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Practice Exam 1

1. 1. Practice Exam 1
2. 2. 1. EPC Generation 2, after being ratified by the International Organization for Standardization (ISO), will be put into ❑ A. ISO 18000 Part 8 ❑ B. ISO 18000 Part 6 C ❑ C. ISO 18000 Part 5 A ❑ D. ISO 19000 Part 1 The 18000 series applies to air-interface management. ➤ 18000-1 Part 1—Generic Parameters for the Air Interface for Globally Accepted Frequencies ➤ 18000-2 Part 2—Parameters for Air Interface Communications below 135 kHz ➤ 18000-3 Part 3—Parameters for Air Interface Communications at 13.56 MHz ➤ 18000-4 Part 4—Parameters for Air Interface Communications at 2.45 GHz ➤ 18000-5 Part 5—Parameters for Air Interface Communications at 5.8 GHz (this part has been withdrawn) ➤ 18000-6 Part 6—Parameters for Air Interface Communications at 860 to 960 MHz ➤ 18000-7 Part 7—Parameters for Air Interface Communications at 433 MHz ISO 18000 part 6A and B specifies the air interface guidelines for passiveRFID in the UHF (900 MHz) band. EPC Class 1 Generation 2 after being ratified by ISO will be established as a part 6C.
3. 3. 2. Define the formula for Effective Radiated Power (ERP). ❑ A. ERP = power input + antenna gain in dBd ❑ B. ERP = antenna length / power input ❑ C. ERP = antenna gain / power input * dBi ❑ D. None of the above ERP (dBm) = Power of transmitter (dBm) – loss in transmission line (dB) + antenna gain in dBd
4. 4. 3. Which of the following statements is true? ❑ A. Thermal transfer uses a special print head that turns label media a dark color. ❑ B. Thermal transfer does not use a ribbon. ❑ C. Direct thermal uses a ribbon. ❑ D. Thermal transfer uses heat to transfer an image from a ribbon to the label media. Answer A is incorrect because that is the method used by direct thermal printing. Answer B is incorrect because the thermal transfer method uses ribbon. Answer C is incorrect because direct thermal does not use a ribbon.
5. 5. 4. Which of the following are true of frequency hopping? ❑ A. It can use the spread spectrum transmission method. ❑ B. It sometimes needs to listen for a signal before using a channel. ❑ C. It reduces the effects of noise and interference in a transmission. ❑ D. It allows an interrogator to read multiple frequency tags. Interrogation signals hop between channels within a certain frequency spectrum. In the United States, they can hop between 902 MHz and 928 MHz, and they can be required to listen for a signal before using a channel. There are two types of frequency hopping: spread spectrum and direct sequence spread spectrum. Frequency hopping reduces the effects of interference and noise by not transmitting on the same frequency at the same time. Answer D is incorrect because frequency hopping does not relate to reading tags; it refers to a way interrogators communicate.
6. 6. 5. Which of the following is not an interrogator’s command? ❑ A. Inventory ❑ B. Select ❑ C. Interrogate ❑ D. Access Interrogate is not an interrogator command. There are three basic command operations to manage tag populations. They are Select, Inventory and Access. The Select command is used to determine which groups of tags will respond. The Inventory command is used to identify (singulate) individual tags from a group. The Access command is used after the tags have been singulated and individual commands can now be addressed to those tags.
7. 7. 6. Which of the following is not generally a component of a fixed RFID interrogator? ❑ A. An oscillator ❑ B. A transmitter ❑ C. A modulator ❑ D. An antenna An antenna is not a component of a fixed interrogator. Fixed interrogators have ports for one or more antennas but generally do not have antennas integrated into them. Handheld interrogators have antennas built into them. Other components of fixed (and handheld) interrogators include a receiver that holds an amplifier and a demodulator, a transmitter that holds a modulator and a power amplifier, an oscillator, a controller/processor, and an input/output port to an antenna.
8. 8. 7. Backscatter refers to what phenomenon? ❑ A. Modulated reflection of an interrogator’s energy ❑ B. The range at which the signal from an active tag begins to break up ❑ C. The dispersion of interrogators at a site to be certain all tags are read ❑ D. The energy received by an interrogator from an active tag UHF and microwave passive tags communicate with an interrogator using passive backscatter (also called modulated backscatter ). The interrogator transmits a continuous-wave RF signal into the reading environment. When a tag appears in the area, it receives the signal and modulates (or breaks up) the RF signal into patterns of ones and zeros that define the tag’s digital data while reflecting it back to the interrogator. Answers B and D are incorrect because backscatter does not apply to active tag technology. Answer C is incorrect because setting up interrogators at a site to ensure all tags are read is called setting up an interrogation zone or creating a “sweet spot,” and not backscatter.
9. 9. 8. Which of the following are characteristics of semi-passive tags? ❑ A. They use a battery to run the microchip’s circuitry. ❑ B. They beacon to the environment. ❑ C. They can use inductive coupling to communicate to the interrogator. ❑ D. They communicate by drawing power from the interrogator. Semi-passive tags have an onboard power source, and that power source is used to run the tag’s circuitry. They can use inductive coupling or passive backscatter to communicate with the interrogator, which by definition means that they draw power from the interrogator to do so. They do not beacon or transmit signals to the interrogator. Beaconing is a term that is commonly used when talking about active tags.
10. 10. 9. Which of the following does not affect interrogator interference when multiple interrogators are present? ❑ A. The distances between antennas ❑ B. The amount of vibration the antennas are subject to ❑ C. The power output of the antennas ❑ D. The presence of shielding Although vibration is a consideration of the physical site, which still should be taken into account when you are evaluating the site survey, it has minimal if any effect on interference. The radio transmissions from the interrogator’s antennas may interfere with other interrogators, so much so that the tags are unable to completely understand the information being read or written and the interrogator may misread the tag. The level of interference depends on a number of factors. They include the size of the antennas, the output power of the antennas, the distances between antennas, and the presence (or absence) of shielding.
11. 11. 10. Which of the following functions can RFID printers perform? ❑ A. Write information to tags on labels ❑ B. Print tag antennas on labels ❑ C. Verify tags on labels ❑ D. Trigger a divert gate RFID printers/encoders can read, write, and print smart labels. The RFID tags are read, written, and verified inside the printer prior to printing due to the embedded RFID interrogator. In the case of a tag failure, the RFID printers mark the tag (usually print a label with the word VOID ) and advance to the next one, assuring high reliability in mission-critical applications. RFID printers cannot print tag antennas or chips on labels; therefore, answer B is incorrect. Answer D is incorrect because printers do not trigger divert gates; software does.
