MXPA97001977A - Method and apparatus for compensation of temperature in a multiplex receiver by tie division - Google Patents

Abstract

The present invention relates to a receiver of fixed signals in a time segment within fixed-length time frames, a method and apparatus for correcting the output of the receiver in accordance with the receiver's ambient temperature as measured with the temperature detectors. An input reference noise signal is provided at the receiver in a predetermined time segment and the corresponding output noise signal from the receiver is processed to calculate a correction factor that is related to the measured value of the current room temperature. This factor is subsequently used to correct the output signals from the receiver at that temperature.

Description

METHOD AND APPARATUS FOR TEMPERATURE COMPENSATION IN A MULTIPLEX RECEIVER BY TIME DIVISION The present invention relates to the correction of temperature in a telecommunications receiver, in particular in a receiver for signals sent in time slots in fixed-length time frames. The present invention is defined in the claims to which reference should now be made. According to one aspect, the present invention preferably consists of a method of correcting the output of the receiver in a time division multiplex emitter unit in accordance with the ambient temperature of the receiver, which comprises providing a reference noise signal of entering a predetermined time segment of a multiple channel per time division of the unit and processing the corresponding output noise signal from the receiver to determine a correction factor that is related to a measured value of the current room temperature, this factor being used subsequently to correct the output signals from the receiver at said ambient temperature. The invention preferably provides a time division multiplex emitting unit comprising a receiver, temperature measurement means and processing means, the noise source selectively providing a noise signal as an input to the receiver in a predetermined time segment. of the multiplex channel by time division so that the receiver provides an output signal dependent on the magnitude of the input noise signal and at least one temperature as measured with the temperature measurement means and the processing means which serve to determine an input signal correction factor from the signal and store the correction factor against the associated temperature. The receiver can be a transmitter / receiver ("transducer"). The transmitting unit may be a base station for time division / time division multiplex access (TDM / TDMA) multiplex communications with a plurality of subscriber units that may be in fixed locations. The receiver can receive TDMA. Preferably, the correction factors for the different associated temperatures are determined and stored for use in a temperature compensation of received signals. The temperature measuring means can measure a first temperature value at a first location of the transmitting unit and a second temperature at a second location. The first location may be adjacent to the antenna. The antenna can be exposed, for example, on the top of a masthead. The second location may be adjacent to the processing circuit, particularly in the body of the transmitting unit. Each correction factor can be determined depending on a plurality of temperatures and stored together with the data representing those temperatures, for example, as a look-up table in the memory of a microprocessor. In particular, a correction value may be related to a temperature measured in a first position and a temperature measured in a second position. The stored correction factors can be updated intermittently or continuously, in accordance with a predetermined rule. In particular, the correction or recalibration update may occur after a predetermined period has elapsed or whenever a novel combination of temperatures is found. Re-calibration can also be started under the control of a microprocessor, whenever a fault condition is suspected. In essence, the search table of correction factors can be filled "as you go". A separate initial calibration procedure is not required. With repeated calibration, changes in correction factors and / or temperatures can be monitored, allowing the detection of fault conditions. In addition, changes in apparent noise received at a site can be monitored.

