The present disclosure relates to an un-manned aerial vehicle (200) for aligning a first directive antenna (101) in a direction D1 towards a second antenna (102), comprising a docking interface (210) arranged to attach the aerial vehicle (200) to a first alignment device (110) of the first directive antenna (101) and an alignment actuator (220) arranged to mechanically interface with the alignment device (110) and to actuate alignment of the first directive antenna (101) based on an alignment control signal. The aerial vehicle further comprises a control unit (230) configured to generate an alignment control signal.

A tentative decision is made for symbols on the basis of a received signal and a decision threshold, and a tentative decision signal including a sequence of the symbols is output. A scale value indicating a rate of increase or reduction of the received signal or a threshold change rate indicating a degree of change in the decision threshold is updated so that an appearance frequency of each of symbols included in the tentative decision signal matches an appearance frequency of each of symbols in a reference signal obtained by modulating a transmitted signal with a modulation method used in transmission which is shared between a transmitting side and a receiving side, and an SN ratio is calculated using the scale value or the threshold change rate when a degree of agreement between the appearance frequencies is within a predetermined permissible range. When the scale value is updated, a tentative decision is made for the symbols on the basis of the received signal increased or reduced by the updated scale value and the decision threshold, and when the threshold change rate is updated, the tentative decision for the symbols is made on the basis of the received signal and the decision threshold to which the updated threshold change rate is applied.

A tentative decision is made for symbols on the basis of a received signal and a decision threshold, and a tentative decision signal including a sequence of the symbols is output. A scale value indicating a rate of increase or reduction of the received signal or a threshold change rate indicating a degree of change in the decision threshold is updated so that an appearance frequency of each of symbols included in the tentative decision signal matches an appearance frequency of each of symbols in a reference signal obtained by modulating a transmitted signal with a modulation method used in transmission which is shared between a transmitting side and a receiving side, and an SN ratio is calculated using the scale value or the threshold change rate when a degree of agreement between the appearance frequencies is within a predetermined permissible range. When the scale value is updated, a tentative decision is made for the symbols on the basis of the received signal increased or reduced by the updated scale value and the decision threshold, and when the threshold change rate is updated, the tentative decision for the symbols is made on the basis of the received signal and the decision threshold to which the updated threshold change rate is applied.

A distributed antenna system of the present invention implements duplication by a method of configuring a first headend unit and a second headend unit in an active state or in a standby state and connecting a hub unit or a remote unit to the first headend unit and the second headend unit and by a method of connecting, through a redundancy link, a hub unit or remote units of a branch group branched from and connected to each headend unit, activating the redundancy link according to the control of an active headend unit when an error occurs in a frame transmission path, and changing logical port states of a hub unit or remote units that cannot transmit frames due to the error in order to change the frame transmission path so that frame transmission is possible through the activated redundancy link.

A distributed antenna system of the present invention implements duplication by a method of configuring a first headend unit and a second headend unit in an active state or in a standby state and connecting a hub unit or a remote unit to the first headend unit and the second headend unit and by a method of connecting, through a redundancy link, a hub unit or remote units of a branch group branched from and connected to each headend unit, activating the redundancy link according to the control of an active headend unit when an error occurs in a frame transmission path, and changing logical port states of a hub unit or remote units that cannot transmit frames due to the error in order to change the frame transmission path so that frame transmission is possible through the activated redundancy link.

A high-frequency 5 measurement method includes generating a test signal (TS), which is a sine-wave signal having a predetermined frequency, in which a period (τ) during which the power level is at a first power level and a period (T-τ) during which the power level is at a second power level lower than the first power level 10 are periodically repeated, inputting the test signal (TS) to a device under test (10) as an input signal, and measuring the difference between an output signal (OUT) of the device under test (10) and an ideal value of the output signal (OUT).

A high-frequency 5 measurement method includes generating a test signal (TS), which is a sine-wave signal having a predetermined frequency, in which a period (τ) during which the power level is at a first power level and a period (T-τ) during which the power level is at a second power level lower than the first power level 10 are periodically repeated, inputting the test signal (TS) to a device under test (10) as an input signal, and measuring the difference between an output signal (OUT) of the device under test (10) and an ideal value of the output signal (OUT).

A test system for testing a device under test includes: a signal processor configured to generate a plurality of independent signals and to apply first fading channel characteristics to each of the independent signals to generate a plurality of first faded test signals; a test system interface configured to provide the plurality of first faded test signals to one or more signal input interfaces of the device under test (DUT); a second signal processor configured to apply second fading channel characteristics to a plurality of output signals of the DUT to generate a plurality of second faded test signals, wherein the second fading channel characteristics are derived from the first fading channel characteristics; and one or more test instruments configured to measure at least one performance characteristic of the DUT from the plurality of second faded test signals.

A test system for testing a device under test includes: a signal processor configured to generate a plurality of independent signals and to apply first fading channel characteristics to each of the independent signals to generate a plurality of first faded test signals; a test system interface configured to provide the plurality of first faded test signals to one or more signal input interfaces of the device under test (DUT); a second signal processor configured to apply second fading channel characteristics to a plurality of output signals of the DUT to generate a plurality of second faded test signals, wherein the second fading channel characteristics are derived from the first fading channel characteristics; and one or more test instruments configured to measure at least one performance characteristic of the DUT from the plurality of second faded test signals.

A UWB ranging performance testing method is disclosed in which a control terminal device sends a test request signal message to multiple devices to be tested. The test request signal message includes communication time slots distributed by the control terminal device to multiple devices to be tested. Communication time slots of different devices to be tested are different. All devices to be tested return the response signal message for UWB ranging performance testing in their respective corresponding communication time slots.