[TEC] How much was radar affected by bad weather?

[LukeFF]

I see this line in Sensors.cfg and it has me curious:

Radar fog factor=0
By upping that number we can simulate the unreliability of early radar systems in bad weather, but how high would be a realistic value? In addition, would tweaking this value affect only the player's sub, or would it affect AI units as well?

[Bulleye]

Frankly, I think radar isnt simulated at all in SH-4, or any naval sim for that matter.
Not even in games like 688i.
(I used to be a fisherman, and I always loved working with radar.)

There is so much more to radar then just a simple 'sweep' and a 'bleep'.

Al we get is a blank screen, apart from the radar sweep and the contact-blips.

But to answer your question, sea-clutter. That and the pitching and rolling of the ship. though of the two, sea clutter has the biggest impact. In real life you can decrease the gain to reduce the clutter, but less gain means less signal return, with the risk of small contacts not showing up on screen.

Now mind you, if you operate a radar at sea, you will ALWAYS have some sea clutter. But, obviously, the heavier the sea the more clutter you get. It's alway a trade of between gain and clutter.

Rain you dont have to worry about, a dont think they used a radar with a small enough wave length to pick up radar, or at least to pick up so much rain for it to become a problem.

But seeing as none of this is actually simulated in silent hunter I doubt anyone can mod the radar enough to get some weather effects.

P.s., can anyone do anything about the size of the contacts?
Right now even a small tramp freighter will show with an echo the size of a small island.

[donut]

See this thread http://www.subsim.com/radioroom/showpost.php?p=558172&postcount=206 (http://www.subsim.com/radioroom/showpost.php?p=558172&postcount=206) My latest WIP - noise effecthttp://www.subsim.com/radioroom/smartdark/post_old.gif 06-05-2007, 08:08 PM Mraah (http://www.subsim.com/radioroom/member.php?u=231002) ,Some nice masks w/range rings:up:

[LukeFF]

Bulleye, you're right. The way radar is modeled right now depicts doppler radar, which only picks up moving objects; pulse radar, which gives a return on both stationary and moving objects, was the standard during the war.

Now, the reason I ask about fog affecting radar is this page I found at hnsa.org (http://www.hnsa.org/doc/radar/part1.htm#pg47):


FACTORS AFFECTING RADAR RANGE
Maximum range factors. In order to give you some reason for the variation in range performance of radar sets, we shall list the factors affecting the maximum range of any radar:
1. Wave length.
a. Long wave length radar is best suited for air search.
b. Micro wave length radar is best suited for surface search.
2. Size of target.
3. Height of target.
a. Height of mast for surface target.
b. Height of plane for air target.
4. Target presentation (target angle).
5. Material of target.
6. Height of antenna.
7. Output power radar.
8. Sensitivity of receiver.
9. Atmospheric condition.
10. Type of indicator ("A" scope most sensitive).
11. Pulse repetition rate (determines maximum range scale that can be used).
12. Beam concentration.
13. Condition of radar equipment.
14. Operator's technique and skill.

Of interest is item 9. Is fog considered an "atmospheric condition" that can affect the range and reliability of pulse radar?

Here is another comment from that manual:

Remember that for all practical purposes radar is not affected by visual limitations. It can detect equally well through darkness and smoke, and almost as well through fog. (empahsis added)

I think I'm going to try a value of 0.2 and see how that affects things.

[tater]

Is fog in game tied to weather?

Meaning does it only appear in high wind states or otherwise stormy conditions?

tater

[LukeFF]

I think it only shows up in stormy conditions. Shame, because it'd be neat to try to navigate and detect ships in calm, yet foggy seas.

[tater]

If it's only storms then the "fog" value would also be simulating choppy seas, , pitching rolling decks (to which the radars are attached), etc.

Wasn't that a factor in RL?

tater

[LukeFF]

For those that are interested, I'm going to test out these settings in Sensors.cfg. My current patrol has only SD radar, so it's a bit hard to test:

Radar range factor=1
Radar fog factor=0.2
Radar light factor=0
Radar waves factor=0
Radar speed factor=0
Radar aspect=1
Radar enemy speed=0
Radar noise factor=0
Radar sensor height factor=0.5
Radar already tracking modifier=10
Radar decay time=150
Radar uses crew efficiency=true

Key changes here are to the fog, sensor height, and crew efficiency. I thought it was pretty silly these were all nulled out by default, since they are all factors listed above that affect radar performance. What's the point in having an Electricity/Sensors-qualified sailor if his efficiency doesn't affect the performance of radar?

[tater]

I'd be curious about waves, too. Seems like the altitude (as in altitude/azimuth) would be somewhat critical to using a radar, paritularly on an unstable, low platform like a sub.

Need to ask someone who knows. Donut?

tater

[Peto]

Simulating radar is even tougher than sonar (and sonar is Much more complicated than it is represented in SH). Having talked to a couple radar and sonar men from WWII I was presented with the following info:

Radar was great--when it worked. It had a tendancy to break down a lot--especially during an approach. Repairing it was a bear.

Atmospherics played havoc with it, gave false returns often. Contacts were frequently watched for quite a while before they were even reported as actual contacts as they tended to blend in so well with back-ground clutter.

Contacts hugging a coast were easily masked by the land mass behind them, often making radar useless in such circumstances.

Radar depth was 45 feet. This did reduce the effective range though.

As for sonar...

The best sonar conditions were NOT a flat calm sea but rather a 2-3 foot chop. During a flat calm in mid-day with clear skies the sun would heat the upper layer of water creating "the afternoon effect". This was basically a weak layer at about periscope depth.