12. 12. 11. Which of the following is not antenna polarity? ❑ A. Spherical polarity ❑ B. Horizontal polarity ❑ C. Vertical polarity ❑ D. Circular polarity There is no spherical polarity in RFID antennas defined. Answers B, C, and D are incorrect. Polarization can be either circular or linear. Linear polarization is relative to the surface of the earth. Linear polarization can also be either horizontal or vertical. Horizontally polarized signals propagate parallel to the earth, whereas vertically polarized signals propagate perpendicular to the earth. Antennas with circular polarization can receive signals from both the vertical and horizontal planes; however, there is a slight loss of signal strength.
13. 13. 12. Low Frequency (LF) tags operate at what frequency? ❑ A. 860–960 MHz ❑ B. 2.45 GHz ❑ C. 120–140 KHz ❑ D. 13.56 MHz The four primary frequency bands for RFID tags are ➤ Low Frequency or LF (120–140 KHz) ➤ High Frequency or HF (13.56 MHz) ➤ Ultra High Frequency or UHF (860–960 MHz) ➤ Super High Frequency/Microwave (2.45 GHz and above)
14. 14. 13. Which of the following are needed to ensure RFID optimum tag/smart label performance? ❑ A. Printer calibration ❑ B. Correct label placement on product ❑ C. Label tag verification ❑ D. All of the above Answer A is correct because printer calibration fulfills the need to set for the correct media length, type, print mode, and sensor values. Answer B is correct because correct label placement on product ensures optimal performance; the polarization, air gaps, and other considerations have to be taken in mind. Answer C is correct because smart label tag verification tests the tag’s function, and the printer should have a method of exception processing that provides a solution for dealing with “bad” tags.
15. 15. 14. Which of the following are usually included in a site survey? ❑ A. Changes in RFID team and cooperation of management with changes due to RFID implementation ❑ B. Determining environmental factors that would affect RFID implementation ❑ C. What operational restrictions are in place that would affect RFID equipment placement ❑ D. What radio frequency equipment is in place that would interfere with new RFID equipment A physical site survey determines whether the environment is a threat to successful implementation and operation of an RFID system. Answer B is correct because environmental conditions in the site that will possibly affect tags, interrogators, antennas, printers, and so on, are important to understand, as well as whether this equipment will be deployed in an area with extreme temperature, humidity, dirt, and other problematic conditions. Answer C is correct because any operational restrictions affecting the location of interrogators, antennas, and printers such as spacerestrictions are essential to a site survey to ensure proper function of RFID devices in the area. Answer D is correct because it is important to understand RF interference challenges. They may come from motors, wireless LANs, microwave ovens, or potentially anything else operating in the same RF spectrum. Answer A is incorrect because management changes and management buy-in are not a part of site survey.
16. 16. 15. What are the types of active system communications? ❑ A. Triangulating ❑ B. Beaconing ❑ C. Triggering ❑ D. Interrogator-talks-first Beaconing tags transmit their signals to the area in preset periods regardless of the interrogator’s presence, and interrogator-talks-first means that the tags answer only when first asked by an interrogator. Answer A is incorrect because triangulation is a method of determining the location of a tag using an RTLS system. Answer C is also incorrect. Triggering devices are used to trigger an interrogation of tags that may be within the interrogator’s range.
17. 17. 16. What is the rule with grading of LMR cables? ❑ A. The higher the number, the thinner the cable. ❑ B. The higher the number, the thicker the cable. ❑ C. The lower the number, the lower the resistance. ❑ D. The higher the number, the lower the cost. The higher the number describing the cable, the thicker and less flexible the cable is. Therefore, answer A is incorrect. Answer C is incorrect because the higher the number, the lower the resistance; the RF mostly move on the surface of the cable, and thicker cable has a larger surface. The thicker and less resistant cable also has higher cost; therefore, answer D is incorrect. Several types of cables on the market can be used in an RFID system. The main types are ➤ Corrugated copper cable ➤ Braided coaxial cable ➤ Smooth wall cable There are several kinds of braided cables. The most common types are LMR and RG. The number following an LMR (LMR-100 up to LMR-1700) identifies the cable thickness in 1/100 of an inch. Generally, the higher the number, the thicker the cable and the lower the cable attenuation and loss. This, of course, mirrors in higher price per foot.
18. 18. 17. What are important considerations when selecting interrogator antennas? ❑ A. Product velocity ❑ B. Product mix ❑ C. Connecting cable shielding ❑ D. Antenna polarization If an interrogation zone is on a manufacturing line, where product orientation and product velocity are constant, it may be appropriate to use linear antennas to control the field because linearly polarized antennas generate a more focused interrogation field and provide further read distance and better penetration. This ensures all tags would be read. In a mixed supply chain application, because tag orientation is most likely not going to be constant, circular antennas are most probably a better option. Answer C is incorrect. Cable shielding has an effect on reduction of interference; it does not affect the selection of antennas.
19. 19. 18. Which of the following are official EPC classes for passive tags? ❑ A. Class 0+ ❑ B. Class 1, Generation 2 ❑ C. Class 0 ❑ D. Class 5 Class 1, Generation 2 (sometimes called Gen 2 ) and Class 0 tags are official EPC passive tag classes. Class 0+ is not an EPC class of tag; it is a Matrics/Symbol proprietary extension of the EPC Class 0 standard, and EPC Class 5 is not specified for passive tags. Therefore, both answers A and D are incorrect.
20. 20. 19. Which of the following components are parts of the required design for an RFID chip? ❑ A. An antenna ❑ B. Control circuitry ❑ C. A processor ❑ D. Memory An RFID chip consists of modulation circuitry, control circuitry, memory, and a processor. Answer A is incorrect because, although an antenna is required for the tag, it is not part of the chip.
21. 21. 20. What are the main differences between a portal and a tunnel? ❑ A. Tunnels allow the forklift to drive through them, getting better read saturation of tags. ❑ B. RFID tunnels are used with conveyor systems where tagged items are taken off pallets and placed on a conveyor. ❑ C. Portals allow one tagged item at a time to be read at a faster pace due to the high speed of the forklift. ❑ D. Tunnels are mounted on the forklift. The tunnel is most often used in conveyor systems where the tagged item is taken off the pallet and sent through a tunnel often enclosed in a Faraday Cage, ensuring an accurate read. Portals are normally used to allow large traffic to pass through such as a forklift or pallet truck. Answer A is not correct because a forklift can drive through portals, not tunnels, which are designed for conveyor belt applications. Answer C is not correct because the portal can scan for multiple tagged items in a rapid manner. Answer D is not correct because tunnels are not normally mounted on forklifts.
