SUBSIM Radio Room Forums - broadband sonar behaviour with lwami

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- Dangerous Waters (https://www.subsim.com/radioroom/forumdisplay.php?f=181)

- - broadband sonar behaviour with lwami (https://www.subsim.com/radioroom/showthread.php?t=221439)

broadband sonar behaviour with lwami

just got a prob/question:

1. the scenario
- created a custom mission to test it
- seawolf vs type 212 (very very silent sub) at 3kn
- my course 270° vs 90° - shipping towards with ~5nm distance between us at the nearest point (see picture - truth on, 10nm circle around the seawolf)
http://i.imgur.com/R24sOo9.png

2. my problem
- at (more or less) exact 10nm between us the contact appears on the mid/long-term waterfall BUT not on the short-term waterfall
http://i.imgur.com/ybKpfXC.png
but the towed also shows nothing
http://i.imgur.com/rRfrI6k.png
until (more or less) exact 5nm between us, then the contact on mid/long-term get bigger and a thin (maybe 1px) line also appears on the short-term

same on the 688i
http://i.imgur.com/UeHPssL.png

without lwami i haven't this problem at the 10nm-mark. there, the type 212 is invisible at all waterfall-screens, until i reach the 5nm-mark. then it appears on every waterfall-screens.

3. my strongly worded question
why? :D

With LwAmi BB is much more sensitive than vanila. Normally NB is the first source of detection (in DW and real world)
Additional this mod removes 10nm detection limit.

The spherical/cylindrical array is also made more sensitive (yay! it's my favorite). The intermediate time interval should definitely see the contact before the short time interval. The main reason for the intermediate interval is that the sonar computer can more readily identify a trend in the sound data in the intermediate interval than the short interval to show a track (or something to that effect). In stock vanilla, this behavior should be very apparent.

Yes, the stock game also has that 10nm cutoff, which explains why you would see both show up at the same time apparently out of nowhere.

so the intermediate/long interval isn't just the short interval shrinked on a longer timescale but rather a own and more detailed plot cause of more information gathered over more time.
ok, this behaviour seems very comprehensible.

Quote:

Originally Posted by apx (Post 2335485)

Yes, here's the language from the manual.

Quote:

Originally Posted by Dangerous Waters Manual, p 12-14

Both the upper and lower waterfall displays show broadband sonar data. It is a good idea to have one display set on Short Time Average (1–60 seconds) and the other on Intermediate (0–30 minutes) or Long Time Averaging (0–2 hours). The longer the time averaging that is employed the better the sonar detection processing. However, the longer the time averaging, the longer the time between updates. Both the spherical sensor and the towed array pick up broadband data. The information displayed depends on which sensor is selected.

In my experience, the long time interval isn't too useful. It doesn't seem to have any better time averaging than the intermediate time interval, and I think the fact that it's over a two hour scale is not a fine enough scale to be of use in a rapidly changing situation.