Radio Frequency Interference in RC Toys
When buying mass market or toy-grade radio controlled vehicles, such as those sold at Walmart, Target, and other retail stores, you typically have a choice of two radio frequencies in the U.S.: 27 or 49 megahertz (MHz). These radio frequencies are how the controller communicates with the vehicle. If you don’t plan to run your RC cars, trucks, boats, or aircraft alongside other radio controlled vehicles, it doesn’t really matter which frequency they use.
However, running two 27MHz or two 49MHz RC cars near each other will usually result in interference—crosstalk. The radio signals get mixed up. One controller will try to control both vehicles or you’ll get erratic behavior in one or both vehicles.
Preventing Radio Frequency Interference
The radio frequency of RC cars appears on the package and can be found clearly labeled on the bottom of the vehicle. With mass market RC toy cars and trucks, there are three ways to avoid or minimize radio frequency interference from other vehicles.
- Keep Your Distance From Other Toy RC VehiclesThe effective operating range for toy-grade vehicles is generally around 75 to 100 feet, although it could be more. Minimize radio frequency interference by keeping two vehicles that use the same frequency outside each other’s operating range. For example, if the maximum operating range of the vehicles is 100 feet, double that amount and operate the two vehicles at least 200 feet from each other.
- Choose Separate Radio Frequencies for Each RC VehicleTo operate in close proximity, make sure each vehicle is a different frequency. A 27MHz and a 49MHz vehicle can run alongside each other with no problem.
- Choose RC Cars and Trucks With Band Selectable FrequenciesMost fixed frequency 27MHz toy RCs use the specific frequency of 27.145 MHz (Channel 4). However, some toy-grade vehicles have band selectable frequencies. This allows the user to select a narrow portion or band of the frequency to use. Typically the band selectable vehicle will have a channel switch on both the vehicle and the controller that changes between two and up to six bands or channels. In this way, two 27MHz band selectable vehicles can operate in the same area if each vehicle (and its corresponding controller) is set to a different band.
If you see an RC toy labeled as 27MHz but it says something like “Play with up to 3 vehicles at once” then what you have is a toy with selectable channels within the 27MHz range. The manufacturer rarely specifies what those specific channels are but if they use standard color coding, you might be able to figure it out:
- 26.995 MHz — Channel 1 (Brown)
- 27.045 MHz — Channel 2 (Red)
- 27.095 MHz — Channel 3 (Orange)
- 27.145 MHz — Channel 4 (Yellow)
- 27.195 MHz — Channel 5 (Green)
- 27.255 MHz — Channel 6 (Blue)
Hobby-Grade: The Next Step in Avoiding Interference
Hobby-grade radio controlled vehicles—usually the more expensive cars, trucks, boats, and aircraft sold in specialty hobby stores or assembled from kits—have a wide range of radio frequencies available. With these vehicles, there are removable crystal sets that allow users to easily change frequencies and channels within frequencies. Six channels in the 27MHz range (also used for toys), 10 channels in the 50MHz range (radio license required), 50 channels in the 72MHz range (aircraft only), and 30 channels in the 75MHz range are all available in the US for operating hobby-grade radio controlled vehicles.
Radio frequency interference becomes less of a problem with this class of RC vehicle. Some hobby models come with a fail safe device—or they can be purchased separately—that detects frequency interference problems and stops or slows down the RC to avoid potential problems. Additionally, the 2.4GHz frequency range used with special software and DSM controllers/receivers virtually eliminates radio interference problems.