PRF frequency on Russian planes

[deckard]

Hello everyone. I have asked the same question in one of my other threads. I have gotten great responses, but I still have some questions about it.

 

I have set up a mission in Mission Editor. SU27 (me) VS F15. Head on. I am flying at 10500 Meters and 7000 Meters for the F15.

 

The High PRF has a quicker acquisition of the plane (If the plane is not using a jammer). If the plane is using a jammer, then the "burn through" is the same distance for High PRF, Medium PRF and Auto PRF. (40 KM)

 

As the target approaches, its marker slowly goes down from the top to the bottom of the HUD and slowly disappears after up to 8KM. I do not loose the target using different PRFs.

 

My question is , at close ranges (40KM or less), does PRF make any difference?

It is for head on, tail , or maneuvering target.

 

Another question, once the target is close (lets say , 25 KM or less) and maneuvering, and I loose the lock on my radar, what is the best PRF to use to reacquire the target (to find him).

 

If I leave PRF on Auto (does it take longer to find a target at close range?) Does the interleaved signal takes (longer) to scan?

 

I find it at close range , if I have no idea where the target is, I switch to IRST by pressing "O" and I have better luck for finding a target.

 

Thank you everyone for all your responses :)

[Exorcet]

At close range PRF matters less. It's probably best to keep it at MID though as high might still drop beaming targets.

 

As for losing the lock at close range, is the target still directly head on? You might be exceeding your radar's gimbal limits or the F-15 might be beaming. If you post a track people can watch it and see exactly what you would see.

[FLANKERATOR]

As Exorcet said, under 20km, forget HI and use ILV first then switch to MED (EOS might do a better job than MED for targets flying away).

 

A quick guide about radar PRF effectiveness according to OBA (estimation)

OBA<20--------> HI

20<OBA<90----->ILV

90<OBA<180---->MED

 

OBA (Off-Boresight Angle) is the angle between the axis of the antenna (boresight axis) and the direction of the target.

Edited August 25, 2014 by FLANKERATOR

[deckard]

Thank you very much for your response.

OBA < 20 . Does this mean that the bandit it less than (the angle of antenna and the location of the bandit relative to the antenna ( antenna is at the nose of the plane)

20<OBA<90 Does this mean that the bandit is between 20 and 90 degrees of the nose. Total coverage 90-20 = 70 degrees

Is Mid better than Auto when the target is beaming or maneuvering (between 10 and 40 KM)

90< OBA <180 means that the coverage is the widest (180-90) is 90 degrees

 

I am a little confused. Please clarify... Thank you

 

Another question...Does Med acquire targets quicker than Auto? (if the bandit it close , less than 40km and I have no idea where he is). Lets say, I am turning around in a circle and trying to find the bandit who is between 10KM and 40KM, do I use Auto or Med PRF?

[SFJackBauer]

Thank you very much for your response.

OBA < 20 . Does this mean that the bandit it less than (the angle of antenna and the location of the bandit relative to the antenna ( antenna is at the nose of the plane)

20<OBA<90 Does this mean that the bandit is between 20 and 90 degrees of the nose. Total coverage 90-20 = 70 degrees

Is Mid better than Auto when the target is beaming or maneuvering (between 10 and 40 KM)

90< OBA <180 means that the coverage is the widest (180-90) is 90 degrees

 

I am a little confused. Please clarify... Thank you

 

Another question...Does Med acquire targets quicker than Auto? (if the bandit it close , less than 40km and I have no idea where he is). Lets say, I am turning around in a circle and trying to find the bandit who is between 10KM and 40KM, do I use Auto or Med PRF?

 

The number indicates the angle between the bandit nose and your nose.

 

Ex. bandit perfectly perpendicular to you: OBA = 90

Larger number means his nose is pointed away. Lower number, his nose is pointed towards you.

 

It has nothing to do with the antenna coverage, but it assumes that the bandit is inside the radar cone, otherwise no matter what, you wouldn't detect it anyway.

 

About acquisition time - its the wrong way to think about it. PRF management lets you tailor the radar emissions depending on the bandits aspect. So while in situation A you may acquire someone inside 40km with HI, in situation B you won't, purely because of different bandit aspects.

