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level: External hardware (NEED)

Questions and Answers List

level questions: External hardware (NEED)

QuestionAnswer
What is a barcode?o Barcodes are printed diagrams that consist of light and dark portions
Describe the operation of an RFID systemReader emits radio waves which are picked up by the tag’s antenna The power induced in the tag’s antenna from these waves is enough to power the chip which then uses its antenna to emit its own radio wave, which contains the information held on the chip This wave is picked up by the reader which decodes the information and returns the information to a computer.
Give the differrence betweens a passive and an active transponder- Passive transponders can be powered by energy from the reader whereas active transponders the energy is stored with it in the form of batteries - Passive transponders are less bulky - Passive transponders cant broadcast constantly - Passive transponders have a shorter read range - Passive transponders are cheaper
What are the uses of RFIDso Protect goods in shops  1 bit transponder  Removed or deactivated at the till  A reader installed at the shops exit goes off if an items transponder is still active (Not been removed/ probably not been paid for) passes through it o Attached to products  Gives them a unique code  Items can be individually recognised o Passive transponders have access control which is means of restriction of certain areas o Passive transponders can be used for smart labels o Passive transponders can be used for races o Smart cards
Explain the process of capturing an imageo Light from objects is focused on the sensor by the lens  Sensors consist of a 2D array of cells which are light sensitive photosensors • Each cell having an electric charge proportional to the brightness o This is converted into a digital format with an analogue to digital converter  This ADC conversion is done by a CMOS or a CCD converter
What are the advatages of CMOS against CCDCMOS has Lower Power consumption Usually cheaper cost
· Explain how a CCD sensor works, and how data is acquiredo Array of photodiodes o 1 red filter, 1 blue filter, 2 green filters cover the photodiodes (Bayer filter mosaic) o Each row shares an ADC converter  Located to the right o Charge is accumulated based on light exposure and frequency o The charges are shifted to the right one cell at a time o Converted into analogue and then into the digital equivalent
· What is a barcode reader?o It’s a device that allows computers to be able to receive data
What are the principles of operation for a barcode readero Barcode readers consist of a laser light source, a lens, photodiodes and a mirror o The mirror directs light from the laser onto a printed barcode o The light reflected by the barcode passes through the lens and is incident on the photodiode which turns light into electrical charge o This electrical charge can be measured and processed to form a digital signal representing the content of a barcode
· What is the output of a barcode reader?Electrical charge
· Explain the difference between one-dimensional barcode and 2D barcodeo 2D barcodes contain more info o 2D require more processing to extract info
Name the two types of 2D barcodeAztec, Tag
Name the two types of 1D barcodeISSN, ISBN
What are the advantages/ good things about barcodes and barcode readerso Very reliable  Even if the item is continuously moving very fast  Can complete thousand of scans a second • So even if dirt is covering the barcode it carries on o Well refined  Great for mass commercial use o Cheap  Been around for years  High volume of use o Easy to use  Just point at the barcode and shoot
What are the parts to a laser printero Laser o Mirror o Lens o Toner o Drum o Fusing section
· Explain in detail the operation of printing (monochrome)o The page description language describes how the page should be printed (as lines, arcs and polygons) o This is translated to a bit map image by the processor and saved in raster memory o A negative charge is applied to the photosensitive drum o Laser beams are directed onto the rotating drums surface o The lasers are then turned on or off by positrons determined by the saved bitmap image o This results in the negatively charged drum being positively charged in these sections hit by the lasers- this corresponds to the black parts of the printing o The charged surface of the drum is then exposed to a toner o * Darker areas are achieved by applying more layers of toner * o * A higher voltage difference between the toner and the drum achieves more toner being deposited into the drum quicker * o The drum is then rolled and pressed onto a sheet of paper which transfers the contents of the projected image onto the page * not needed *
which primary colours are used in colour laser printing? Cyan, magenta, yellow + black
What is the simple explanation of the process of colour printing Goes through the printing cycle 4 times- one for each colour  Layering the colours on top of each other
What are the advatages of monochrome laser printers compared to colour laser printers?Faster printing speeds Cheaper per page Lighter
What are the advatages of colour laser printers compared to monochrome laser printers?Has colour Two in one- still have black and white More versatile (Images, leaflets etc...)
Describe an RFID generallyo Transmission of data using radio frequencies
List the components of a RFID systemo Transponder o Reader o Clock o Coupling element (Antenna) o ‘Energy’ o ‘Data’
What are the two types of RFID transponders calledActive Passive
What are the advatges of RFIDs against barcode scanningRFIDs can scan many tags at one time RFIDs does not to be in LOS RFIDs can add timestamps to avoid multiple counting RFIDs uniquely tags and labels each item
Why donesnt barcode scanning timestamp itemsbecause items are not unique
What are the two types of sensor calledCMOS and CCD
What are both types of sensor fabricated fromfrom metal oxide semiconductors
Has CMOS or CCD been around longer and since when?CMOS since 1975
Why for a CCD sensor are there 2 green filters?2 green represent that the human eye is most sensitive to green light
State how for printing the toner can be applied to the drum quickerApplying a higher voltage difference between the toner and th drum
Explain how darkeer areas are acheived when pritingApplying more layers of toner