23. 23. 22. Which of the following are true of passive tags? ❑ A. They can use passive backscatter to communicate. ❑ B. They can use inductive coupling to communicate. ❑ C. They can have their own transmitter to broadcast signal. ❑ D. They can operate in very harsh environments. UHF and microwave passive tags typically use passive backscatter, and LF and HF passive tags usually use inductive coupling as communication methods with the interrogator. Some passive tags are specifically designed to withstand many harsh environmental conditions like extreme heat or cold. Passive tags do not have their own transmitter and do not broadcast signals to the interrogator. This is a capability and main distinguisher of active tags. Therefore, answer C is incorrect.
24. 24. 23. Which is the best type of tag to track high-value goods from long ranges? ❑ A. Active tags ❑ B. Passive tags ❑ C. Semi-passive tags Active tags, due to their onboard power supply, can transmit or beacon their information over long ranges. They do not have to be powered by an interrogator and are less susceptible to interference. Because they cost more to produce than passive tags and their market price is much higher, they are widely considered a better option for tagging high-value products. Therefore, answers B and C are incorrect.
25. 25. 24. Which of the following tracking types are important to interrogation zone configuration? ❑ A. Item-level tracking ❑ B. Case-level tracking ❑ C. Pallet-level tracking ❑ D. All of the above Correct interrogation zone configuration is based on the types of tracking the application requires. In item-level tracking, the tag is placed on an individual item within a case to ensure complete visibility of the item throughout the supply chain. In caselevel tracking, the tag is placed on the case. The case may contain several items of the same product; however, it may also be a combinationof products. This type of tracking is currently used in retail. In palletlevel tracking, the tag is placed on a pallet and can provide information about the products on the pallet. This type of tracking is used often in a supply chain where tags on pallets accompany the tags on the cases.
26. 26. 25. Which of the following is not a part of a business process analysis? ❑ A. Collection of process documentation ❑ B. Discussion with management to understand system goals ❑ C. Discussion with equipment vendors to understand hardware limitations ❑ D. Photographing product flow Although discussions with outside vendors are certainly important to an RFID implementation, these discussions deal with issues more relevant to design selection. Answers A, B, and D are all important to business process analysis. It is important to collect any documentation available that describes existing process flows. Talking with the management staff of the location helps you to understand what level of visibility they will require and assists you in deciding the type of equipment to be used in the overall design. Part of the documentation of the process should include pictures of every step along the path that the product follows.
27. 27. 26. Which of the following is not a commonly used feedback system? ❑ A. A divert gate ❑ B. A motion sensor ❑ C. A light stack ❑ D. An audible alarm A motion sensor could be used to detect the presence of an item that should have an RFID tag on it. It would then trigger an interrogator to try to read the tag, and then a feedback system would inform about the condition of the tag. The motion sensor is a triggering device, and not technically a feedback system. Answers A, C, and D are all feedback systems. Divert gates are used to divert certain products off a production line or conveyor line. It could be diverting products that have been identified as having nonreadable tags, or tags that contain specified information such as would be used in product-sorting operations. A light stack may be used by having a network-enabled PLC that could be used to turn on and off the light based on data it receives from its connected devices. For instance, a light sensor could indicate that a tag has entered the read zone or that a tag applied to a product is void. Audible devices are used for the same reasons as a light stack, except that they can be used in conditions when the light stack is not in the direct sight of the personnel in the area.
28. 28. 27. What equipment is talked about when mentioning LMR? ❑ A. An RFID interrogator ❑ B. An RFID printer ❑ C. Cable ❑ D. Frequency Certain types of electrical cable have LMR grading, which is usually followed by a number that indicates the cable characteristics, its thickness, and resistance. Answers A, B, and D are incorrect. RFID interrogators and printers are not called or graded as LMR, and neither is frequency. Frequency can be LF, HF, UHF, or microwave, where the acronyms indicate Low Frequency, High Frequency, and Ultra High Frequency, respectively.
29. 29. 28. Which part of the EPC Gen 2 tag memory includes the EPC? ❑ A. User memory ❑ B. TID memory ❑ C. EPC memory ❑ D. None of the above UHF Generation 2 tags have four banks of memory: ➤ Bank 0—Reserved Memory —Reserved memory holds the tag’s passwords and can be read locked. ➤ A 32-bit Kill password allows a tag to be permanently silenced. The default Kill password value is zero. The Kill command executes only if the password has been set; that is, it is something other than zero. ➤ A 32-bit Access password allows the tag to transition to the Secured state (a tag in the Secured state can execute all Access commands, including writing to locked blocks). ➤ Bank 1—EPC Memory —EPC memory contains 32 bits for different protocol controls and a 96-bit EPC (Electronic Product Code) of the object the tag is attached to. ➤ Bank 2—Tag Identification Memory (TID Memory) —TID memory contains an 8-bit ISO allocation class identifier, a 12-bit tag maskdesigner ID, and a 12-bit tag model number. Manufacturers can include other information, if required—for example, a tag serial number. ➤ Bank 3—User Memory —User memory is an optional area of memory (usually 32-bits but can be larger) that contains user-specific data. The memory organization is user defined.
30. 30. 29. North America is a part of which ITU radio region? ❑ A. Region 1 ❑ B. Region 2 ❑ C. Region 3 ❑ D. Region 4 North America, together with South America, is a part of radio Region 2. Answer A is incorrect because Region 1 includes Europe, the former Soviet Union, the Middle East west of the Persian Gulf, and Africa. Answer C is incorrect because Region 3 includes the rest of Asia (excluding the former Soviet Union), Australia, and Oceania. Answer D is incorrect because ITU Region 4 is not defined.
31. 31. 30. Which statement is true when talking about linear and/or circular polarized antennas? ❑ A. A tag’s orientation matters more when using a linear antenna. ❑ B. A tag’s orientation matters more when using a circular antenna. ❑ C. With a linear antenna the RF field is narrower than with a circular antenna. ❑ D. Linear antennas can only be mono-static. Answer B is incorrect. Since circular antennas emit an RF field with signal propagating on several planes in a circular motion, the tag orientation matters much less than when using linear antennas. The read field of linear as well as circular antennas depend on the design and gain of each antenna and not whether the antenna is linear or circular. Therefore, linear antennas do not necessarily have a narrower field versus circular antennas. Answer C is incorrect. Linear antennas can be both mono-static as well as bi-static. Therefore, answer D is incorrect.
