On What Frequency Does a Radio Controlled Toy Bus Work?

Radio controlled toys are likely included in the “Wireless Equipments exempted from licensing” according to the Indian National Frequency Allocation Plan 2022. According to that 26.957 – 27.283 MHz, which is essentially the Citizen band, permit use of low power equipment with (Exemption from Licensing Requirement) Rules, 2005, cited as GSR No. 533(E) dated 12-Aug-2005. This radio control remote of the toy bus shows frequency as 27 MHz. I have seen that other radio controlled toys like cars also operate in the Citizen Band.

I tried tuning in from 26.957 – 27.283 MHz in my FT-710 radio to locate signals from the remote control, without success. As the frequency range is below the 28 MHz ham band, there was no waterfall display for that frequencies. May be my 40/10m dipole antenna above my terrace was not picking up the weak signal from the remote control of the toy bus.

Later I connected my quarter wave magnetic mount VHF antenna to FT-710 and kept it over the linear power supply of the VHF radio. The power supply had an iron cover which would act as a good ground plane. Still I could not pick the signals from the remote control operating on 27 MHz, possibly because I was using a 144 MHz magnetic mount quarter wave antenna.

Both the toy bus and the remote control have only small wire antennas, nowhere near the quarter wavelength of 27 MHz (11m) Citizen Band. May be they can function at short distances needed for operating a toy bus inside a room. Wonder whether they are electrically shortened dipoles with loading coils inside. I dare not open up a working toy meant for the kid at home, to check whether there is a loading coil! May be I will need a wide band Software Defined Radio like RTL-SDR connected to a computer with required software and a waterfall display to detect the exact output freqeuncy of the remote control.

Had a look at other frequencies in the “Wireless Equipments exempted from licensing”. Frequencies alloted have a wide range from 9 kHz to 77 GHz with only small segments in each band and restrictions like low power and very low power. 402 – 405 MHz was the range allocated for very low power cardiac
monitoring radio frequency wireless medical devices and medical implant communication systems (MICS). 433 – 434 MHz is for low power devices or equipments for indoor applications. Radio Frequency
Identification Devices (RFID) have been alloted the range from 865 – 867 MHz. I am sure most of your will be aware of 2400 – 2483.5 MHz in 2.4 GHz band and 5150 – 5350 MHz and 5470 – 5875 MHz for WiFi and Radio Local Area Network (RLAN) in 5GHz band. There are many more such applications listed in the National Frequency Allocation Plan 2022.