How many AM broadcast stations can be accommodated in 6 MHz bandwidth of each station transmits a signal which was modulated by an audio signal having a maximum frequency of 5 kHz?

Answer 1

-- So long as the AM modulation index doesn't exceed 100%, only one set of

sidebands exists, and the spectral width of an AM signal is double the highest

modulating frequency ... 10 KHz in this case.

-- Dealing strictly with the arithmetic ...

6 MHz/10 KHz = 600 AM channels in the equivalent of one analog TV channel.

-- But 6 MHz of AM spectrum could never be used that way, because ordinary

consumer-grade AM radios can't deliver a listenable program in the presence of

another signal of equal nominal level on the adjacent channel. With all of these

AM stations all in the same metro area, you'd need to figure at least one guard

channel between adjacent AM stations ... reducing the capacity of your 6 MHz

to no more than 300 stations, because of typical receiver quality (or lack thereof).

-- Also, of course, notice that with 300 AM stations in one market, none of them

could sell any appreciable amount of commercial time, because none of them would

have any appreciable audience, and half of them would die in the first month.

-- Finally, when you start thinking about commercial spectrum utilization, it's

important to be aware that whereas this little exercise speaks in terms of the

equivalent of one whole analog TV channel dedicated to AM broadcasting, the

entire real-world AM broadcast band is barely 1/6th of that much ...

530 KHz - 1700 KHz = 1.17 MHz !