> For the complete documentation index, see [llms.txt](https://docs.didge.io/home/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.didge.io/home/foodcore-sensors/end-user/core-functions/calibrations/multi-point-comparison.md).
# Multi Point Comparison
### 1. Purpose of Calibration
Calibration is a fundamental process that verifies the accuracy of temperature sensors used within critical control points, such as refrigerators and cold rooms in food safety environments. Ensuring sensor accuracy is vital for maintaining compliance with food safety standards.
### 2. Accessing Calibration Data
Users can view calibration records through the **Calibration** tab on the Sensors Dashboard. This tab provides access to completed calibration reports for each unit, displaying whether each device has passed or failed the calibration process. Reports are generated automatically and are tied to specific sensors, timestamps, and users.
### 3. Calibration Frequency
The calibration frequency varies depending on the business's food safety program. It may occur monthly, bi-annually, or annually as outlined in the organization's verification plan.
### 4. Calibration Process Overview
The calibration process is carried out by admin-level users, typically members of the engineering or maintenance teams. The steps include:
1. **Setup**: Pair a pre-calibrated **Master Sensor** with a **Target Sensor** (installed in the unit).
2. **Pre-Calibration**: The master sensor undergoes validation using:
* Boiling point method (\~100°C)
* Ice point method (\~0°C) (Note: Digital ambient sensors cannot be submerged, so reference methods are used instead.)
3. **Execution**:
* Place the master sensor next to the target sensor (in situ, no removal required).
* Allow 15–20 minutes for stabilization.
* The system records and compares readings from both sensors every minute over a 2-hour period.
4. **Evaluation**:
* A minimum of **five consecutive readings** must fall within the acceptable tolerance (default ±1°C).
* Custom tolerance thresholds (e.g., ±0.5°C) can be configured.
### 5. Calibration Criteria
* **PASS**: Two to five consecutive in-range readings within tolerance.
* **FAIL**: Persistent deviation beyond tolerance, typically over 1–2 hours. Requires sensor replacement.
### 6. Calibration Types
* **Reference Method** (most common for digital sensors): Based on ambient temperature.
* **Hot Point Method**: Boiling water (≈100°C) for probe sensors.
* **Cold Point Method**: Ice water (≈0°C) for probe sensors.
* **Custom Method**: Specialized equipment with a preset value.
### 7. Reports and Certification
Each calibration event generates a detailed **Calibration Report**, including:
* Device labels and DevEUIs for both Master and Target
* Capabilities (e.g., Probe, Ambient, Humidity)
* Calibration status and type (Automatic)
* Timestamp and user ID
* Visual graphs of temperature over time
* Log of each minute's readings with deviations
These certificates are stored and accessible via the platform, providing traceability and proof of compliance.
### 8. Dashboard Features
* View calibration status (Passed/Failed) per sensor
* Filter by date range or search by label/DevEUI
* Zoom into specific reports for visual and tabular data
* Supports both device-level and site-level calibration overviews
### 9. Summary
The calibration module in the sensor platform ensures that temperature readings are accurate, traceable, and aligned with regulatory standards. It is designed for minimal manual input, with high automation and system-driven validation, reducing the risk of human error while improving food safety assurance.
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