B network
The B-Netz was an analog mobile radio system that was in operation from 1972 to 1994. It replaced the A network that was discontinued in 1977 and was in turn replaced by the C network (from 1985).
On January 14, 1972, the B-network operation was opened with the activation of the Zeven radio traffic area . The main innovation was the ability to establish dial-up connections in both directions, from the telephone network to the radio network and vice versa. This was a significant step forward compared to the A network , which was only accessible via exchanges. The B-Netz worked with 38 speech channels until 1980. By expanding to 75 voice channels in 1980, the B network became the B / B2 network . This reached its highest level in 1986 with 158 base stations and around 27,000 participants and at the same time the largest possible number of participants. On December 31, 1988, the B / B2 network still had 24,382 participants nationwide. In the west of Berlin there were still 1,078 participants. The B / B2 network was shut down on December 31, 1994.
A serious problem with the B / B2 network was that a caller from the fixed network had to know the presumed location of the cell phone in order to be able to reach it via the area code of the radio traffic area . The Federal Republic of Germany was divided into 150 zones with a diameter of up to 150 km. For example, if you knew that the participant was moving in the Munich area, you first dialed the Munich area code (089), then the number sequence 05, then the participant's number. When leaving the area of the associated base station - this was relatively small with a radius of approx. 27 km - the call was interrupted and had to be set up again.
Roaming was possible to a limited extent in the neighboring countries of Austria , the Netherlands and Luxembourg .
The transmission between the base station and the mobile phone was analogue and unencrypted; anyone who had a radio with a suitable reception range could overhear. Both participants had to use additional devices for encryption, which were only used in rare cases, for example during discussions with important politicians.
As a further technical development, the C network was put into operation on May 1, 1985, which brought numerous advantages compared to the B / B2 network.
Technical specifications
- Initially 16,000 participants, after an expansion of the radio channels 27,000 participants were possible
- Maximum expansion:
- Germany (1985):
- 27,000 participants
- 850 radio channels (including reuse of the same channels in radio zones that are sufficiently far apart)
- 158 radio stations
- Austria (end of 1984):
- 1,770 participants
- Speech channels:
- 38 to 1980 in the B1 network
- 75 after the expansion of the frequencies from the deactivated A network to the B / B2 network in 1980
- Frequency ranges: 2 meter band
- B1 network
- B2 network
- Sub-band (subscribers) 157.61 MHz - 158.33 MHz
- Upper band (base station) 162.21 MHz - 162.93 MHz
- Channel 19 nationwide call channel on 153.370 MHz (upper band only)
- 4.6 MHz duplex spacing
- Channel spacing: 20 kHz
- Bandwidth per channel: 14 kHz
- Modulation method: FM , 4 kHz frequency deviation
- Transmission power:
- stationary 10–30 watts
- movable 10 watts
- Small power channels (KKL): Additional channels with reduced power (0.1 watts) offset by 3.92 MHz to relieve the strain in urban areas
- limited roaming in Austria , the Netherlands and Luxembourg
literature
- Christel Jörges and Helmut Gold : Telephones 1863 until today; From the collections of the Museums for Communication; Edition Braus, 2001; ISBN 3-926318-89-9 ; Pp. 284-285