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Phase Jitter Modulation
Phase-jitter modulation (PJM) is a modulation method specifically designed to meet the unique requirements of passive RFID tags. It has been adopted by the high-frequency RFID Air Interface Standard ISO/IEC 18000-3 MODE 2 for high-speed bulk conveyor-fed item-level identification because of its demonstrably higher data rates. The MODE 2 PJM data rate is 423,75 kbit/s; 16 times faster than the alternative MODE 1 system ISO/IEC 18000-3 MODE 1 and the legacy HF system ISO/IEC 15693. Method PJM works by representing data as very small phase changes in the instantaneous phase of a carrier signal. PJM can be regarded as a very low-level phase-modulation (PM) signal where amplitude-modulation (AM) components are suppressed to provide a constant-modulus signal. Most of the power (greater than 99%) in a PJM signal is transmitted as an un-modulated carrier and conveys no information. Less than 1% of the transmitted power is used for conveying the modulated data. Passive RFID Radi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RFID
Radio-frequency identification (RFID) uses electromagnetic fields to automatically identify and track tags attached to objects. An RFID system consists of a tiny radio transponder, a radio receiver and transmitter. When triggered by an electromagnetic interrogation pulse from a nearby RFID reader device, the tag transmits digital data, usually an identifying inventory number, back to the reader. This number can be used to track inventory goods. Passive tags are powered by energy from the RFID reader's interrogating radio waves. Active tags are powered by a battery and thus can be read at a greater range from the RFID reader, up to hundreds of meters. Unlike a barcode, the tag does not need to be within the line of sight of the reader, so it may be embedded in the tracked object. RFID is one method of automatic identification and data capture (AIDC). RFID tags are used in many industries. For example, an RFID tag attached to an automobile during production can be used to track ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ISO/IEC 18000-3 MODE 2
ISO/IEC 18000-3 is an international standard for passive RFID item level identification and describes the parameters for air interface communications at 13.56 MHz. The target markets for MODE 2 are in tagging systems for manufacturing, logistics, retail, transport and airline baggage. MODE 2 is especially suitable for high speed bulk conveyor fed applications. General description MODE 2 RFID tags are passive deriving their power from the interrogating signal generated by an RFID interrogator. Power is transferred from the interrogator to the tag by a high-frequency magnetic field using coupled antennae coils in the reader and the tag. The powering field frequency is 13.56 MHz ± 7 kHz. Dialogue between the interrogator and the tag is conducted on an Interrogator-Talks-First (ITF) basis. Following activation of the tag by the interrogator’s interrogating signal the tag waits silently for a valid command. After receiving a valid command the tag transmits a reply in respons ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ISO/IEC 18000
This is a list of publishedThis list generally excludes draft versions. International Organization for Standardization (ISO) standards and other deliverables.ISO deliverables include "specifications" (ISO/PAS, ISO/TS), "reports" (ISO/TR), etc, which are not referred to by ISO as "standards". For a complete and up-to-date list of all the ISO standards, see the ISO catalogue. The standards are protected by and most of them must be purchased. However, about 300 of the standards produced by ISO and 's Joint Technical Committee 1 ( |
ISO/IEC 15693
ISO/IEC 15693, is an ISO/ IEC standard for ''vicinity cards'', i.e. cards which can be read from a greater distance as compared with proximity cards. Such cards can normally be read out by a reader without being powered themselves, as the reader will supply the necessary power to the card over the air (wireless). ISO/IEC 15693 systems operate at the 13.56 MHz frequency, and offer maximum read distance of 1–1.5 meters. As the vicinity cards have to operate at a greater distance, the necessary magnetic field is less (0.15 to 5 A/m) than that for a proximity card (1.5 to 7.5 A/m). Example applications * Ski pass: each of those has a unique ID and the system knows for how long the pass is valid etc. Communication to the card Communication from the reader to the card uses an amplitude-shift keying with 10% or 100% modulation index. The data coding is: ;1 out of 4 pulse-position modulation: 2 bits are coded as the position of a 9.44 μs pause in a 75.52 μs symbol time ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phase-modulation
Phase modulation (PM) is a modulation pattern for conditioning communication signals for transmission. It encodes a message signal as variations in the instantaneous phase of a carrier wave. Phase modulation is one of the two principal forms of angle modulation, together with frequency modulation. In phase modulation, the instantaneous amplitude of the baseband signal modifies the phase of the carrier signal keeping its amplitude and frequency constant. The phase of a carrier signal is modulated to follow the changing signal level (amplitude) of the message signal. The peak amplitude and the frequency of the carrier signal are maintained constant, but as the amplitude of the message signal changes, the phase of the carrier changes correspondingly. Phase modulation is widely used for transmitting radio waves and is an integral part of many digital transmission coding schemes that underlie a wide range of technologies like Wi-Fi, GSM and satellite television. It is also used ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amplitude-modulation
Amplitude modulation (AM) is a modulation technique used in electronic communication, most commonly for transmitting messages with a radio wave. In amplitude modulation, the amplitude (signal strength) of the wave is varied in proportion to that of the message signal, such as an audio signal. This technique contrasts with angle modulation, in which either the frequency of the carrier wave is varied, as in frequency modulation, or its phase, as in phase modulation. AM was the earliest modulation method used for transmitting audio in radio broadcasting. It was developed during the first quarter of the 20th century beginning with Roberto Landell de Moura and Reginald Fessenden's radiotelephone experiments in 1900. This original form of AM is sometimes called double-sideband amplitude modulation (DSBAM), because the standard method produces sidebands on either side of the carrier frequency. Single-sideband modulation uses bandpass filters to eliminate one of the sidebands and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Logistics
Logistics is generally the detailed organization and implementation of a complex operation. In a general business sense, logistics manages the flow of goods between the point of origin and the point of consumption to meet the requirements of customers or corporations. The resources managed in logistics may include tangible goods such as materials, equipment, and supplies, as well as food and other consumable items. In military science, logistics is concerned with maintaining army supply lines while disrupting those of the enemy, since an armed force without resources and transportation is defenseless. Military logistics was already practiced in the ancient world and as the modern military has a significant need for logistics solutions, advanced implementations have been developed. In military logistics, logistics officers manage how and when to move resources to the places they are needed. Logistics management is the part of supply chain management and supply chain engine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sensors
A sensor is a device that produces an output signal for the purpose of sensing a physical phenomenon. In the broadest definition, a sensor is a device, module, machine, or subsystem that detects events or changes in its environment and sends the information to other electronics, frequently a computer processor. Sensors are always used with other electronics. Sensors are used in everyday objects such as touch-sensitive elevator buttons (tactile sensor) and lamps which dim or brighten by touching the base, and in innumerable applications of which most people are never aware. With advances in micromachinery and easy-to-use microcontroller platforms, the uses of sensors have expanded beyond the traditional fields of temperature, pressure and flow measurement, for example into MARG sensors. Analog sensors such as potentiometers and force-sensing resistors are still widely used. Their applications include manufacturing and machinery, airplanes and aerospace, cars, medicine, robot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
