What is the grard channel?

[jp203000]

I see this sentence in the manual:' When the radio is set to FM/AM,the guard channel is automatically selected."

But I don't understand what the guard channel is , what is it for ,and how to use it properly.:helpsmilie:

[BlueRidgeDx]

Guard is 121.5Mhz, and is the standard international distress frequency. It's called "guard" because you're supposed to maintain a listening guard on that frequency.

 

Guard is the frequency to use when you don't know what freq the recipient is using...because he should be "guarding" 121.5, right? It's also the frequency that Emergency Locator Transmitters use(d) - the newer civilian ones use 243.0 now.

 

Its also the frequency that fighters will attempt to contact an airplane being intercepted; of course, I mean homeland defense type of intercepts...not CAP.

[jp203000]

so what's the difference between AM guard channel and FM guard channel.? Thank you.

[BlueRidgeDx]

The difference between VHF and UHF is 121.5 vs. 243.0. I'm not sure there's a difference between AM and FM in this context. But then I'm not an expert on the frequency spectrum.

 

I was wrong about the new ELTs, by the way, they're 406Mhz now. I knew it changed a few years ago, but I guess I remembered wrong.

[msalama]

I'm not sure there's a difference between AM and FM in this context.

 

Just the modulation protocol, i.e. AM = amplitude modulation = carrier's amplitude is modulated by the audio signal & FM = frequency modulation = carrier's frequency is modulated by the audio signal.

 

http://en.wikipedia.org/wiki/Amplitude_modulation

http://en.wikipedia.org/wiki/Frequency_modulation

 

HTH :)