## BER measurement | BER test set | Bit Error Rate measurement

This page describes BER measurement and BER test set up. It menetions different types of BER i.e. Bit Error Rate measurement methods viz. BER meter, XOR, FPGA Method used for BER testing.

**What is BER (Bit Error Rate)?**

As we know BER stands for Bit Error Rate. It is the ratio of number of bits received in error
compare to the transmitted bits with the total number of bits transmitted.

BER (%) = {(Erroneous bits)/(Total number of bits)} x 100

Refer BER Basics which describes BER and
mention setup used to measure BER of following two scenarios:

• VSAT system with satellite

• VSAT to VSAT via satellite

### BER Test Set up

The figure-1 depicts simple **BER test** set up.
Usually BER meter such as HP 4951C protocol analyzer is used for measurement.
The BER test tool like this is enough to test BER of any system.

Figure-1 : BER test set up

Following steps are performed for **BER measurement** using BER meter:

➨STEP-1:Connect the output of BER meter, which generates PRBS sequence(i.e. binary sequence)
to the input of the transmitter.
If required, provision need to be provided to disconnect the binary source and connect the
output of BER meter. The same is shown in the figure.

➨STEP-2:The output of receiver (i.e. binary data) is connected back to another input port of
BER meter.

➨STEP-3:BER meter compares output and input binary sequence and determines BER and displays the same.
In order to measure stability of the prototype system BER measurement usually will be run for
3 days (for short term stability) or for 40 days (for long term stability).

➨For the Software Code or prototype hardware having provision to tap binary source data,
BER is calculated by comparing delayed version of input binary source and decoded
binary pattern of receiver part. This calculation can be done using code written on DSP or FPGA or in
any language (C, C++, MATLAB, Labview etc.) as per requirement.

### Types of BER Measurement Methods

There are different types of BER measurement methods.
It includes XOR method, FPGA Method, Using Digital Pin and Using Digitizer.

In XOR method, two patterns are compared i.e. delayed version of input binary source data and
output digital bits of DUT's receiver part. As we know XOR gate produces zero output
when both of its input bits are equal and nonzero output when they are unequal.
This is used to determine whether received and transmitted binary
data are in error or not. This comparison will provide number of erroneous bits and
hence BER can be easily calculated as per formula/equation mentioned above.
This can be done in hardware (On DSP or FPGA) or software.

The other method is using digital input pins available on FPGA or other ICs.
Digitizers having analog inputs and digital inputs can also be used for BER measurement.

### BER Measurement Equipment Vendors

The popular BER equipment vendors include Tektronix, Keysight Technologies, Anritsu, Fluke Networks, Lecroy etc. Refer complete list of companies manufacturing BER T&M Equipments.