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Bluetooth personal area networks (PANs) share the 2.4 GHz ISM spectrum with the IEEE 802.11b wireless local area networks (WLANs). With the popularity of wireless devices, this ISM spectrum is becoming more and more crowded. As a result of this interference between WLANs and PANs, the performance of each network is decreased. Current research has not significantly covered the degrading impact of an 802.11b interferer on Bluetooth voice transmission. Within this project, simulations were carried out to precisely study the impact of an 802.11b interferer on the performance of Bluetooth voice transmission at different ratio levels of Bluetooth power to WLAN power at the receiver side. Furthermore, the impact of SNR on the Bluetooth voice performance and the benefit of using the SCORT packet type was analysed as well. Based on the results presented, network performance can be evaluated at the desired activity level.
This paper treats the Brillouin backscattering in a single mode optical fiber and its implications on the Brillouin Ring Laser Gyroscope (BRLG). The BRLG consists of a fiber ring cavity in which stimulated Brillouin scattering is induced and provides two resonant counterpropagating backscattered waves. If this cavity is rotating around its axis, the backscattered waves get different resonant frequencies because of the Sagnac effect. The frequency difference is proportional to the rotation rate (Omega) by inducing a frequency offset between the counterpropagating waves. Some reported Brillouin spectra exhibit several peaks, which means that one pump wave provides at least two backscattered waves with distinguishable frequencies. In order to understand this multi-backscattering and to take advantage of it for the BRLG, we present results of a simulation of the Brillouin backscattering in a single mode optical fiber.
The prototype of an optical gyro encoder (OGE) has been successfully tested on the NTT telescope in September '93. The OGE consists of a ring laser gyro and a fiber optic gyro with their input axis parallel. The gyro outptu signals are compensated for earth rotation and misalignment and are subsequently integrated to get the angles. An adaptive digital control loop locks the fiber optic gyro to the laser gyro data. Thus the combined output has the precision of the laser gyro and the low noise of the fiber optic gyro. Specifically, the bias stability is better than 2 X 10-3 deg/h, the scale factor accuracy better than 1 ppm, the random walk coefficient better than 5 X 10-4 deg/(root)h and the resolution better than 3 X 10-4 arcsec. The OGE has been mounted in the altitude and in the azimuthy axis of the telescope. The data were compared with the telescope disk encoder data. The test data show that the pointing accuracy is about 1 arcsec and the tracking accuracy 0.1 arcsec over a time of 30 seconds. This accuracy is sufficient for the very large telescope, for instance.
An investigation is underway regarding the usefulness of altazimuth-mounting telescopes' incorporation of laser gyros for pointing and fiber gyros with extremely small random-walk coefficient for telescope inertial stabilization during tracking. A star tracker is expected to help stabilize long-term gyro bias. Gyro and telescope specifications have been derived by means of computer simulations and systems analyses.
The invention concerns a method for spectrum monitoring a given frequency band, in which the spectral power density (S(f)) within the given frequency band is determined for all noise and signal components in the frequency band and, in order to detect the presence of one or more signals within the given frequency band, it is evaluated whether the spectral power density (S(f)) exceeds a threshold value (&lgr;). According to the invention, the threshold value (&lgr;) is calculated in accordance with an estimation of a distribution density (hR(S)) for the noise component of the spectral power density (S(f)) within the given frequency band and in accordance with a predefined value for the false-alarm probability (Pfa).
The invention relates to a container (1) for a liquid medium (3), in particular a blood bag, comprising a flexible outer wall (5) and a device (13) connected to the container (1) for acquiring and/or storing data. According to the invention, the device (13) for acquiring and/or storing data is arranged within the flexible outer wall (5), wherein positioning means (15) are provided which hold the device (13) for acquiring and/or storing data in a floating manner in the liquid medium when the container (1) is filled with said liquid medium (3), and wherein the device (13) or the device (13) and the positioning means (15) are designed such that the mass of liquid medium (3) which is displaced in each case is essentially equal to the mass of the device (13) or to the mass of the device (13) and the positioning means (15).
The invention relates to a method for determining properties of a pipeline, more particularly the position of a branch in a waste water pipeline, in which: a sound wave transmission signal (S, S') is fed into the pipeline (1) at a predetermined infeed point and propagates in the axial direction of the pipeline (1), wherein the frequency spectrum of the sound wave transmission signal (S, S') has a frequency component or a spectral range, the maximum frequency of which is lower than the lower limit frequency (fc) for the first upper mode; in which method components (Sr1, Sr2, Sr3, S'r1, S'r2, S'r3) of the sound wave transmission signal (S, S') reflected inside the pipeline (1) are detected as a sound wave reception signal (E, E'); and in which method, by evaluating the sound wave reception signal (E, E') in relation to the sound wave transmission signal (S, S'), the pipeline (1) is examined for the presence of reflection sites along the pipeline (1) that cause sound wave reflections (Sr1, Sr2, Sr3, S'r1, S'r2, S'r3), wherein at least the distance (I) of a reflection site from the infeed point is determined by evaluating the respective sound wave reception signal (E, E'). The invention further relates to a device for implementing said method.
The application relates to an electronic pill for dispensing a substance, in particular a drug, in a human or animal body in a controllable manner, said electronic pill having a housing (3) in which the substance (17) to be dispensed is accommodated and in which a dispensing opening (47) for dispensing the substance (17) is provided, wherein the substance (17) can be subjected to a predetermined pressure in order to be dispensed from the housing (3), having an electronic control unit (53, 59, 61, 63), and having a valve unit (33) which is arranged in the course of a dispensing path and can be moved from an open position to a closed position by the control unit (53, 59, 61, 63). In the housing (3), a throttle section (45) is provided in the course of the dispensing path for the substance (17) to be dispensed.