trol not only the frequency you can transmit on, but also the maximum power and bandwidth you can use. There may also be controls placed on the type of data sent, hours of operation and location of transmission.

Frequency assignment: The frequencies  defined by the FCC for use by our hobby.

We are currently allocated frequencies in the 27, 72, and 75 MHz and the 6 meter ham band. These frequencies and their associated channel numbers are listed in the tables.

Most aircraft operate within the 50 channels (frequencies) assigned in the 72 MHz band which are restricted to aircraft use. The following definitions apply to these channels. For additional information and limitations refer to FCC part 95 of CFR 47.

No license is required for the 27, 72, or 75 MHz bands. Use of the Ham Band frequencies does require a Ham Band license.



Band Width: The maximum allowable deviation from the defined carrier frequency (assigned frequency) which you may use.

Our current frequencies are allowed a maximum band width of 20KHz (20,000 cycles). This would be 10KHz above and 10KHz below our assigned frequency. From our chart we see that our frequencies are 20KHz apart. If we were transmitting on channel 48 (72.750), then our signal could vary from a low of 72.740 to a high of 72.760. Channels above or below us could transmit to their bandwidth boundaries  but would not overlap our usable space.

Beyond the bandwidth allowed, your transmission must be attenuated to a defined level. This attenuation is normally defined in Decibels, which is a method of measuring power. In general, a +/- of 3 db equates to twice/half the power. The scale is logarithmic, and as such can easily measure large variations. A signal which is down (reduced) 3 db

is 1/2 the original power. Down 6 db is 1/2 of  3 db or 1/4 the original power. -9 db would be 1/2 the power of -6 db or 1/8 the power of the original signal.

Our uses of the frequency states that the signal must be -55 db at the limits of our allocated bandwidth. This equates to a power of less than 1 10,000 th of the original power.

Narrow vs Wide Band Operation:

Wide band: A term used in R/C to describes a system which utilizes a 40 KHz maximum bandwidth. This was termed Silver Stickered.

Narrow Band: A term used in R/C to describe a system which utilizes a 20 KHz maximum bandwidth. This was termed Gold Stickered.

These terms were created to identify the evolution of bandwidth restrictions in getting from our initial 72Mhz  allocation to our current 50 channel  operation. Initial operation in the 72Mhz band used equipment which operated at an 80 KHz bandwidth. Newer equipment operating in the 40 KHz bandwidth was introduced around 1986 and is what is know today as wideband. This equipment operated on channel 38 thru 56 (even numbered)

A two part evolution to 50 channel operation began in 1988. First the use of the old 80 KHz bandwidth equipment became illegal on Dec 20, 1987.
Twelve new channels 12 thru 34 (even numbered) were allocated to replace the old 80 KHz bandwidth channels. These channels were defined as narrow band and were required to operate in a 20KHz bandwidth.

Wide band equipment continued in use on the upper channels until 1991 when the remaining channels were implemented. Most clubs banned the use of wide band transmitters at this time.

The use of wide band transmitters became illegal under FCC rule on March 1, 1998.     

Power output: The maximum power which may be transmitted. Usually defined in Watts or a fraction