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| Gain linearization with coplanar waveguide |
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| Channel correction transceiver |
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| Adaptive digital predistortion linearization and feed-forward correction of RF power amplifier |
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| Predistortion system and method using analog feedback loop for look-up table training |
| OF A PREFERRED EMBODIMENT The present invention provides a predistortion system and method for ... |
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| FM demodulator including tuning of a filter and detector |
| OF THE PREFERRED EMBODIMENT A demodulator circuit embodying the invention is shown in FIG. 2 and ... |
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| Satellite communication system |
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Test circuit of multiplex equipment
| Details |
Inventors: Yajima, Noboru;
Assignee: Fujitsu Limited (Kanagawa, JP)
Primary Examiner: Safourek; Benedict V.
Assistant Examiner:
Attorney, Agent or Firm:
In a multiplex and transmission system, multiplex equipment in one station having a plurality of low speed units and a high speed unit, is connected through two transmission lines to other multiplex equipment in another station having a plurality of low speed units and a high speed unit. The system further includes a test circuit of multiplex equipment comprising a switch group for connecting the low speed units in tandem, on an input line and an output line of the low speed unit in each channel in the one station. When a test is carried out, the low speed output of each low speed unit is connected to the low speed input of the next low speed unit. A low speed signal loop back is executed in the low speed units in the other station. A pulse pattern generator is connected to the low speed input of the low speed unit in the first channel in the one station and a certain pulse pattern is supplied to the low speed input. The low speed output of the last low speed unit in the one station is input to an error detector, and bit error is detected in the low speed unit of all the channels in both stations. |
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DETAILED DESCRIPTION An object of the present invention is to provide a test circuit for multiplex equipment to be used when the multiplex equipment is installed or a failure occurs in the equipment, wherein the number of the connecting cables and the time taken for the test are reduced.
In a first aspect of the present invention, there is provided a test circuit of multiplex equipment in a multiplex and transmission system, wherein signals supplied to a plurality of first low speed units, each of which is provided in one channel, are multiplexed using a first high speed unit, in multiplex equipment provided in one station.
The multiplexed signal is transmitted to a second high speed unit in multiplex equipment in another station.
A signal from the second high speed unit is demultiplexed to derive signals that are supplied to a plurality of second low speed units in the multiplex equipment in the other station.
The signals supplied to the plurality of second low speed units are multiplexed using the second high speed unit, the multiplexed signal is transmitted back to the first high speed unit, and the signal from the first high speed unit is demultiplexed to derive signals that are supplied to the plurality of first low speed units.
The test circuit comprises a switch group, on an input line and an output line of the first low speed unit in each channel, the switch group being provided to connect the first low speed units in tandem.
When a equipment is tested, by using the switch group for connecting the low speed units in tandem, the low speed units are connected in tandem so that a low speed output of the first low speed unit in each channel in the one station is connected to a low speed input of the first low speed unit in the next channel.
A low speed signal loop back is circulated so that a high speed output of each first low speed unit is connected to a high speed input of the first low speed unit.
A pulse pattern generator is connected to a low speed input of the first low speed unit of the first channel, to input a certain pulse pattern
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Multiplexer-related 
