Changing Calibration Reflectivity

In the command prompt, type cal
Zcal displays the prompt:
```
Enter pulse width (choices 1):
```
Enter the pulse width in microseconds (for example, 1, 1.0, 1.00).
Zcal displays the prompt:
```
Enter new cal reflectivity (old was -34.51):
```
Enter the calibration reflectivity (dBZ₀) in dB.
Typically this is a negative dB number, such as -35, which corresponds to the minimum detectable dBZ at 1 km (0.6 mi).

Zcal displays the prompt:
```
Enter new cal noise (old was -93.11, nan for none):
```
Enter the new value for the calibration-time noise level.

If you do not know this number, you enter nan (short for "Not a Number"). This disables the feature for adjusting the calibration if the noise level changes from that observed at calibration time.

Zcal redisplays the calibration information, showing the new calibration reflectivity and noise that you entered.