 

The factor that influences the acquisition time is the size of the radar volume - a larger volume takes more time to scan, but obviously it is a tradeoff. You can adjust the azimuth (horizontal volume) and, if in the smallest volume, slew it left and right.

 

Also consider that in these airplanes the radar steering is mechanical, so the antenna takes a fixed minimum amount of time it takes to survey the smallest possible radar volume. Therefore if you are wildly slewing the radar around, or turning it on and off quickly, the chances of finding something goes down the drain. I try to wait at least two seconds in a given radar configuration (azimuth/elevation/PRF) before changing it. If we had electronic steering radars (PESA/AESA) this time would be much smaller.

Edited August 26, 2014 by SFJackBauer

[Frostie]

Another question...Does Med acquire targets quicker than Auto? (if the bandit it close , less than 40km and I have no idea where he is). Lets say, I am turning around in a circle and trying to find the bandit who is between 10KM and 40KM, do I use Auto or Med PRF?

PRF does not affect acquisition time.

 

What does is sweep pattern. Typically radars have the ability to choose different sweep patterns eg. 6 sweeps of 2 degrees each or 2 sweeps of 3 degrees each etc. The later will give faster updates but scan less area (6deg) while the former would have more coverage (12deg) but take longer to complete the scan.

 

The radars in FC3 are limited to one mode in their sweep, that is they sweep four times at 2.5 degrees every sweep, therefore the entire area covered is 2.5deg x 4 regardless of PRF mode.

 

With FC3 in the F-15 you can reduce scan time by narrowing the azimuth to 60 degrees coverage instead of the standard 120 degrees.

[FLANKERATOR]

@deckard:

 

As Jack and Frostie said, those numbers are about using the right PRF in relation to your target's aspect angle.

 

Realize that using the right PRF is only part of the detection effectiveness and surely not the most important one.

 

What really matters first is to steer your radar antenna both horizontally and vertically in order to put your target into your radar's cone (Think of it as trying to see something using a flashlight in a pitch-dark room, you will see only what you illuminate - also realize how narrow the light cone is at the source and how the further, the wider it becomes). This is how your jet radar operates, it will see only what's inside the scanning 'cone', therefore, it's up to you pilot to move your antenna to detect your targets.

 

We said the further, the wider, so realize that the further, the more space you will cover and that the closer, the less space you'll cover. This means you'll have to be more active with your scanning to detect closer targets as your radar cone is narrower at that range.

 

Learn how to fly while scanning methodically with your radar, once you start getting a good picture of what's around you, then you can add up the PRF task. Priority is to move that radar and it can take a bit of time and training to really get the hang of it. Also many other things are involved to scan properly like your own altitude and the terrain type, though at this stage, better to tackle those later on. Step by step...

Edited August 26, 2014 by FLANKERATOR

[deckard]

thank you - more questions :)

 

thank you guys for all the responses. Jack....I think that changing azimuth coverage in Russian planes, turns the antenna to the left, center, and to the right. Does

the antenna physically turn left or right?

From the Flaming Cliffs 3 Manual

"

The scan pattern can be slewed discretely through three azimuth positions, center – right – left. "

"

Orient the radar azimuth scan zone in the direction of the target. On Russian fighters, the azimuth scan zone moves discretely and has three positions: central ±30

degrees, left –60 - 0 degrees and right 0 - +60 degrees. If the target is out of the central ±30 degrees zone, then it is required to move the scan zone to the left

or right with the [RShift-,] or [RShift-/] keys.

 

I am still confused about what this means. Does the antenna physically turn, or it changes the scan pattern (so when you turn the radar left or right, is scans more

space, but it takes longer to scan that space)

 

From the manual again

 

"

To search for both high and low targets aspect, use the AUTO sub-mode. Using AUTO however incurs about a 25% reduction in detection range compared to the HI (PPS) and

MED (ZPS) sub-modes. "

 

High aspect - does it mean that the bandit is above me and low aspect - the bandit is below me?

 

From the manual

 

"

 

High PRF (HPRF), which provides the longest detection range against approaching forward-hemisphere targets, is indicated by ППС (HI), whereas medium PRF (MPRF) for

receding rear-hemisphere targets is indicated by ЗПС (MED). In АВТ (ILV) mode, high and medium PRFs are interleaved on alternate bars of the radar scan pattern. This

provides all-aspect target detection at the expense of a 25% reduction in maximum range. "

 

Does this mean that ABT mode's limitation is only for the range reduction? (not how quickly it can detect the bandit)

What does "rear-hemisphere target" mean? The bandit is behind me? I can't see him on the radar , if he is behind me.

