Telecommunications – Transmitter and receiver at separate stations – Having measuring – testing – or monitoring of system or part
Patent
1993-08-19
1995-10-10
Eisenzopf, Reinhard J.
Telecommunications
Transmitter and receiver at separate stations
Having measuring, testing, or monitoring of system or part
455103, 455115, 4552261, 4552791, 333125, 333132, H04B 1700
Patent
active
054578124
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to an arrangement for establishing a radio test loop in a radio unit comprising several radio transmitters and several radio receivers, wherein each radio transmitter comprises a test signal output which is adjustable during an operation of testing the radio transmitter from a high-impedance state to a low-impedance state, for outputting a test signal derived from a signal transmitted by the radio transmitter to a frequency converting means for conversion to the receiving frequency before looping to the respective radio receiver.
The operation of the radio sections of a radio transceiver can be supervised and tested by establishing a so-called radio test loop, that is, by feeding back a test signal derived from a radio-frequency test signal transmitted by the radio transmitter to the radio receiver after converting it to the receiving frequency. Radio units comprising several radio transceiver pairs, such as the base stations of cellular mobile radio systems, usually employ a single frequency converter to which test signals from the different transmitters are applied in successive turns. A separate cable is provided between the test signal output of each transmitter and a special combiner unit which combines the test signal outputs to the single supply line of the common frequency converter. When the number of transceiver pairs in the radio unit is high, such as 16 or 32, the realization of the radio test loop by this conventional technique requires a significant number of printed circuit boards and cables and, as a result, a substantial amount of space.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a radio test loop arrangement which is simpler and requires less space than previously.
This is achieved by means of an arrangement wherein according to the invention the test signal outputs of all the radio transmitters are connected with spacings of approximately n.lambda./2 to a common combiner cable connected to the input of the frequency converter, where .lambda.=the wave length at the transmitting frequency and n=1, 2, 3, . . . .
The basic idea of the invention is that when a certain number of high-impedance test signal outputs are combined by the common combiner cable by utilizing a so-called half-wave-length technique, each high-impedance test output appears to present a high impedance to every other test output and so the test outputs do not load each other. In the test situation, solely the low impedance of the test signal output of the radio transmitter being tested loads the input of the frequency converter coupled to the combiner cable. By means of the invention, a single cable can replace the separate combiner means and the great number of cables used previously, and so the invention enables considerable savings in space and costs.
BRIEF DESCRIPTION OF THE DRAWING
In the following, the invention will be described in greater detail by means of an illustrating embodiment with reference to the attached drawing, wherein:
The sole figure shows a block diagram of a radio unit comprising a radio test loop realized in accordance with the principles of the invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
The radio unit shown in the figure comprises several radio transmitters 10-1, 10-2, . . . , 10-N and several radio receivers 20-1, 20-2, . . . , 20-N. For the sake of clarity, only three radio transmitters and three radio receivers are shown in the figure, but their number can be considerably greater, e.g. 16 or 32. Power outputs 11 in the radio transmitters 10 are coupled to a common antenna line I for supplying radio-frequency (RF) transmission power to a transmitting antenna 2. RF power received by a receiving antenna 4, in turn, is supplied through an antenna line 3 to a branching means 3 which distributes the signal received from the antenna 4 to the radio receivers 20.
The operation of the radio sections of the radio unit is supervised and tested by establishing a so-called radio test loop, that is, by f
REFERENCES:
patent: 3737782 (1973-06-01), Pierce
patent: 4048564 (1977-09-01), Gleeson, Jr.
patent: 4175257 (1979-11-01), Smith et al.
patent: 4785267 (1988-11-01), Covill
patent: 4825175 (1989-04-01), Tsuda et al.
patent: 4875024 (1989-10-01), Roberts
patent: 5283540 (1994-02-01), Myer
Wo, A1, 9119363, Dec. 1991, see abstract.
Patent Abstracts of Japan, vol. 13, No. 386, E812, abstract of JP 01-135138, published May 1989.
Huovinen Timo
Sarkka Veli-Matti
Siira Anne-Marie
Eisenzopf Reinhard J.
Nokia Telecommunications Oy
Sobutka Philip J.
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