Hytera DMR System Planner
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2.11.7 Real-time Transport Service (RTP)
In radio wireless communication, the radio equipments communicate with each
other via air interface. In DMR Systems, the voice is transmitted by encapsulating in
DMR frames and encoded in AMBE (or SELP, or some other wireless
communication speech coding algorithms). However, as many applications, which is
usually deployed in a PC, do not support encoding/decoding with those vocoder, in
order to communicate with radios, there must be a voice transport protocol to
transport the voice stream and a common known encoding/decoding vocoder
between radio equipment and the application.
Figure below illustrate a common topology for communications between radios and
PC application. From the figure below, the repeater is responsible for converting
voice stream between radio network and UDP/IP network.
Figure 2.11.7-1: Communication between Distinct Networks
Real-time Transport Protocol (RTP) is used to transmit voice stream between the
application and Dispatcher Station. RTP provides end-to-end delivery services for
data with real-time characteristics, such as interactive audio and video. To satisfy
the special requirements of radio wireless communication, RTP header extension is
defined to carry particular radio information that allows the application to know more
of the call information that is extracted from the DMR protocol.
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