Telefonaktiebolaget Lm Ericsson (publ)

Rosemount Tank Radar Ab

Rosemount Inc.

Fabian Wenger

Udo Wachsmann

Peter Schramm

Valter Nilsson

Uwe Dettmar

Jan Lindskog

Mathias Pauli

Mats Nordlund

Hui Li

Ulf Peter Hansson

G&ouml;ran Malmgren

Gerd Zimmermann

Lorens Almehag

Lennart Hägg

Göran Malmgren

Stefan Davidsson

Johan Ebenhard

Roger Walther

Ulf Hansson

Method for determining product surface distance in a tank comprising:

Radar level gauging

A method of calibrating a level gauge system using electromagnetic signals to determine a filling level of a product in a tank. The level gauge system comprises a real time sampler for sampling a reflection signal with a sampling period between consecutive samples. The method comprises the steps of: receiving timing signals from a wireless communication network; generating time stamp signals based on the timing signals; registering a number of the sampling periods between a first time stamp signal and a second time stamp signal; and determining the sampling period based on the registered number of sampling periods and a time between the first time stamp signal and the second time stamp signal. Various embodiments of the present invention provide for high accurate determination of the filling level in a tank without the need for a temperature stable and highly accurate clock reference in the level gauge system.

Calibration of a level gauge system

A method of determining a filling level of a product contained in a tank, the method comprising the steps of: a) transmitting an electromagnetic probing signal towards a target area of a surface of the product; b) receiving a reflected probing signal being a reflection of the electromagnetic probing signal at the surface; c) determining a parameter value indicative of an amplitude of the reflected probing signal; if the parameter value is indicative of an amplitude larger than a predetermined threshold value: d) transmitting an electromagnetic measuring signal towards the target area of the surface; e) receiving a return signal being a reflection of the electromagnetic measuring signal at the surface; and f) determining the filling level based on a time relation between the electromagnetic measuring signal and the return signal.

Intermittent surface measurement

A device for using electromagnetic pulses to determine a distance to a surface includes a pulse generator, a real time sampler and a calibration unit having a signal generator for generating a calibration signal with a predefined frequency. In a calibration mode the real time sampler receives the calibration signal, and an average sample time delay of the sampler is determined based on the sampled calibration signal and the known calibration frequency. In a measurement mode, the real time sampler receives a reflection signal and the distance is determined based on a sampled reflection signal and the average sample time delay. Knowledge of the average delay of the sampler makes it possible to exactly determine the distance (in time and thus space) between two points in the sampled signal.

Calibration of a distance measuring device

A process measurement instrument adapted for wireless communication, comprising a measurement unit () arranged to determine a measurement value of a process variable, a memory () arranged to store a current measurement value of the process variable, a wireless communication unit (), arranged to access the current measurement value and communicate the current measurement value over a wireless communication channel according to a protocol with intermittently active communication, and arbitration logic (), in communication with the measurement unit and the wireless communication unit, and arranged to ensure that active periods of the measurement unit occur when the wireless communication is inactive. The measurement unit and communication unit are thus able to share information via the common memory, e.g. by sequential read/write access. This avoids the need for simultaneous activity. The invention can be especially advantageous when the instrument is powered by an internal power store, such as a battery, and extend the lifetime of such a power store.

Process measurement instrument adapted for wireless communication

The present invention relates to a method for determining a distance between a wireless transceiver and a wireless receiver arranged to communicate with each other in a wireless communication network, the wireless receiver having an active and an inactive reception state, the method comprising transmitting, with the wireless receiver in the active reception state, a first transmission signal, receiving a first reflection signal, the first reflection signal being a reflection of the first transmission signal and influenced by the active reception state of the wireless receiver, transmitting, with the wireless receiver in the inactive reception state, a second transmission signal, receiving a second reflected signal, the second reflection signal being a reflection of the second transmission signal and influenced by the inactive reception state of the wireless receiver, and determining a distance between the wireless transceiver and the wireless receiver based on the second reflection signal.

Wireless transceiver

A flow meter for measuring flow rate and flow composition of a process fluid includes a microwave source configured to generate a microwave signal. A probe tip is coupled to the microwave source and in near field proximity to the process fluid. The probe tip is configured to apply the microwave signal to the process fluid. A microwave detector coupled to the probe tip is configured to detect a near field microwave signal from the process fluid in response to the applied microwave signal. Flow calculation circuitry determines flow rate and/or composition of the process fluid as a function of the detected microwave signal.

