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Choosing between UHF and Microwave based AVI systems

Selecting uPASS or TRANSIT for your AVI application

Nedap Identification Systems has launched the uPASS Reach in 2010 as an addition to its portfolio for long range identification of vehicles and people. The uPASS Reach is a UHF reader and operates at a frequency of approximately 900 MHz. Nedap has been selling its TRANSIT system for over 10 years. This system is using a very different, microwave, frequency (2,45 GHz). We now often get asked if UHF systems will replace our microwave based systems. Our answer to that would be 'no': for the next decade we expect both systems to be out there in the field in different types of applications. Each system has its own characteristics and its own qualities which makes it suitable for specific applications. Let's review some of these characteristics to hopefully enable you to select the right type of technology for your application.

What industry will be served?
Although the acronym AVI refers to automatic vehicle identification, it is important to realize that our systems are used in a wide variety of applications across many different industries: Chemical plants use it to allow their staff safe and convenient access to their sites. Taxi queues at airports use it to manage the flow of taxis looking for passengers. Mining companies use it to keep track of vehicles within their logistical processes. Bus depots use ours systems to manage access to the depot and keep track of their vehicles. Parking facilities use it to allow clients convenient access. Condominiums use it to allow residents secure and convenient access. Many different types of applications are out there. Some of these suitable to equip with UHF based systems, other more suitable to equip with microwave based systems.

   
UHF based windshieldtag                          Microwave based Booster 2G 

To be able to select the right technology you will have to decide for yourself which of the following system characteristics are most relevant to your type of application:

System robustness
Once you have installed an AVI system, you would like it to keep operating no matter what happens. There might be severe weather conditions sometimes. Or maybe unsuspected types of vehicles are added to the population. Other systems might interfere with the frequency bandwidth that your system is using. Windshields might be equipped with solar protection. Dirt and dust might be affecting the performance of the system.
In general one can say that at this moment microwave based systems are more robust and are less likely to be affected by circumstantial influences when compared to UHF based systems. In Nedap terms: if you want to apply the system in difficult situations and want to be 100% sure the system keeps working: choose TRANSIT. In other words: are you dealing with buses, taxis, trucks or other vehicles that are of the upmost importance to ensure operational business continuity, then the TRANSIT microwave system  should be your first option to consider. It is using semi-active battery empowered transponders and a very robust IP66 reader. The technology has been around for more than a decade and has proven to be well performing technology. If you can afford a little less resilience, then UHF readers, including the uPASS Reach, might be a good alternative.

Investment
When AVI systems were still solely equipped with microwave based technology or something comparable, we noticed that sometimes the systems were budget wise out of reach for some of our clients. The technology inside readers and the fact that transponders have a PCB and battery, result in a specific price level. Not everybody has the budget to spend to implement those types of long range RFID solutions.
And although we feel that the increase in convenience and security allow for a quick return on the initial investment, we are now also glad that by embracing UHF technology we have been able to introduce a friendly priced long range reader that supports passive UHF cards and tags that are in their turn also cheaper than their battery empowered counterparts from the microwave system. So if price is an issue, our uPASS UHF technology might be a good option.

Guaranteed read range
When debating about the quality of AVI systems, many people will refer to the maximum read range. Nedap Identification Systems has always felt that the contest with our competitors should not be about having the longest read range. It should be about the level of guarantee we can provide to offer a fit for purpose read range that will best support your application. Both microwave and UHF based systems are able, depending on  design and power of readers and transponders, to support very long read ranges of sometimes over 20 meters. For most AVI applications having a read range of more than 10 meters is useless. That is why for TRANSIT we have been specifying a read range of approximately 10 meters. Our very small and slimline design UHF reader was developed for applications where approximately 4 meters should be sufficient. So that is what we specify. Both technologies require line of sight between reader and transponder (tag).
The modulated backscatter principle of communication between reader and transponder has proven to be more resilient to external influences when compared to the air interface of UHF systems in general.
If you want a guaranteed long read range, the TRANSIT microwave system would be your first option. With UHF based AVI systems it is the combined quality of readers, tags and circumstances that will define the success of the implementation.

Driver and vehicle identification
One thing that has set our TRANSIT microwave system apart from competitive systems is the fact that using our booster technology we have been able to offer the option to, besides the vehicle, also identify the driver and thus be able to authorize the combination of driver and vehicle. This is a truly unique and valuable aspect.
Although UHF systems were developed to support “multi tagging” scenarios, there currently are no systems that offer a good “out of the box” solution to identify both the driver and the vehicle.

