carried so it gets washed out. The receiver then receives a mix of crap and valid signal and doesn't know what to do (or "guesses" wrong) and you get erratic behavior.

FM:
FM stands for Frequency Modulation. In this type, the carrier wave frequency shifts in proportion to the control signals. During transmission, noise still affects the tops and bottoms of the carrier wave, but the receiver chops these off (and therefore the noise is gone as well) and focuses on the shift in frequency, not the amplitude. Therefore, noise rejection is a lot better. However, if the noise is bad enough, or close enough in frequency, you can still "confuse" the receiver and get erratic behavior similar to AM.

2.4:
This is a whole different animal. Not only is it more than 30X times higher in frequency (helping to avoid the common noise sources), but the control signals are converted to data packets and then modulated into the high carrier frequency. At the receiver end, it performs data integrity checks (like error correction) to make sure the packets are valid. There is a bit more to it, but as you can see, 2.4 is a lot more tolerant to noise.

	(#2)
BrianG RC-Monster Admin Offline Posts: 14,609 Join Date: Nov 2005 Location: Des Moines, IA	04.15.2009, 09:42 PM Before you can ask that question, one should ask what the differences between the various types are. AM: AM stands for Amplitude Modulation. The control (throttle, steering, etc) signals are superimposed onto a carrier wave (radio frequency) such that the amplitude of the radio signal varies in proportion to those control signals. This works fine, except it is vary susceptible to noise. Noise (RF interference, power line induction, etc) affects the tops and bottoms of the radio waves. Unfortunately, this is where the signal is carried so it gets washed out. The receiver then receives a mix of crap and valid signal and doesn't know what to do (or "guesses" wrong) and you get erratic behavior. FM: FM stands for Frequency Modulation. In this type, the carrier wave frequency shifts in proportion to the control signals. During transmission, noise still affects the tops and bottoms of the carrier wave, but the receiver chops these off (and therefore the noise is gone as well) and focuses on the shift in frequency, not the amplitude. Therefore, noise rejection is a lot better. However, if the noise is bad enough, or close enough in frequency, you can still "confuse" the receiver and get erratic behavior similar to AM. 2.4: This is a whole different animal. Not only is it more than 30X times higher in frequency (helping to avoid the common noise sources), but the control signals are converted to data packets and then modulated into the high carrier frequency. At the receiver end, it performs data integrity checks (like error correction) to make sure the packets are valid. There is a bit more to it, but as you can see, 2.4 is a lot more tolerant to noise.