Radio frequency communication systems require two essential components: a transmitter and a receiver. But how do you know which receiver is right for your project?
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Radio frequency transmission is a method of sending information from one place to another without the need for physical wires. Instead, the message is encoded onto radio waves and sent through the air. The message is sent from a transmitter at one end of the system to a receiver at the other end. The receiver’s job is to pick up the radio waves and demodulate them – convert them from radio waves back into a usable format.
Receivers and transmitters must be compatible with one another in order to successfully send data. Installers must also analyse the site where the system is going to be fitted and make a number of decisions about which type, size, and format of receiver is appropriate. Making the right choice of receiver depends on a number of factors: how many people need to use it, what action the receiver is going to trigger in the system, and what level of security is required.
A relay is a switch that opens or closes a circuit. When a receiver picks up a valid signal from a valid transmitter, its job is to trigger a relay either from open to closed or from closed to open. The switch is what controls the action in the system – it might turn on a light, unlock a door, or start an automation cycle. A receiver can be equipped with more than one relay to trigger more than one action. You’ll need to work out how many actions you need to trigger in order to know how many relays you’ll need.
The memory capacity of a receiver dictates how many transmitters can be paired with it. Each paired transmitter takes up one space in the receiver’s memory. In some systems you might only need one transmitter. In others, you might give a hand-held transmitter to multiple users. You’ll need to choose a receiver that has sufficient memory capacity for your needs.
Modulation is the name given to the process of converting the data being transmitted into a type of radio wave so that it can be sent through the air to the receiver. There are various types of modulation, including AM and ASK, which are the most common. You will need to ensure that the transmitter and the receiver you choose for the system utilise the same method of modulation in order for the data to be sent successfully.
Frequency is a measure of how long it takes for a radio wave to oscillate from top to bottom in one complete cycle. It is measured in cycles per second, also known as Hertz. When choosing a receiver, you must ensure that it operates on the same frequency as the transmitter.
In transmission, encoding is the conversion of data into a binary signal. The binary signal is what the receiver uses to trigger an action in the circuit. That process of conversion can be protected with additional security, such as KeeLoq® hopping code, which constantly changes the valid password that allows the receiver to accept the transmitted signal. AES encryption is another option for protecting data transmission. When choosing a receiver, it’s important to evaluate the level of risk in the system and the appropriate level of security to combat it.
Both transmitters and receivers require a power supply to function. Some utilise a wired power supply, while others are equipped with a battery. The environment of the installation, the style of transmitter and receiver, and the power availability on-site will dictate the type of powering that you need.
If your receiver is going to be installed outdoors or exposed to the elements, you will need to choose one which is protected. The measure to look out for is an IP rating. These ratings indicate how much the receiver can withstand solids and liquids getting into its casing and potentially disrupting the system. The highest possible IP rating is IP68.
