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Sonntag, den 29. Juli 2007 um 20:14 Uhr
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D-STAR
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Folie 6

Digital voice communication works in the same way as data communication, by using one digital voice repeater, it is possible to communicate with another station. However, voice communication differs from data communication in the fact that it is necessary to have real-time communication. In data communication, even if there is a slight time delay in the response, there is almost no effect in the communication quality. However, for voice communication, if there is a long delay against the initial call made from this end, or the delay is erratic, smooth communication is not possible. For this reason, in D-STAR the data and voice communication is separated into separate systems.
For VoIP voice communication by data communication, actual use is permitted, but in Amateur radio due to the limit in the number or capacity of lines available, it is likely that smooth VoIP voice communication would be difficult.
Direct communication with another station is possible without being relayed through the repeater.

Folie 7

The accumulation of data or voice repeaters in a place is typically called a repeater site, and it is the backbone that links multiple repeater sites. In D-STAR, this backbone communication is carried out in the 10 GHz band, at a transfer rate of 10 Mbps. This 10 Mbps transfer rate was decided on by an analysis of the frequency of use of data and voice communications, and by what types of 10 Base-T components etc. were most easily acquired in the market.
The frequency used (10 GHz) is the frequency that had the spectrum to be able to transmit a 10 Mbps signal. At present, the 10 GHz band and the 5.6 GHz band metes this requirement. There are many frequencies above 10 GHz that have the broadband for this, however, by using these high frequencies, the communication distance becomes shorter, and is not suitable as a relay for the backbone.

Folie 8

ID-1 is the terminal used for this digital communication. To compare between digital data communication, digital voice communication and existing analog, an analog FM communication function is included.
The transceiver RF unit and controller a separate units, and digital data/voice communication is possible even without connection to a computer.

Folie 9

This diagram shows the basic block diagram of the ID-1. For digital voice communication, the CODEC converts the voice signal input from the mic to a digital signal after amplification. That digital signal is GMSK modulated, and is amplified to the required voltage and output.
The received signal input from the antenna is GMSK demodulation, is converted back to the original analog signal, and after amplification, is output from the speaker.
A data signal is input to the 10 Base-T connector from the connected computer, and after passing through the interface is GMSK modulated and out put in the same way as voice communication. For the reception of a data signal, the same GMSK demodulation as a voice signal is carried out, and then it passes through the interface and is input to the computer by the 10 Base-T.
The USB connected to the controller is used in the control of the ID-1, and is not directly related to communication. It is possible to control the operation by using only the RC-24 controller, but it is even more convenient to operate using the USB connected to a computer. (This will be explained later)
The existing analog FM in included in this set-up, but it has not been indicated in this block diagram.

Folie 10

This panel shows the characteristics of the ID-1. As mentioned, the modulation is GMSK, and the interference to adjacent channels is minimal, and also like existing analog it is possible to be able to use a C grade amp.
The data transfer rate is 128 kbps, and voice communication is 8 kbps.



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