Using GPS receivers

Quite a few recorders in the county are now using GPS Receivers to help locate the position for records more accurately, and they are proving very useful, but a few pointers may help to improve the use.

The accuracy is still limited; although many will give 8-figure grid references (or even better), this implies an accuracy of 10 metres, whereas the quoted value in good conditions seems to be about 17 m. However, this still makes an 8-figure reference more accurate that a 6-figure, which only gives you a 100 m x 100 m square. For most records 6 figure is sufficient, unless it is a rare plant or an ancient tree that you want to pin-point more accurately. If the extra accuracy really does seem important, it might be worth contacting us for an aerial photograph of that bit of the county.

To save batteries, many of us switch the receiver off between readings, but experience suggests that it does take a few minutes to get the best readings, even when the machine says it is o.k. - just watch the drift in the numbers.

Readings in valleys and woodlands are still difficult, due to blocking out the signals from satellites, and it is even more worth while leaving the receiver switched on.

Rounding readings: If you have an 8-figure reference, and you only want 6-figures, do round down, NOT up, because rounding up puts the record into the next 100 m square .( see notes on Grid References)

If you have any observations you would like to add to these, please contact us.