 

From manual

"

Changing the PRF is used to increase the radar’s sensitivity when detecting targets flying at different aspect angles. High PRF is used to detect targets flying

towards your aircraft (high aspect), medium PRF is used for targets with low closure rate or you are behind. In the default operation mode, the radar cycles between

high and medium PRF to provide all target aspect detection. "

 

This brings a question... when do I use Med PRF VS Auto PRF?

 

Thank you all for all the responses! :)

[SFJackBauer]

I am still confused about what this means. Does the antenna physically turn, or it changes the scan pattern (so when you turn the radar left or right, is scans more

space, but it takes longer to scan that space)

 

Check the light green cone on the russian planes MFD. It indicates the radar coverage. See that when you slew left and right, the light green cone moves. Therefore the scan volume does not increase or decrease.

 

High aspect - does it mean that the bandit is above me and low aspect - the bandit is below me?

 

Aspect refers to the aspect of the bandit when seen from your point of view - is his nose pointing at you? Then its "high" aspect. Is it pointing away? "Low" aspect. Another way of saying it is "hot" when its incoming or "cold" when its pointing away, and "notching" when its perpendicular.

 

Does this mean that ABT mode's limitation is only for the range reduction? (not how quickly it can detect the bandit)

 

Interleaved mode limitation is that the radar scans its volume half the time with one PRF, and half the time with other. That's why it is called "interleaved". This incur in a slight range penalty for far targets, which you would otherwise detect using HI. From this you should interpret when you should use which mode.

 

What does "rear-hemisphere target" mean? The bandit is behind me? I can't see him on the radar , if he is behind me.

 

Another way of saying "low aspect target" or "cold bandit". Note it is a "receding" target, he is moving away from you. In this situation a HI PRF radar has the hardest time picking it.

 

"

Changing the PRF is used to increase the radar’s sensitivity when detecting targets flying at different aspect angles. High PRF is used to detect targets flying

towards your aircraft (high aspect), medium PRF is used for targets with low closure rate or you are behind. In the default operation mode, the radar cycles between

high and medium PRF to provide all target aspect detection. "

 

This brings a question... when do I use Med PRF VS Auto PRF?

 

The answer is in the paragraph itself that you quoted from the manual. Read it again. You seem to be looking for ready-to-use answers. Not trying to sound like Yoda, but its better in the long run to understand the principles. You will then know by default when to apply them.

[Ironhand]

...

From manual

"

Changing the PRF is used to increase the radar’s sensitivity when detecting targets flying at different aspect angles. High PRF is used to detect targets flying

towards your aircraft (high aspect), medium PRF is used for targets with low closure rate or you are behind. In the default operation mode, the radar cycles between

high and medium PRF to provide all target aspect detection. "

 

This brings a question... when do I use Med PRF VS Auto PRF?

 

...

You certainly are fascinated with PRFs. :) Keep in mind that, while setting a specific PRF is helpful when you already know the aspect angle of what you want to track, it's less helpful in a complex changing environment. For the most part it's best to simply use the interleaved mode so that you don't end up missing something important by being in the wrong mode at the wrong time. As someone has already said, learn how to use you radar to search the sky ahead of you effectively first (by slewing, etc). Be concerned with altering the PRFs much, much later. What you gain with specific PRFs often isn't all that beneficial in practice.

 

Rich

[Alfa]

thank you guys for all the responses. Jack....I think that changing azimuth coverage in Russian planes, turns the antenna to the left, center, and to the right. Does

the antenna physically turn left or right?

From the Flaming Cliffs 3 Manual

"

The scan pattern can be slewed discretely through three azimuth positions, center – right – left. "

"

Orient the radar azimuth scan zone in the direction of the target. On Russian fighters, the azimuth scan zone moves discretely and has three positions: central ±30

degrees, left –60 - 0 degrees and right 0 - +60 degrees. If the target is out of the central ±30 degrees zone, then it is required to move the scan zone to the left

or right with the [RShift-,] or [RShift-/] keys.

