1. | A customer calls you up and tells you that their RFID portal has stopped reading tags completely. What is the first thing you should do when you get on-site?
|
|
2. | What is the best kind of cable to use for a dock door that is 15˝ to the center of the door from one side, if you are installing a reader on one side and antennas on both sides?
|
|
3. | What type of software is required to change if you are going from reading one protocol to another, such as ISO to EPC, or Gen 1 to Gen 2?
|
|
4. | A UHF tag was applied to a corrugated cardboard box and was read successfully when shipped. The box was transported by sea. The tag was well protected from any damage. On receiving the box, the tag did not read. What can be a probable cause for the failure?
|
|
5. | What accessory used with the spectrum analyzer helps determine the performance of an antenna?
|
|
6. | A particular read zone did not have optimal performance. You tested the cable and noticed one of the following. Please indicate the reason that can lead to the poor reads.
|
|
7. | You are attempting to write to tags with a newly installed reader; however, the process is constantly failing. What is the most likely problem?
|
|
8. | You are reading tags on pallets of oatmeal in an interrogation zone but some of the tags do not get read. You find out that you are usually missing tags in a similar spot. What can be the problem?
|
|
9. | You found out that in a particular interrogation zone, the UHF tags were not read at random times during the day, in periods varying from 1 to 10 minutes. What could have been the problem?
|
|
10. | How do you prevent reader interference from adjacent dock door interrogation zones? (Select two options.)
|
|
11. | When you are trying to connect the reader to your laptop via a serial port, which of the following will be required?
|
|
12. | You are on a client site, trying to troubleshoot poor read rates. After some analysis, you come to a conclusion that tags may be the reason for the poor reads. You are equipped with only a reader, an antenna, a measuring tape, and a laptop. How can you evaluate the performance of 100 tags? (Select two options.)
|
|
13. | Which of the following can result in power loss? (Select two options.)
|
|
14. | An HF RFID system is deployed in a conveyor system in a manufacturing plant. The system is surrounded by a lot of metal. The read performance is poor. How can you improve the performance?
|
|
15. | From the following list, select the options that can introduce noise in a UHF RFID system.
|
|
16. | You need to buy cables for deploying a UHF RFID system. What type of coax cable and RF connector connection (joint) method should you opt for?
|
|
17. | What is the best method for troubleshooting an RFID handheld device?
|
|
18. | You are receiving shipping containers in the European Union, where ETSI is the governing body. What is the first thing to check if you are not reading the active 433 MHz tag that is attached to each container? (Select two options.)
|
|
19. | A UHF RFID system is deployed in a data center to track servers coming and going through the door. The software attached to the portal and four antennas (two on each side) have stopped giving information on whether the server is coming into or out of the data center. What could be wrong?
|
|
20. | An HF RFID system is deployed on a shelf in a hospital pharmacy. Recently the shelves were replaced and the system stopped working. What can you do to remedy the problem?
|
|
Answers
1. | D. The first thing you should do is to reboot the reader. Readers are small computers, without the keyboard, video, and mouse, so occasionally they will lock up when things go wrong. The simplest first step after you've checked to see whether the power is on is to reboot the reader and see whether that fixes the problem. |
2. | B. Because the dock door has to be 30" wide (15" to the center from one side, times two), that run is likely to cause excessive loss over LMR-240. Therefore, the correct choice is to use LMR-400, which will have less loss because of increased insulation. |
3. | A. Firmware is the software that sits on the reader and controls what it can or can't do. Allowing it to read one type of tag and not another is part of its functionality. Middleware accepts read data from an interrogator and creates business logic or actionable items from the RFID data. The only time middleware can affect an interrogation zone is when the middleware is programmed to change the reader settings. |
4. | B or D. Corrugated cardboard boxes have a high affinity to store humidity. The box was transported by sea, so the box must have absorbed humidity, which can detune the tag. (Moisture is RF unfriendly at UHF.) The tag could also be read by a different protocol reader, for instance a proprietary system might be trying to read an ISO tag. |
5. | C. The VSWR bridge along with the spectrum analyzer helps determine the performance of an antenna. The larger the dip in the VSWR graph, the less loss exhibited by the antenna, and hence the better performance it will have. |
6. | A. A kinked cable can introduce high losses resulting in less power for the tag to operate. This can lead to poor read rates. |
7. | C. In this case, the reader is improperly configured, and most likely the air interface protocol and data protocol of the reader and the tag do not match. |
8. | B. Multi-path interference or imperfections in antennas can cause holes in RF coverage in the interrogation zones. The unread tags in the same spot were most likely falling into the hole in the antenna field. This could be solved by overlapping fields as well as by moving the tagged objects. |
9. | C. Completing the full Faraday cycle analysis will show things on the periphery of the frequency, and also show the power level. Having something close to one of the end frequencies (either 902 or 928 in the USA) can bleed over into the range used. |
10. | B, D. To prevent interference from adjacent interrogation zones, you may need to use proper shielding and adjust the power going to the antenna. This will prevent interference by containing the RF fields within their own interrogation zones. |
11. | D. To achieve serial connectivity between the reader and the laptop, it is essential that you have a serial cable with DB9 connectors and know the COM port number on the laptop, so you can configure the COM port. It is very important that you know what baud rate settings are required to connect with the reader. This information can be obtained from the reader manual. |
12. | A, C. By determining a set distance where some tags for the batch respond and some don't, you can find superior, average, and under-performing tags. You can also find the superior, average, and under-performing tags by varying the reader power and keeping each tag from the batch at a set distance. By reducing the power below a certain value, tags will stop responding, allowing you to determine the MEP value for each tag and sort them as superior, average, and under-performing. |
13. | A, B. In an RFID system setup, longer cable lengths and connectors add to power loss. In cables, the loss is due to impurities in conductors and leakage. In connectors, losses are due to contact resistance and leakage. |
14. | A. The high amount of metal surrounding the conveyor system detunes the antenna. By using a VSWR bridge and tuning screwdriver, you can tune (change the inductance and capacitance) the system to operate at 13.56 MHz. |
15. | D. Adjacent readers can be the biggest source of interference or noise; a reader that is noisy can easily kill a tag response, resulting in poor read rates. Cables that have a damaged insulation can directly add noise to the center conductor carrying the signal of interest. Just like the adjacent readers, the wireless handheld systems can also act as noise sources. |
16. | A. The soldering approach provides the best connectivity in terms of both electrical and mechanical connectivity. Crimped connections result in mechanically weak joints. Wrapped connectors are difficult to use as RF connectors; also, wrapping the thick coax core conductor can result in higher resistance at the point of contacts, resulting in heat, which results in oxidation. |
17. | D. RFID handhelds usually work out of the box, and you know the performance you are getting. If there is a problem, it's usually due to the handheld being dropped or damaged, and is best dealt with by the manufacturer. |
18. | B, C. The battery tag is the first thing to check; it could have failed for a number of reasons, but an active tag without a battery will not read. The other issue is that the reader may be for a passive RFID tag for 968 MHz, and you are trying to read an active tag. Although this last point may seem obvious, you'd be surprised at the number of times it happens. |
19. | D. The combination of middleware, firmware, and reader settings can create a number of issues. If something is working well and there is any change to the system, then it will be highly likely that one of the "soft" components of the RFID network has caused the problem. |
20. | A. The shelves that were swapped out were likely metal shelves instead of wood, or perhaps the reader was tuned for metal shelves but wood shelves were installed. A simple check is to see whether the antenna has been detuned because of the change in material. |