Support of open standards
Microwave based AVI systems are using proprietary technology by definition. There is no globally standardized air interface and transponder setup scheme available. When you buy a microwave based AVI reader from a manufacturer, you will need to procure the transponders from that same manufacturer. The good thing about this is that this one manufacturer can be held responsible for the performance of the system. This is very different for UHF based systems. The EPC Gen II standard is currently supported by virtually all manufacturers of UHF readers and tags. Our UHF readers also support this standard and so do our UHF tags and cards. This potentially means that you can procure our readers and source your UHF tags or cards elsewhere. We do advise to make sure that the UHF tags are of sufficient quality to ensure a well working implementation. It will also require a certain level of expertise from the manufacturer or supplier of the  tags to program the tags according to your requirements. Nedap Identification Systems for example will be able to supply you with tags that will only work in your installation and will seamlessly fit into your access control or vehicle management system.

Globally harmonized frequency
The use of the 2,45 GHz frequency is globally harmonized, which means that you will be able to use any microwave reader, including our TRANSIT reader and transponders, virtually anywhere in the world without having to fear influencing local systems that use a radiofrequency or be in breach with local laws and regulations. The UHF band is not harmonized which means that different regions will require different readers that are tuned for the right section of the band. Please be aware that also UHF tags and cards will be tuned to be used for a specific section of the available bandwidth. In itself this will not be a problem, as long as you aware of regulations and are well supported by your manufacturer of choice.

Support of volatile population
Microwave transponders are usually too expensive for a short period of one-off use. Thankfully they can, depending on the type of transponder, easily be moved from one car to another. This makes microwave transponders very suitable for installations with a base of users with a very high change rate. Employees, bus drivers, truck drivers, taxi drivers: usually these populations do not change dramatically overnight. The logistics involved in the management of transponders is limited. When the population is changing more rapidly, there might be an increased need for cheaper alternatives that are more suitable for one-off use. This could for example be applicable for audiences like temporary employees, hired personnel, contractors, event visitors, exhibitors and other populations of vehicles (and people) that require temporary authorization to get access. The cost effective passive UHF tags and cards would be an appropriate technology to apply. They can be left in the car. When the authorizations are revoked by the management system, it will render the tags useless and they will no longer pose a threat to security.

ATEX certified
In explosion hazardous environments (oil refineries for example) very often only the installation of ATEX certified equipment is allowed. Microwave technology has been used successfully in these environments for years. Our TRANSIT ATEX reader and “Heavy Duty Tag” are ATEX certified and have been used in numerous installations around the world.

Security
Defining which technology is more secure to use is always a bit tricky. A secure solution could be described as a solutions that people cannot easily abuse to get access to goods or areas they are not authorized for. There is always a security risk attached to any technology you might select to use. Long range AVI very often is more about convenience than it is really about security. But of course security risks should always be considered when using technology like this to allow vehicles and drivers access to a closed perimeter. In general one could argue that microwave systems are the more secure option. The proprietary nature of the product does not make it more secure by definition, but breaking into the system will require more effort from people who are trying to do such a thing. Another argument is that equipment for things like eavesdropping and emulating signals is less commonly available when compared to UHF equipment. It is also more difficult to reproduce or reprogram TRANSIT transponders when compared to UHF tags and cards. And then there is the booster option which allows authorization of the combination of vehicle and driver which is currently unavailable in the UHF portfolio.

Summary
Although both microwave and UHF systems can offer a good level of quality, convenience, resilience and security to integrators and end users. Both systems support the safe, secure and speedy flow of traffic and people. The nature of the underpinning technology leads to different product characteristics, which makes the technology more or less suitable for different types of applications in different industries. Please find a summary of the characteristics we reviewed below: 

Topic:

Microwave (TRANSIT)

UHF (uPASS)

System robustness

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Investment

 

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Guaranteed read range

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Driver and vehicle identification

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Support of open standards

 

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Globally harmonized frequency

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Support of volatile population

 

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ATEX certified

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Security

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Please understand that we will agree with people arguing that some of the statements made here will require a more indepth approach and should be open for more debate. Translating technical matters into real life implementation considerations is not always an easy thing to do. We do however hope you will appreciate our effort to shed some light on the differences between UHF and microwave. Please consult your designated Nedap business developer for more information.