32. 32. 31. Which of the following types of tags use passive backscatter? ❑ A. Passive ❑ B. Active ❑ C. Semi-passive Passive backscatter works on the following principle: An interrogator transmits a continuous-wave RF signal into a reading environment. When a tag appears in the area, it receives the signal and modulates (or breaks up) the RF signal into patterns of ones and zeros that define the tag’s digital data while reflecting it back to the interrogator. Passive backscatter is used in passive tag communication. Active tags transmit or send their data; therefore, answer B is incorrect.
33. 33. 32. The Office of the Telecommunications Authority (OFTA) regulates RFID in ❑ A. Japan ❑ B. Europe ❑ C. Hong Kong ❑ D. The United States OFTA regulates communications including RFID in Hong Kong. In Japan, RFID is regulated by the Ministry of Public Management, Home Affairs, Posts and Telecommunications (MPHPT); therefore, answer A is incorrect. Answer B is incorrect because in Europe, RFID is regulated by the European Radiocommunications Office (ERO) that supports the Electronic Communications Committee (ECC) [formerly called the European Radiocommunications Committee (ERC)], and the European Telecommunications Standards Institute (ETSI). Answer D is also incorrect. In the United States RFID is mainly regulated by FCC.
34. 34. 33. What is the Q factor? ❑ A. Measurement of antenna gain ❑ B. Part of RFID tag memory ❑ C. Impedance of the electrical cable ❑ D. A measure of a tag’s efficiency The Q, or quality, factor of a resonant circuit is a measure of the ratio of the energy stored in it to the energy lostduring one cycle of operation. Answer A is incorrect because the antenna gain is specified in decibels (dB) and in formulas is usually referred to as G . The Q factor is not part of RFID tag memory; therefore, answer B is incorrect. Answer C is incorrect because the impedance of electrical cable in formulas is referred to as Z .
35. 35. 34. Which of the following factors are essential in determining whether the interrogator will successfully communicate with a tag? ❑ A. The orientation and type of the antenna that is being used by the interrogator ❑ B. The tag’s “dwell time” ❑ C. The distance from the interrogator to the tag ❑ D. The amount of memory on the tag’s chip Antenna orientation and type are essential to ensure that the tag can be interrogated. The tag’s dwell time, the time the tag is in the interrogator’s signal, is critical to consider ensuring the interrogator has enough time to communicate successfully with the tag. Successful communication is heavily dependent on the read range of the tag. A tag outside or near to its read range limit cannot communicate reliably with the interrogator. Answer D is incorrect because the amount of memory on the chip on the tag has no bearing on the ability of the interrogator to successfully communicate with the tag.
36. 36. 35. An externally facing system should have which of the following qualities? ❑ A. It should have good documentation of interrogation zones. ❑ B. It should have an RF frequency and a protocol compatible with trading partners. ❑ C. It should take into consideration governmental regulations in countries where applied. ❑ D. It should have Internet access from outside the site. An externally facing RFID system has to take into account issues that are common to the trading partners of the company. The choice of tag frequencies and data protocol are examples of issues that need to be coordinated. Tag frequencies are virtually always regulated by government agencies; therefore, careful planning is necessary when trading with partners from different countries or regions governed by different regulatory agencies. Answer A is incorrect because site documentation is an inward-facing issue, not an outward-facing one. It has to do with your site and needs, not those of your trading partners. Answer D is also incorrect because Internet access from outside the site is not essential for successful information sharing with external partners.
37. 37. 36. Which types of printing methods are usually used by RFID printers? ❑ A. Thermal transfer ❑ B. Laser ❑ C. Direct thermal ❑ D. Direct transfer Printers use thermal transfer and direct thermal methods of printing. Answer B is incorrect because the high temperatures induced by a laser beam when printing would disable the tag. Direct transfer is not a defined printing method; therefore, answer D is incorrect.
38. 38. 37. Which of the following are characteristics of active tags? ❑ A. Active tags support larger memory than passive tags. ❑ B. Active tags can perform more processing functions than passive tags. ❑ C. Active tags can support environmental sensors. ❑ D. Active tags communicate with an interrogator by using modulated backscatter. Active tags support larger memory and processing functions due to having their own power source. They can carry various sensors to monitor environmental conditions such as temperature, humidity, or motion and report this information to backend systems and/or store it in memory. Answer D is incorrect because active tags do not communicate by using backscatter; they communicate directly by broadcasting a signal to the interrogator.
39. 39. 38. Ultra High Frequency (UHF) tags operate at what frequency? ❑ A. 860–960 MHz ❑ B. 13.56 MHz ❑ C. 5.8 GHz ❑ D. 120–140 KHz The four primary frequency bands for RFID tags are ➤ Low Frequency or LF (120–140 KHz) ➤ High Frequency or HF (13.56 MHz) ➤ Ultra High Frequency or UHF (860–960 MHz) ➤ Super High Frequency/Microwave (2.45 GHz and above)
40. 40. 39. What two factors primarily govern the ability for successful communications in free space? ❑ A. The relative distance between an interrogator and a tag, plus the tag’s dwell time ❑ B. The frequency that an interrogator is transmitting a modulated signal, plus the tag’s dwell time ❑ C. Output power of an interrogator and the size of the tag’s antenna ❑ D. B and C Answer A is correct. Because an RF signal attenuates in free space, the closer the tag to the interrogator’s antenna, the more likely the tag will still be activated. The dwell time is the time that a tag is in the interrogator’s signal. The longer the dwell time, the more likely the tag will achieve uninterrupted communications with the interrogator. Answer B is incorrect because the frequency is irrelevant; a tag’s antenna is designed to function within the entire operating bandwidth of an interrogator (in the United States in a band of 860–950 MHz). Answer C is incorrect. Although the size of a tag’s antenna increases the distance that a tag can operate relative to an interrogator, one of the most important factors for successful communication is dwell time, which was not included in this answer. Therefore, answer D is incorrect as well.
41. 41. 40. When implementing an active RFID system for tracking automobile parts in the United States what standard do you have to comply with? ❑ A. International Organization for Standardization ISO 18000 – Part 6C ❑ B. ISO 17363 ❑ C. ERC Recommendation 70-03 ❑ D. ISO 18000 – Part 7 ISO 18000 Part 7 pertains to systems operating at 433 MHz. Most active RFID systems operate at this frequency. Answer A is incorrect because Part 6C of ISO 18000 pertains to Class 1 Generation 2 of passive tags. Answer B is incorrect because ISO 17363 regulates freight containers. Answer C is incorrect because ERC Recommendations are made by European Radiocommunications Office (ERO) and are not used in the United States.
