# CheckFox Uplink Payload Description

### Each test message (uplink) consists of following data content:

### 1st Byte

Proprietary “message sequence number” MSB *(Proprietary “message sequence number” is a 16-bit value.)*

### 2nd Byte

Proprietary “message sequence number” LSB *(Proprietary “message sequence number” is a 16-bit value.)*

### 3rd Byte

#### Upper 4 bits (“main menu selection” identifier)

| VALUE | MEANING           |
| ----- | ----------------- |
| 0x01  | Outdoor above 1m  |
| 0x02  | Outdoor 1m refer. |
| 0x03  | Outdoor 0m ground |
| 0x04  | Indoor            |
| 0x05  | Deep Indoor       |

#### Lower 4 bits (“measurement type” identifier)

| VALUE | MEANING                           |
| ----- | --------------------------------- |
| 0x01  | Survey 1x immediately             |
| 0x02  | Survey 1x delayed                 |
| 0x03  | Final 6x immediately              |
| 0x04  | Final 6x delayed                  |
| 0x05  | Downlink test                     |
| 0x06  | Periodic measurement 1min + GPS   |
| 0x07  | Periodic measurement 10min + GPS  |
| 0x08  | Periodic measurement 60min + GPS  |
| 0x09  | Periodic measurement 10min no GPS |
| 0x0A  | Periodic measurement 60min no GPS |
| 0x0B  | Audit 100x immediately            |
| 0x0C  | Audit 100x delayed                |

### 4th Byte

#### Non-periodic measurements

Number (1-255) of messages being sent in present test batch.

#### Periodic measurements

Batch sequence number (0-255). This value is incremented by 1 each time a batch is started by the user.

### 5th Byte

#### Non-periodic measurements

Actual message counter (1-255) = sequence number of message in present test batch.

#### Periodic measurements:

*N/A (fifth byte not used)*


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