> ## Documentation Index
> Fetch the complete documentation index at: https://docs.valar.space/llms.txt
> Use this file to discover all available pages before exploring further.

# Sensors

> Managing ground station and tracking sensor configurations

> For the complete documentation index, see [llms.txt](/llms.txt).

Ground sensors are required to track spacecraft and collect telemetry data. The Sensors page allows you to create, view, and delete sensor configurations that are used for processing tracking measurements.

A tracking sensor is a fixed ground-based observer that watches spacecraft from the surface — not to be confused with an on-board spacecraft payload, which is a sensor carried by the spacecraft itself (see [Payloads](/features/spacecraft-management#payloads-tab) on the Spacecraft page).

**Route:** `/orbits/measurements/sensors`

## Page Layout

The sensors page has a split-panel design:

<img src="https://mintlify.s3.us-west-1.amazonaws.com/valar-8bbb18b5/images/sensors.png" alt="Sensors" />

When multiple sensors are selected, a floating action bar appears at the bottom.

## Viewing Sensors

The sensor list (left panel) displays all ground sensors in your organization. Each row shows:

* **Sensor ID** (e.g., "DSN-15")
* **Latitude** (e.g., "35.43° N")
* **Longitude** (e.g., "116.89° E")
* **Altitude** (e.g., "1000 m")

The first sensor is automatically selected when the page loads.

## Viewing Sensor Details

Click any sensor row to view its details in the right panel:

| Section         | Field          | Format                                          |
| --------------- | -------------- | ----------------------------------------------- |
| **Identity**    | Sensor ID      | Text (e.g., "DSN-15")                           |
| **Location**    | Latitude       | XX.XXXX° N/S                                    |
|                 | Longitude      | XX.XXXX° E/W                                    |
|                 | Altitude       | XXXX m                                          |
| **Calibration** | Azimuth Bias   | Scientific notation (e.g., "1.00e-03°") or "--" |
|                 | Elevation Bias | Scientific notation or "--"                     |
|                 | Downlink Delay | Seconds (e.g., "0.5 s") or "--"                 |

## Creating a Sensor

Click **+ New Sensor** in the top-right corner to open the creation dialog.

<img src="https://mintlify.s3.us-west-1.amazonaws.com/valar-8bbb18b5/images/new-sensor.png" alt="New Sensor" title="New Sensor" className="mx-auto" style={{ width:"74%" }} />

### Required Fields

| Field               | Description                        | Example  |
| ------------------- | ---------------------------------- | -------- |
| **ID**              | Unique sensor identifier           | DSN-15   |
| **Latitude (deg)**  | WGS84 latitude in decimal degrees  | 35.4261  |
| **Longitude (deg)** | WGS84 longitude in decimal degrees | 116.8895 |
| **Height (m)**      | Elevation above WGS84 ellipsoid    | 1000     |

### Optional Fields (Calibration)

| Field                    | Description                | Default | Example |
| ------------------------ | -------------------------- | ------- | ------- |
| **Azimuth Bias (deg)**   | Systematic azimuth error   | Not set | 0.001   |
| **Elevation Bias (deg)** | Systematic elevation error | Not set | 0.0005  |
| **Downlink Delay (s)**   | Signal propagation delay   | 0       | 0.5     |

### Default Configuration

When created, sensors are automatically configured with:

| Setting           | Default Value      |
| ----------------- | ------------------ |
| Type              | GROUND\_STATION    |
| Available         | true               |
| Elevation Mask    | 0° at all azimuths |
| Measurement Types | AZEL and RANGE     |

### Sensor Types

The platform supports two sensor types:

| Type                | Description                   | UI Support    |
| ------------------- | ----------------------------- | ------------- |
| **GROUND\_STATION** | Ground-based tracking station | Yes (default) |
| **TELESCOPE**       | Optical telescope             | API only      |

<Note>
  Only GROUND\_STATION sensors can be created through the UI. TELESCOPE sensors must be configured via the API.
</Note>

### Outcomes

* **Success:** Toast notification "Sensor ID created", sensor list refreshes
* **Error:** Toast with error message from API

## Deleting a Sensor

### Single Delete

1. Select a sensor by clicking it
2. Click the **⋮** (three-dot menu) in the details panel header
3. Click **Delete Sensor**

A confirmation dialog appears:

<img src="https://mintlify.s3.us-west-1.amazonaws.com/valar-8bbb18b5/images/sensor-delete.png" alt="Sensor Delete" title="Sensor Delete" className="mx-auto" style={{ width:"76%" }} />

**Outcomes:**

* **Success:** Toast "Deleted sensor ID", list updates, next sensor auto-selected
* **404 Error:** Toast "Sensor 'ID' could not be deleted. It does not exist"
* **Other Error:** Toast "Something went wrong deleting sensor ID", list refreshes

### Bulk Delete

1. Select multiple sensors using checkboxes (checkboxes appear on hover)
2. A floating action bar appears at the bottom
3. Click **Delete**

| Button         | Action                         |
| -------------- | ------------------------------ |
| **X selected** | Shows selection count          |
| **Select All** | Selects all visible sensors    |
| **Delete**     | Opens bulk delete confirmation |
| **Clear**      | Clears all selections          |

**Outcomes:**

* **Success:** Toast "count sensor(s) deleted successfully", list updates
* **Partial Failure:** Toast "Failed to delete some sensors", list refreshes
* Selections are cleared after operation

## Important Limitations

<Warning>
  **No Edit Functionality:** Sensors cannot be modified after creation. To change a sensor's configuration, you must delete and recreate it.
</Warning>

| Limitation                  | Description                                                              |
| --------------------------- | ------------------------------------------------------------------------ |
| **Fixed Measurement Types** | All sensors are created with AZEL and RANGE. Cannot be customized in UI. |
| **Elevation Mask**          | Default 0° at all azimuths. Custom masks require API configuration.      |
| **Organization Scope**      | Sensors are scoped to your organization.                                 |
| **Irreversible Deletion**   | Both single and bulk delete operations are permanent.                    |
| **Sensor Type**             | Only GROUND\_STATION available in UI. TELESCOPE requires API.            |

## Doppler Ingestion Configuration

Each sensor may declare a per-sensor `twoWayDopplerConvention` field that tells the TDM ingestion pipeline how to interpret two-way `DOPPLER_INSTANTANEOUS` observables produced by that sensor. The two valid CCSDS conventions (MEAN and SUM) differ by a factor of two and are not distinguishable from the keyword alone — declaring the convention explicitly avoids a 100% bias in the observable.

| Setting        | Behaviour                                                                                      |
| -------------- | ---------------------------------------------------------------------------------------------- |
| **MEAN**       | Observable is the arithmetic mean of uplink and downlink instantaneous rates (DSN convention). |
| **SUM**        | Observable is `d/dt` of round-trip range; halved at ingest to normalise to MEAN.               |
| **UNDECLARED** | Magnitude-based auto-detection (warning) when within the 10 km/s sanity bound.                 |

See [Doppler (Range-Rate) Measurements](/file-formats/tdm#doppler-range-rate-measurements) for the full convention contract, default sigma values, and error code reference.

## Related Pages

* [Import measurements](/features/measurements-import): Upload TDM, OEM, and SP3 files
* [View measurements](/features/measurements-data): Filter and manage measurement data by sensor
* [TDM file format](/file-formats/tdm#doppler-range-rate-measurements): Doppler observable contract, default σ, and error codes