42. 42. 41. Which of the following is not a part of an RF survey? ❑ A. Identification of potential sources of interference ❑ B. Identification of the radio RFID frequency that will be used ❑ C. Visual inspection of the facility ❑ D. Identification of ambient RF noise throughout the facility Identifying the radio frequency that will be used in the system is not part of the RF survey. It would have been selected during the design phase and will already be known by the time an RF site survey is conducted. Answer A is incorrect because it is an essential part of the RF site survey. It identifies interference in or near this frequency range. For this portion of the survey, spectrum analyzers are needed. If interference is found, shielding or other solutions need to be deployed so that the interference does not degrade the capabilities of the interrogation zone. Answer C is incorrect because the visual inspection of facility is also an important component of the site survey. Sometimes facility drawings or blueprints do not include things like stored goods, metal shelving, or other potential barriers to RF signals. Answer D is incorrect because, although knowing the ambient RF noise throughout the entire facility is not required, knowing those levels in your operational areas (in and around the interrogation zones) is essential to your design.
43. 43. 42. What functions would a programmable logic controller (PLC) perform in an RFID system? ❑ A. Detect the presence of a nonreadable tag ❑ B. Trigger controlling software based on input from a connected device ❑ C. Turn lights on and off depending on the state of a relay circuit ❑ D. Control a divert gate to remove a product from a production line A PLC is a microprocessor-based industrial control system. It communicates with other process control components through data links and is used for simple switching tasks and process and machine control. The PLC connected to a sensor would trigger an event to the controlling software of the interrogator. The software would initiate the interrogator polling, verify the result, and then send a signal back to the PLC to turn on or off the lights to indicate the condition of the tag. It could also control a divert gate to control the flow of product along a line. Answer A is incorrect because a PLC acts based on input from sensors, but it is not a sensor itself.
44. 44. 43. The time required for write operations can be up to ______ longer to complete than a read operation. ❑ A. 10 times ❑ B. 3 times ❑ C. 4 to 5 times ❑ D. 20 times Writing to a tag takes approximately 4 to 5 times longer than reading a tag.
45. 45. 44. Which factors can cause holes in an antenna’s coverage? ❑ A. Reflections of RF energy ❑ B. Overlapping RF wave fields ❑ C. Interference from external sources ❑ D. Imperfections in the antenna’s reflector A hole in an RF field is a region within the field where it is inadequate to perform RF activities. Holes can be caused by a number of factors: reflections of RF energy interfering with the radiated wave field, imperfections in the antenna’s reflector, or interference from external sources. Answer B is incorrect because, by using several overlapping wave fields, you counteract the effect of holes in an antenna-radiated wave.
46. 46. 45. Which of the following statements are correct? ❑ A. Low Frequency tags do not use induction coils. ❑ B. High Frequency tags use induction coils. ❑ C. Microwave tags use induction coils. ❑ D. Ultra High Frequency tags have antennas. Low Frequency tags use induction coils, and microwave frequency tags have antennas;
47. 47. 46. Which of the following are Gen 2 tag characteristics? ❑ A. Gen 2 tags are slightly larger than Gen 1 tags. ❑ B. Gen 2 tags have 64 bits of user-programmable EPC memory field. ❑ C. Gen 2 tag standards allow for cross-vendor compatibility. ❑ D. Gen 2 tags can be killed by an interrogator Gen 2 specifications, more correctly called Class 1, Generation 2 , allow tags to have cross-vendor equipment compatibility due to vendor-neutral design specification and can be accessed, locked, and killed by an interrogator, giving more options to users for securing their tags against illicit use. Answer A is incorrect because Gen 2 tags are one-half to one-third the size of Class 1 tags. Answer B is incorrect because Gen 2 tags have 96 bits of user-programmable EPC memory field.
48. 48. 47. Which of the following is a triggering device? ❑ A. Motion sensors ❑ B. Light stacks ❑ C. Divert gates ❑ D. All of the above Industry best practices dictate that, when you are designing an interrogation zone, you should use devices to trigger an interrogation. Some of the most used triggering options are motion sensors, devices that can detect when a product enters the interrogation zone and triggers the interrogation; time triggers, devices that cause interrogation at certain times; and manual triggers, devices operated by personnel. Answers B and C are incorrect. Light stacks and divert gates are not triggering devices, but are peripheral feedback devices. Therefore, D is also incorrect.
49. 49. 48. What is the advantage of a sweet spot? ❑ A. The advantage of the sweet spot is that the area of signal saturation is such that the probability of a successful tag read is high. ❑ B. The sweet spot is the best place to put a reader so that it can generate a higher frequency transmission. ❑ C. The sweet spot is the location where a tag is placed on a pallet or package, ensuring a perfect read no matter where the interrogator is located. ❑ D. The sweet spot is built into the antenna and allows a better signal to be sent from the interrogator to the antenna. The sweet spot is the area where the radiated signal has the maximum probability of a successful read for the type of tag being read.
50. 50. 49. Which of the following are true of active tags? ❑ A. They have their own power source. ❑ B. They have a transmitter to broadcast the signal. ❑ C. They draw power from the interrogation field. ❑ D. They are relatively inexpensive to produce. Active tags have their own power source that is used to run the chip’s circuitry and used to broadcast their signal. The concept of drawing power from the interrogator or interrogator field is called passive backscatter and is the communication method used by some passive tags. Answer C is incorrect. Active tags, because of their onboard power supply, are among the most expensive RFID tags produced; therefore, answer D is incorrect.
51. 51. 50. Why can Low Frequency (LF) systems be used for Real-Time Location Systems (RTLS)? ❑ A. LF radio waves travel through walls and other barriers better than UHF or microwaves. ❑ B. Active LF tags are less expensive than other active tags. ❑ C. Active LF systems use the enormous wavelength and its measurements to identify quite precisely the position of the tag. ❑ D. LF systems are only passive and cannot be used for RTLS. LF tags penetrate materials such as water, metal, and wood better than the other types of tags. Answer C is also correct because using LF systems allows simpler and more accurate calculations based on the properties of the LF waves rather than difficult and less precise calculations based on the time it takes the signal to travel from the tag to the interrogator. Answer B is incorrect. Generally, assuming you hold the cost of powering the active tag constant for any type of tag, LF tags are more expensive than the other types of tags because they require longer, more costly copper antennas. Answer D is also incorrect because the LF systems can be active and can be used for RTLS.
