OPINION OF THE COURT
Memorandum.
Judgment of conviction is unanimously reversed, on the law, information dismissed and fine remitted.
While the general reliability of radar as a competent speed detection device, while in a stationary position, has long been recognized (People v Magri, 3 NY2d 562), the reliability of this particular type of unit to accurately measure the speed of an oncoming vehicle while the unit is located in a police car traveling in the opposite direction has not been established. Before such readings can be considered reliable, there must be testimony detailing the operative principles underlying the capability of this type of radar unit to accurately compensate for the relative speeds and directions of the respective vehicles (People v Mangelberg, NYLJ, Nov. 21, 1977, p 14, col 5; People v Lampert, NYLJ, May 31, 1977, p 14, col 2; cf. People v
Concur: Farley, P. J., Pittoni and Slifkin, JJ.