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.

참고:
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.
  참고:
  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.