SOP BCC Transceiver Tuning

From PTAGISWiki

	Standard Operating Procedure
Subject:	SOP BCC Transceiver Tuning
Author:	Scott and Alan
Approved by:	UNAPPROVED

Contents 1 Objective 2 Scope 3 Responsibilities 4 Tools Required 5 Adjustment Descriptions 6 Setup 7 Procedure 8 References

Objective

This procedure defines calibration of the transceiver deployed at BCC - Bonneville PH2 Corner Collector.

Scope

This procedure is to be used as necessary to verify and/or restore peak system performance of the BCC transceiver itself. During the execution of this procedure, problems may be discovered that are outside the realm of this procedure. Remedies to problems found during the execution of this procedure could possibly be found in the SOP Troubleshooting Sub-Group. This procedure is intended to provide periodic optimization of transceiver performance.

Responsibilities

This procedure is to be performed by or under the supervision of qualified PTAGIS staff.

Tools Required

The following tools or equivalents will be required to perform this procedure:

• Fluke 192C Scopemeter or equivalent
• Potentiometer adjusting tool (Tweaker)
• Tektronix Current Probe P6021 or equivalent
• BNC Cable
• TX1400SST test stick
• Audible Tag Detect Buzzer

Adjustment Descriptions

Auto Tuner Adjustment

• C3: Auto Tuner Vari-Cap.

Receiver PCB Adjustments

• R42: 2 and 4 Khz Amplitude Adjustment.
• R27: High Frequency Filter Cutoff Adjustment.
• R38: 3rd Stage Amplifier Gain Adjustment.
• R34: Phase Shift Offset Adjustment.
• R17: 1st Stage Amplifier "Q" Adjustment.

Note added 2/25/10:

• Turn 2nd and 3rd stage gain pots to minimum resistance settings (Adjust if necessary) later in this procedure.
• If or when gain stages are adjusted , adjustment of the HFF R27 should follow.
• Base all adjustments on a 20 percent reading efficiency. Baseline distance for tag needs to be established to achieve the 20 percent HR.

Definitions:

Ambient Noise Floor (ANF) All in-band noise that is present in the atmosphere, not the readings of the FBB input.
Reader Noise Floor (NF) The actual readings taken on the reader at the FBB input.

Filter/Detector Adjustment

• C20: Vari-Cap, for detector tuning.

Setup

• Remove the protective plexi-glass cover in the transceiver to expose the antenna drive leads.

WARNING - HIGH VOLTAGE - To access the antenna current, the Plexiglas cover must be removed. Use caution to avoid shock hazard during this procedure.

• Attach the current probe to channel 1 (or A) of the scope and to the white wire coming out of the Filter and Detector.
• Attach one end of the BNC to BNC cable to channel 2 (or B) of the scope and the other end to the “FBB OUT” output of the Transceiver or the Receiver (input to the DSP). Refer to Figure 1 for exact locations.

Note: Adjust the scope so that both signals can be displayed and measured at the same time. Both channels need to be AC coupled and set to measure the signal peak to peak. Set trigger on channel 1 and turn ON the high frequency noise reject filter, this will allow viewing the signal at “FBB OUT” easier.

• Connect BNC cable to the "Tag Detect" connector located on the side of the transceiver enclosure and the other end to the Beeper Box.See Figure 1.

Figure 1 - Overall View

Procedure

1) Preset the Receiver

The following steps are only performed during the initial setup. They should not be required when optimizing the performance during the course of the season.

1. Turn potentiometers R17 and R34 fully counterclockwise (CCW).
2. Set potentiometers R27 and R42 to mid-range.
3. Adjust potentiometer R38 so the signal on channel 2 of the scope is around 250mVp-p.

2) Course Tune Variable Capacitors

1. Monitor the antenna current and FBB signal with an oscilloscope.
2. View the FBB signal as shown as shown in Figure 1 - Overall View
3. Select the coarse capacitors via the switches on the tuner board until the "TUNED" LED on the Diagnostics Module is lit.Goal: select capacitors such that the variable capacitor is centered in it's adjustable range.

Figure 2 - Tuning Capacitors

3) Optimize Drive Signal

1. Slowly adjust variable capacitor C3 until the reader tunes the antenna to the maximum possible current (monitor channel 1 of the scope).Reference Figure 3 - Overall View for location of C3.
2. Continue to adjust capacitor C3 until the moving plates of the Antenna Tuning Variable Capacitor slightly move inward and the current amplitude just starts to decline. Monitor channel 2(FBB Signal) of the scope, you should see the noise level is reduced. This is a slight adjustment.
3. Repeat until optimized

Figure 3 - Auto-tuner Board

2) Adjust the Receiver

1. Place a tag in the field to where it just starts to read.
2. Adjust potentiometer R42 so that the amplitudes of the 2kHz and 4kHz components of the signal on channel 2 (wide and narrow waves) are as equal as possible. For this adjustment set the scope time base to 0.5mSec/Div. The reading efficiency should improve.
3. Move the tag out of the field to where it barely reads and adjust potentiometer R42 to improve reading efficiency. Repeat this until reading efficiency can not be improved.
4. Adjust potentiometer R38 so the signal on channel 2 is minimized while maintaining good reading efficiency.
5. Adjust potentiometer R27 (High Pass Filter adjustment) fully CW so that the signal on channel 2 is minimized. Begin rotating R27 counter clockwise (CCW) until the reading efficiency is peaked (should be approx. between 1/3 and 1/2 of the way).
6. Adjust Filter and Detector capacitor C20 to improve reading efficiency.This should be a very slight adjustment.The half way point on the cap is a good starting point if this is the initial setup. Reference Figure 7.
7. Repeat steps 7 through 9 until reading efficiency is peaked.
8. Check if the antenna current measurement on the channel 1 of the scope and exciter voltage measurement on the display of the main power supply match the values measured by the transceiver. If not – calibrate the transceiver (refer to Calibration Procedure and API Guide page 15).
9. Note: Set up channel 1 of the scope so the best resolution of the signal is achieved (stretch the signal across the entire display so that only two or three cycles are visible).
10. Reinstall and secure all the covers.
11. Set up the desired transceiver operational mode by customizing the rest of its parameters.

Figure 4 - Receiver Board

- R42: 2 and 4 Khz Amplitude Adjustment.
- R27: High Frequency Filter Cutoff Adjustment.
- R38: 3rd Stage Amplifier Gain Adjustment.
- R34: Phase Shift Offset Adjustment.
- R17: 1st Stage Amplifier "Q" Adjustment.


Figure 5 - Oscilloscope showing FBB signal

Figure 6 - Diagnostics Board

Figure 7 - Filter and Detector Board

3) Verify transceiver performance

• Place an SST test stick at the mark on the downstream grating (see Figure 8).
  • Verify that this test stick is being read by the BCC transceiver. Acceptable readability at this range is 1 detection every 5 seconds or better.

**The goal is to have the reader detect the stick tag at the baseline mark. Repeat all the above procedures until the reader detects the test tag at the baseline mark.

Figure 8 - SST Test Stick on Downstream Grating

• REMOVE STICK TAG FROM GRATING AFTER CALIBRATION IS COMPLETE

4) Restore the Plexiglas cover over the tuning capacitors

• Procedure complete.

References

Digital Angel B2CC Operations and Maintenance Manual