Error rate measuring apparatus and codeword position display method

An error rate measuring apparatus that inputs a Pulse Amplitude Modulation 4 (PAM4) signal of a known pattern as a test signal to a device under test, receives a signal from the device under test with the input of the test signal, and measures whether or not a forward error correction (FEC) operation of the device under test is possible based on a comparison result of the received signal and the test signal, the error rate measuring apparatus comprising:

• a processor configured to sets a codeword length and an FEC symbol length of the FEC as a setting parameter to the signal received from the device under test corresponding to a communication standard of the device under test;
• and
• a display configured to displays most significant bit string data and least significant bit string data of each piece of symbol string data obtained by converting the signal received from the device under test in parallel on a display screen,
• wherein the processor is configured to, from the FEC symbol length, codeword head symbol information indicating that a head symbol of a codeword is present, the codeword length, and a position of a cursor to select a symbol of the most or least significant bit string data on the display screen, to calculate position information of a codeword indicating a position of the symbol currently selected by the position of the cursor in a codeword and a position of the codeword in the received signal, and
• wherein the display is configured to displaying the position information of the codeword calculated by the codeword position calculation means on the display screen.

A codeword position display method for an error rate measuring apparatus that inputs a Non Return to Zero (NRZ) signal of a known pattern as a test signal to a device under test, receives a signal from the device under test with the input of the test signal, and measures whether or not a forward error correction (FEC) operation of the device under test is possible based on a comparison result of the received signal and the test signal, the codeword position display method comprising:

• a step of setting a codeword length and an FEC symbol length of the FEC as a setting parameter to the signal received from the device under test corresponding to a communication standard of the device under test;
• a step of displaying bit string data obtained by converting the signal received from the device under test on a display screen of a display;
• a step of, from the FEC symbol length, codeword head symbol information indicating that a head symbol of a codeword is present, the codeword length, and a position of a cursor to select a symbol of the bit string data on the display screen, calculating position information of a codeword indicating a position of the symbol currently selected by the position of the cursor in a codeword and a position of the codeword in the received signal;
• and
• a step of displaying the calculated position information of the codeword on the display screen.

A codeword position display method for an error rate measuring apparatus that inputs a Pulse Amplitude Modulation 4 (PAM4) signal of a known pattern as a test signal to a device under test, receives a signal from the device under test with the input of the test signal, and measures whether or not a forward error correction (FEC) operation of the device under test is possible based on a comparison result of the received signal and the test signal, the codeword position display method comprising:

• a step of setting a codeword length and an FEC symbol length of the FEC as a setting parameter to the signal received from the device under test corresponding to a communication standard of the device under test;
• a step of displaying most significant bit string data and least significant bit string data of each piece of symbol string data obtained by converting the signal received from the device under test in parallel on a display screen of a display;
• a step of, from the FEC symbol length, codeword head symbol information indicating that a head symbol of a codeword is present, the codeword length, and a position of a cursor to select a symbol of the bit string data on the display screen, calculating position information of a codeword indicating a position of the symbol currently selected by the position of the cursor in a codeword and a position of the codeword in the received signal;
• and
• a step of displaying the calculated position information of the codeword on the display screen.