IRAN UNVEILS UNUSUALLY BLUE COLORED SUBMARINE

[tyrant]

Whenever you make a declaration, especially in the technical realm, it would help the readers, and your credibility, to support your argument, like this...



This is assuming single/fixed point/location transmission.

We know that sound velocity profiles (SVP) are affected by many factors such as salinity, temperature, and pressure...

Sound Transmission in the Ocean - sea, depth, oceans, temperature, salt, system, wave, marine, salinity, Pacific


Sonar Propagation in Statified Waters - March/April 2010, Volume 14, Number 2 - Archive - Hydro International


Some use sound speed (SSP) profile instead of 'velocity'...

Multibeam Systems - Sound Velocity Instruments


Coastal regions, estuaries, and river/sea connections have highly brackish water -- for example -- that can produce salinity stratifications that will produce diverse localized VSP that no standard sonar system can adequately compensate as explained by the above source when it demand that these profiles must be updated even by the hours.

This is why the US regularly conduct overt and covert profiling of the world's coastal regions to gather as much data over time as possible to create -- for each country that have sea access -- a 'meta-profile' of its sonar characteristics. The electronic warfare (EW) analogy is electromagnetic (EM) reconnaissance of a country based upon everything EM, from radars of military and civilian nature to daily television and radio transmissions.

There are also multi-paths propagation, same as radar detection, in shallow waters due to sea floor and those temperature/salinity layers...

Ghosting is a common problem in both radar and sonar detection because of multi-paths propagation.

So deep channel tracking is highly successful because of the constant SVP created by high pressure and fairly uniform salinity but only if a sub is in deep water.

A 'variable depth sonar' is essentially a sonar whose operating depth can be changed on demand to compensate for those layers that can hide a body. Intentionally or not.


No, I will not. There are many parallels between radar detection and sonar detection, especially in the data processing realm where they are practically identical and I do not have civilian experience in either. The military does not have exclusivity in using 'variable depth sonar' systems. There are many natural threats to civilian vessels that are hidden by those underwater characteristics that require the use of these systems to expose those natural threats and enhance marine safety.

What I normally do is bring to the discussions foundational principles that many interested lay readers do not know and ended up making baseless claims. You failed to bring up those foundational principles as how I demonstrated above. Then once a reader did his own research to verify my sources, those baseless claims usually disappeared. The reader is free to make up his own mind on whether the military applications of those foundation principles, as claimed by the military and/or manufacturer of said equipment, are credible or not. It is very difficult for anyone to dispute an operational capability -- as claimed -- once he understood the foundations of said capability. That is the way it should be without me crossing any infosec threshold.


Sonar 'jamming', while technically is real, is practically and tactically dangerous. More so than with radar detection. If you do not know where and how radar and sonar detection are similar and diverge, at the theoretical level, then there is no need to discuss this further.


How is infrared applicable in sonar detection? I could be missing something here. Must be old age and memory loss.

Hi again Gambit,

I am glad you are back.
The links you have provided are nice but I think you just Googled them and you have not deeply realized the basic physics underlying the beam forming techniques.

My main point in the last post was:

'variable depth sonar' is not one entity. It is highly dependent on the beam-forming strategy and dynamic electronic focusing.
http://www.curtistech.co.uk/papers/beamform.pdf

You can not just say 'variable depth sonar' is the answer to shallow water objects. Which type of 'variable depth sonar' strategy?
The strategy for 'variable depth sonar' relies on these parameters that you failed to address:
%%%%%%%%%%%%%
1. Number of arrays? array shape?
2. Kerf, array spacing
3. Sound frequency
4. single pulse, multi-pulse, Doppler, back propagation, combined
5. focusing on transmit (# of focal points)
6. focusing on receive (# of focal points)
%%%%%%%%%%%%

Since you are interested in technical points, I suggest you address these points and then we can run a simulation on the acoustic field together and observe the results of its interaction with the object.
Copy and pasting a link does not prove anything but you can Google.
Conclusions are made upon simulations, experiments, and statistical analysis.

 

[tyrant]

How is infrared applicable in sonar detection? I could be missing something here. Must be old age and memory loss.

Multiple modality tracking (multiple sensor tracking) is a computational technique to register IR, radar/sonar and optic signals to overcome the individual artifacts of each sensor and increase the total accuracy.

 

[tyrant]

Coastal regions, estuaries, and river/sea connections have highly brackish water -- for example -- that can produce salinity stratifications that will produce diverse localized VSP that no standard sonar system can adequately compensate as explained by the above source when it demand that these profiles must be updated even by the hours.

