Advantages of RFDC
The advantages of RFDC depend on what kind of system is currently in place – on-line, batch or manual. The advantages of RF over alternative systems are outlined in the following table:
Advantages of RF
|On-Line||Connects a host computer to remote readers via wires and cables. The data is transmitted instantly||Eliminates wires and cables, and the costs associated with them. Offers portability while providing instant access to collected data.|
|Batch||Stores data off-line in readers for later upload to the host computer. Permits use of portable readers.||Eliminates delay between data collection and transmission without sacrificing portability. Minimises risk of lost data.|
|Manual||Uses human labor to record to remote readers via wires and cables. The collected data is transmitted instantly.||Speeds up data collection. Eliminates delay between data collection and its availability to users. Improves data accuracy and drastically reduces labor costs relative to data collection.|
RFDC Offers The Following Benefits:
- User-Friendliness: No new routines need to be learned by an operator already trained in ADC
- Data Security: Data is immediately transmitted to the host computer without delay, minimising the risk of lost data.
- Security: Different security measures such as passwords and addressing are also used to ensure security of data.
- Economies of Scale: The marginal cost of additional RF units is relatively low.
Understanding The Technology
Until the early 1990s, all commercial RFDC technology focused on what has become known as narrow band RF. In 1985, the FCC authorised the use of spread spectrum RF technology in the commercial realm. In 1990, the first commercially available spread spectrum systems were offered for sale.
Spread Spectrum Technology
In the past several years, the use of spread spectrum RF has become widespread. Because of the many advantages of the technology, it has become the prevalent form of RFDC in use today throughout manufacturing and other industrial environments. Spread spectrum technology is a technique for distributing the content of a data signal over a frequency range that is considerably wider than the range normally required for reliable transmission of data. The two most common spread spectrum frequency bands are 902-928 MHz and 2.4 – 2.4835 GHz.
902 MHz and 2.4 GHz
902 MHz and 2.4 GHz systems have different attributes which center around the two areas of geographic coverage and data rates. If a data collection application requires great coverage (e.g. a large warehouse), a 902 MHz system may be the best choice to cover the large area. If there is a requirement for high data rates (e.g. the application requires large packets of data to be sent from the device to the network), a 2.4 GHz system may be more appropriate.
Many 2.4 GHz systems provide easy access or connectivity directly to the corporate network. They do this by means of an access point which functions as a bridge between the enterprise network and the devices on the 2.4 GHz radio system. While 2.4 GHz systems may provide more openness in terms of connectivity, concerns should also be focused on the openness of the end device.
Questions to ask include:
- Does the end device have a standard operating system to provide maximum flexibility?
- Does the architecture of the end device help minimise the work involved in developing the application program?
Choosing an RF System
When choosing an RF system you should consider its compatibility with your current system as well as its versatility. Ask yourself these questions:
- What are the limitations in the proposed system? If you have to purchase additional equipment to integrate the system into your current operations, it will become more costly and complicated.
- Can the equipment be upgraded? In what direction? How expensive is an upgrade? If your operations expand, you will also want to be able to expand your data collection system.
- What are your likely future needs? Can they be addressed by an RF system? Designing your system with an eye toward the future will help avoid problems later on.
Is It Worth It?
Most businesses find their automated data collection systems pay for themselves in less than one year, making them extremely cost effective. To precisely evaluate the profitability of investing in RFDC, you should conduct a cost justification analysis of your proposed system. Cost justification analysis weighs the cost of an investment against its expected savings over time.
The Next Step: A Site Survey
Once you have identified a need for an RF system, you should have a vendor conduct a site survey. Site surveys identify environmental factors that can effect the performance of your RF system. With the results of this survey, your vendor can help you determine your exact needs (e.g. whether you need a 902 MHz or 2.4 GHz system).