![]() ![]() ![]() Depending on the jammed frequency, it can prevent GPS signal, mobile connections, WiFi, or Bluetooth communication. Unfortunately, a jammer is doing precisely that. Imagine playing music so loud that nobody around can talk to each other. In this way, the crosstalk between the hop frequency bands is eliminated in fast frequency hopping.In a nutshell: A jammer creates a lot of random noise to prevent communication on a specific frequency. Usually, non-coherent detection is used and the orthogonality between the FSK tones is ensured by keeping a minimum distance between them, which is equal to the multiples of fH, where fH is the hop frequency. Signal DetectionĬoherent signal detection is difficult when fast frequency hopping is utilized. Along with fast frequency hopping, the modulations commonly used are frequency shift keying (FSK) and multiple frequency shift keying (MFSK). Applicationsįast frequency hopping is mainly employed in communication systems where anti-jamming is required, as it is the best spread spectrum technique to use along with non-coherent modulations to combat jamming. A ratio greater than unity indicates that the carrier frequency changes repeatedly during the duration of the signal to be transmitted. When the fast frequency hopping spread spectrum technique is employed, the ratio TS/TH is greater than unity, where TS is the duration of the information signal or symbol and TH is the frequency hopping time. In fast frequency hopping (FFH), multiple frequency hops are utilized for transmitting one data bit. Let’s focus on one method of frequency hopping: the fast frequency hopping method. This prevents communication failures due to signal fading or jamming. There is no distinctive frequency corresponding to the signal transmitted to interfere or jam it. ![]() The signal transmitted sees several channels and various sets of interfering signals during each frequency hopping event. In the frequency hopping technique, the transmitter injects the carrier frequency according to a specific hopping pattern known only to the sender and receiver. ![]() The Frequency Hopping Spread Spectrum Technique
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