A preferred embodiment of the invention will now be described by way of example and with reference to the drawings illustrating a preferred base station in accordance with the present invention. The drawing shows a base station comprising a mast supporting an antenna 1 on top and a radio unit near the antenna with an input-output connection to the antenna. This connection comprises a diplexer unit 3 through which a transmitter 4 and a receiver 5 are connected to the antenna. The radio unit 2 also incorporates a reference noise source 6 which can be selectively connected to the input of the receiver 5 under the control of the switch means 7 to determine the temperature correction data, as described below in the I presented . The radio signal received by the receiver 5 is amplified and converted to an IF signal and is supplied by means of a cable 8 to a converting and demodulating unit 9 at the base of the mast. A downconversion step 10 receives the IF signal and, after conversion, passes the signal to a demodulator stage 1 1 which produces an output data signal 1 1 which produces an output data signal to another equipment 12 of the communication system in the base station The downconversion step 10 has a variable gain that is controlled by a controller 1 3 in accordance with the temperature T 1 of the receiver 5, as determined by an electronic thermometer 14 and, the temperature T "of the downward conversion stage, as determined by an electronic thermometer 15. A search table stored in the memory 16 maintains the appropriate gain values for the predetermined combinations of the temperature scales and, these are retrieved by the controller 13 of T1 and T2 in accordance with the values of the two measured temperatures.The gain values stored in the memory 16 are they determine from a calibration procedure that is carried out while the communication system is in operation receiving radio signals and, which involves the use of the reference noise source 6 to provide a reference input to the receiver 5 in a default channel of the TDM input. The switch means 7 is closed to initiate calibration and this causes the noise signal to be sent to the receiver 5 in a predetermined TDM time slot in each TDM time frame. The corresponding output of the receiver 5 is monitored and, by comparison of the known reference noise signal, the system is able to determine a correction factor or gain value of the particular temperatures T! , T2 that prevail at that time. The controller 13 can operate to receive the output signal from the receiver as well as the temperature data T 1 and T 2. The controller calculates the correction factor / gain values and updates the values stored in the memory 16 for the different combinations of temperature bands. The values are maintained, for example, in a matrix of 10 x 10 temperature bands corresponding to the temperatures T1 and T2. In other embodiments, arrays of different sizes may be used. Controller 13 may be the central control entity of the base station. The noise source 6 preferably generates a noise signal at a first level above the reference level of the system. This reference level is the minimum level at which reception will be presented with a satisfactory Bitio Error Range. In the preferred embodiment the reference level of the system is 101 dBm and the Bitio Error Range is no more than one in 103. The noise signal was preferably applied to the transducer t during a TDM time segment selected in a quad. Multi-segment TDM which preferably has 10 segments. This segment is one that is not currently being used for data transfer. The TDM frames are sent on TDM channels. In practice, the circuit associated with three channels are in proximity to a base station. The application of noise on one channel should only cause cross-channel interference to the other channels. To overcome this, the noise signal is simultaneously provided on all three channels in simulated time segments, none of which carries data. The temperature corrections are determined by the three channels.

The calibrations or re-calibrations can be started for a predetermined time, for example, 30 minutes, or, provided that the temperatures T1 and T2 are in combination of scales that have not been previously determined or, whenever a failure condition is suspected. Repeated re-calibration ensures that variations in receiver sensitivity are compensated accurately over time. In addition, trends in corrections and temperature values can be followed, giving rise to the initial detection of failure conditions. Repeated re-calibrations also provide an initial warning that the apparent level of noise at a base site changes significantly. This effect could be due to a faulty antenna or other equipment or, it could be due to a real increase in noise at that site. Both conditions would require investigation of how they are monitored in a useful way. The calibration data in the matrix can be read by a remote processor to monitor system performance and provide timely warning of problems.

Claims (31)

1. The apparatus for receiving signals in time segments within fixed-length time frames comprising operating calibration means for repeated calibrations of a receiver during the operation of the receiver, the calibration means comprising a noise source, temperature measurement means and processing means, the noise source selectively providing a noise signal of predetermined magnitude towards the receiver at a predetermined time segment within a fixed-length time frame, the receiver detecting the noise signal and providing an output signal dependent on the detected magnitude of the noise signal and at least one temperature as measured with the temperature measurement means and, the processing means to determine a signal correction factor from the output signal and store this correction factor against the associated temperature for subsequent use in the cor direction of output signals from the receiver.

2. The apparatus for receiving signals according to claim 1, wherein the predetermined time segment in which the noise signal is applied is not one that is being used to transmit signals

3. The apparatus for receiving compliance signals with claim 1 or claim 2, wherein the processing means determines the correction factors from the output signal from the receiver for different associated temperatures measured by the temperature measuring means and, the processing means store the correction factors for use in the temperature compensation of the received signals.

4. The apparatus for receiving signals according to claim 3, wherein the receiver comprises an antenna for receiving the signals that are sent by the radio and, the temperature measuring means measure a first temperature at a first location and, a second temperature at a second location, the first location being adjacent to the antenna.

The apparatus for receiving signals according to claim 4, wherein the antenna is exposed on a mast head.

The apparatus for receiving signals according to claim 4 or claim 5, wherein the second location is adjacent to the processing circuit.

