Doc F4HOF

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====== Data frames in D-Star ======

===== Mini header =====
^ Value ^ Scope ^ Usage ^ Remarks ^
|  0X  | | Reserved | |
|  1X  | | Reserved | |
|  2X  | | Reserved | |
|  3X  |  1~5  | Simple data communication | Data communication of D-PRS used for character transfer of user's data communication such as PC-handled simple data communication. The range indicates the number of valid characters per block. |
|  4X  |  0~3  | Message function | Use it for messages handled by radio unit alone. Only the message function indicates the data block number |
|  5X  |  2  | Wireless header retransmission | |
|  6X  | | Reserved | Except for 66 |
|  66  | | Null packet | Padding data frame |
|  7X  | | Reserved | |
|  0X  |  1~F  | Fast Data | Indicates Fast data length from 1 byte to 15 bytes |
|  9X  |  0~C  | Fast Data | Indicates Fast data length from 16 byte to 28 bytes |
|  AX  | | Reserved | |
|  BX  | | Reserved | |
|  CX  |  2  | Code squelch | Two-digit value of code squelch|
|  EX  | | Reserved | |
|  FX  | | Reserved | |

For 8x and 9x, refer to the chapter related to Fast Data.

===== Simple data =====

When communicating using simple data communication, the following characters can not be used:

  * 0x00
  * 0x11 (XON)
  * 0x13 (XOFF)
  * 0x76 (Used for packet loss notification)
  * 0x84 (Used for packet loss notification)
  * 0xE7 (Used for packet loss notification)
  * 0xFE 
Note: Handle as packet loss when the data frame is the following string "0xE7, 0x84, 0x76" and the voice frame is the silence pattern "0x9E, 0x8D, 0x32, 0x88, 0x26, 0x1A, 0x3F, 0x61, 0xE8" It can not be used. (See "Packet loss").


Example of data configuration on the transmitting side / receiving side when transferring user's data communication by simple data communication

<pic>

===== Messaging function =====

This function is used to send and receive 20-character messages to be displayed on the radio. It is specified as follows. The characters that can be used depending on the radio used.

<pic>

===== Header retransmission =====

Header information retransmission

It is possible to transmit by using a data frame in a state where error correction is not applied to information excluding bit synchronization and frame synchronization in radio section header information. In the case of transmission, it occupies nine frames of data frame after the [Sync] frame, (further in the case of transmitting the code squelch information, thereafter) and transmits one header information at a cycle of 420 ms.

Note: Since the occupancy rate of the header information is high in the retransmission of the header information, there are cases where the retransmission of the header information is not performed in the case of performing simple data communication by the user or during the message transmission of the message function.

===== Code Squelch =====
When using the digital code squelch (CSQL) feature, the following two-digit code is transmitted as a data frame. The code data is transmitted at a cycle of 420 ms using the data frame of two frames immediately after the [Sync] frame.