53. 53. 52. When you are tagging carton boxes and run out of tags (labels), can you use the tags that you purchased for tagging metal objects? ❑ A. Yes. As long as I have a way to attach these tags to carton boxes. ❑ B. Yes. Tags intended for use on metal are specially designed to perform on metal, which is an RF problematic material. Therefore attaching them to a non- problematic material like a carton will make them perform even better. ❑ C. No. Tags intended for use on metal are tuned for best performance when placed on metals. Attaching them to a carton will make them lose their performance. ❑ D. No. Tags intended for metal are approved by the FCC to be attached only to metal. Answers A and B are incorrect because tags intended for use on metal are tuned for best performance placed on metals, therefore attaching them to a carton will make them lose their performance. Answer D is incorrect; the FCC does not guide the usage of the tags with different materials.
54. 54. 53. Why is it important to know about Free Space Loss (FSL)? ❑ A. To be able to determine whether there will be enough power to activate the tag ❑ B. To make sure flying insects will not get harmed ❑ C. To make it easier to choose a specific interrogator ❑ D. To recognize that the relative power of an RF signal attenuates in free space Answer B is incorrect because the level of power is not high enough to “zap” a bug. Answer C is incorrect because the readers all generate the same amount of power per FCC Part 15.
55. 55. 54. You have a dock door. How would you ensure that the dock door RFID antennas are not damaged by the ongoing shipping or receiving process? ❑ A. RFID antennas are durable enough to withstand a hit from a forklift. ❑ B. Implement special rugged antennas. ❑ C. Mount antennas behind a pylon or have a pylon installed to protect the antennas. ❑ D. Mount antennas only on top of the dock door and not on the sides. Pylons are a good way to protect antennas or any equipment from being accidentally hit by vehicles. Make sure that a pylon does not shield the antenna due to its material and design. Answer A is incorrect because the antennas are usually not made for extreme harsh environments unless specially ordered. Answer B is also incorrect. Special rugged antennas would incur more lead time for the equipment as well as higher cost. They should not be used unless absolutely necessary and in special conditions. For a simple dock door in a warehouse where the operational abuse can certainly be avoided, it is better to choose a different design. Answer D is incorrect because, to achieve best results when reading the tags on sides of the pallet, mounting the antennas on the sides of the door is recommended.
56. 56. 55. Which of the following is not an interface of an RFID printer? ❑ A. Cat-5 shielded ❑ B. RS-485 port ❑ C. USB port ❑ D. RS-232 serial port Cat-5 is a cable standard, not an interface type. Answers B, C, and D are incorrect. The connection to an RFID printer can be made through many interfaces such as RS-232 serial data port, USB port, RS-422, and RS-485 interfaces.
57. 57. 56. The term dense interrogator mode refers to ❑ A. The ability of interrogators to read tags on cases packed very close together. ❑ B. The ability of interrogators to have many antennas attached. ❑ C. The ability of interrogators to avoid interference with other interrogators in the field. Dense interrogator mode, also called dense reader mode, provides each interrogator the capability to operate at a slightly different frequency, which helps reduce the radio interference between interrogators in the field. Answer A is incorrect because dense interrogator mode refers to interrogators, not tags that are packed closely together. Likewise, answer B is not correct because it refers to the number of antennas attached to an interrogator.
58. 58. 57. Which items in the following list are important issues that relate to providing clean power in the installation of RFID interrogators? ❑ A. Ground faults ❑ B. RMS voltage quality ❑ C. Speed of the Ethernet network ❑ D. Transient voltage quality Clean power is very important. It is important to avoid various power conditions. They can include ground fault, reverse neutral/hot, reverse neutral/ground, poor RMS voltage quality (sags, swells, flickers), poor impulsive voltage quality (transient voltage), and poor harmonic voltage quality. Answer C is incorrect because the speed of the Ethernet network has no bearing on power issues.
59. 59. 58. Which of the following would be considered a “smart label”? ❑ A. A label with both an RFID tag and a bar code ❑ B. A label with just an RFID tag embedded in it ❑ C. A label with a bar code ❑ D. All labels are “smart” A smart label is a label that contains an RFID tag, can store information such as a unique serial number, and can communicate with an interrogator. Because a label with a bar code does not include an RFID tag, answer C is incorrect, and answer D is incorrect because not all labels are smart.
60. 60. 59. Which of the following actions does not occur when transmitting a signal from an interrogator? ❑ A. An oscillator provides the base signal to the modulator. ❑ B. The modulator changes the signal from an analog to a digital signal. ❑ C. The amplifier amplifies the signal and routes it to the antenna. ❑ D. The antenna transmits the signal to the tag. When transmitting, the oscillator provides the base-band signal to the modulator and a reference signal to the demodulator circuits. The modulator adds information to thebase-band signal to be transmitted to a tag. Then the power amplifier amplifies the modulated signal and routes it to the antenna. The antenna transmits the signal to a tag. B is correct because modulation does not involve changing the signal from analog to digital, and this does not occur when interrogating. Therefore, answers A, C, and D are incorrect.
61. 61. 60. Which of the following types of tags use inductive coupling? ❑ A. Active ❑ B. Passive ❑ C. Semi-passive Inductive coupling is used in passive tag communication; semi-passive tags use the same communication methods as passive tags because they do not have their own transmitter as do the active tags. Active tags transmit or send their data; therefore, answer A is incorrect.
62. 62. 61. Coupling refers to what phenomenon? ❑ A. The attachment of the chip to the RFID tag ❑ B. The communication technique between devices ❑ C. The connection of several antennas to one interrogator ❑ D. The creation of an electrical current by exposing a conductor to a magnetic or electric field When a conductor is exposed to a magnetic field, the magnetic field causes a current to flow in the conductor. This is known as inductive coupling , as a current is generated by the influence of the magnetic field. This is the communications process used by Low Frequency (LF) and High Frequency (HF) band RFID devices. The antenna on the RFID tag, when exposed to the magnetic field generated by interrogator’s antenna, generates the current in the tag that powers the tag’s circuitry and allows it to communicate to the interrogator. Answers A and C are incorrect because coupling has nothing to do with chip attachment to the tag or antenna connection to interrogators.
