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| Method and apparatus for checking continuity of optic transmission |
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| Transmission power control circuit |
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| Protected amplifier apparatus |
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| Transmitter testing method |
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| Digital premodulation filter |
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| Modulator having direct digital synthesis for broadband RF transmission |
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| Amplitude and phase error normalization of subcarrier generator |
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Measuring device with optical signal transmission
| Details |
Inventors: Adolfsson, Morgan; Brogardh, Torgny;
Assignee: ASEA Aktiebolag (Vesteras, SE)
Primary Examiner: Karlsen; Ernest F.
Assistant Examiner:
Attorney, Agent or Firm: Watson, Cole, Grindle & Watson
The invention relates to a measuring device having a transmitter side and a receiver side, arranged for signal transmission from the transmitter side to the receiver side via an optical connection. The transmitter side comprises members for combining an incoming measuring signal with a signal from a reference voltage source to two different signals, arranged to be transmitted to the receiver side via each of two parallel optical channels. The receiver side comprises means for receiving the two transmitted signals and for controlling the amplification in the signal paths with a view to obtaining compensation for variation of parameters included in the two channels and other elements in corresponding signal paths. In addition, the receiver side includes a device which, from the two transmitted signals, forms a signal (U.sub.ut) independent of the input measuring signal of the transmitter side. |
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DETAILED DESCRIPTION FIG.
1 shows an optically coupled measuring device according to the invention for transmitting and transforming an analog electric input signal U.
sub.
in into an analog electric output signal U.
sub.
ut.
The measuring device consists of a transmitter side S and a receiver side M, which are interconnected by means of at least two light conductors 8, 9.
The transmitter and receiver sides may be separated a distance of up to several kilometers, and they may be located at different electric potentials.
Alternatively, for example where only a potential difference, which is not too great, is to be bridged, the transmitter and receiver sides may be connected to each other, in which case the light conductors with associated light-emitting diodes (LEDs) and photodiodes may consist of optic couplers.
FIG.
1 shows an optically coupled, analog measuring amplifier, in which the stabilization of the analog transmission takes place according to the "bridge principle".
The measuring signal U.
sub.
in is input symmetrically to the middle node or midpoint of voltage divider 1.
The signals +U.
sub.
in /2 and -U.
sub.
in /2 are then obtained at each respective end node of voltage divider 1.
The signal +U.
sub.
in /2 passes via an analog contact device, for example field effect transsistor 2, to a summation device 31 where this signal is added to a reference voltage V.
sub.
ref from a constant voltage source, and the composite signal (+U.
sub.
in /2+V.
sub.
ref) passes to the input of the amplifier 4.
In a corresponding manner, a composite signal (-U.
sub.
in /2+V.
sub.
ref) is obtained from the summation device 32 after -U.
sub.
in /2 has passed the field effect transistor 3.
Summation signal output of summation device 32 is supplied to amplifier 5.
The two signals thus combined, +U.
sub.
in /2+V.
sub.
ref and -U.
sub.
in /2+V.
sub.
ref, enter two parallel signal paths, consisting of the following respective components: amplifiers 4 and 5, which are optically linearized by means of feedback photodiodes 27 and 28, light-emitting diodes (LED) 6 and 7, the two optical channels 8 and 9 (light conductor fibers), photodiodes 10 and 11, the controllable photo-amplifiers 12 and 13, and a variable amplifier 15 and an amplifier 14 with fixed amplification
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Audio Signal Processing 
