What Is Frequency Hopping Spread Spectrum (FHSS)?

It's like a game of hopscotch but with radio waves. If you've ever played hopscotch—or any children's game involving hopping—you know it can be fun. What if you could hop around with radio waves? That would be pretty cool, right? Well, that's precisely what the frequency hopping spread spectrum (FHSS) is all about! FHSS uses a pseudorandom sequence to determine which carrier frequency to use at any given time. The sender and receiver already know what series they will use and when they will use it. When the sender wants to send a message, it hops from one carrier frequency to another with pseudorandom sequence—but only briefly before moving on to another carrier frequency. This keeps the signal from being easily intercepted by anyone trying to listen in. Frequency-hopping spread spectrum is a bit of a misnomer in that it doesn't hop. What it does is hop from one frequency to another. It works by modulating the amplitude of the carrier wave at a rate of 1 MHz, switching between 79 "channels" or frequencies every two milliseconds. This synchronizes the transmitter and receiver's clocks, which makes for much more reliable communication. The advantages of this technique are speed and security—it's faster than FM because the data rate is higher (1 Mbps vs. 300 kHz). Since each frequency is only used for a few milliseconds before being moved on to another, it's harder for an eavesdropper to find where you're transmitting from. Frequency-hopping spread spectrum is a technology that uses a hopping sequence to transmit data over radio waves. The information is sent in short bursts, each shipped at a different frequency. This makes it harder for someone to detect the transmitted data because it's spread out over many frequencies. Each burst is only on one frequency for a small amount of time—making it difficult for anyone to intercept the signal.