Tha soundmen I talked with said they never (nor did they know anyone) who had located a submarine using passive sonar. The information gained from passive was from a known target so they could hear hull popping from depth changes and activity from repairs/damage etc. When a sub changed depth they could usually hear it.

The way they knew which way a target was turning was red-shift/blue-shift doppler effect. Hard to explain without sound assistance...

In a nut-shell: All this is (IMHO) is nearly impossible to mod without having direct access to the hard-code and pretty much gutting and recoding what is already there... Not my cup of tea. I just fix computers. The guys who code them are in a whole different mind-set.

Cheers!

Peto

[Sailor Steve]

That's great stuff, Peto!:rock:

As a non-submarine side-note, I would like to add that radar was also the bane of surface ships, especially the much-touted fire-control radar. It also had a tendency to break down...when the guns were fired! Seems the shock would shatter those big glass fuses and unplug connections. Graf Spee reported this happening, Nelson reported it while firing at Bismarck, and U.S. battleships had it happen...a lot.:down:

[Ducimus]

Radar fog factor
Radar waves factor
Radar uses crew efficiency=true


I think these are your best bets for a more realistic radar. Although i wonder if fog really would inhibit radar, wave factor however is directly tied into weather. The more wind, the bigger the waves, the crappier the reception.

[LukeFF]

Radar fog factor
Radar waves factor
Radar uses crew efficiency=true


I think these are your best bets for a more realistic radar. Although i wonder if fog really would inhibit radar, wave factor however is directly tied into weather. The more wind, the bigger the waves, the crappier the reception.
My rationale with the fog is the above statement with says radar works nearly as well in fog, which I deduce to mean fog could have a slight negative effect on radar effectiveness.

What is Noise Factor, btw?

Thanks for the post, Peto!

[sneekyzeke]

I was a "scope dope" in USN 1981 - 1994. My duties on the radar navigation team for leaving/entering port was shipping and later piloting officer. We would practice/simulate low visibility navigation from time to time and were even required to maintain qualifications on a yearly basis. However, being a warm water sailor in Mayport, Florida, I only experienced TRUE low vis (heavy fog) conditions twice, sailing in and out of Newport, RI, and New York, NY. It was considered too risky to attempt during peacetime simply because we didn't want to run over some poor sailboat or fisherman. But this was because VISUAL conditions were hindered, not radar. We had an AN/SPS-55 surface search/navigation radar that was basically the MILSPEC version of the common "pathfinder" radars found on damned near every merchant/commercial vessel in the world. It performed admirably during fog; if the fog was truly dense you could tell by the noise on the PPI but it didn't have much effect on radar returns. What DID have effect besides very heavy seas where contacts would disappear/reappear in "valleys" was high winds. As noted earlier, this would cause a large garbage ring around own ship that could be controlled by carefully adjusting gain but it was very annoying. Hope I didn't put 'yall to sleep; and radar propogation and theory is one of my faves so ask away if you want...Zeke.

Edit: Oh yeah, I know SURFACE sonar/wave path propogation/target motion analysis (TMA) pretty well too. That TMA stuff was classified forever, but I've seen it in games from folks like Sonalyst and it's pretty darned accurate...:up:

[DyingCrow]

i was a navy radar operator for 13 years, and had the chance to work with a couple of 50's surface and air search, to civilian and military, and modern digital radars,and now i have to wear glasses :-?.
range is mostly defined by the antenna height to sea, which will define the distance to the horizon. then comes propagation, a major factor in radar operation, and the details are not always easy to understand when it comes to operate. by experience i can say that, in the perfect awesome exceptional unbelievable conditions, normal radar range can go from double to 5x the normal range. i had superb propagation ducts in fogy weather (?), but usually they occur only in heavenly days.
normally, fog doesnt affect radars in such a way that it really makes a difference, unless its really thick fog (visibility less them 100m or so), when noise can occur. sea clutter is something that is always present unless the sea is flat (up to 2.5nm), also the ships pitch and roll, for there was no such thing as antenna stabilization by then, and in stormy weather this a major factor (if the ship is rolling port and the antenna if facing starboard, the beam will scan the sky instead). in heavy rain conditions, noise will occur, the more the worse. other, is the clouds; stormy or not, if theres low altitude clouds (500m less) they will show up in some ways, sometimes as a sort of "ethereal " blobs, sometimes small sometimes big, easily identified as clouds, sometimes as a series of contacts that might be interpreted as a group of ships.
i dont know about the absence of any kind of filters in the game, basic ones like anti clutter sea and anti clutter rain, the wavelength selector (short and long, which will also affect performance in some meteo conditions, along with range, of course) that some still have, and more.
these are not really necessary for the game experience, as its all about shooting stuff; if radars were well implemented, tho, you could get basic things like course, speed and cpa directly from it, as its (was) supposed to be done by the radar operator, by drawing lines directly on the ppi, also have a first hand notion in important changes in the contacts behaviours, like changes in course and speed out of the search pattern. also, radar contacts in game are not accurately displayed, they are more like "beans", not "blobs", small, not huge as they are displayed, and they leave persistance trails in the ppi.
huh, coffee is also a factor, because if you dont have some, youll fall asleep sooner or later:p

[sneekyzeke]

Yeah, the returns on radar are always called "blips" by the media/TV/public, but in USN they are "pips".

[louist]

Great thread. I have never made it past mid war, but feel somewhat that using the radar is cheating, as it gives such accurate range and bearing information, without any Japanese equivalent. I imagined that such early radars would be far less reliable and nearly useless when the targets were near land, etc. There should be numerous false/spurious images and blobs where there is land . . . . Wish there were some way to model it, I guess I will stop using the scopes personally and wait for the radar operator to make their occasional report.