Making Radio Waves in Motor Fueling

Mobil’s new Speedpass system brings refueling one giant step closer to total automation through Radio Frequency Identification (RFID) technology developed by Texas Instruments (TI). TI strategic managers Susy d’Hont and Mike Ollivier explain how it works.

1997 will be remembered in the retail fueling industry as the year that a unique automatic payment system was launched thanks to a small radio frequency identification (RFID) tag that attaches to a keyring or to a vehicle. After three years of development and a successful launch earlier this year, more than a million Mobil customers and some 2,500 stations have clearly shown the value of RFID. This article will explain how this newest technology works.

Around for more than a decade, RFID has a host of applications—from automotive security and personnel access to electronic highway tolling. Even the security system for the 1996 Atlanta Olympic Games used RFID technology. All of these applications offer new and convenient ways for people to interact with automated systems.

In theory, RFID makes sense. It eliminates the need to manually swipe a credit card at the pump, thus saving the customer time and making the transaction safer and more convenient. However, applying RFID in a retail fuel setting has until recently been a challenge for most RFID systems and developers because of interference from the outdoor equipment at a retail fueling station; the need to read multiple tags in defined and discrete read zones; possible sources of electronic noise interference; and the requirement for an immediate and secured transaction. (A read zone is the broadcast area in which the reader unit’s interrogation-signal is received, or the electromagnetic field generated.)   

In the spring of 1994, Texas Instruments (TI) began working with the Wayne Division of Dresser Industries to create the first retail refueling RFID solution. It was successfully implemented by Mobil as “Speedpass” and attracted the interest of other key players in the petroleum industry. This first-of-its-kind solution is based on TI’s TIRIS™ technology.

Mapping out the signals
While the customer’s interaction with RFID is simple, the technology behind new refueling applications is actually a sophisticated blend of radio frequency technology and advanced systems integration.

The RFID system begins with a transponder, or tag, that contains a secure and unique ID code. The code is programmed into the tag and registered to an individual customer, who can link the code to a credit card account of choice. When passed near a reader unit housed within the dispenser, the tag is powered by radio frequency interrogation signals emanating from that reader. This prompts the tag to transmit its ID code to the reader, which then interfaces with a central host computer for authorization, via a local point-of-sale terminal.

TIRIS retail refueling transponders are available in two forms: a keyring tag and the industry’s only vehicle tag. The keyring tag is a hand-held device that is placed directly in front of a dispenser read-point panel. The vehicle tag, mounted unobtrusively on the rear window, automatically initiates refueling authorization as the vehicle approaches the dispenser.

Every transponder holds two main components: an antenna to communicate radio signals between the tag and the reader; and an integrated circuit to store the unique ID code and perform various radio frequency functions. Transponders can differ in their power source. Some are battery-free, such as the keyring tag, drawing their power from an internal capacitor that collects and stores RF energy issued by a reader unit. Conversely, there are battery-powered transponders, such as the vehicle tag. The battery provides for an extended read range and more powerful signal strength. (A read range refers to the distance tag and reader can be from one another without compromising communication.)   

Transponders can be either Read Only (RO), with a unique factory-programmed code, or Read/Write (R/W), allowing users to reprogram codes many times. Although TIRIS offers both versions, a Read Only tag is used in this application for three reasons:

• There is on-line access to the host computer available through the local POS system so that important data can be held securely in a central location.
• Actual credit card data is never transmitted.
• Cash values associated with a tag are not lost if the device is misplaced.

The RFID/POS link-up
Conceiving of a way to integrate TI’s TIRIS technology into a retail refueling point-of-sale (POS) system was a project undertaken by Wayne Dresser. After a three-year collaborative effort with TI, engineers produced the Wayne TRAC® System. This system provides a means to integrate the underlying TIRIS RFID sub-system into a POS framework, namely the Wayne Plus Retail Control System. Wayne Dresser makes this system available to other dispenser manufacturers in the industry.

Before initiating development of the RFID and POS linking system, it was imperative to learn how government regulations applied. The FCC, Weights and Measures, and Underwriter Laboratories (UL) all influenced the design basics, so across-the-board compliance was no small matter. For example, an in-ground antenna was proposed early on in the development cycle; however, it was changed to an on-the-pump version to fit within the safety guidelines set by UL.

Although RFID had earned high marks in other applications, its viability as a POS technology for retail refueling operations was not a given. Therefore the technological approach and specific implementation of RFID had to be carefully chosen and customized for this application.

Above The keyring tag has a sophisticated electronic device with an application to specific integrated circuitry. It is well packaged to withstand rigorous use. Courtesy of TIRIS, Technology by Texas Instruments.

Radio frequency bands
RFID systems can be designed to work over a broad range of radio frequencies. In reality, frequencies used in RFID systems are limited to bands licensed in various countries and world regions. RFID systems can be categorized as low, medium, and high. The specific frequencies referred to below are the most commonly available, and therefore most commonly used, frequencies in the three ranges discussed.

Low Frequency (LF) systems generally operate below the European Long Wave band, more specifically, between 120 and 140 kHz. As this region of the radio spectrum is sparsely used by others, LF systems are generally licensable worldwide. The advantages of LF include its low cost, worldwide usability, clear definition of read zones, the capacity of its signals to pass through most all non-metallic materials, and it has a well-documented history of success. However, it’s limitations include slow data rates and a restricted read range.

