Unit 3 — Setup Procedures

TM-CAL-003 — Open Handout TM Chapter: Chapter 4 ELOs: Execute setup steps in correct sequence; verify readiness before calibration Estimated time: 15 minutes

Step 1: Read the TM

Open TM-CAL-003. Read Chapter 4 — Assembly Procedures completely.

Then come back here.

Chapter 4 Content

  1. Verify all components with multimeter before assembly.
  2. Install ESP32 board on DIN rail or in enclosure, securing with 4 M3 screws.
  3. Mount Si5351 breakout board adjacent to ESP32. Keep I2C traces short (<5 cm).
  4. Mount NEO-M8N module. Route UART and TIMEPULSE connections to ESP32.
  5. Install SMA connector on enclosure panel. Solder short RG-174 pigtail from Si5351 CLK0 output to SMA center pin. Minimize trace length.
  6. Install GPS antenna SMA bulkhead connector on enclosure lid or side panel.
  7. Wire 5 V supply to all modules. Verify +5 V on each module before applying full power.
  8. Load ESP32 firmware (simple PLL algorithm: measure 1PPS → count Si5351 cycles → adjust frequency word in PI loop).
  9. Apply power. Observe serial debug output: GPS acquiring, then position fix, then TIMEPULSE valid, then PLL locking.
  10. Allow 15 minutes for full phase lock. Output frequency should stabilize to <1 Hz of 10.000000 MHz.

Setup is Part of Calibration

Chapter 4 specifies 10 setup steps.

A calibration is only valid if the setup is correct. Common setup errors that invalidate results: - Skipping warm-up time - Wrong input range or measurement mode selected - Reference connected to wrong terminal - Ground loops or interference from adjacent equipment

If Chapter 4 specifies a verification at the end of setup (e.g., "confirm instrument reads X before proceeding"), do it. That check exists because someone discovered a failure mode that made it necessary.

Self-Check Questions

SC3-1. How many steps does Chapter 4 specify for setup?

SC3-2. What is the first step? State it exactly from the TM.

SC3-3. Does Chapter 4 require any verification before proceeding to calibration? If so, state it.

SC3-4. What is the last step of Chapter 4 (immediately before you begin the Chapter 5 calibration)?

SC3-5. What would you do if a setup step produced an unexpected result?

Answer Key

SC3-1. Count the numbered steps in Chapter 4. The answer is in the TM.

SC3-2. See Chapter 4, step 1. Copy it exactly.

SC3-3. Scan Chapter 4 for steps containing "verify," "check," "confirm," or "measure." If present, they are hold points.

SC3-4. See the last numbered step in Chapter 4.

SC3-5. Stop. Do not proceed to calibration. Diagnose the unexpected result — it may indicate a setup error, a faulty reference, or a failed instrument under test.

Checkpoint

Before proceeding: - [ ] You have read Chapter 4 completely - [ ] You can state the number of setup steps - [ ] You understand setup errors invalidate calibration results

→ Proceed to Unit 4