## Wndsn Quadrant Telemeter Tutorials

*Making the most out of our graphical telemetry computers.*

Like with many complex instruments, there are multiple ways to solve certain problems and to measure the required inputs. Combining the various functions leads to a multitude of advanced uses.

## Using the Telemeter as Coordinate Scale

How to measure distances on a map with the Telemeter.

The majority of our Telemeters feature an angular scale (those that show 180/π or 57 as eye-to-scale distance) that doubles as a metric ruler, where 1° = 1 cm. A handy application of a metric scale is that of a coordinate scale to measure or transfer right-angled coordinates from or to topographical maps with UTM, MGRS, USNG or other metric coordinate systems.

Most maps are in 1:25,000, 1:50,000, or 1:100,000 and 1:250,000 scale. On our metric Telemeter, on the angular scale, 5° ≙ 5 cm.

Hence:

**at 1:100,000, 5 cm = 5 km and 0.1 cm ≙ 0.1 km**- at 1: 50,000, 5 cm = 2.5 km and 0.1 cm ≙ 0.05 km
- at 1: 25,000, 5 cm = 1.25 km and 0.1 cm ≙ 0.025 km
- at 1: 250,000, 5 cm = 12.5 km and 0.1 cm ≙ 0.25 km

... as well as multiples/fractions of these, by multiplying or dividing the respective scale by 10.

We can derive a simple rule here, namely that:

**at 1:100,000, we use the measured value as is**- at 1:50,000, we divide the measured value by 2
- at 1:25,000, we divide the measured value by 4
- at 1:250,000, we multiply the measured value by 2.5

To determine a position, check the scale of the map, then read the Easting (right) value, and then the Northing (up) value.

### Example

We have a 1:25,000 topo map, here is how to get the Easting and Northing values.

#### Easting

To get the Easting value, position the Telemeter horizontally on the map with the 0 of the angular scale aligned at the next (left) grid line. Read the value where the scale touches the target.

We have a reading of 3.4 cm, which at 1:25,000 means:

```
3.4 × 0.025 = 0.85
or even easier:
3.4 / 4 = 0.85
```

For an Easting value of 0.85 km or 850 m.

#### Northing

To get the Northing value, position the Telemeter vertically on the map with the 0 of the angular scale aligned at the next (lower) grid line. Read the value where the scale touches the target.

We have a reading of 0.5 cm, which at 1:25,000 means:

```
0.5 × 0.025 = 0.125
or even easier:
0.5 / 4 = 0.125
```

For a Northing value of 0.125 km or 125 m.

#### The Position

The last step is to combine the two values with the base values of our grid:

```
422.000 E + 850 m
5022.000 N + 125 m
```

For a resulting position of:

**422.850 E 5022.125 N**