 

I am still confused about what this means. Does the antenna physically turn, or it changes the scan pattern (so when you turn the radar left or right, is scans more

space, but it takes longer to scan that space)

 

The Russian radars in the game(N019 and N001) do not have the ability to scan through the entire azimuth range in one go, but need to "slice" it up into smaller sectors, so you need to pre-select the sector within which you expect to find your target.

 

The antenna physically turns into the direction of the selected sector and then moves forth and back within the limits of the sector as it scans it.

 

 

From the manual again

 

"

To search for both high and low targets aspect, use the AUTO sub-mode. Using AUTO however incurs about a 25% reduction in detection range compared to the HI (PPS) and

MED (ZPS) sub-modes. "

 

High aspect - does it mean that the bandit is above me and low aspect - the bandit is below me?

 

From the manual

 

"

 

High PRF (HPRF), which provides the longest detection range against approaching forward-hemisphere targets, is indicated by ППС (HI), whereas medium PRF (MPRF) for

receding rear-hemisphere targets is indicated by ЗПС (MED). In АВТ (ILV) mode, high and medium PRFs are interleaved on alternate bars of the radar scan pattern. This

provides all-aspect target detection at the expense of a 25% reduction in maximum range. "

 

Does this mean that ABT mode's limitation is only for the range reduction? (not how quickly it can detect the bandit)

What does "rear-hemisphere target" mean? The bandit is behind me? I can't see him on the radar , if he is behind me.

 

From manual

"

Changing the PRF is used to increase the radar’s sensitivity when detecting targets flying at different aspect angles. High PRF is used to detect targets flying

towards your aircraft (high aspect), medium PRF is used for targets with low closure rate or you are behind. In the default operation mode, the radar cycles between

high and medium PRF to provide all target aspect detection. "

 

 

"Encounter"(high PRF) search mode is used only to detect head-on targets at maximum range, but is prone to loosing contacts if they change aspect - and in fact cannot detect a receeding target.

 

"Pursuit"(medium PRF) search mode is, as the name suggests, mainly for receeding targets - it can also detect head-on ones, but only at short range.

 

"Automatic"(interleaved high/medium PRF) is the "default" seach mode as it provides good detection range against head-on contacts, while being able to detect targets at all aspects.

 

This brings a question... when do I use Med PRF VS Auto PRF?

 

Again "Automatic" is the "multi-purpose" scan mode that works in most conditions and as such should be the "default option". Med PRF("Pursuit") is very short ranged, so you would use it at close range and if you are chasing a receeding target.

[deckard]

Thank you , thank , thank you everyone! Yes, I have a fascination with PRFs lol.

Someone (I am going to leave the person's name out since I do not know if that person minds to be mentioned) in on-line multiplayer. That guys is really good, flying MIG29S

 

He said that I should use High PRF when the bandit is low to spot him or burn through his ECM quicker. Keep on Auto, if I see the bandit already. Switch to Med within 25KM and the target is maneuvering.

During my own testing in mission editor, a SU27 will burn through F15C ECM at 42 KM, regardless of PRF.

 

My (again) lol question is.

Auto VS Med PRF. I lost the bandit and he is close (within 5-25KM). Will Auto pick him up better than MED? The bandit is also maneuvering.

During on-line engagements, I use mostly Hi, I lock him and then he disappears. I start looking for him and change PRF to Auto , MED and back to High and at the same time (keep my range setting at 25) change elevation up and down while waiting 2 seconds before I change something else (also, I change the azimuth left, center and right ). I only fly Russian planes.

 

I would switch to IRST to see if "he" shows up. I do to vertical scan (when I am desperate and he has a lock on me and he "should me there, but I don't see him" . once in vertical scan I hold the "lock" button instead of tapping it.

 

Also, I noticed that once I am in vertical scan mode (button 3), if I press "I" and turn on my radar, my scan range (lock) drastically decreases. Again, this is from my testing off- line. When I use IRST , I press (2) and try to find the bandit. I use it more than the vertical scan. (this applies to bandit being very close and I am panicking).

 

Now, close engagements - does Auto PRF takes longer to detect a target VS High PRF and Med? Do I sacrifice the acquisition time or just loose 25% of range? I have been told by the same person on-line to "leave my range at 25KM with the CTRL + key". Once I am close to the bandit, should I decrease the expected range to 10KM? I know that range works with conjunction with elevation setting.

