Asdic "only" - Page 2

Mister_M · 02-10-21, 04:23 AM

Quote:

Originally Posted by Fifi

So in Sim.Cfg, giving a higher value for sonar sensitivity will decrease the detection time...and giving a lower value will increase the detection time?

Or is it the inverse?

A bit lost this time

Need other coffee cup!

There is also a sensitivity factor for each device in AI_Sensors.dat (in the Library)... And if this parameter = 1, the device doesn't work anymore, even if the definition given in S3D is : "Sensitivity = At (Sensitivity * MaxRange) distance, we have a double detection time", which doesn't make sense in case of =1 (in this case, according to S3D's definition, the device still should be able to work, and with the same detection time, whatever the distance is (between 0 and max range)...).

Moreover, S3D says : "If 0, then the value from sim.cfg is taken". So if Sensitivity is not =0, then the sensitivity factor of Sim.cfg would just not be taken into account ?...

Mister_M · 02-10-21, 04:55 AM

Quote:

Originally Posted by Randomizer

Here Arctic Convoy Instructions there is a throw away entry regarding horrible acoustic conditions in the Arctic using ASDIC and the context suggests active rather than passive detection means.

Quoting :

"Article 9014

Asdic Conditions

Owing to temperature layers, asdic conditions in these northern waters have often found to be very bad, and experienced escort groups which have had success in the Atlantic have frequently reported this fact when escorting North Russian convoys. Cases have often occurred of a U-Boat torpedoing a ship and completely escaping detection both before and after the attack.

Experience has also shown that echoes can often be obtained from surface craft while a submerged u-Boat remains undetected."

John Pancoast · 02-10-21, 06:35 AM

Quote:

Originally Posted by Randomizer

Looking at some of the primary sources I suspect that active and passive searches were the norm.

Here US Fleet Anti-Submarine Instructions differentiates between search patterns and active-sonar search patterns (Echo Searches) so presumably passive listening with hydrophones were an option if conditions were suitable.

Buried in this tome is warnings about interference between escorts depending on the frequency of the active sonar (ASDIC) but not too much specific data. I suspect that these issues would have been addressed at the Operator/ASW Officer level and so not part of the Big Picture covered by this document. I had not considered this but it makes sense that coordination and control would be required to keep escorts from jamming each other.

Here Arctic Convoy Instructions there is a throw away entry regarding horrible acoustic conditions in the Arctic using ASDIC and the context suggests active rather than passive detection means. I think that it was Milner, in his book about U-Boats Against Canada, commented on the inability of ASDIC to find U-Boats in the Gulf of St Lawrence for a variety of reasons including fresh-water eddies bottom conditions and irregular thermal zones.

Food for thought though as these days active sensors can bring all sorts of nasty countermeasures but in WW2 it seems that the rules were "Ping all you want".

-C

Yes everything I've found states that asdic was constantly banging away 24/7 with fixed search patterns. I.e., x degrees arc port/starboard of the bowline with x degrees between each movement of the device.

John Pancoast · 02-10-21, 06:38 AM

Quote:

Originally Posted by Fifi

So in Sim.Cfg, giving a higher value for sonar sensitivity will decrease the detection time...and giving a lower value will increase the detection time?

Or is it the inverse?

A bit lost this time

Need other coffee cup!

Two different items Fifi; raising the sensitivity level makes the sensor more sensitive to input, lowering the detection time makes it need less (time) of an input before the sensor says "Hey dummy, I've got something here".

John Pancoast · 02-10-21, 06:44 AM

Quote:

Originally Posted by Mister_M

There is also a sensitivity factor for each device in AI_Sensors.dat (in the Library)... And if this parameter = 1, the device doesn't work anymore, even if the definition given in S3D is : "Sensitivity = At (Sensitivity * MaxRange) distance, we have a double detection time", which doesn't make sense in case of =1 (in this case, according to S3D's definition, the device still should be able to work, and with the same detection time, whatever the distance is (between 0 and max range)...).

Moreover, S3D says : "If 0, then the value from sim.cfg is taken". So if Sensitivity is not =0, then the sensitivity factor of Sim.cfg would just not be taken into account ?...

That's part of the problem with the SH3 ai imo. There are numerous such examples of duplication of effects, overlap, etc.
Such a structure is a recipe for problems. Sometimes the KISS principle is the best way to go.