Arrakis, I am looking through the forum, will complete in the evening if not now. So far foun link to fixer's page of RSP-6M2 (locator system), Volgograd factory (defence ministry sub-division)
????????????? ????? ????????????????? ???????????? ?????? ???????????????? ?????? ???????: ???-6?2, ???-10??1 google first paragraph into English and you'll see it is intended for "consequitive bringing airplanes (without ground visibility) to the aerodrrome runway and control after their descend to the height 150-200m in complex meteorological conditions by means of giving commands to the airplanes' crews through radiostations of connection". Forum is awful swollen hard to look at but surely for natives in Russian it's quicker than for you :o)