Corrector
In analog exchanges, the corrector is the central control point in a long-distance exchange and was used in the German state long-distance network. The first developments in conversion were made without the use of relays. For the control were electronic components such as diodes and transistors used. The corrector was first used in long-distance dialing technology in the main exchanges. Its working method was fully electronic with no electromechanical parts.
In the later versions of the corrector, however, relays were used again to evaluate key figures . For this purpose relays with protective gas contacts in small glass tubes were used ( Herkon relays ).
construction
Its task is to answer the inquiries of a node (KRg or KRg 62) or main office register (HRg or HRg 62) and thereby inform the register of the most favorable route. At the same time, the tariff for metering charges is communicated to the metering pulse generator (ZIG) from the KRg via a relay search selector (RSW) for the zone setting selector. In the tariff, a distinction was also made between a normal subscriber line and a payphone .
During the further expansion of the long-distance dialing network, the corrector was also used in the node exchanges as a route control with zoning.
It was also planned to introduce route control with revaluations in the central offices as a third route level if necessary.
In terms of its construction, the corrector can be operated as a single system. To be on the safe side, however, two correctors are always installed in an exchange. Three correctors are only used in very large remote exchanges.
In a system with two correctors, the ring cables leading to the registers are divided into two groups and each connected to a corrector. In the event of a fault, the ring cable can be quickly plugged into the other corrector.
The first correctors were built according to System 62 and did not yet have any plug-in boards. It was not until the next generation based on System 69 that they were usually set up as a slide-in design with circuit boards. For reasons of speed, SRK (protective tube contact) relays are used for the relays still required for various bundle shutdowns.
Before the introduction of local service in 1980, the corrector consisted of a single frame. Due to the local service, the correctors were supplemented by a second frame. The tasks such as evaluation, zoning and routing tasks were then divided between these two frames. The routing and special expenses were determined on the first rack frame, the base rack frame. The tasks for zoning were accommodated on the new, second rack frame, the additional rack frame. The additional frame was no longer built using technology 62, but rather using more modern technology 69.
Function groups in a corrector
- Test multiple
- Key figure button for input
- Evaluation of key figures
- Evaluation control panel for the output
The test multiple ensures that only one register can be connected to the corrector via the ring cable at the same time. Due to the electronic operation, a request to the corrector takes an average of only 80 ms. Thanks to this fast working method, a single corrector can process approx. 20,000 inquiries per hour.
The input and output lines are structured in a similar way to coordinate panels. For all possible combinations of digits, the connections are made by diodes at the crossing point. As a rule, this is a 4-fold AND link.
To save on components, so-called filler cores with the designation HF and KF can be used as a replacement for an entire group of digits.
The input of the information about the corrector for the first 3 digits, the Z, H and K digits, is made as a parallel input; 3 × 10 input lines are available for this. There is also an input group A with 2 lines for evaluating the first digit, if it has the value 1, and for differentiating one or two-digit ZA digits, where not 3 but 4 digits are required for evaluation.
The individual groups of digits are arranged in individual lines. If several groups of digits lead to exactly the same results with regard to the zone and the route, these can be summarized in one line.
A maximum of 180 lines are available for wiring. This number is also sufficient for the largest switching centers for the evaluation including the local service.
The evaluation of the key figures is carried out in the base frame. These are AND circuits with 4 inputs. At least one marker line must be marshalled in a row at each input group A to D.
For the lines of the input group B and C, the circuit runs via the two relays Z and H and via group D in the KRg. Through the two contacts z and h of the evaluation relay, the potential earth of the input group A is switched through to the output part of the line concerned and the associated result relay in the KRg is activated via the evaluation routing.
In order to protect the contacts of the relays, there is a short delay of 12 ms for switching through. The relays for the evaluation therefore close when the power is off, which increases the service life. For the same reason, the contacts are opened again when the power is off. The result relays in the KRg maintain their own contact.
Various control routings and monitoring relays were also installed. This logically checks most of the corrector's outputs. In the event of an error, the connection to the KRg is disconnected and an alarm is activated.
The key figure evaluation takes place in the additional GR. Four input groups are available for evaluating the digits of the local area code. The origin of the calling subscriber is determined via a fifth input. This zoning of the local service is carried out at the level of EVSt to EVSt.
So that the corrector can make a statement about the cheapest route, he receives the information from the BAC relay via the bundle shutdown. This is the case when all lines are busy on a certain QW (cross route).
If this transverse direction is operated with overflow, the corrector will immediately make a different statement through the active line break. Multiple overflows can also occur.
Web links
- Corrector with functional description from the manufacturer
- Umwerter - Telekom-Historik (accessed on July 13, 2017)