Device and method for position information

Translation of description of equivalent WO 2007045002 A1

Apparatus and method for position information

The present invention relates to a device for position information, comprising a satellite-based position measuring system with an energy-sapping measuring mode, in which it provides the current location of the device at an output, and an energy-saving sleep mode, a load connected to said output mobile network-based communication means for transmitting the position over a cellular mobile network, wherein the communication device, the local reception field strength and the local cell identifier of the mobile network providing at an interface. The invention further relates to a method for the position information by means of such position measuring and communications facilities.

Combined satellite navigation and mobile devices, for example, to track ( "Tracking") of cargo or used in fleet management. A big problem here the high power consumption of the known devices is because especially on mobile cargo such as containers, chilled-goods, etc. not always a board power supply to available. therefore, there have been alternative supplies solar panels and batteries suggested. Especially in the logistics industry but often arise long downtimes in the dark, for example in a warehouse, on an unlit siding, etc., which would require very large accumulators.

From EP 1132713 a Positionsinformationsvor- direction of the aforementioned type is known in which the satellite-based position measuring system is a GPS receiver, which can be in a low-power sleep mode ( "standby") supply sets. EP 1132713 proposes before, the GPS- Receiver only then move to the measuring mode if eg a key on the communication device (a mobile phone) is pressed, a specific number is dialed, a call is received on the mobile phone, the mobile phone is outside its reception area or a timer expires. The first versions require an active user intervention to initiate the position determination, while the version with the timer has a periodic power consumption of the GPS receiver result. The invention has the aim to provide an apparatus and a method for position information to develop so that they have a particularly low average energy requirement under practical conditions. This object is in a first aspect of the invention, achieved with an apparatus of the type mentioned, which is characterized by a load connected to the output of the position measuring device and the interface of the communication device control means which at a threshold exceeding change in the received field strength or by a change of cell identifier the position measuring device to the measuring mode on and if the position remains the same for a predetermined period, the position measuring device goes into sleep mode.

The invention is based on the recognition that the "rough" position information can be obtained from a change in the received signal strength or the cell identifier of the cellular mobile radio network, can be utilized to the satellite-based position measuring system for the "fine" switch position determination. If the determined position on a time does not change long, the position measuring device is reset to the power-saving sleep mode. This can be achieved in the time average a decisive reduction in power consumption and energy demand.

A preferred embodiment of the invention is characterized in that the position a GPS Receiver and the communication device is a GSM mobile radio module, whereby commercially available components can be used and a wide applicability is ensured.

According to a further preferred embodiment of the invention, said threshold value from 2 to 10 dBm, more preferably 3 to 5 dBm. Furthermore, the said time period preferably 3 to 15 min, more preferably about 10 min. These values ​​represent a practicable compromise between sufficient accuracy and minimal average electricity consumption represents.

it when said threshold in turn a function of the local reception field strength is, leads to a substantially same Positionsmeßgenauigkeit throughout Mobilkfunknetz can be achieved is particularly favorable. In a second aspect, the invention provides a process for the position information by means of a satellite-based position measuring system with an energy-sapping measuring mode and a power-saving sleep mode and a mobilfunknetzge- assisted communication means for sending the position via a cellular mobile network, which according to the invention is characterized by the following steps in any Sequence:

Determining the local reception field strength or the local cell identifier of the mobile network using the communication device and, when the received signal strength changes by at least a predetermined threshold or the cell identifier changes, switching of the position in the measuring mode;

Determine the current location of the device by means of the position and, if the position for a predetermined period stays the same, switching of the position in the sleep mode.

Further features and advantages of the invention will become apparent from the following invention of a preferred embodiment in conjunction with the accompanying drawings, their FIG. 1, the apparatus of the invention in. A schematic block diagram shows.

In Fig. 1, an apparatus 1 is shown with a GPS receiver 2, the navigation signals 3 of one or more satellites 4 receives, it determines its position and heading provides at an output the fifth The output 5 a GSM mobile radio module 6 is connected, which transmits the determined position heading over a cellular mobile radio network 7 to a central station 8 for further evaluation, for example, the headquarters of a fleet management or cargo tracking system.

Instead of the GPS receiver 2, any other known in the art satellite-based position measuring system can be used, for example, an A-GPS, D-GPS, GLONASS, Galileo, EGNOS, WAÄS receiver, etc. Similarly, instead of a GSM mobile radio module, any other known in the art mobile network-based communication means are used, for example, a mobile phone or -modern after TDM, GPRS, UMTS standard, etc.

The GPS receiver 2 has two different operating modes, namely an energy-absorbing measuring mode (mode of operation), in which he determined the current position heading and the output 5 provides, and an energy-saving sleep mode ( "standby"), in which he as the stores last determined position or is simply switched off completely. via a control input 9 schematically shown, the GPS receiver can be 2 switched between its measurement and its sleep mode.

Commercial GSM receiver 2 have, for example in the measurement mode (mode of operation) a current consumption of 200 mA, in the sleep mode or standby power consumption of about 20 mA. Also the GSM mobile module has 6 different modes, including an energy-sapping transmission mode in which it sends the detected position heading to the Central 8, and a power-saving standby or receive mode. The GSM mobile radio module 6 includes an interface 10 to which it at least in each mode^'local reception field strength E and the cell identifier cell of the cellular mobile radio network 7 provides.

In case of a GMS network, the local reception field strength E is defined for example as a power level in the ETSI specification GSM 05.05, and the cell identifier cell ( "cell ID") in the ETSI specification GSM 03.03.

The device 1 further comprises a device connected to the output 5 of the GPS receiver 2 and the interface 10 of the GSM module 6 controller 11, which heading from the position of the reception field strength E and the cell identifier of cell a control signal PWR for the control input 9 of the GPS -Empfängers 2 generates, in the following manner:

1. GPS receiver is in idle mode:

If the reception field strength E changes by at least a predetermined threshold S, ie | .DELTA.E | > S, then switches the control device 11 the GPS receiv^'nger 2 to measuring mode to.

2. GPS receiver is in measuring mode:

If the determined by the GPS receiver 2 position heading over a prescribed period T remains the same (or several times consecutively determined heading the same position at periodic determination of the position), then the GPS receiver 2 switches the control device 11 returns to the idle mode , The threshold value S is determined in view of the minimization of the average energy consumption of the whole apparatus 1 in the selected target environment; preferably the threshold value S is 2 to 10 dBm, more preferably 3 to 5 dBm.

The measure used here for the reception field strength E is the power level (received power level) after the ETSI specification GSM 05.05 in dBm.

The local reception field strength E is the distance between the device 1 to the nearest base station of the cellular network 7 dependent. For example, at a distance of 250 m, the reception field strength E -20 dBm, and a change of +/- .DELTA.E 5 dBm corresponds to a change in distance of approximately 150 m. At a greater distance to the nearest base station the same distance change corresponds to a lower change .DELTA.E for example, +/- 3 dBm, so that the threshold value S is to be reduced accordingly if the position change is to be determined with the same accuracy.

It is therefore also possible to set the threshold value S as a function of the local reception field strength E, in order to always achieve the same positioning accuracy, ie S = f (E). Also, the time period T is determined with a view to minimizing the average energy needs; preferably, the time period T 3 to 15 min, more preferably about 10 min.

The invention is not limited to the embodiments illustrated, but includes all variations and modifications that fall within the scope of the appended claims.