How can I get the power in dBm?

Question

How can I display the remote power readout of a NRP.Zxx power sensor in "dBm" on the NRP or NRP2?

Answer

The NRP and NRP2 base unit has a "dBm" and a "Watt" readout. Conversion to "dBm" takes place in the NRP or NRP2. A remote command always returns the measured power values in "Watt". The sensors cannot internally convert the power values to "dBm".

However, a computer and a program are always needed for remote operation. In the computer program, it is easy to convert the unit from "Watt" to "dBm" using equation [1]:

a = 10 * (log10(P / 1 mW)) dB [1]

Sometimes compilers only provide a base 2 logarithm function. In this case, you can calculate the base 10 logarithm function with equation [2]:

log10(x) = log2(x) / log2(10) [2]

Using the base 2 logarithm function, equation [2] and equation [1] give you equation [3]:

a = 10 * (log2(P / 1 mW) / log2(10)) [3]

Equation (4) is the general way to calculate the base 10 logarithm from other logarithm bases (note the subscripts b and c):

logc(x) = logb(x) / logb(c) [4]

Where:

a -> power level in "dBm"

P -> power returned from the sensor

log2 -> base 2 logarithm function

log10 -> base 10 logarithm function

logb -> base b logarithm function

logc -> base c logarithm function

Thank you.

Your request was successfully sent!

We will get in touch with you soon.

Your Rohde & Schwarz Team

Request Support
Please specify the type of request:
Please tell us which topic.

Please enter your inquiry.
Contact information

Please enter your first name.

Please enter a valid email address.

Please enter your company name.

Please enter your postal code.

Please enter your name.

Please enter your phone number.

Please enter your location.

Please enter your city name.
Product Information


Please enter your serial number.
(e.g. 123456)
Contact me by...*
Please tell us how we may contact you.
Marketing permission
Security Response Code
show captcha

The input was not correct.
*Mandatory Field
International Website