Telecommunication
The other meaning of the term "channel" in telecommunications is seen in the phrase communications channel, which is a subdivision of a transmission medium so that it can be used to send multiple streams of information simultaneously. For example, one radio station can broadcast radio waves into free space at frequencies in the neighborhood of 94.5 MHz (megahertz) while another radio station can simultaneously broadcast radio waves at frequencies in the neighborhood of 96.1 MHz. Each radio station would transmit radio waves over a frequency bandwidth of about 180 kHz (kilohertz), centered at frequencies such as the above, which are called the "carrier frequencies". Each station in this example is separated from its adjacent stations by 200 kHz, and the difference between 200 kHz and 180 kHz (20 kHz) is an engineering allowance for the imperfections in the communication system.
WHA (AM)
Initially there were no formal standards for stations providing a broadcast service, so there was no problem with 9XM broadcasting under an Experimental license. However, effective December 1, 1921, the Department of Commerce adopted regulations defining a broadcast service. The new regulations specified two transmitting wavelengths — 360 meters (833 kHz) for "entertainment", and 485 meters (619 kHz) for "market and weather reports" — and also required stations making broadcasts intended for the general public to hold a "Limited Commercial" license. Professor Terry filed an application for the new license, and on January 13, 1922 the University was issued its first broadcasting station authorization, with the randomly assigned call letters of WHA. In addition to the two broadcasting wavelengths, the station was authorized to use 410 meters (731 kHz) "for intercommunication between college stations".