How do older SAM radars work? What role does a "Height Finder" radar play?

[Jack Johnson]

Im talking about older SAMs, like the SA-2 or the S-200. On older pictures of SAM sites I often see the P-35 "Bar Lock" radar paired with a PRW-13 „Odd Pair” height finder radar.

P-35 "Bar Locke": P-35 radar - Wikipedia, the free encyclopedia
PRW-13 "Odd Pair": PRW-13

How do these two work, are they actually responsible in guiding SAMs, or are they just for first detection? Normally it would be clear, the P-35 is for detection, and the PRW-13 for precise height determination. But sometimes there seems to be only a P-35, without a height finder...

And then there seem to be Radars like the "Fan Song" that can do both, despite being just as old: [ame="http://en.wikipedia.org/wiki/Fan_Song"]Fan Song - Wikipedia, the free encyclopedia[/ame]

 

[My2Cents]

The PRW-13 and P-35 were search radars for long range detection and tracking, and have 3x the range of the Fan Song. The P-35 would be used alone when precision height information isn’t critical, like for air traffic control.

The Fan Song was the fire control radar for the SA-2 with very limited scan capability. It was, for example, only capable of tracking 1 aircraft at a time. Targets detection was done using the Flat Face serch radar.

 

[Jack Johnson]

The PRW-13 and P-35 were search radars for long range detection and tracking, and have 3x the range of the Fan Song. The P-35 would be used alone when precision height information isn’t critical, like for air traffic control.

The Fan Song was the fire control radar for the SA-2 with very limited scan capability. It was, for example, only capable of tracking 1 aircraft at a time. Targets detection was done using the Flat Face serch radar.

Ah so a SA-2 *could* operate with an Fan Song alone, but it would limit its reaction time?

The Wiki Artikle for the S-200 also only lists the "Square Pair" radar as main radar system, but then lists an additional (optional?) six radars, one of which is the "Odd Pair" height finder. So apparently both the SA-2 and the S-200 dont need the height finder radar, but benefit from it.
http://en.wikipedia.org/wiki/S-200_Angara/Vega/Dubna

 

[StobieWan]

You'd have to be pointing right at the target already to use Fan Song alone. Fan Song, like most fire control radars was built with a narrow field of regard. With no accompanying search radar, it'd be kind of like scanning the skies through a drinking straw.