The problem in coastal/shallow waters is not salinity or pressure but the acoustic impedance matching artifact that makes a shadow near the rigid object boundaries.

 

[gambit]

Multiple modality tracking (multiple sensor tracking) is a computational technique to register IR, radar/sonar and optic signals to overcome the individual artifacts of each sensor and increase the total accuracy.

Then infrared have nothing to do with sonar at all. What you are talking about is on data processing side. In radar detection, we have what is called 'multi-static' radar detection where there is either one transmitter with more than one physically distinct receivers, or multiple transmitters with multiple physically distinct receivers. For data processing, each receiver must accept the target data from other receivers in the network and perform appropriate correlation. The 'artifacts' are variables from individual receiver to individual receiver such as noise, Doppler since each receiver would have a different aspect angle from the target, or even EW interference. Currently, multi-static systems should not and usually outside of the laboratory do not employ different transmit frequencies and pulse repetition freq (PRF) between transmitters because the target returns would increase in complexity and correlation time and this would reduce combat response time. The data processing -- not infrared sensor -- is more applicable to sonar.

The problem in coastal/shallow waters is not salinity or pressure but the acoustic impedance matching artifact that makes a shadow near the rigid object boundaries.

Yes it is...We already established that acoustic propagation is affected by salinity, temperature, and even turbidity...

Cookies Required

Current sonar performance models are incapable of accurately predicting the performance of high‐frequency sonars in highly variable turbid coastal waters.

Turbid coastal waters are characterized by relatively high levels of suspended particulate matter, the presence of which leads to increased attenuation through viscous absorption and scattering, leading to a significant reduction in the detection range of high‐frequency active sonars at moderate concentrations.

Seawater Properties

Water gets denser as it gets colder and more saline. For water, the maximum density is attained at 4°C. Below 4°C, the density decreases until water freezes (1% drop in density).

Salt in water lowers the specific heat as well as the freezing and boiling points. As seawater freezes (2°C), salts are expelled from the sea ice to make the surrounding water even denser and saltier. Such water sinks as an entity and may become part of thermohaline circulation in the deeper ocean.

Because temperature and salinity control water density; as temperature varies in the ocean water column, density varies too.

And that shallow water in coastal regions have the highest variations.

Acoustic impedance is essentially the result of fluid density and sound speed, which varies with factors cited above. Impedance mismatch give us reflections, hence, impedance matching give us no reflections. Air, for practical purposes, have zero impedance. Metals have the highest. Sound travels faster as the material or media get progressively denser, such as water or salt water or steel. When different materials meet, such as air and steel, there is an interface and it is here we have the incomplete coupling of the wave's energy from air into steel that give us a reflection.

Ultrasonic Couplants

Ultrasonic couplants are used in virtually all contact testing applications to facilitate the transmission of sound energy between the transducer and the test piece. Couplants will typically be moderately viscous, nontoxic liquids, gels, or pastes. Their use is necessary because sound energy at the ultrasonic frequencies typically used for nondestructive testing is not effectively transmitted through air. Aside from attenuation effects, air represents a severe acoustic impedance mismatch with respect to both transducer wearplates and typical test materials. Even an extremely thin air gap between the transducer and the test piece will prevent efficient sound energy transmission and make conventional testing impossible.

In ultrasound testing, a 'couplant' such as a gel is used to facilitate a more orderly or less abrupt transition of sound waves betweenn transducer to body. The gel provides a superior coupling than air.

Acoustic impedance matching and mismatch are applicable against any material at any depth, not just shallow regions. So am not exactly sure what you mean here unless you are talking about the shadow zones created by side scan sonars.

 

[gambit]

Hi again Gambit,

I am glad you are back.
The links you have provided are nice but I think you just Googled them and you have not deeply realized the basic physics underlying the beam forming techniques.

Beamforming exists in radar detection, from the classical concave dish to planar antenna to electronic scanning (ESA). Prior to my participation here, people here have no understanding on how radar beamforming works, particularly in ESA systems. They were unaware of the beamwidth, resolution cells, or ghosting. All associated with beamforming.

You can not just say 'variable depth sonar' is the answer to shallow water objects.

Sure I can, and I can bring real world examples to support it as well...

Sub collides with sonar array towed by U.S. Navy ship - CNN.com

WASHINGTON (CNN) -- In what a U.S. military official calls an "inadvertent encounter," a Chinese submarine hit an underwater sonar array being towed by the destroyer USS John McCain on Thursday.

