Chapter 8: Testing One, Two, Three: Developing Your Own Lab
3. Connect the hubs and servers so that if any of your readers need to be controlled, they can all communicate via the one dedicated reader
This allows you to connect multiple readers to the same server without having to plug and unplug each one.
SKU testing station
If you start with the grid, the servers, and the readers as anchor points in your lab, the next geographically located test station is the product or SKU testing station. This station consists of a reader or tag testing appliance, a single antenna, an antenna stand, an RF-friendly stand (made of dried wood or plastic) for the product to be tested, and power access. The floor needs to be measured, but being on the grid is not a requirement. Mark off the floor with 1-inch increments, but a full grid is not necessary. If the station is close enough to the server cabinet to run a couple of CAT-5 cables, that’s perfect.
Conveyor
If you have a conveyor, you should put it as far away from the static testing area as possible. All that metal can have an unwelcome reflective effect on your testing. Using a Cyclotron (described in Chapter 10) is a better solution, but it still might cause enough noise to warrant separating it as far from the test grid as possible. The ideal is a room that’s 75 feet long, which is big enough so that a loop conveyor at one end has a minimal effect on testing at the other end of the room.
Print-and-apply station
The last segregated area of your lab is the print-and-apply station. This station requires relatively little power and only a few points of network connectivity.
You can run most print-and-apply solutions during other testing without interference because print-and-apply machines are such low-power output devices and are directionally focused.
As you begin to understand which areas need to be in close proximity to each other, you can move the areas around to suit your needs. In general, starting off with a lab design like the one shown in Figure 8-3 will get you off to a good start.
Build specific test equipment
The RFID industry is so new that you can’t yet go down to your local Home Depot and pick up a couple of RFID antenna racks; you have to build them yourself. In the production environment, you have to think about protection, durability, and other considerations, but in the lab environment, you need to think about two things — portability and RF friendliness. Fortunately, the solution is cheap and simple. In the words of The Graduate, “Plastics.”
You may wonder why PVC is on the list of must-have tools described earlier in the chapter. The reason is that PVC is the perfect material to make antenna racks, temporary portals, and conveyor stands. You can cut through it with a
$5 handsaw, and you can put it together and pull it apart like LEGO bricks. If you add an assortment of connection joints, some plastic zip ties, and a bit of heavy-duty Velcro, you’ve got the makings of most of your lab gear.
Portal Simulation Work benches
Server
rack SKU
testing
Work bench
Print & Apply
Conveyor or Cyclotron Figure 8-3:
A basic RFID lab design and layout.
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The process of building PVC antenna holders and racks is pretty self- explanatory, so rather than give you step-by-step instructions, I’m just going to show you a picture of a design to hold a single antenna to give you the basic idea. Figure 8-4 shows the back of a PVC antenna mount on the testing grid.
You can make these PVC racks just about any shape or size that suits your needs. The important thing to remember is that you are trying to simulate the real-world environment. So if your conveyors are 12 inches off the floor, your test stands should be 12 inches tall. And if they really are that tall, you should let Mr. Claus know that you won’t have any problems passing OSHA inspections, and the entire facility will be RFID-enabled by next Christmas because of your way-cool lab.
Using the PVC material for testing apparatus does have one drawback: It can’t hold a significant amount of weight. To test cases of items or heavy objects for their RF suitability or for basic SKU testing, you need an RF-friendly material that also strong enough to hold up things like a 30-pound case of SPAM or a 75-pound uninterruptible power supply (UPS). For this, nothing works like good ol’-fashioned kiln-dried lumber. Lumber has minimal moisture content, but for purposes of SKU testing, not enough to affect your results. And what- ever liquid the lumber has is a consistent factor. Figure 8-5 shows a sturdy, homemade, 2-x-2-foot SKU testing bench about countertop high.
Figure 8-4:
A home- made, freestand- ing PVC antenna rack.
Develop and implement standardized test procedures
When you’re done setting up the lab, it’s time to document your testing pro- cedures. The purpose of documenting your testing procedures is to ensure that any new lab rat you hire can perform a test and compare the results with a test that someone else did six months or six years ago. In addition to being able to compare testing results, documentation enables new folks to get up to speed quickly on how things are done.
In your RFID lab, you can perform tests for an infinite number of purposes.
However, to start with, perform the following four tests to quickly address some common issues:
Antenna patterning test
Reader performance test (for distance, speed, and accuracy) SKU test
Tag characterization test
Antenna patterning and reader performance tests are performed in the area Figure 8-5:
A SKU testing bench made of kiln-dried lumber.
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place in the area with the least amount of interference and likelihood of reflection or standing waves.
The four tests you perform in the lab directly correlate to the real-world envi- ronment. If you document your information well, you can take that data and use it to design and select your final system.
Antenna patterning test
This simplest test, perhaps the most insightful for those new to RFID technol- ogy, is to pattern an antenna and reader by following these steps: