[WAD] Radar, A/B bands, different range?

[ClaudeJ]

Once upon a time, there were two brother radars.
Both ended up in a band. One went for a career at sea, operating in band B, the other stayed on land, operating in band A.
At a family reunion, they had a chat about their respective experience and were quite surprised that they were able to spot the same bird at different ranges.

Family album

• Brother B, the seaman, aka 052DL.

  

  052DL.png (18.45 KiB) Viewed 533 times

• Brother A, the earthman, aka JY27A.

  

  JY27A.png (18.66 KiB) Viewed 533 times

• The bird, aka F-35B.
  

On average, based on 20 occurrences, Brother B spotted the bird at 80 nm.
On average, based on 20 occurrences, Brother A spotted the bird at 138 nm.

Having examined both, the only difference I could notice is their RangeMax and their band.


(to reproduce their experience, load the scenario, and let it run. Detection happens after circa 24 or 16 minutes, respectively.)


Now, my question:
- is it supposed to happen this way? (Does the same signature displayed identically for bands A to D should produce different detection ranges?)
- if it is that so, what about having a more granular signature displayed in the DBViewer? So playusers can deduce a better threat assessment based on their information.

Caveat: I wasn't able to find radars identical but on their band. These two are the closest I can find in the current DB3K, 504.

[thewood1]

Wouldn't the radar's power impact detection capabilities? I would think that would give you your difference in detection for very similar systems. I would also think range would be an analog for power for a player to compare initial detection ranges.

[ClaudeJ]

That was my thought too, thewood.

However, they both have the same value of 65000.0 for the RadarPeakPower parameter.

[thewood1]

I'm just not sure peak power is the only power parameter that impacts range.

[blu3s]

As a general rule, same radar, with the same emitted power and the same receiver antenna, the one with the longer shortwave will be able to detect an object at a greater distance since its attenuation is lower in the atmosphere.

P.D: Peak Power is not the only one that affects detection in Command.

[rmeckman]

As a general rule, same radar, with the same emitted power and the same receiver antenna, the one with the longer shortwave will be able to detect an object at a greater distance since its attenuation is lower in the atmosphere.

P.D: Peak Power is not the only one that affects detection in Command.

I don't think atmospheric attenuation is the main factor. Even basic forms of the radar range equation that ignore atmospheric attenuation still show the maximum detection range being proportional to the square-root of the wavelength. All other parameters being equal, an A-band radar with wavelengths > 1.2 m should have a greater range than a B-band radar with wavelengths between 0.6 and 1.2 m.

[blu3s]

Yes, you're absolutely right.

[ClaudeJ]

Thanks guys! That is good to know.

What would be the best way to convey that information to the playuser in layman's terms?

[rmeckman]

Thanks guys! That is good to know.

What would be the best way to convey that information to the playuser in layman's terms?

There are many other things affecting radar performance that cannot be seen directly from the CMO database viewer, such as maximum transmitted power, antenna configuration, system noise, etc. The land-based JY-27A appears to have a large vertical antenna that looks quite different from the mattress antenna seen midship on the 052DL destroyers. The CMO database does have a comment that the 052DL radar may be related to the JY-27A, maybe that is just a guess.

The two key pieces of information you get while playing CMO is the radar cross section σ of the target and the maximum range R_mdb of the radar as specified in the database. Based on these two values, it is possible to develop a simplistic range model as shown below. R_max is the maximum detection range for a target with cross section σ. σ_e is a scaling parameter that folds the radar properties (maximum power, antenna configuration, frequency band, etc) into a single value. It is a fixed value for each radar model. This simple model assumes larger targets with σ > σ_e are first detected at the maximum range shown in the database.

In your case, R_mdb is 310 nm for the JY-27A and 216 nm for the 052DL. If we assume the F-35 is detected from the front, this would indicate that σ_e = 0.19 m2 for the JY-27A and 0.39 m2 for the 052DL. So the answer to your original question is that even though the F-35 radar cross section is the same for both radars, their maximum ranges and design features (represented by σ_e) result in different detection ranges. I can't really say whether the commercial CMO follows something along the lines of this simple model before accounting for radar horizon and terrain masking.

[BDukes]

Thanks guys! That is good to know.

What would be the best way to convey that information to the playuser in layman's terms?

There are many other things affecting radar performance that cannot be seen directly from the CMO database viewer, such as maximum transmitted power, antenna configuration, system noise, etc. The land-based JY-27A appears to have a large vertical antenna that looks quite different from the mattress antenna seen midship on the 052DL destroyers. The CMO database does have a comment that the 052DL radar may be related to the JY-27A, maybe that is just a guess.

JY-27A is the tall one. JY-27 is the wide one. This caused a bunch of confusion when the "A" variant emerged.

Take a look:

https://www.radartutorial.eu/19.kartei/ ... 27.en.html

Nobody has exact stats (yet) on the shipborne model, so I wouldn't spend too much time on this. Its terms of why the ship and land models don't match, they are two different entries. It happens, and given the unknowns, I don't care as long as things are sensible.

Thanks

M

[ClaudeJ]

Hey there,

thanks for your comments, R and M.
Still getting my head around that one, but you guys made it clearer.