> For the complete documentation index, see [llms.txt](https://docs.holybro.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.holybro.com/radio/microhard-radio/specification.md).

# Specification

### Specification 

| <p><br></p>                          | P900                                                                                                                     | P840                                                                                  | P400-C1S                                                                              |
| ------------------------------------ | ------------------------------------------------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------- |
| Frequency Range                      | 902 to 928 MHz                                                                                                           | 840 to 845 MHz                                                                        | 410 to 480 MHz                                                                        |
| Transmit Power (Software Adjustable) | <p>100mW to 1W (20-30dBm) <br></p>                                                                                       | 100mW to 1W (20-30dBm)                                                                | 100mW to 1W (20-30dBm)                                                                |
| Link Rate                            | Up to 276 kbps                                                                                                           | Up to 345 kbps                                                                        | Up to 345 kbps                                                                        |
| Serial Baud Rate                     | Up to 230.4kbps asynchronous                                                                                             | 300 bps to 230 kbps                                                                   | 300 bps to 230 kbps                                                                   |
| Spreading Method                     | Frequency Hopping Spread Spectrum (FHSS)                                                                                 | <p>Frequency Hopping/Fixed Frequency,<br>GMSK, 2GFSK, 4GFSK, QPSK</p>                 | <p>Frequency Hopping,<br>GMSK, 2GFSK, 4GFSK, QPSK</p>                                 |
| Operating Modes                      | <p>Mesh, Point-to-Point, Point-to-Multipoint, Store and Forward,<br>Auto Routing, Self Healing, Packet Routing Modes</p> | <p>Point-to-Point, Point-to-Multipoint,<br>store & Forward Repeater, Peer-to-Peer</p> | <p>Point-to-Point, Point-to-Multipoint,<br>store & Forward Repeater, Peer-to-Peer</p> |
| Input Voltage                        | <p>DC7\~35V<br>(4-position JST-GH)</p>                                                                                   | <p>C7\~35V<br>(4-position JST-GH)</p>                                                 | <p>C7\~35V<br>(4-position JST-GH)</p>                                                 |
| Power Consumption                    | <p>Sleep < 1mA<br>dle 3.5mA<br>Rx: 45mA to 98mA<br>Tx : 1000mA to 1400mA</p>                                             | <p>Sleep < 1mA<br>dle 3.5mA<br>Rx: 45mA to 98mA<br>Tx : 1000mA to 1400mA</p>          | <p>Sleep < 1mA<br>Idle 20mA<br>Rx: 45mA to 98mA<br>Tx Peak: 2A</p>                    |
| Error Detection                      | 32 bits of CRC, ARQ                                                                                                      | 32 bits of CRC, ARQ                                                                   | 32 bits of CRC, ARQ                                                                   |
| Antenna Gain                         | 5dBi                                                                                                                     | 5dBi                                                                                  | 5dBi                                                                                  |
| Weight                               | <p>44g (without antenna) <br> 71g (with antenna)</p>                                                                     | <p>44g (without antenna) <br> 71g (with antenna)</p>                                  | <p>44g (without antenna) <br>67g (with antenna)</p>                                   |
| Weight (V2)                          | <p>51g (without antenna) <br> 81g (with antenna)</p>                                                                     | NA                                                                                    | <p>51g (without antenna) <br> 76g (with antenna)</p>                                  |

### P400 Frequency 410 to 480 MHz (Frequency Hopping)

| Rate (kbps) | Power (W) | Sensitivity (dBm) | Bandwidth (kHz) | Regulatory |
| ----------- | --------- | ----------------- | --------------- | ---------- |
| 56.0        | 1         | -113              | 60.0            | None\*     |
| 115.2       | 1         | -109              | 150.0           | None\*     |
| 172.8       | 1         | -108              | 180.0           | None\*     |
| 230.4       | 1         | -106              | 230.0           | None\*     |
| 276.4       | 1         | -105              | 230.0           | None\*     |
| 345.0       | 1         | -103              | 400.0           | None\*     |

### P840 Sensitivity (Frequency Hopping)

<table><thead><tr><th width="147"></th><th width="115"></th><th width="160"></th><th></th></tr></thead><tbody><tr><td>Rate (kbps)</td><td>Power (W)</td><td>Sensitivity (dBm)</td><td>Bandwidth (kHz)</td></tr><tr><td>19.2</td><td>1</td><td>-116</td><td>25</td></tr><tr><td>56</td><td>1</td><td>-113</td><td>60</td></tr><tr><td>115.2</td><td>1</td><td>-109</td><td>150</td></tr><tr><td>172.8</td><td>1</td><td>-108</td><td>180</td></tr><tr><td>230.4</td><td>1</td><td>-106</td><td>230</td></tr><tr><td>276.4</td><td>1</td><td>-105</td><td>280</td></tr><tr><td>345</td><td>1</td><td>-103</td><td>400</td></tr></tbody></table>

### P900 Sensitivity (@10-4)

| Rate (kbps) | Sensitivity (dBm) |
| ----------- | ----------------- |
| 57.6        | -114              |
| 115.2       | -112              |
| 172.8       | -109              |
| 230.4       | -107              |


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