We are using the BCM943362WCD4 eval kit, where it is powered up by the USB connection, which is obviously around 5V.
However when we monitored the UART signal lines, the voltage level found to be 1.8V level, can we know is that the right behaviour or is there any settings to be done to make it 3.3V.
As well how about the SPI lines, what would be the voltage level ??
There are no settings for the 3.3V. It is fixed and regulated by the LDO, LT1963EST-3.3_TRPBF. Perhaps your USB hub does not provide enough power for the board.
Try using different USB hub, perhaps powered by an external power supply, or use the "5V PWR" jack to power the board with 5V power supply.