Outdoor computer

1. A method for implementing a weather alarm in an outdoor computer, in which method

atmospheric-pressure data is defined repeatedly,

altitude data is defined repeatedly and essentially simultaneously with the atmospheric-pressure data, with the aid of a satellite positioning system, and both measured variables are converted into the same measurement unit, either pressure or altitude,

characterized in that

the difference between the converted variables is determined and is stored as a reference value,

the difference between the converted variables is repeatedly monitored, and

when the difference changes by more than a preset limit-value relative to the reference value, a weather alarm is given.

2. A method according to claim 1 , characterized in that the variable used is pressure.

3. A method according to claim 1 , characterized in that the variable used is altitude.

4. A method according to any of the above claims, characterized in that the value ±4 hPa over a three-hour estimating period is used as the change limit-value in the pressure comparison.

5. A method according to any of claims 1 - 3 , characterized in that the value ±30 m over a three-hour estimating period is used as the change limit-value in the altitude comparison.

6. An apparatus for implementing a weather alarm in an outdoor computer, which apparatus includes

measuring means for repeatedly determining the atmospheric-pressure data,

means for determining the altitude data repeatedly and essentially simultaneously with the atmospheric-pressure data, with the aid of a satellite positioning system, and

conversion means for converting both measured variables into the same measurement unit, either pressure or altitude,

characterized in that the apparatus includes

means for determining the difference between the converted variables and

storing means for storing the difference as a reference value,

monitoring means for monitoring the difference of the converted variables, and

alarm means for giving an alarm if the difference changes by more than the preset limit-value relative to the reference value.

7. An apparatus according to claim 6 , characterized in that the alarm means is a vibrating element, which is able to give an acoustic or vibration alarm.

8. An apparatus according to claim 6 , characterized in that the alarm means is a light source with a varying lighting effect.

9. An apparatus according to claim 6 , characterized in that the alarm means is text or a symbol on the display.

10. A method for implementing a weather alarm in an outdoor computer comprising the steps of:

determining first data comprising a first one of atmospheric pressure data and altitude data at a time t 1 and at a first plurality of times after time t 1 , the first data being expressed in first units;

determining second data comprising the other one of atmospheric pressure data and altitude data at time t 1 and at a second plurality of times after time t 1 , the second plurality of times corresponding to the first plurality of times, the second data being expressed in second units;

said step of determining first data or said step of determining second data comprising a step of obtaining data from a satellite position measurement system;

converting the second data into first units;

determining and storing a difference between the first data and the converted second data at t 1 as a reference value;

setting a limit-value based on the reference value;

monitoring a difference between the first data and the converted second data at the second plurality of times; and

giving a weather alarm when the difference between the first data and converted second data varies from the reference value by more than the limit-value.

11. The method of claim 10 wherein said step of giving a weather alarm comprises the step of giving a weather alarm only when the difference between the first data and converted second data varies from the reference value by more than the limit-value over a given estimating period.

12. The method of claim 10 wherein said step of giving a weather alarm comprises the step of giving a weather alarm when the difference between the first data and converted second data varies from the reference value by more than +/−4 hPa over a three hour period.

13. The method of claim 10 wherein said step of giving a weather alarm comprises the step of giving a weather alarm when the difference between the first data and converted second data varies by more than +/−30 m over a three hour period.

14. The method of claim 10 wherein said step of giving a weather alarm when the difference between the first data and converted second data varies from the reference value by more than the limit-value comprises the steps of giving a weather alarm when the difference between the first data and converted second data is greater than the reference value by more than the limit-value and giving a weather alarm when the difference between the first data and converted second data is less than the reference value by more than the limit-value.

15. An apparatus for implementing a weather alarm in an outdoor computer comprising:

first determining means for determining first data comprising a first one of atmospheric pressure data and altitude data at a time t 1 and at a first plurality of times after time t 1 , the first data being expressed in first units;

second determining means for determining second data comprising the other one of atmospheric pressure data and altitude data at time t 1 and at a second plurality of times after time t 1 , the second plurality of times corresponding to the first plurality of times, the second data being expressed in second units;

one of said first determining means and said second determining means comprising a satellite position measurement system;

converting means for converting the second data into first units;

third means for determining and storing a difference between the first data and the converted second data at time t 1 as a reference value;

monitoring means for monitoring a difference between the first data and the converted second data at the second plurality of times;

limiting means for setting a limit-value based on the reference value; and

alarm means for giving a weather alarm when the difference between the first data and converted second data varies from the reference value by more than the limit-value.

16. The apparatus of claim 15 wherein said alarm means gives a weather alarm only when the difference between the first data and converted second data varies from the reference value by more than the limit-value over a given period of time.

17. The apparatus of claim 15 wherein said alarm means for giving a weather alarm gives a weather alarm when the difference between the first data and converted second data is greater than the reference value by more than the limit-value and when the difference between the first data and converted second data is less than the reference value by more than the limit-value.

18. An apparatus for implementing a weather alarm in an outdoor computer comprising:

a pressure measurement unit for determining atmospheric pressure data at a time t 1 and at a first plurality of times after time t 1 , the atmospheric pressure data comprising first data expressed in first units;

a satellite positioning unit for determining altitude data at time t 1 and at a second plurality of times after time t 1 , the second plurality of times corresponding to the first plurality of times, the altitude data comprising second data expressed in second units;

a memory;

an alarm; and

a processor for converting the second data into first units or the first data into second units, determining a difference between the first data and the second data at time t 1 as a reference value, storing the reference value in the memory, setting a limit-value based on the reference value, monitoring a difference between the first data and the converted second data at the second plurality of times, and actuating the alarm when the difference between the first data and second data varies from the reference value by more than the limit-value.