TA-29 vs Sphere sensitivity ...

[Hangman]

I have a question regarding the TB-29 TA and the Sphere array with their sensitivity, using LwAmi 3.10.
I was running one of the training missions where you can practice ASW against several subs, running an SSN21, Conneticut.
When I first started, the TA was already deployed, so I went to the Narrow Band and set the frequency to 150 and started a search for low frequency noise.
I picked up a very faint low frequency noise and was just about to start trying to figure out which side it was on, when I found in the intermediate history waterfall of the Wide Band, the high frequency noise from the Sphere array. Not very strong as it was not present in the Short time or present waterfall.
This of course gives me the answer, the SSN I was hunting was to the starboard.

I've tried this at least three times, and two of those times I was able to get a reading from the Sphere array immediately in the intermediate history waterfall on the Broad Band display.

Is this suppose to be this way ? I was to the understanding the high frequency noise doesn't travel as far as low frequency noise. If my understanding is correct, I shouldn't be picking up any trace in the Sphere array at all - not even in the history - until I am closer to the target.

Now, of the three times I have tried it, the two times I picked up high frequency noise immediately was when I was going after 688's.
The one time I didn't get high frequency noise immediately was when I was chasing a Project 877KM (RU).
Do the 688's (and I am assuming the SeaWolf) emit a very strong high frequency noise ?

I am wondering if I have a fluke or if this should be brought up to the LwAmi modders for possible fix in LwAmi 3.11 ?.

Also, I have noticed that these contacts are less than 10 nm. Shouldn't I be hearing the low frequency noise at around 15 to 20 nm and the high frequency at around 7 - 10 nm ?

Thank you in advance for your thoughts and suggestions.

[Molon Labe]

Originally Posted by Hangman

I have a question regarding the TB-29 TA and the Sphere array with their sensitivity, using LwAmi 3.10.
I was running one of the training missions where you can practice ASW against several subs, running an SSN21, Conneticut.
When I first started, the TA was already deployed, so I went to the Narrow Band and set the frequency to 150 and started a search for low frequency noise.
I picked up a very faint low frequency noise and was just about to start trying to figure out which side it was on, when I found in the intermediate history waterfall of the Wide Band, the high frequency noise from the Sphere array. Not very strong as it was not present in the Short time or present waterfall.
This of course gives me the answer, the SSN I was hunting was to the starboard.

I've tried this at least three times, and two of those times I was able to get a reading from the Sphere array immediately in the intermediate history waterfall on the Broad Band display.

Is this suppose to be this way ? I was to the understanding the high frequency noise doesn't travel as far as low frequency noise. If my understanding is correct, I shouldn't be picking up any trace in the Sphere array at all - not even in the history - until I am closer to the target.

Now, of the three times I have tried it, the two times I picked up high frequency noise immediately was when I was going after 688's.
The one time I didn't get high frequency noise immediately was when I was chasing a Project 877KM (RU).
Do the 688's (and I am assuming the SeaWolf) emit a very strong high frequency noise ?

I am wondering if I have a fluke or if this should be brought up to the LwAmi modders for possible fix in LwAmi 3.11 ?.

Also, I have noticed that these contacts are less than 10 nm. Shouldn't I be hearing the low frequency noise at around 15 to 20 nm and the high frequency at around 7 - 10 nm ?

Thank you in advance for your thoughts and suggestions.

If you're saying that you're getting nearly equal detection ranges for BB sphere and NB TA, then I think the most likely cause would be display settings that aren't bright enough to allow you to see the NB contact from further out. The TACMAN has a bitmap that helps you test gamma levels for the 688I, but the SW display is even harder to see so trial and error might still be necessary.

I'd be happy to try to reproduce this if you'll say what the acoustic conditions and target speed are.

The 688I doesn't produce more BB or high-freq noise than the Kilo (Improved), at least not proportionally compared to PSL (it's actually the other way around---very, very slightly). The 688I is just louder.