To add to the things that make this possible. Take a look at DSSS or signal spreading.
This is a method of spreading the power of your transmission over a much wider part of the spectrum. Hence, this doesn't help much if your transmit power is limited. However, it does help if your transmit power per slice of bandwidth is limited.
This is used for a few methods. The first is spectrum-sharing (which requires orthogonal codes). The second is detection avoidance (lower power per bandwidth makes it much harder to recognize the signal unless you already know how to de-spread). The third method is to avoid 'point noise sources' from blocking your signal. E.g. a wifi burst of 1MHz might drown out your signal if you use 1Mhz of bandwidth. But if you use 10 MHz, it only blocks one tenth of your signal.
This is a method of spreading the power of your transmission over a much wider part of the spectrum. Hence, this doesn't help much if your transmit power is limited. However, it does help if your transmit power per slice of bandwidth is limited.
This is used for a few methods. The first is spectrum-sharing (which requires orthogonal codes). The second is detection avoidance (lower power per bandwidth makes it much harder to recognize the signal unless you already know how to de-spread). The third method is to avoid 'point noise sources' from blocking your signal. E.g. a wifi burst of 1MHz might drown out your signal if you use 1Mhz of bandwidth. But if you use 10 MHz, it only blocks one tenth of your signal.