[Question][help]how to subscribe Lidar Radar and real ground truth state of the system in ROS for EKF.

[arjunshetty955]

FOR example ROS(kinetic/noetic)
L(for lidar) m_x m_y t r_x r_y r_vx r_vy
R(for radar) m_rho m_phi m_drho t r_px r_py r_vx r_vy

Where:
(m_x, m_y) - measurements by the lidar in Cartesian coordinates / *sensor_msgs/pointcloud).
(m_rho, m_phi, m_drho) - measurements by the radar in polar coordinates
(t) - timestamp in unix/epoch time the measurements were taken
(r_x, r_y, r_vx, r_vy) - the real ground truth state of the system

Based on above inputs EKT predict position like estimate path. Here I would like to know,
(1) how to subscribe lidar,Radar and real ground truth state
(2) display EKF like pose estimator?