User:Darkblackflower/Radio Message System

Radio Message System
The radio message system (RMS) is a sound-frequency transmission system in analog AOS radio operation at the German authorities and organizations with security tasks (AOS). It is used for the automated transmission of defined status messages from the emergency vehicles to the control center using digital short telegrams instead of analogue language, and vice versa of standardized instructions from the control center to the emergency vehicles.

The main advantage of the RMS is that routine messages (e.g. that an emergency vehicle is on the way to the mission) are transmitted quickly and automatically at the push of a button. This relieves both the AOS radio and the dispatchers in the control center and the voice radio is kept free for further and more important communication. In addition, the connection of the RMS to an operations control computer system enables automated vehicle and operation management.

Functionality
With the help of the AOS radio reporting system, so-called short telegrams (e.g. the information that a vehicle has arrived at the destination) are exchanged between vehicles and the control center. The digital data is transmitted as an acoustic signal via the normal operating channel of the respective AOS. For this purpose, every vehicle has a device with a unique digital identifier that is always transmitted together with the information. This identifier is made up of the associated organization (AOS identifier), the federal state, a location identifier and the vehicle identifier (first name). This is followed by the current status (0–9).

On the vehicle side, status information is transmitted to the control center via a number (0-9) and an additional level (I-IV, Tactical Brief Information (TBI)), the control center, however, is not used. The control center can selectively transmit instruction information to an individual vehicle, which is displayed there as a letter (including E, C, F, H, J, L). The transmission is automatically confirmed by the system with an acknowledgment telegram.

A control center can also send longer texts, so-called short text telegrams, to vehicles. This technique, which is not very widespread, is mostly used in the ambulance service to transmit the location. However, the short text telegram uses a different transmission protocol than the RMS.

The following digits are defined across services:

0 = emergency call

9 = hand receipt

By pressing the status 0, the radio remains in transmission mode for 30–60 seconds, depending on the setting, to enable an emergency announcement. The emergency call function is especially intended for acute threats (crew is violently attacked). Most radio devices are configured in such a way that the button of status 0 has to be pressed longer or twice in quick succession to avoid accidental triggering and thus blocking of the radio channel.

The details of the technology, equipment and function are specified in the Technical Guideline AOS (TR-AOS wireless reporting system).

Reporting Veicle - Control center
The RMS of the AOS is usually coded as follows:

Technical implementation
With the radio message system, data telegrams of 48 bits length are transmitted, these contain 40 bits of user data. Before the data telegram, a series of 12 bits of the value "1" and then the block synchronization byte "00011010" are transmitted to synchronize the receivers. The data bits are transmitted in low-frequency shift keying at a speed of 1200 baud, whereby the frequencies 1200 and 1800 Hz are used as frequency pairs. A complete status transmission takes a total of 0.055s and is usually only audible as a short gating or noise. The complete structure of the transmission looks as follows: The representation of the status bits (Nos. 33 to 36) as digits and certain letters is due to the representation possibilities according to the state of the art at the time the radio communication system was introduced in the 1970s. In the RMS operating devices, the display of the operational status (vehicle - control centre) and the instruction (control centre - vehicle) was realised in each case by an element of the seven-segment display

System failures
The computer-supported evaluation of the individual statuses is no longer possible in the event of a computer system failure. Higher reliability is achieved by redundant systems. In the event of a total system failure, the occupancy of the radio channel increases enormously, as all vehicles must transmit their status by radiotelephony. In addition, there is an accumulation of automated transmissions, such as GPS location transmission, because they are no longer acknowledged by the operations control computer and are therefore transmitted twice or - depending on the configuration of the radio equipment - several times (unsuccessfully).

Digital AOS-Radio
The radio alarm system is a technology that dates back to the 1970s. In Germany, AOS digital radio has been introduced nationwide and has been used nationwide since 2016, initially by the police in real operation. In the final stage of development, the other AOS will also be integrated. However, it will still take a few years until the analogue AOS radio and thus the radio reporting system will go out of service. The digital radio includes SDS (Short Data Service), a functionality for exchanging short messages, which also covers functions similar to RMS.

Itemization
https://de.wikipedia.org/wiki/Funkmeldesystem - 12.2.19