Hydrophone Distance Estimation

[ChrisPhoenix]

Thank you Fanders! That was exactly what i was looking for. I Can't wait to test that out.

[Fanders]

Relevant question!

My settings of the high and low pass filters was at the deaufult level:

High Pass - o khz (clockwise maximum)
Low Pass - 22 khz (counter clockwise maximum)

[stellaferox]

Originally Posted by Fanders

Hi everyone!

I just did some data collection with the hydrophone in tutorial mode (where you can se the other ships distance and bearing on the map).
I focused the hydrophone in the exact vector to the target, then I turned the gain knob to the point that the sound turned into distorsion. At that point I collected the distance of the target from the map.

I plotted the data in google sheets and found out that the relationship between the gain and the distance is linear.
Thats quite strange btw, because the sound preassure should decrease with the square of the distance.

One more thing that was a bit strange is that gain level of 2 seems to be the limit. There was no point lowering the gain below 2 -no matter how close i got to the target.

Anyway,

from the data colleced i managed to make a trendline/regression curve of the plot. In my website below you can download the pdf of the diagram i did and use if you want!

Of course this could be done with more precision, but i think its a good diagram to use for rough estimations!



www.gnomon.se

Hi Fanders,

Would you mind sharing the mathematical equation resulting in that line? From the graph I get something like Y = 5555.55 * X - 10833.33 (meter) right? Or in hm Y = 55.55 * X - 108.33

[Fanders]

Of course!

The linear equation for the trendline is:

y=5273x-9656

[Kermit the Frog]

Ok Here's what i have:

Tutorial,
we'll start out with a basic setup. High/low pass rotated to the right, gain at about 1-2.

We hear a contacts, but they're very "wide", it's almost impossible to give a precise bearing.

1. slowly raise "gain" level. At some point your contact rapidly becomes louder. Stop immediately.

2.
hight pass - will help us to isolate engine/screw sound
low pass - will help to isolate asdic source.

(i am not sure if it shall work like that but it's how it works right now).

3.
Rotate "High pass" a littlebit to the left - 2 points will do.

4. now check your contact how it "behaves" if you're rotating from side to side it shall sound like this "thumbthumbthumbthumb - HRKSZRKSZ - thumbthumbthumbthumb" you shall have an area where your contact sounds like very loud, broken radio.

5. Turn "high pass" more to the left and adjust "gain" accordingly: if you can't hear "broken radio" type of noise right in the middle, add some more "Gain" lvel and scan again. if "broken radio" is to wide - lower "gain" level.

6. Now you narrowed you contact to 2-3 deg. Bravo! You have precise bearing. ( in tutorial i reached precise bearing for "High pass " set about 12-14)

7. if your contact suddenly stops making "broken radio" type of noises it means that he's moving away, and you have just discovered it. Report to the commander! contact, bearing XX, moving Away. A "Gain" level will give you quite good info about how far is your contact, and if he's moving away, or getting closer.

Good luck!

[VonHoffman]

A method I use to center a contact is to look for where the "ends" of the sound are (where it fades out completely and I can no longer hear it). The contact is in the center.

When dealing with a convoy at distance, I use this method to discover which way the convoy is moving before I move to intercept. I head for the quiet end of the sound in the forward direction of the convoy, as it will take me some time to get there, putting me ahead of the convoy where I can wait...

The "width" of the sound tells me if they are getting closer or moving away. The wider the spread, the closer the convoy/ship.

I like the idea of using the training mode for learning the ranging with the hydrophone! I will give this a try later!

[Captain Adonis]

so I watched a youtube video and the guy said take your gain level, and that is a guess, times 5 minus 8.5 and that is your range. Example gain is 2.2
2.2*5-8.5=2.5 then times 1000 for a range of 2500 meters
I have not tested this fully

[Pisces]

There will be changes how the hydrophone station and it's gain works in the newer versions (not yet released) So I would not count too much on learning that rule of thumb.

Besides, that range doesn't tell you much. You know where it is, so just head there until you see something of it. The convoy is large enough so you won't miss it. Then consider how best to maneuvre to get visual data. Turn away to not get closer initially 'as you get your bearings' on what to do. You want to focus on speed and angle on bow (or something giving their course away). Range doesn't help you much when the torpedoes will leave your tubes and head straight away. It only helps in telling you when the impact is likely to occur. That is, if speed and AOB was correct to begin with. Otherwise it is a likely miss. Range is just a minor input to a correction for when the torpedo makes a turn towards the target.It is also a value for the torpedo salvo spread calculation if you decide to use that.

[Kralizec]

When you are on the right bearing, the sound disappears at exactly 5000m for each gain step. Gain 1: 5000m, Gain 2: 10000m and so on.

I use this to measure the distance. In most cases it works better than trying to use overdrive when ranging the closest ship.

From this gain setting, you can turn it up 1.5-1.7 gain steps before the sound starts clipping. This is more subjective so less accurate. Onset of clipping is different depending on the type of ship so you won't get the best result, but on the other hand, you can get an accurate bearing at the same time.

So a ship at 5000m distance:
- sound will disappear at 1 gain
- sound will go into overdrive at around 2.5 - 2.7 gain

You can turn it around:
- the sound disappeared at 0.4 gain
- distorts at 1.9 - 2.1
Distance is 2000m

[Kralizec]

Originally Posted by Aktungbby

kamini982

Do you think it would be possible to reduce the number these types of comments? It takes up so much space and contributes nothing, while reducing the signal to noise ratio of every single thread on subsim

[Aktungbby]

Originally Posted by kamini982

yes sir you are right.......

No doubt thru trial and error

The Discord Channel is a little messy in terms of finding information in my opinion. I rejoined it, read thourgh some stuff but hard to find anything. There is just too much going on.

[Aktungbby]

Originally Posted by karamaujlay

The Discord Channel is a little messy in terms of finding information in my opinion. I rejoined it, read thourgh some stuff but hard to find anything. There is just too much going on.

karamaujlay!