Train radio
As train radio is wireless communication by radio waves between vehicles and fixed communications points , respectively. While different analog modulation methods were used at the beginning of the deployment in accordance with the state of the art , continuous digitization has been recorded since the early 2000s. Since the start of the introduction, the focus has been on voice communication between the driving staff and the control center . Soon, however, elements of data transmission were added in which coded commands could be transmitted. By the end of the 2010s in Germany and other European countries, the various, incompatible analogue train radio types for railway operations had already been largely replaced by the internationally standardized GSM-R standard .
Terrestrial Trunked Radio (TETRA), Wireless Local Area Network (WLAN), Worldwide Interoperability for Microwave Access (WIMAX) and Long Term Evolution (LTE) are also used as digital radio technologies in other modes of transport . The radio technologies are increasingly only used as a medium for IP-based transmissions.
The term Zugbahnfunk was used in the area of the Deutsche Bundesbahn for analogue radio. At the Deutsche Reichsbahn the term train radio was used until 1970 for an announcement and music service within the express trains. . After the unification of the two German railways, the term train radio was used uniformly.
history
While in the early days of the railway, the fixed facilities (signal boxes, stations and gatekeepers) were connected to each other via telegraphy and later by telephone , over the years, the ever faster moving trains made it necessary to be able to establish communication with the moving trains . In 1953, when the Alsternordbahn opened in northern Hamburg, the "train radio" was introduced. With the VHF radio devices installed on the railcars , the train drivers obtained permission to continue on to the next section of the route.
The Deutsche Bundesbahn began to set up such radio links in the 1970s. As early as 1969, tests by the AEG-Telefunken company were carried out on the technically demanding route from Stuttgart to Ulm ( Geislinger Steige ). The Lübeck – Puttgarden and Cologne – Aachen connections were the first two test routes to be equipped with this system in 1971. The radio control centers built later each served a larger section of about 100 km.
In 1980 8,000 locomotives and 13,000 kilometers of route were equipped. The system developed jointly by AEG-Telefunken and the Federal Railroad was considered to be the largest coherent corporate radio network in Europe. The system was also used in Austria, Yugoslavia and England.
At the end of 1980, around 13,500 route kilometers were in operation with ZBF, a further 1,500 under construction or planning and a total of 20,800 route kilometers were measured. The antenna systems, which were usually 20 m above the top edge of the rails, with peaks 30 m, had a range of a few hundred meters up to 20 km, depending on the terrain. The average distance between the ZBF train radio stations was approx. 7 km. Of the 9277 locomotives to be equipped, 8,444 were equipped (full equipment), and a further 697 were prepared for installation (basic equipment).
In 1998, after successful tests of the digital radio technology GSM-R in Germany, it was decided to replace all analog radio networks of the railway company with this new radio technology. This was almost completely achieved by 2010. Most of the old systems have now been shut down and dismantled; however, the technology is still used in the area of larger stations for direct connections in shunting operations, train provision and train completion reports.
technology
The frequency range for train radio was set to be 460 MHz across Europe . This area is in the 70 centimeter band . The special thing about train radio is the unknown, constantly changing locations of the vehicles. A continuous transmission is carried out (continuous carrier). A special frequency scheme with automatic frequency changes ensures that constant transmission is possible. In the downlink (from the infrastructure to the train), three frequencies (referred to as a channel group, 50 kHz apart) are used alternately, from which the train radio always automatically selects the best receivable. The uplink (from train to the infrastructure) always takes place on the uplink frequency assigned to the middle downlink frequency.
Regularly repeating messages, for example "drive slower" or "stop immediately", were transmitted by means of coded data telegrams at the touch of a button, and corresponding displays then lit up in the driver's cab. In the event of operational irregularities, voice connections were possible that had to be registered with the control center beforehand by pressing a button. Immediate connection was possible in emergencies. A pre-installation for the automatic stopping of trains in the area of a train radio control center has been prepared.
In regions with high frequency required (ie, for. Example, large cities, where many railway lines meet), it is also common for the route areas with single-frequency radio to power, which instead of three pairs of frequencies only one is necessary. The middle of the three frequency pairs of a channel group is used. If the route then leaves the metropolitan area, there is a change to normal operation with three alternating downlink frequencies.
The channel occupancy is regulated between the railway administrations across Europe using standardized pilot tones. A continuous tone in the downlink direction indicates that the channel is free. A collective call tone speaks to the loudspeakers in all locomotives in the radio coverage area of this channel, so that an open voice call to a specific train is possible. Existing calls are interrupted by an emergency tone and the loudspeaker in all locomotives is switched on.
Germany
Selective call
The unspecific, open voice call according to international standards represented a great burden for the people involved when there was heavy radio traffic and thus contradicted the concern of increasing transport security. For this reason, selective call procedures were developed at the Deutsche Reichsbahn and the Deutsche Bundesbahn in order to be able to address certain traction vehicles in a targeted manner. However, the technical systems were implemented differently. In the area of the Federal Railroad, the subscribers were called using digital AFSK telegrams with 600 bit / s, in the area of the Reichsbahn, on the other hand, with a tone sequence calling procedure. Newer design train radio systems had to master both modes of operation. In addition to the selective call, ready-made short messages (such as “drive faster”, “watch the train”, “report at the next stop”) could be transmitted in both directions.
In 2005 there were around 3,500 fixed radio systems and around 20,000 radio systems on the trains.
Technical specifications
- 2 times 35 radio channels with 25 kHz channel spacing, channels numbered from 11 to 45
- Frequency range:
- Sub- band (vehicle transmission frequency ) 457.450 to 458.300 MHz
- Upper band (vehicle reception frequency ) 467.450 to 468.300 MHz
- Duplex spacing 10 MHz
- Modulation type: Narrowband FM
- Channels 14 to 16 were intended for inland waterway transport by the Federal Railroad
See also
- Train mail radio (commercial telephone traffic from the train to the fixed network)
literature
-
Handheld electrical telecommunications dictionary
- 1st edition; Volume 2: "Zugfunk" article by Kölsch; Pp. 871-874.
- 2nd Edition; Volume 3: " Zugpostfunk "; P. 1966
- Elsner's paperback for the telecommunications railway service; Tetzlaff-Verlag, Frankfurt am Main 1963
- Leaflet UIC751-3 "Technical regulations for analog train radio systems in international service"
Individual evidence
- ↑ https://www.radiomuseum.org/forum/zugfunk_in_der_ddr.html
- ↑ a b The technology of train track radio . In: Railway technical review . tape 29 , no. 11 , 1980, ISSN 0013-2845 , pp. 789 f .
- ↑ Peter Hill: Control of the radio coverage for train radio (= Elsner's pocket book of railway technology ). Tetzlaff, 1982, ISBN 3-87814-063-0 , ISSN 0071-0075 , p. 325-342 .
- ↑ Claus Kandels, Klaus-Dieter Wittenberg: The introduction of GSM-R at DB Netz AG - GSM-R as a technical network access criterion . In: Eisenbahn-Revue International , Issue 8–9 / 2004, ISSN 1421-2811 , pp. 345–348.