Changing the NVP - MicroScanner2

Calibrating Length Measurements
The tester uses a nominal velocity of propagation (NVP) value and the signal delay through the cable to calculate length. The tester’s default NVP values are usually accurate enough to verify length; however, you can increase the accuracy of length measurements by adjusting the NVP to a specified or actual value.

The default NVP values are 70% for twisted pair cable and 82% for coaxial cable.

Hinweis
NVP values can vary among cable types, lots, and manufacturers. In most cases, these differences are minor and may be disregarded.

Setting the NVP to a Specified Value
To enter the NVP value specified by the manufacturer:

• Turn on the tester while holding down the PORT and UP ARROW keys. 
• To set the NVP for the coaxial port, press PORT.
• Use UP ARROW and DOWN ARROW to set the NVP value.
• To save the setting and exit NVP mode, turn the tester off then on again.

Determining a Cable’s Actual NVP
You can determine a cable’s actual NVP by adjusting the measured length to match a known length of cable. To determine a cable’s NVP:

• Turn on the tester while holding down the PORT and UP ARROW keys.
• To set the NVP for the coaxial port, press PORT.
• Connect a known length of the cable to be tested to the tester’s twisted pair or coaxial connector.
  Hinweise
  The cable must be at least 49 ft (15 m) long. If the cable is too short, “---” appears for the length. For the best accuracy, use a cable between 49 ft (15 m) and 98 ft (30 m) long. The cable must not be connected to anything.

• To switch between meters and feet, press MODE.
• Use UP ARROW and DOWN ARROW to change the NVP until the measured length matches the actual length of the cable.
• To save the setting and exit NVP mode, turn the tester off then on again.