The apparatus for receiving signals according to claim 6, wherein the second location is in the body of the sending unit.

The apparatus for receiving signals according to any one of claims 3 to 7, wherein each correction factor is determined depending on a plurality of temperatures and stored together with the data representing those temperatures.

9. The apparatus for receiving signals according to claim 8, wherein the correction factors and the temperature data are stored as a look-up table in the memory of the microprocessor.

The apparatus for receiving signals according to claim 8 or claim 9, wherein the correction factors are stored with a first temperature measured at the first location and a second temperature measured at the second location. eleven .

The apparatus for receiving signals according to any preceding claim, wherein the correction factors are determined intermittently or continuously according to a predetermined rule.

12. The apparatus for receiving signals according to claim 1, wherein a correction factor is determined whenever a lapse of time has elapsed.

The apparatus for receiving signals according to claim 1 or claim 12, wherein a correction factor is determined whenever a novel combination of temperatures is encountered.

The apparatus for receiving signals according to any one of claims 1 to 13, wherein the determination of the correction factors is carried out under the control of a microprocessor whenever a failure condition is suspected.

15. The apparatus for receiving signals according to any of claims 11-14, wherein the changes in correction factors and / or temperatures are monitored to detect a fault condition.

16. The apparatus for receiving signals according to any of claims 11-15, wherein the change in apparent received noise is monitored to detect a fault condition.

17. The apparatus for receiving signals in accordance with any preceding claim, wherein the receiver is a transducer.

18. The apparatus for receiving signals according to any preceding claim, wherein the apparatus is a base station for TDM / TDMA communications with a plurality of subscriber units and comprises, three receivers, the noise signal being simultaneously provided to the subscribers. receivers to avoid cross-channel interference and determine the correction factor thereof.

19. A method for correcting the ot signals of a receiver of signals sent in time segments within time frames of fixed length in accordance with the ambient temperature of the receiver including the repeated calibration cycles during the operation of the receiver, each cycle of calibration comprising providing an input reference noise signal to the receiver at a predetermined time slot set within fixed time frames and processing the corresponding ot noise signal which depends on the detected amount of the noise signal from the receiver to determine a correction factor that is related to at least one measured value of the current ambient temperature, using this factor subsequently to correct the ot signals from the receiver at said ambient temperature.

20. A method of correcting the ot signals of a receiver according to claim 19, wherein the predetermined time segment in which the noise signal is applied is not one that is being used to transmit signals.

21. A method of correcting the ot signals of a receiver according to claim 19 or 20, wherein the correction factors for the different associated temperatures are determined and stored for use in the temperature compensation of the signals received.

22. A method of correcting the ot signals of a receiver according to claim 21, wherein the receiver comprises an antenna, a first temperature is measured at a first location, and a second temperature is measured at a second location. , the first location being adjacent to the antenna.

23. A method of correcting the ot signals of a receiver according to claim 22, wherein the second location is adjacent to the processing circuit.

24. A method of correcting the ot signals of a receiver according to any of claims 21 to 23, wherein each correction factor is determined depending on a plurality of temperatures and stored together with the data representing those temperatures .

25. A method of correcting the ot signals of a receiver according to claim 24, wherein the correction factors and the temperature data are stored as a look-up table in the memory of the microprocessor.

26. A method of correcting the ot signals of a receiver according to any of claims 19 to 25, wherein the correction factors are determined intermittently or continually in accordance with a predetermined rule.

27. A method of correcting the ot signals of a receiver according to claim 26, wherein a correction factor is determined whenever a lapse of time has elapsed.

28. A method of correcting the ot signals of a receiver according to claim 26 or 27, in which a correction factor is determined whenever a novel combination of temperatures is found.

29. A method of correcting the output signals of a receiver according to any of claims 26 to 29, wherein the determination of the correction factors is carried out under the control of a microprocessor whenever a failure condition.

30. A method of correcting the output signals of a receiver according to any of claims 26 to 29, wherein changes in the correction factors and / or temperatures are monitored to detect a fault condition.

31 A method of correcting the output signals of a receiver according to any of claims 25 to 30, wherein the change in apparent received noise is monitored to detect a fault condition.