High Frequency (HF) systems operate in the upper ultra high frequency (UHF) and Microwave bands. As this region is crowded by other services (e.g., television, military, walkie talkie radio and cellular telephones), bands vary by country. In the USA, 915 MHz is commonly used, followed by 2.45 GHz. HF offers high speed data transmission, longer read ranges and immunity to electronic noise interference. Drawbacks include higher cost, especially for GHz range frequencies that often require specialized semiconductor materials. Furthermore, line-of-sight between tag and reader unit is required because HF signals tend to reflect off metal surfaces, puddles and other objects found in and around service stations.

Medium Frequency (MF) bands are situated around 6.8, 13.56 and 27 mHz. Characteristics fall between LF and HF, with some of the benefits and some of the drawbacks of both. A fundamental advantage of MF systems is that the components are size- and cost-effective, making them suitable for myriad applications. This advantage is offset somewhat by the overuse of mid-range bands, particularly 27 mHz. The most common side effect of overuse is signal interference from competing services.

There are pros and cons to each band relative to the automatic refueling application. The TIRIS keyring tag system functions at the low frequency of 134.2 kHz. Electronic noise interference can be a problem in LF systems where signals emanating from machine motors, fluorescent lights, or computer monitors can actually step on the RF (radio frequency) signal. However, the TIRIS LF system was designed with a patented approach that results in a strong signal-to-noise ratio within the three to six inch read range. This technology provides a cost-effective and reliable solution in situations where a limited read range is all that is needed.

Although the vehicle tag obviously requires a longer read range (up to eight feet), there still must be a well-defined read zone for accuracy. This TIRIS system employs a hybrid low/high frequency (LUHF) transponder that takes advantage of the benefits of both LF and HF. The downlink is still 134.2 kHz, while the uplink is 903 MHz. The defined read zone remains; however, it is augmented by high-speed data transmission that ensures the data is transmitted back to the dispenser reliably.

How RFID Works

Penetrating challenge
Ensuring the security of the transaction has been a major concern for both the keyring and vehicle tag approach. Obviously, purchase transactions of any type must be as secure as possible to prevent fraud and theft of confidential financial information. The solution involves a series of safeguard measures. First, there is built-in protection against duplicate ID codes since TI programs each transponder with a unique, tamper-proof code at the factory. In addition, rigorous engineering has gone into ensuring that there is a clearly defined read zone when a tag is presented to a dispenser. This keeps the transmission of ID codes highly localized and eliminates the probability of tag cross-reads.

The TIRIS systems also include a proprietary challenge/response authentication mechanism. Along with the unique ID code stored in each tag, there is a 40-bit encryption key and a fixed algorithm. The reader in the dispenser generates a random 40-bit code of its own, and transmits this code to the tag as a “challenge.”

Using its algorithm, the tag combines the “challenge” code with its encryption key and outputs a 24-bit digital signature. Both the ID code and digital signature are transmitted by the tag back through the reader and then on to the authenticating host computer. The computer performs the same algorithmic calculation as the tag. The resulting 24-bit solution is subsequently compared with that received from the tag. If the two solutions match and the computer locates an ID code within its database that is identical to that of the tag’s, the transaction is approved. The system’s high-speed data transfers take only four to five seconds, during which a credit authorization check is also being performed.

Grid window defrosters (standard on just about every vehicle on the road), and tinted glass posed another challenge. Traditional high-frequency signals are susceptible to blocking and deflection. However, the TIRIS vehicle tag’s 134.2 kHz low-frequency downlink means that signals can be read through any non-metallic material.

TI’s experience has been useful in designing RFID components for use in some of the most inhospitable environments, such as for electronic toll road collections or for product carriers going through production ovens. Because the tags may be exposed to any number of extreme conditions, they had to be rugged to withstand abuse.

Testing has been still another element of the integration process, both in controlled (laboratory) and uncontrolled settings. Thorough field evaluations were crucial in determining system compatibility and potential sources of adversity. Exposing the system to the harshness of outdoor environments and repeatedly staging scenarios of actual operating conditions helped designers troubleshoot for problems and fine tune where necessary.

Extending RFID’s benefits
TIRIS tags can be programmed with customer-specific information that supports data transactions at the reader unit. For example, a tag can contain information that designates a vehicle as part of a fleet. At the dispenser display, for example, a driver might be prompted to key-in a validation or time-date codes. With a tag permanently attached to the fleet vehicle, management can be sure that the fuel it pays for is going into the right gas tank. Credit cards simply do not have the same level of theft deterrence. RFID, always a valuable data collection tool, is giving fuel retailers access to better information on customers. Consider the value in being able to automatically collect, store and recall customer-specific data based on routine POS transactions. Generating computer records of the “when, where and what” of each transaction could pay enormous dividends in devising more effective marketing strategies or customizing services. More intimate knowledge of the individual customer leads to improved service, repeat business and increased revenues. Retail fuelers are going to great lengths to provide customers with the best possible buying experience. This RFID approach underpins the value that retail fuelers can offer customers in terms of speed and convenience. These two factors will be crucial in differentiating successful retailers from their competitors.

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