Review Questions

1.	What materials are the best to use for shielding of adjacent interrogation zones? (Select two options.) Sheet metal Anechoic foam Metal mesh Polyurethane
2.	Which anticollision algorithm uses 16-bit numbers randomly generated by tags as a handle? FM0 Time-division algorithm Q algorithm Beta algorithm
3.	Which statement is true about the write operation? The write operation is faster than the read operation. The write operation is more reliable in shorter distances from the reader's antenna. The write operation is less sensitive to interference than the read operation. The write operation can be performed only by Generation 2 interrogators.
4.	Which technique should you use if you install 51 readers in one area? Dense reader mode Dense antenna mode Miller subcarrier Transmit power settings under 0.5 W
5.	Which type of an interrogator is the most suitable for exception processing? Vehicle-mounted interrogator Fixed interrogator RFID tunnel Handheld interrogator
6.	What happens to the antenna field when you increase the interrogator output power? Field increases in size; holes change size and location. Field decreases in size; holes change size and location. Field increases in size; holes stay the same and at the same location. Field decreases in size; holes stay in the same location.
7.	Which devices can be directly managed by a smart reader? (Select two options.) Light stacks Horns Conveyors Vehicles
8.	Where would you run the cables from the antennas to the interrogator on a forklift? The antennas are on the forks, while the interrogator is mounted near the operator's cabin. Affix them to the frame of the forks and the vehicle. Run them through the hydraulic hoses used for moving the forks. Keep them freely hanging between the forks and the rest of the vehicle. Connect the antennas wirelessly.
9.	Handheld interrogators can come with which of the following? (Select two options.) A circular antenna Up to four linear antennas A light stack A barcode scanner
10.	How can you ensure the success of your reading operation? (Select two options.) Avoid the interference. Use the least possible power. Speed up the conveyor. Provide sufficient dwell time.
11.	Why would you use bi-static antennas over mono-static? They are smaller in size. They are more efficient. They have much longer read ranges. They are supported by all interrogators on the market.
12.	Which type of antenna would you use in conjunction with a manufacturing line where the product and tag orientation are constant? A circularly polarized antenna A linearly polarized antenna A receiving antenna A transmitting antenna
13.	What causes multi-path interference? Tags talking to adjacent readers Readers talking to adjacent tags Reflected waves crossing the transmitted waves Not using the anticollision mechanism
14.	Which type of antenna requires a circulator in the reader? Mono-static Bi-static Linear All antennas
15.	What is the Select command used for? To select the tag class when configuring the interrogator To select the group of tags based on part of the EPC number To singulate a tag from the group of tags To access a tag after it is singulated
16.	What is the maximum allowed transmitted power in Europe (ERP)? 0.5 W 1 W 2 W 4 W
17.	What is frequency hopping? A method of transmitting in dense reader mode A method of receiving in time-division scheme A method of backscatter A method used by the tags to avoid collisions
18.	How will the installation of 50 readers affect network traffic? It will not affect network traffic. It will decrease network traffic. It will increase network traffic. It will absolutely take down the network.
19.	Where is data filtering usually done? (Select two options.) In middleware In the application At the reader level At the tag level
20.	What is the function of the oscillator in the interrogator? It modulates the signal for transmitting. It produces the carrier wave. It amplifies the carrier frequency. It facilitates the data transfers.

Answers

1.	B, C. To shield adjacent interrogation zones you need to use an RF absorptive material, such as an anechoic foam or a metal mesh with openings a lot smaller than the wavelength of the used frequency. Sheet metal could cause unwanted reflections that could cause interference in both interrogation zones. Polyurethane is relatively transparent to RF waves.
2.	C. The Q algorithm is based on a technique in which the reader sends a query with a parameter Q and a session number to a tag and then creates a slotted time. The tag generates a random 16-bit number as a handle. When the reader inventories tags in a selected session, the tag has to generate a random number for a slot number, which has to be between 0 and 2Q-1.
3.	B. The write operation requires a lot more time than the read operation, requires a stronger signal and shorter distances than the read operation, and is more sensitive to interference. It can be performed by any interrogator that has write capability, regardless of whether it is a Gen 1, a Gen 2, or an ISO compatible interrogator.
4.	A. If you are installing 51 interrogators in one area, you will have to set your interrogators to work in dense reader mode to avoid interference with each other.
5.	D. The most suitable interrogator for exception processing will be the handheld interrogator because it has great mobility. You can take it to a pallet or a product, and you are not restricted by power or network cables or by space.
6.	A. Increasing the power output of the interrogator (which means increasing input into the antenna) increases the antenna coverage, and the holes in its field move and change their size (usually get larger).
7.	A, B. Smart readers can directly manage certain low-voltage devices, such as light stacks or horns.
8.	B. The cables can be run through special hydraulic hoses that are used to move the forks, if they have a space for inserting the cables. Sometimes these hoses can come with the cables already integrated. However, today the vehicle-mounted interrogators are often made in dimensions that allow them to be mounted between the forks, and therefore the cables are not being moved and stretched as the forklift works, which reduces the possibility of damage.
9.	A, D. Handheld interrogators usually come with an integrated barcode scanner and one antenna. This antenna can be either circular or linear.
10.	A, D. To make your reading operation successful, you should try to avoid interference or protect your interrogation zone from interference as well as provide a sufficient dwell time for the tag.
11.	B. Bi-static antennas are slightly more efficient than mono-static antennas because they have dedicated antennas for transmitting and receiving functions and they do not use a circulator as mono-static antennas do.
12.	B. Linearly polarized antennas are most suited for applications where the tag orientation is constant. Linear antennas are a bit more efficient than circular because they give out a coherent wave without a phase distortion.
13.	C. Multi-path interference is caused by a wave that is reflected and crosses the path of a transmitted wave. The points where the waves cross can have a null or very strong signal. To avoid multi-path interference, you should use absorptive materials for shielding.
14.	A. A circulator must be integrated into the reader to operate mono-static antennas. Such a reader usually has only four ports and can run up to four antennas.
15.	B. The Select command picks out a group of tags based on certain characteristics, such as specific manufacturer's ID or other parts of the EPC number. Because this command concentrates on only a small part of the data within the tag, it is able to quickly locate and target certain tag groups within the whole tag population.
16.	C. The allowed maximum transmitted power in Europe is 2 watts in a frequency band of 865.6–867.6 MHz.
17.	A. Frequency hopping is a method of switching channels when operating in a dense reader mode. Readers may be required to hop across multiple channels within a given frequency spectrum mainly because of the time interval restrictions for transmitting in one channel.
18.	C. Installation of many readers will definitely increase network traffic. Before you start such a project, you should make sure that the network is not already maxed out by other devices such as PCs, laptops, or handhelds and that you have sufficient bandwidth for your interrogators to send data through.
19.	A, C. Data filtering is usually done first at the reader level, especially with smart readers. Then the data also can be filtered in the middleware so that the application gets only the data carrying some business logic.
20.	B. An oscillator is a component of an interrogator that produces the carrier wave. This carrier wave is then modulated by a modulator and amplified to be transmitted through the antenna to the tag.