geostationary telecommunications satellites electronic telephone set ...

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ter, TRT m70. It is planned to be gradually
introduced into all parts of the
Netherlands with 113 controlling and
738 terminating units in accordance
with fig. 2.
TRT m70 is programmed from an electric
typewriter or loading tape. The
testing can be very extensive and suitable
phases can be repeated every
twenty-four hours. The programming
period is a maximum of 99 days and
during this time the daily program may
vary as required.
The phases during one day may include
various tests for the investigation
of the service quality. Additional
tests may also be made for charging
and careful check of the transmission
level.
The processed results are written on a
typewriter, which can be remotely connected
through a fixed modem connection.
As a great many test numbers can
be programmed a comprehensive and
effective test program can always be
prepared.
Number of lines, maintenance efforts
and fault rate
The development of the number of
local and incoming transit lines in the
Netherlands is shown in fig. 3 a. The
prognosed maintenance staff requirements
in case of preventive maintenance
compared with CCM are shown
in fig. 3 b which figure also illustrates
how the fault rate gradually has decreased.
References
1. Harriers, J. A.: The Introduction
of a New Maintenance Method
into the Telephone Area of Rotterdam
and its Influence on the
Maintenance Organization. Ericsson.
Rev. 45 (1968): 2 pp. 46—60.
2. Hamers, J. A.: Six Years of controlled
Corrective Maintenance
(CCM) in the Rotterdam Telephone
District. Ericsson Rev. 49
(1972) pp. 74—85.
Fig. 3 b
Comparison between staff required for pure
preventive maintenance and for CCM with a
yearly increase in accordance with fig. 3 a
1. 1966 CCM was introduced in Rotterdam
2. 1969 TRT in combination with CCM was
introduced throughout the Netherlands
The blue curve is only valid for the Rotterdam
district