 

Can someone walk me (Russian planes) through their search patters for bandits? I mean, give examples of their personal experience with working with the radar.

 

I know I am driving everyone nuts with the questions LOL and I did not even get into BVR yet :)

 

Thank you everyone for all the responses.

I noticed that the best Russian plane fighters (highest kills) is by MIG29S. F15C dominates the sky. Only a couple of people fly MIG29S good enough to put up a fight. I rarely see a SU 27 on top of the chart, it is mostly F15C.

 

You might ask , why am I flying the Russian planes though. I was born in Tbilisi and I know a lot of the places on the map in game and moved to US in 1993. You can call me Russian-American. I like to be the underdog as well and an iconoclast (not like everyone else). I tried the F15C for a short while. Very fast , can outrun anyone, but I cant maneuver in it and that sound "overG" drives me nuts. I like the sounds in Russian planes better. Mig29S is a very sexy plane :)

[deckard]

I forgot to mention. TWS mode. I rarely use it. I know some people like TWS 2 mode on MIG29S (to lock up 2 targets). I think it is too advanced for me at this point. I use SCAN mode, lock the target , then unlock it and fly in it's direction, unless he disappears, that's one of the reasons of my PRF questions. I like technical stuff. I never take ECM in Su27, and in MIG29S. I was told that once I notch , I need to turn off the ECM or when the bandit launched the missile.

I only turn on ECM when I know that "he sees" me. I never broadcast with ECM from far away.

 

As a matter of fact, I began to fly with my radar off and look at my Beryoza on the bottom right of the screen to see if anyone is nearby and turn on my radar when they are less than half the circle away Half the circle is 100 km.

 

Please share your methods of scanning for targets. Thank you!

[FLANKERATOR]

I like to scan in relation to my own altitude - Take your altitude at any time, convert it to KM (Kilometer) and scan as much as this downwards, then scan as much as what's left out of 9 or 10 upwards.

 

For instance at 5km high, I'll go -5/+5 in elevation (Russian fighters). At 7km high, I'll cover -7/+3. Below 1km, I'll usually go from 0 to +8 or +9. Obviously, you want to slew left, center and right before you move to the next one and stay at least half a second at each increment to allow the radar to refresh. I call this pyramidal scanning pattern and it saved my virtual butt countless times. Of course if you have wingmen who you can trust, then you can divide the air space into sections for each one of you for faster scanning.

Edited August 29, 2014 by FLANKERATOR

[deckard]

Thank you so much for your response Flankentrator and everyone else :)

[SFJackBauer]

I know I am driving everyone nuts with the questions LOL and I did not even get into BVR yet :)

 

Perhaps you meant BFM?

 

You are going through that huge initial lump of information that seems to overwhelms you completely. It's like learning how to drive a car, you don't learn it all in one day. You may imitate someone else's movements at the first moment and even get away with it, but its a while before you actually understand what you are doing, and then begin to take advantage of it.

 

After my best flying, it seems during the combat portion of it that time slows down and you know exactly what to do and the consequences of everything. But in my bad days, it seems like I am going with the motions, and even though sometimes I survive and even get kills, I know I did badly and survived by sheer luck. So to get better I think sometimes you have to slow down and roll a movie in your mind of what you are going to do (a bit like the Formula One pilots, before going for a hotlap, they sit in the car, close the eyes and imagine all the lap, braking points, turns and visual references).

 

You might ask , why am I flying the Russian planes though. I was born in Tbilisi and I know a lot of the places on the map in game and moved to US in 1993. You can call me Russian-American. I like to be the underdog as well and an iconoclast (not like everyone else). I tried the F15C for a short while. Very fast , can outrun anyone, but I cant maneuver in it and that sound "overG" drives me nuts. I like the sounds in Russian planes better. Mig29S is a very sexy plane :)

 

That's interesting, a friend of mine is born in Ukraine but moved here to Brazil early on age. He was mentioning the cities on the Black Sea coast he used to visit as a kid, and as I listed all the cities from memory by flying in DCS, he said "how the hell you know all that?" When I told him "I know it by flying over there" he didn't believed :)