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Sonntag, den 29. Juli 2007 um 20:14 Uhr
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D-STAR
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Folie 16

The software and protocol shown here is related in the ID-1.
The protocol is the D-STAR system protocol. What ID-1 USB terminal uses is not called the protocol, but is expressed as the control command. In this way, the communication via the ID-1 USB is not the original communication protocol, so care is needed regarding this point.
Also, communication from the computer connected to the ID-1, in this manner is simply connected to the local repeater or backbone only, thus in reality various applications are necessary. Connection to a wired line and access to the Internet and access to an added server is a part of this application, how this is used is a point of interest, and we look forward to seeing the introduction of applications from user’s.

Folie 17

The structure of the packet used in the data communication of the D-STAR protocol is shown in this diagram. The Radio Header part is the part used to connect to the station you are communicating with. The parts other than the Radio Header will be explained later in the structure of the Ethernet packet.
The Radio Header part is as follows:

  • Bit Sync
    The bit synchronization signal that obtains synchronization in the input signal.
  • Frame Sync
    The frame synchronization signal that indicates that this is a signal from here on.
  • Flag
    This distinguishes this header’s attributes. If it’s a repeater relay/direct communication, repeatr control signal etc.
  • Destination Repeater Callsign
    Indicates the final repeater destination callsign when relayed through the backbone
  • Departure Repeater Callsign
    Indicates the repeater callsign of that, that terminal belongs to.
  • Companion Callsign
    Indicates the called station’s callsign
  • Own Callsign
    Indicates your callsign
  • P-FCS
    The frame check sequence indicating the validity of this Radio Header part.

Folie 18

This diagram indicates the process of how a message is sent by digital data communication. The left side ‘s User A sends a message to the right side’s User B. The respective TCP, IP and Ethernet headers are attached in the wired part in the message made. The computer that is connected automatically processes this.
The Radio Header explained in the previous page is attached to the Ethernet packet that comes from the 10 Base-T. On the receive side, this Radio Header is decoded, then the header is removed and is passed as an Ethernet packet to the connected computer from the 10 Base-T. After that the computer automatically carries out the processing, and the message is displayed on User B’s screen.

Folie 19

Next, we will explain the voice communication protocol. The voice communication packet is as shown in the diagram, and the Radio Header part is exactly the same as data communication.
The data part after the Radio Header is the Voice Frame, which is a 160-bit signal that is, digitalized every 30mS in the Codec. It is possible to send small still pictures and memos etc, with the 80-bit data frame after that. In the ID-1, this function is not available as it is difficult to change the whole CPU capacity etc. at a later stage. However, this function is planned for implementation in the second-generation model.
At the end of the transmission, the Last Frame is added to indicate that this is the end of the transmission. Also, a synchronous signal is input 1 time out of every 20. This is to prevent the occurrence of non-reproduction because of the loss of synchronization on the receiver side when the signal is interrupted, which is caused by phasing etc., during communication.

Folie 20

The backbone protocol that connects between repeater sites is sent as multiplexed data and voice signals according to the ATM (Asynchronous transfer Mode) method. The ATM packet is made up of a short 53-byte packet that consists of a 5-byte header part and a 48-byte payload, as shown in the diagram.
Because the designation of priority level can be done in this header part, the priority level is added to the voice signal that requires real time processing, and is sent so that when it arrives, the real time condition is kept. The ATM method is such that the ATM packet is sent to the required destination according to the preset list that is set by the ATM switch set at each repeater site. For more details, please refer to technical material on Asynchronous Transfer Mode.



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