Barcodes were a milestone in improving the efficiency of point-of-sale systems in stores and warehouses, subsequently finding applications in many areas of the economy. They have achieved international standards, and when young people are asked about their history, they reply that
they have actually always been there… Yet Poland only joined EAN-UCC in 1990. A breakthrough in retail occurred in the field of product labeling when the Wal-Mart chain improved its logistics processes by implementing the Electronic Product Code (EPC). Synonyms are also used in reference to them: “tag”, “transponder”, “RFID (Radio Frequency Identification) tag”. However, specific commercial applications of the Electronic Product Code (EPC) are hindered by factors such as:
• relatively high price (approx. 0.20 EUR/piece; even with orders over 1 million pieces, it is 0.15 EUR/piece). American companies, often wealthier than European ones – suppliers to the Wal-Mart chain – label their goods at the delivery terminal without yet using EPC technology in their own enterprises
• small data transmission range (0.1÷1.5 m); in special solutions, depending on the operating frequency, this range can be increased to 6 m, or even up to 10 m. This is associated with higher transponder costs
• sensitivity to the positioning of the EPC relative to the base antenna (clear differences in operating range)
• sensitivity to interference caused by shielding from packaging in the form of metal foils.
• small data transmission range (0.1÷1.5 m); in special solutions, depending on the operating frequency, this range can be increased to 6 m, or even up to 10 m. This is associated with higher transponder costs
• sensitivity to the positioning of the EPC relative to the base antenna (clear differences in operating range)
• sensitivity to interference caused by shielding from packaging in the form of metal foils.
Where does the difference between EPC and a barcode lie? In the method of signal transmission, i.e., data to the “heart” of the logistics system – the database system. In barcodes, reading takes place based on the modulation of laser light reflected from the background with the applied
code pattern (Fig. 1). This modulation is caused by the movement of a beam deflected by electromagnetic coils, similar to a cathode-ray tube. The deflected beam moves across the dark and light stripes of the code, inducing an analog voltage signal in the circuit of the
photoresistors. As indicated in Fig. 1, this signal is subject to amplification and processing by a digital former. The signal transformed in this way is the object of further analysis. After dividing by the time base corresponding to the module width, we obtain the binary form of the module sequence. Knowing the code symbology and the character length (number of modules), we can read the value of the encoded character. In EPC (passive transponder, i.e., without its own power source), radio wave emission is used. The transmission of the signal between the base antenna of the receiving station and the transponder antenna (in transponders operating at frequencies below 100 Hz) must be preceded by an energy transmission wave necessary to power the transponder.
The article comes from the magazine “Logistyka” 5/2006.