63. 63. 62. Which part of Federal Communications Commission (FCC) standards applies to RFID? ❑ A. Part 2 ❑ B. Part 15 ❑ C. Part 16 ❑ D. FCC does not regulate RFID FCC Part 15 regulates RFID in the United States. Therefore, answers A and C are incorrect. FCC does regulate RFID; therefore, answer D is also incorrect.
64. 64. 63. Which of the following would result from a frequency spectrum analysis? ❑ A. Identifying the frequency range of any devices in the environment ❑ B. Determining how to shield existing RF sources ❑ C. Identifying possible unstable power sources ❑ D. None of the above The spectrum analyzer identifies radio frequency emanating from sources capable of generating it. The spectrum analyzer identifies RF energy coming from a source that needs to be shielded, but not the manner of shielding it; that is a design issue. Therefore, answer B is incorrect. Answer C is incorrect because the spectrum analyzer detects RF energy, not the condition of electrical power. Answer D is incorrect.
65. 65. 64. High Frequency (HF) tags operate at what frequency? ❑ A. 860–960 MHz ❑ B. 120–140 KHz ❑ C. 13.56 MHz ❑ D. 2.45 GHz High Frequency (HF) tags operate at 13.56 MHz. UHF tags operate in the 860–960 MHz band; therefore, answer A is incorrect. Low Frequency (LF) tags operate in the 120–140 KHz band; therefore, answer B is incorrect. Microwave tags operate at 2.45 GHz; therefore, answer D is incorrect.
66. 66. 65. Which of the following is an important consideration for the design of an interrogation zone? ❑ A. Dwell time ❑ B. Antenna orientation ❑ C. Product orientation ❑ D. All of the above Answer A is correct; dwell time, how long the tag stays in the interrogation zone, is an important component of the design selection of the interrogation area, articularly when using passive RFID tags. Answer B is correct; antenna orientation to maximize the size of the interrogation field is very important because, if the tags are in the interrogation zone for too short of a period, they may not collect enough energy to power up fully and talk back to the interrogator. Answer C is also correct; product orientation would have a big impact on antenna selection. In applications where product orientation and velocity are constant, it may be appropriate to use linear antennas to control the field because linearly polarized antennas generate a more focused interrogation field and provide further read distance and better penetration. This ensures all tags would be read. However, in a mixed supply chain application, because tag orientation is most likely not going to be constant, circular antennas are most probably a better option.
67. 67. 66. Which antenna should you use when the tag orientation is dynamic? ❑ A. Circularly polarized ❑ B. Linearly polarized ❑ C. None of the above ❑ D. Try to make the orientation constant When the tag orientation is not known or is changing, and also if tag polarization is changing (different vendors may use different types of tags), it is best to use the circular antenna. Therefore, answers B and C are incorrect. Answer D is also incorrect because making the orientation constant would probably require a total change of the business process, which would be more time- and money-consuming.
68. 68. 67. Which of the following can be functions built into an RFID interrogator? ❑ A. Writing data to tags ❑ B. Performing anticollision processing ❑ C. Reading bar-code data ❑ D. Generating an Advanced Shipping Notice (ASN) The following can be functions of an RFID interrogator: (a) reading and writing data to tags, (b) operating on either a single or on multiple frequencies, (c) performing anticollision processing, and (d) if the interrogator is a hybrid interrogator it will be able to read bar codes or other Automatic Data Collection data. Answer D is incorrect because an Advanced Shipping Notice (ASN) is typically generated by a back-end inventory system.
69. 69. 68. Which of the following cable characteristics will most likely not affect RF performance? ❑ A. Cable resistance ❑ B. Cable grade ❑ C. Shielding color ❑ D. Cable length Shielding color does not affect the RF performance. Answers A, B, and D are all variations of the same issue, all of which affect RF performance. Because cables have certain resistances, the longer the cable, the more power the interrogator must output to achieve the same results. If custom cables are required, make sure that they are cut to optimal lengths. This ensures that the cables do not cause resistance to the transmitted power in the interrogation zone. The optimal length depends on the wavelength of the type of RF that is to be used. The best practice for RFID cable construction is to cut on full, one-half, or one-quarter increments of the wavelength for the targeted frequency.
70. 70. 69. What part of the EPC tag data format holds the manufacturer identifier? ❑ A. Header ❑ B. Manager number ❑ C. SKU ❑ D. EPC number Answer A is incorrect because the header specifies the length, type, structure, version, and generation of EPC. Answer C is incorrect because the SKU is the stock keeping unit that identifies the object class. The EPC number includes header, manager number, object class, and serial number specific to each unit; therefore, answer D is incorrect.
71. 71. 70. Which are the characteristics of passive tags? ❑ A. Passive tags can communicate with each other. ❑ B. Some passive tags communicate using inductive coupling. ❑ C. Passive tags are less susceptible to interference than active tags. ❑ D. The read range of passive tags can be up to 30 feet. Answer B is correct because passive tags use either modulated backscatter or inductive coupling to communicate. Answer D is correct because the read range of passive tags is around 10 feet but can be up to 30 feet. Answer A is not correct because passive tags cannot communicate with each other; they do not have their own transmitter. Answer C is incorrect because passive tags have a shorter read range and rely on RF electromagnetic energy for both power and communication and are therefore more susceptible to RF interference.
72. 72. 71. What would you do first if you see that the interrogator is showing an error light and does not function? ❑ A. Check whether the interrogator is connected to the power source ❑ B. Restart the interrogator ❑ C. Check whether the interrogator is connected to the network ❑ D. Replace the interrogator immediately The first thing recommended to do in this situation is to restart the interrogator. Answer A is incorrect because the error light is on and the light indicates that the interrogator is powered up. Answer C is incorrect because a failing network connection would not indicate an interrogator error; you would find the failed network connection by connecting a functioning device to the network, by verification through the computer, or in the back-end systems. Answer D is incorrect because replacement of an interrogator should be a last resort; interrogators are expensive devices, and sometimes a simple reboot could solve the problem.
73. 73. 72. Which of the following would be good examples of applications where Low Frequency (LF) tags should be used? ❑ A. Animal tracking ❑ B. Electronic Article Surveillance (EAS) ❑ C. Electronic toll collection ❑ D. Automobile security Low Frequency (LF) tags operate at 120–140 kHz. They are well suited for applications requiring reading small amounts of data at relatively slow speeds and at short distances. Their read range varies from 1&quot; to 70&quot;, typically below 18&quot; (0.5 m). They penetrate materials such as water, tissue, wood, and aluminum well and are therefore well suited for animal tracking, in which the signal needs to penetrate the bodily fluids of the animal; Electronic Article Surveillance, which requires small data to be read at small ranges; and automobile security, which requires very short read ranges inside metal environments (for example, an RFID tag is contained in an encased car key and the automobile will start only if that key is inserted into the steering wheel column). Answer C is incorrect because UHF tags are better suited for electronic toll collection; they perform well at greater distances than LF tags (UHF passive tags usually reach to about 30 feet (10 meters), UHF active tags up to 1,000 feet (330 meters), have good non-line-of-sight communication, have ahigh data range, can carry relatively large amounts of data, and allow for simultaneous reads, and can read up to 1,700 tags per second.