The array was damaged, but the sub and the ship did not collide, the official said. A sonar array is a device towed behind a ship that listens and locates underwater sounds.

The incident occurred near Subic Bay off the coast of the Philippines.

USS McCloy (FF 1038)

The USS McCLOY is towing a sonar array when suddenly the cable goes slack. The next day a Soviet Victor III - class nuclear-powered attack submarine is sighted motionless on the surface 282 miles west of Bermuda and 470 miles east of Charleston, SC, by a US P-3 Orion patrol aircraft. US Navy officials believe that while the submarine was following the McCLOY, the sonar array caught in the submarine's propeller. There is no indication of leaking radiation, according to a Navy spokesman. On November 5, the submarine is taken under tow by a Soviet salvage ship in the direction of the Cuban port of Cienfuegos. Further observations while the submarine is under tow leads the Navy to believe the damage is relatively minor and relates to the submarine's propeller.

In each event, we can safely assume that the towed array is not on the same plane as the ship's own sonar array. It was an underwater array. Why was it an underwater array? To bypass certain layers that would affect the ship's sonar. The events occurred off Subic Bay and off the Bermudas, hardly open seas.

This mean the towed arrays were 'variable depth' devices and if the Chinese and Soviet subs collided with them, it mean the towed arrays were passive and the subs also had their sonar passive tracking the ships. What it really mean is that 'variable depth sonar' use by surface combatant ships can be effective against diesel/battery sub in shallow waters or against subs that uses layers to hide.

If the arrays were passive and the ships were tracking the subs, why did the ships' sonarmen not conscious of the risk of collisions since they would be tracking the subs' movements via the subs' own noises? Answer: Of course they were. The closer the sub gets to the array, the greater the information about the sub could be gathered. The towed array is much cheaper compared to the tactical and even strategic consequences that can be imposed upon an adversary.

Which type of 'variable depth sonar' strategy?
The strategy for 'variable depth sonar' relies on these parameters that you failed to address:
%%%%%%%%%%%%%
1. Number of arrays? array shape? (Cylindrical for transmit and planar for receive)
2. Kerf, array spacing (Filler material -- decoupling)
3. Sound frequency (Affect scattering mechanisms)
4. single pulse, multi-pulse, Doppler, back propagation, combined (Doppler for speed changes)
5. focusing on transmit (# of focal points)
6. focusing on receive (# of focal points)
%%%%%%%%%%%%

Since you are interested in technical points, I suggest you address these points and then we can run a simulation on the acoustic field together and observe the results of its interaction with the object.
Copy and pasting a link does not prove anything but you can Google.

I have no interests in getting into a numbers slingfest. Been there and done that and found out it is more about a person stroking his ego via esoteric information than about education. All it does is clutter up the thread with the readers no wiser than what they learned from publicly available information they can find for themselves and which is about the depth most want to know anyway. Further, while radar and sonar detection shares many similarities, there are many divergences and my specialty was in radar and general avionics.

Conclusions are made upon simulations, experiments, and statistical analysis.

If you are that keen on 'proving' to the Iranians that they have supremacy in submarine warfare in their backyard, I have no doubt you can manipulate any and all data points to suit your intent.

 

[tyrant]

Acoustic impedance is essentially the result of fluid density and sound speed, which varies with factors cited above. Impedance mismatch give us reflections, hence, impedance matching give us no reflections. Air, for practical purposes, have zero impedance. Metals have the highest. Sound travels faster as the material or media get progressively denser, such as water or salt water or steel. When different materials meet, such as air and steel, there is an interface and it is here we have the incomplete coupling of the wave's energy from air into steel that give us a reflection.

Ultrasonic Couplants

You have Googled and provided a basic lecture in this part. Good job, thanks.

In ultrasound testing, a 'couplant' such as a gel is used to facilitate a more orderly or less abrupt transition of sound waves betweenn transducer to body. The gel provides a superior coupling than air.

This (Gel) is for other applications such as medical ultrasound and etc and irrelevant to sonar.
By shadow, I mean the shading artifact near rigid objects when an abrupt acoustic impedance shift occurs. A midget sub can safely harbor in that shadow and stay immune of any active sonar. Of course, you may still detect it by IR or optics.