Flow measurement using near field microwaves

A method for determining a process variable of a product in a tank based on a time delay of electromagnetic waves. The method further comprises forming a measurement signal comprising a sequence of values, each value representing a time correlation between a pulse of a reference signal and a reflected signal, sampling and digitizing this measurement signal to form a digital signal, identifying a time window of the digital signal including the surface echo peak, determining a relative time period between a reference time corresponding to the predefined reference and a beginning of the time window, time-to-frequency transforming the digital signal in the time window to obtain a phase spectrum, determining a relative phase shift of the spectrum and using the relative phase shift to calculate a corresponding time shift, and determining the time delay by adding the relative time period and the time shift. The invention is based on the realization that major improvement of measurement performance, compared to amplitude detection only, can be achieved by discrimination of the phase difference between the reflected signal and a reference. The detection is further independent of the pulse waveform and modulation, significantly reducing the requirements on pulse modulation.

Pulsed radar level gauging with relative phase detection

A method and a device of providing timing information within a wireless communication system is described. The timing information is extracted from a received transmit signal. The inventive method comprises the steps of providing a training signal on the receiver side relating to a known signal portion of the transmit signal, scaling the training signal, quantizing the scaled training signal, correlating one or more parts of the received transmit signal with the scaled training signal to obtain one or more correlation results, and determining the timing information on the basis of the correlation results.

Method and device for providing timing information in a wireless communication system

In a packet transmission system, especially wireless transmission system, where data is transmitted in packets at different error protection levels and where the error protection level of one packet (=the succeeding packet) may differ from the error protection level of a preceding packet without providing code termination between the said preceding and the said succeeding packet the performance may degrade in case a different error protection level is used by the preceding packet and the succeeding packet. The invention proposes in these cases to insert a supplementary packet between the preceding and the succeeding packet whereby the error protection level of the supplementary packet is higher than the lowest error protection level that is used either by the preceding or the succeeding packet.

Unequal error protection in a packet transmission system

A radio receiver system () comprises a radio receiver (), a receiver sample clock (), which is used for sampling a modulated base-band signal; and a timing correction unit (). The timing correction unit () performs, in the frequency domain, a timing drift compensation between a transmitter sample clock () and the receiver sample clock (). In one example context of implementation, the plural modulated radio frequency carriers have been modulated using Orthogonal Frequency Division Multiplexing (OFDM).

Timing drift compensation in wireless packet-based systems

In a WLAN where an AP and MTs use a duplex airlink having a MAC frame structure to communicate with each other, the AP places wakeup PDUs at different locations in a MAC frame to allow the MTs to conserve energy by maximizing sleep time. In other embodiments, the wakeup PDUs are sequenced by MAC-ID so that a MT can conclusively determine whether remaining wakeup PDUs in a sequence can contain its MAC-ID, and go to sleep early if they cannot. In another embodiment, a wakeup PDU type can indicate to a corresponding MT whether the MT can expect downlink data later in the same MAC frame. In addition, the wakeup PDU type can indicate to the MT that the MAC frame that it should awaken and remain awake to receive downlink data in the future.

Method to put a mobile terminal into sleep when a frame control channel containing a location of slow broadcast channel does not include wakeup information

Device (,) for minimizing the quantization noise in conversion between analogue and digital form of a multi-carrier signal comprising an AC component (V,) with a particular RMS value (V,). The device comprises means (,) for converting between analogue and digital form with a limited number (b) of bits within a quantization range (&plusmn;V,), means (,) for minimizing the noise by creating an ideal ratio (VQR/VRMS) between the quantization range and the RMS value of the AC component, and means for reducing unwanted DC components in the signal and centering the signal by the wanted DC components being placed in the centre of the quantization range. The device is characterized by the fact that it comprises means (,) for calculating a scaling factor a for the AC component which is used to create an ideal ratio between the root mean square value, the RMS value, of the signal and the quantization range (&plusmn;V,), means (,) for multiplication of the AC component by the scaling factor &agr; before the conversion (,), whereby the required ratio (V,/V,) between the RMS value of the AC component (V,) and the quantization range (V,) is obtained.

Method and device for maximizing the ratio between signal and quantization noise when converting between analogue and digital form of a multi-carrier signal

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Göteborg, Sweden

Fabian Wenger