Automated PIT Tag Test System (APTTS)

From PTAGISWiki

APTTS (Automated PIT Tag Electrical Test System) with the original PETF (PIT Tag Electrical Test Fixture) in the foreground

Video

Click the following link to see the APTTS in action:

APTTS Video

The clip opens with the vibratory bowl dispensing the PIT Tags into the in line feeder. After enough PIT Tags have been fed to the in line feeder, the bowl stops vibrating. The PIT Tags continue down the in line feeder to the shuttle (the brown plastic piece seen at the right side of the screen) which then dispenses a PIT Tag onto the V-block.

The next section of the clip shows PIT Tags being dispensed onto the V-block, transported under the camera (note the red back-light) and into the antenna for electrical testing. At the completion of electrical testing, the PIT Tag is diverted down the chute to the sorting bin.

The last section of the clip shows the positioning of the sorting bins for disposition of the PIT Tags based on the testing.

Downloads

The visual aids used in the demo are presented here in Adobe Acrobat format:

APTTS Data
Antenna Theory
Anatomy of a Waveform
Q and Bandwidth

APTTS Brochure (essentially, this wiki page in brochure format)

History

The PIT Tag Information System (better known as PTAGIS) has been tracking anadromous salmonids since the late 1980’s. This has been accomplished using passive integrated transponders (PIT Tags) and a system of equipment interrogating those tags at 400 kHz. Between 1986 and 1999, essentially all PIT tag research and monitoring projects in the Columbia River basin (CRB) marked salmon and steelhead using 400 kHz full duplex (FDX) tags manufactured by Destron Fearing Corp. These tags were approximately 11.5 mm long and 2.1 mm in diameter.

In the late summer and fall of 2000, researchers in the CRB transitioned from the use of 400 kHz PIT tags and detection equipment to equipment compatible with 134.2 kHz FDX-B tags conforming to the International Standards Organization standards ISO 11784 and 11785. Again, Destron Fearing (later Digital Angel) has been the primary manufacturer of the 134.2 kHz ISO FDX-B tags used in the CRB. Almost all of these tags are 12.5 mm long and 2.1 mm in diameter.

At times Digital Angel has made changes to the design of the PIT Tags supplied to researchers. These design changes were made improve the PIT Tag with respect to performance, cost efficiency, etc.

An approximate summary of Digital Angel PIT Tags is shown in the following table:

Occasionally the design changes come unannounced. Sometimes the changes have deleterious effects. In 1996, a change was made to the 400 kHz PIT Tag that caused an approximate 20% reduction in read range. The signal received from the PIT Tag was weaker than previous PIT Tags. Data loss from this occurrence is a possibility. PTAGIS personnel spent many hours trying to determine what happened to the readers, but the problem turned out to be degraded PIT Tag performance. To their credit, Destron Fearing quickly re-designed the PIT Tag and increased the sensitivity of the transceivers (through a firmware change) to restore performance.

Around 2000, due to a raw material supplier oversight, some of the ferrite antennas broke when subjected to impact. 20% of these PIT Tags broke in shipping. Due to this occurrence, Digital Angel recalled all of the PIT Tags in question. This included 80,000 PIT Tags already distributed to researchers by PTAGIS.

In 2005 Digital Angel released an interim tag, the TX1400SGL, prior to the completion of the present SST PIT Tags. These tags were needed for early testing of the Corner Collector System. Desiring a process to qualify these PIT Tags prior to distribution in the CRB, PTAGIS created the PIT Tag Electrical Test Fixture (PETF). The PETF is a system used to measure various electrical properties of PIT Tags. Tests performed using the PETF, along with practical application testing at the PTAGIS Kennewick office, showed a variability in the performance of the TX1400SGL PIT Tags. Subsequently, Digital Angel also saw the variability with their equipment. PTAGIS returned their stock of TX1400SGL PIT Tags to Digital Angel, who retested the PIT Tags, removed the outliers, and sent the consistent performers back to PTAGIS.

Although very labor intensive for PTAGIS staff, the additional testing proved beneficial. These occurrences illustrate the need to be able to test PIT Tags in an efficient manner prior to deployment in the CRB.

They also facilitated the creation of the Automated PIT Tag Test System (APTTS). In late 2005 and early 2006, the PTAGIS project contracted with Wintegra, Inc. (PSMFC Contract No. 06-51) for the development of the APTTS. The machine was delivered, installed, and became operational on June 23, 2007.

The APTTS will be used to qualify new PIT Tag models from potential new manufacturers for use in the Columbia River Basin.

