In this type of spread spectrum approach, both units (base and subscriber or handset and base) hop from frequency to frequency in a simultaneous fashion. The theory is that noise tends to occur at different frequencies at different times. Therefore, even though a part of a transmission may be lost due to interference, enough of the message will come through by hopping the interference to create a noticeably better output when compared to fixed frequency systems.
Bluetooth's way of creating less interference between two devices. By quickly jumping frequencies, there is a very minute chance of devices interfering by connecting on the same frequency. There are five different types for the 79MHz range, and five different types for the 23MHz range (mainly used in Spain and France).
Frequency hopping is one of two basic modulation techniques used in spread spectrum signal transmission. It is the repeated switching of frequencies during radio transmission, often to minimize the effectiveness of "electronic warfare" - that is, the unauthorized interception or jamming of telecommunications. It also is known as frequency- hopping code division multiple access (FH-CDMA).
The transmitter hops to one of many channels. The receiver knows the sequence of the frequency hopper and follows each hop.
A radio frequency transmission method. Typically this uses the ISM band from 2.4000 to 2.4835 GHz with 85 one-megahertz channels or "hops." Also, CDPD uses frequency hopping on analog cellular systems to unoccupied voice channels. Transmissions hop from one channel to the other, staying only 1/10 of a second on any given channel. The channels are visited in a predefined order specified by a hopping sequence.
Bluetooth devices change the frequency that they broadcast on in order to overcome interference. Packets affected by interference on one frequency will be retransmitted on a different frequency, hopefully with better results. Bluetooth devices hop every 625 microseconds while connected and every 312.5 microseconds while establishing a connection.
Frequency-hopping spread spectrum (FHSS) is a method of transmitting signals by rapidly switching a carrier among many frequency channels, using a pseudorandom sequence known to both transmitter and receiver.
The continual switching of transmitted frequencies based on a shared algorithm to minimize unauthorized interception or jamming of a radio transmission.
FH Spread Spectrum is a RF technology that uses up to 79 1MHz wide channels. Each "channel" is actually a preset sequence of frequencies. Transmissions will run the sequence for a given channel, in other words, it hops from one frequency to another during transmission. It can stay on a given channel for up to 400ms before hopping. As a result, this technology is more immune to interference than DSSS. Intermec's devices with Open Air radios and Symbol's Spring and 802.11 radios use Frequency Hopping.
A spread spectrum modulation technique where the transmitter frequency hops from channel to channel in a predetermined but pseudo-random manner. The signal is de-hopped at the receiver by a frequency synthesizer controlled by a pseudo-random sequence generator synchronized to the transmitter's pseudo-random generator.
Describes a system of communication based on radio waves whose frequencies change (or hop) over time. For example, the frequencies used by Bluetooth hop 1600 times a second. The advantage is that it is less susceptible to interference, and confers some security on the signal.
A radio that rapidly changes it's operating frequency several times per second following a pre-determined sequence of frequencies. The transmitting and receiving radios are programmed to follow the same frequency hopping sequence.
A method of spread spectrum using multiple radio channels to reduce interference and increase security. The signal is rapidly switched from channel to channel many times per second in a pseudo-random pattern which known by both the sender and receiver(s). Because of this switching, interference from a radio source at a particular frequency can be overcome by retransmitting packets with errors. Also, data is generally more secure because it is not possible to receive more than a fraction of the data unless the hopping pattern is known. Bluetooth utilizes frequency hopping in the 2.4GHz radio band.
A spread spectrum technique by which the band is divided into a number of channels and the transmissions hop from channel to channel in a pre-specified sequence.
Radio communications technique that involves changing the radio frequency in use by the transmitter and receiver on a regular (and possibly frequent) basis. Can be used to confuse potential eavesdroppers and/or avoid radio interference that can occur at any time within the radio spectrum.
The spread spectrum technique where two or more associated radios change their operating frequencies several times per second using a set pattern. Since the pattern appears to jump around, it is said to hop from one frequency to another.
A technique used to prevent interference in a transmit/receive system by rapidly switching the carrier among many frequency channels.
A technique by which an earth station changes transmission frequency to access different satellite channels. This is required when the satellite has several spot beams and the transmission has to be directed to different areas.
A technique used to prevent readers from interfering with one another. In the United States, UHF RFID readers actually operate between 902 and 928 MHz, even though it is said that they operate at 915 MHz. The readers may jump randomly or in a programmed sequence to any frequency between 902 MHz and 928 MHz. If the band is wide enough, the chances of two readers operating at exactly the same frequency is small. The UHF bands in Europe and Japan are much smaller so this technique is not effective for preventing reader interference. Back to the alphabetical list at the top.
A method of jumping from frequency to frequency in synchronization with one another in a random order at a rate of up to 100 times per second. Frequency hopping is the preferred method of communication with SINCGARS radios.
A digital communication modulation scheme where the frequency-channel that an RF device is using can jump from frequency-channel to frequency-channel, on an ongoing basis. For Example, if an RF device determines that it is utilizing a hoisy frequency-channel then the RF device can change to a different frequency-channel. This technique is referred to as frequency hopping.
While talking, your phone signal changes channels up to 90 times a second. This provides security to cordless telephone conversations.