Description: The uncalibrated echo response, UER(i* UER_G*Df), shall be represented in linear format by a scale factor and a normalized complex number a(i)+j*b(i), where i is a frequency index i ranging from 0 to NSC-1, the subcarrier spacing, Df = 4.3125 kHz, and (NSC-1) * UER_G * Df is the highest frequency supported by the SELT-PMD functionality. The UER granularity parameter, UER_G, has two valid values: 1 and 2, indicating whether the measurements were performed using a tone spacing of 4.3125 kHz or of 8.625 kHz. If the uncalibrated echo response is being reported over a frequency range of 17.664 MHz or lower, UER_G shall be set to 1. If the uncalibrated echo response is being reported over a frequency range that is greater than 17.664 MHz, UER_G shall be set to 2. The scale factor shall be coded as a 32-bit unsigned integer. Both a(i) and b(i) shall be coded as 32-bit 2's complement signed integers. The value of UER(i* UER_G*Df) shall be defined as: UER(i* UER_G*Df) = (scale/2^31)*(a(i)+j*b(i))/2^31. In order to maximize precision, the scale factor shall be chosen such that max(|a(i)|, |b(i)|) over all i is equal to 2^31-1. NOTE - This data format supports an UER(f) granularity of 2^-31 and an UER(f) dynamic range of approximately +6 dB to -186 dB, however it does not imply any future accuracy requirements. An UER(i*UER_G* Df) value indicated as a(i) = b(i) = -2^31 is a special value. It indicates that no measurement could be done for this subcarrier either because it is not supported by the SELT-PMD function, or that the value is out of range to be represented.