Testing Capabilities

The APTTS has the ability to make many electrical and physical measurements to each PIT Tag. The measurements can be automated to obtain data from small samples of PIT Tags, large (thousands) samples of PIT Tags, or they can be performed individually.

The ability of the test equipment to accurately measure a physical quantity changes with a number of factors. Time in service, temperature, humidity and environmental exposure can affect measurement accuracy. Calibration quantifies this change in measurement accuracy and, when required, adjusts the device's measurement capability to decrease error.

The electronic test equipment in the APTTS is calibrated to National Institute of Standards and Technology (NIST) traceable equipment. PTAGIS has the APTTS test equipment re-calibrated as per the manufacturer’s suggested two-year schedule.

During APTTS power up, a self-check is performed and the results are printed on each report. If an error occurs during a test run, the test run will be halted immediately. The data from the tags that have already been completed will be saved to a report. The error will be displayed in the Error Status indicator on the Main Screen.

SIZE

A camera takes a picture of the PIT Tag under test; the software analyzes the picture and reports the length and diameter of the PIT Tag to the nearest 0.01mm.

WEIGHT

Prior to testing, the entire sample is weighed on a computerized scale. After testing, the software divides the weight by the number of units tested and reports this weight to the nearest 0.001g.

FREQUENCY RESPONSE

Frequency response is quantified in amplitude vs. frequency for a given PIT Tag.

Resonant Frequency

The PIT Tag under test is aligned in the antenna. It is then energized with a fixed-amplitude swept radio frequency of the operator’s choice. Typically, the range of frequencies is from 94.2 kHz to 174.2 kHz (40 kHz above and below the nominal 134.2 kHz of the PIT Tag). The frequency steps during the sweep are also adjustable, typically 100 Hz or less for a detailed sweep and 1 kHz for a quick sweep.

The signal returned from the PIT Tag is then analyzed for amplitude. The frequency at which the highest amplitude is measured is the resonant frequency of that PIT Tag.

Band Width

During the amplitude analysis, the amplitudes at all frequencies are logged to create a “curve.” The bandwidth at the -3dB points (half of the power at the resonant frequency, an RF standard) on that curve are included in the report.

“Q-Factor”

“Q-Factor” (quality factor) is a function of how narrow the bandwidth is. It's the resonant frequency divided by the bandwidth. A narrow bandwidth translates to better noise rejection performance. "Q" is an indicator of how the PIT Tag will react to off-frequency signals vs. on-frequency signals. A higher “Q” leads to better performance in our application. The “Q” of the of the PIT Tag is included in the report.

MINIMUM “TURN ON VOLTAGE”

A test can be run to quantify a particular PIT Tag’s ability to transmit information. The PIT Tag under test is aligned in the antenna. It is then energized with a single radio frequency of the operator’s choice at a very low amplitude. The voltage driving the antenna is increased until the PIT Tag successfully sends it’s data. The voltage at that point is the “turn on” voltage for that PIT Tag and is included in the report.

RF MODULATION

RF modulation is a measure, quantified in a percentage, of the intensity with which the PIT Tag signal is transmitted by the PIT Tag once it is fully activated. Higher modulation percentages are better. During the minimum turn on voltage test, the RF modulation is measured and included in the report.

ABILITY TO DECODE A PIT TAG

The APTTS is able to read the code of the PIT Tag under test. This code is presented in its usual hexadecimal format (i.e. 3D9.257C663DDD) in the report. The APTTS also has the ability to graphically show the signal received from the PIT Tag. This allows the operator to analyze the individual “ones” and “zeros” as read during the interrogation.

SIMULATE MANUFACTURER’S QUALITY ASSURANCE

Digital Angel qualifies PIT Tags using a fixed-frequency/fixed-amplitude test. The PIT Tags under test are energized with an RF waveform of a particular frequency and qualified PIT Tags must respond with an amplitude higher than a preset threshold. The APTTS can simulate this test.

Future

The APTTS has been designed as a platform that can be expanded. It is able to perform a wide variety of qualification testing. The Wintegra design of the system and the components allow for the integration of future hardware and software expansion. This could make the implementation of any future tests and/or tasks possible without the expense of having the system completely redesigned.
Some of the future tests and tasks being discussed by PSMFC are:

• Grouping tested PIT Tags into batches of 100.
• Enhancing the sorting capabilities of the APTTS to include:
  • Placing these groups of 100 (assuming they pass testing) into separate vials for distribution to researchers.
  • Possibly sorting these groups of 100 into their original vials.
• Testing larger diameter tags such as but not limited to 23mm and 42mm, and separating tags by code.