74. 74. 73. Which of the following are not part of an RF survey? ❑ A. Identification of potential sources of interference ❑ B. Identification of the hardware used in following RFID implementation ❑ C. Network analysis ❑ D. Identification of ambient RF noise throughout the facility Identification of the hardware used in following RFID implementation is not part of the RF survey. It would have been selected during the design phase. Answer C is correct because the network analysis is not a part of an RF site survey. Sometimes facility drawings or blueprints do not include things like stored goods, metal shelving, or other potential barriers to RF signals. Answer A is incorrect because the identification of potential sources of interference is an essential part of the RF site survey. It identifies interference in or near this frequency range. For this portion of the survey spectrum, analyzers are needed. If interference is found, shielding or other solutions need to be deployed so that the interference does not degrade the capabilities of the interrogation zone. Knowing the ambient RF noise throughout the entire facility is not required, but knowing those levels in your operational areas (in and around the interrogation zones) is essential to your design; therefore, answer D is incorrect.
75. 75. 74. Which of the following is a type of printer calibration? ❑ A. Media calibration ❑ B. Quasi dynamic auto feed method ❑ C. Ultra low speed form feed verification ❑ D. All of the above There are several ways to calibrate a printer, depending on the manufacturer and the type of the printer: ➤ Auto-calibration —This type of calibration happens when the printhead is closed, the printer is on, and the media are fed through. The printer automatically sets the value it detects for the spaces between the labels. ➤ Long Calibration —This procedure fully calibrates the printer for media length, type, and print mode, and it updates the sensor values. ➤ Short Calibration —This is an abbreviated version of long calibration but uses fewer labels and may be less reliable. ➤ Sensor Profile Calibration —This procedure auto-calibrates the printer and usually prints out the label with sensor profile information. ➤ Media and Ribbon Sensor Sensitivity Calibration —This type of calibration resets the sensor sensitivity to detect correctly the medium and ribbon that are being used.
76. 76. 75. What conditions can impair the performance of a Real-Time Location System (RTLS)? ❑ A. Reflection ❑ B. Interference ❑ C. Low humidity ❑ D. Absorption Real-Time Location Systems depend on RF conditions to triangulate and locate tags. Reflection, interference, and absorption are RF conditions that can distort the time/distance calculations of the RTLS system and prevent them from working accurately. As a result, most RFID RTLS companies certify an accuracy of only 7 to 15 feet. Answer C in incorrect because low humidity does not negatively affect RF conditions.
77. 77. 76. Gen 2 tags can be killed for a time and then be resurrected for a new inventory round. ❑ A. This statement is true. ❑ B. This statement is false because the Kill command is not defined for Gen 2 tags. ❑ C. This statement is false because the tag will not respond to interrogation signals after being killed. ❑ D. This statement is true, but the resurrection may not be 100 % effective. After a tag is killed, it no longer responds to interrogation signals and hence is useless. Answer A is incorrect because the answer is false. Answer B is also incorrect because the Kill command is defined for Gen 2, unlike for Gen 1. Answer D is incorrect because the killed tags generally cannot be resurrected.
78. 78. 77. Which of the following are generally considered peripherals? ❑ A. Printers/encoders ❑ B. Signaling devices ❑ C. Handheld interrogators ❑ D. Label applicators RFID peripheral is a term that refers to RFID hardware such as printers and signaling and ancillary devices, such as light or horn sensors. In the case of RFID printers, they are used to fully or partially automate the labeling process. In most cases today, the printers are implemented as a retrofit to existing print and apply procedures. Answer C is incorrect because interrogators are not considered peripherals.
79. 79. 78. You are installing an RFID system in Europe. What is the rule about triggering interrogation? ❑ A. There is no rule. Interrogators can transmit fully all the time. ❑ B. Triggering devices should only be used in areas with high interference. ❑ C. Interrogators should only transmit when necessary and not at any other time. Triggering devices or other methods should be used to ensure this. ❑ D. If the reader transmits within officially allowed parameters (1 Watt, up to 4 Watts with a directional antenna when hopping minimally across 50 channels), it can transmit all the time. Answers A and B are incorrect because in Europe, due to the high density of RF devices, European regulations dictate that interrogators should transmit only when necessary and should use triggering devices and other methods to ensure compliance with these regulations. Answer D is incorrect, because Europe allows only 0.5 Watt, up to 2 Watts with a directional antenna and the interrogation still has to be triggered only when necessary.
80. 80. 79. Which of the following are considerations that should be taken into account when installing a printer/encoder? ❑ A. The printer should have sufficient space for adequate ventilation. ❑ B. The printer’s power cord should be at least 3 meters in length but less than 25 feet. ❑ C. The connection to a data source must be made with a standard parallel cable. ❑ D. The printer should be located on a solid, level surface. The printer should be standing on a solid, level surface, with sufficient space to open the side and top for media changes and to allow proper ventilation and cooling. Answer B is incorrect because it is essential to make sure to select a cord no longer than 9.8 feet (3 meters) with an AC power plug (for the country where the printer is to be operated), 3-conductor HAR cable, and an IEC 320 connector with a certification mark from at least one of the international safety organizations. Answer C is incorrect because the connection to the data source can be made through many interfaces such as RS-232 serial data port, USB port, RS-422, and RS-485 interfaces.
81. 81. 80. Which of the following are not important considerations for tag placement? ❑ A. Tag orientation with regard to the polarity of the interrogator ❑ B. Tag placement relative to other nearby tags ❑ C. Tag being in line of sight relative to interrogator ❑ D. Proximity of tag to metal RFID tags do not need line of sight from the interrogator. Answer A is incorrect because it is important for some types of tags, particularly single dipole tags, to be oriented along the axis of the read field of the interrogator. Answer B is also incorrect. The tag placement relative to other nearby tags is important because tags need to be placed so that there is adequate space between them. This prevents one tag from being in the “shadow” of another tag. Answer D is important to tag placement because certain tags do not perform well close to metal or liquids.
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