Then infrared have nothing to do with sonar at all. What you are talking about is on data processing side. In radar detection, we have what is called 'multi-static' radar detection where there is either one transmitter with more than one physically distinct receivers, or multiple transmitters with multiple physically distinct receivers. For data processing, each receiver must accept the target data from other receivers in the network and perform appropriate correlation. The 'artifacts' are variables from individual receiver to individual receiver such as noise, Doppler since each receiver would have a different aspect angle from the target, or even EW interference. Currently, multi-static systems should not and usually outside of the laboratory do not employ different transmit frequencies and pulse repetition freq (PRF) between transmitters because the target returns would increase in complexity and correlation time and this would reduce combat response time. The data processing -- not infrared sensor -- is more applicable to sonar.

The most important side of object detection and tracking is signal/image processing. IR/radar/sonar fusion is very important to increase tracking accuracy. The data processing as well as infrared sensor is applicable to sonar. Acquiring IR data is independent of acquiring the pulses. Multiple PRF acquisition is a totally different method that I did not talk about and you brought it up for unknown reasons. As you said, Multiple PRF acquisition increases the processing time since you can not transmit a new pulse until you fully acquire the last pulse. However, there are several methods in the literature to apply the different PRFs at the same time such as 2D Hilbert transform in space/time + Frequency analysis, and Fourier/Wavelet packets analysis.

Yes it is...We already established that acoustic propagation is affected by salinity, temperature, and even turbidity...

Cookies Required


Seawater Properties

And that shallow water in coastal regions have the highest variations.

There is a bulk of literature on temperature variation and sound speed. The amount of temperature induced variation is little.
I have done an experiment myself in 2008 using the following parameters:
%%%%%%%%%%%%%
1. Number of arrays? (320 Christal piezoelectric) array shape? convex 90 deg
2. Kerf, array spacing about 0.3 mm
3. Sound frequency 4 MHz (more than sonar), speed: 1470 (more than salt water)
4. single pulse, multi-pulse, Doppler, back propagation, combined: multi pulse
5. focusing on transmit (# of focal points): 3 by 4 cm spacing
6. focusing on receive (# of focal points): no focus on receive
%%%%%%%%%%%%
The amount of displacement after 50 degrees of heating for 10 cm width of a polymer (Gelatin-Agar) was less than 1 mm.
It is negligible compared to an awful artifact.

 

[T@brizi]

Why so many childish comments? The colour of this submarine is perfect for the waters of Persian gulf. It's such a shame this forum which is suppose to be a defence forum has turned into a troll forum.

 

[TheRafael00000]

Why so many childish comments? The colour of this submarine is perfect for the waters of Persian gulf. It's such a shame this forum which is suppose to be a defence forum has turned into a troll forum.

Get the fact right-some people are jealous. Yahoo made it feature news. Why? They think Iran is something like North Korea and when they talk about Iran, they also bring in North Korea. Good achievements for Iran and Iran should keep on bringing establishment. I hope Iran play a vital role to bring the stalemate to a win in Afghanistan. Saudi Arabia and Iran should reduce their differences and start trading. Or both of them can turn out to be like Iraq.

 

[tyrant]

Beamforming exists in radar detection, from the classical concave dish to planar antenna to electronic scanning (ESA). Prior to my participation here, people here have no understanding on how radar beamforming works, particularly in ESA systems. They were unaware of the beamwidth, resolution cells, or ghosting. All associated with beamforming.


Sure I can, and I can bring real world examples to support it as well...

Sub collides with sonar array towed by U.S. Navy ship - CNN.com


USS McCloy (FF 1038)

In each event, we can safely assume that the towed array is not on the same plane as the ship's own sonar array. It was an underwater array. Why was it an underwater array? To bypass certain layers that would affect the ship's sonar. The events occurred off Subic Bay and off the Bermudas, hardly open seas.

This mean the towed arrays were 'variable depth' devices and if the Chinese and Soviet subs collided with them, it mean the towed arrays were passive and the subs also had their sonar passive tracking the ships. What it really mean is that 'variable depth sonar' use by surface combatant ships can be effective against diesel/battery sub in shallow waters or against subs that uses layers to hide.

If the arrays were passive and the ships were tracking the subs, why did the ships' sonarmen not conscious of the risk of collisions since they would be tracking the subs' movements via the subs' own noises? Answer: Of course they were. The closer the sub gets to the array, the greater the information about the sub could be gathered. The towed array is much cheaper compared to the tactical and even strategic consequences that can be imposed upon an adversary.


I have no interests in getting into a numbers slingfest. Been there and done that and found out it is more about a person stroking his ego via esoteric information than about education. All it does is clutter up the thread with the readers no wiser than what they learned from publicly available information they can find for themselves and which is about the depth most want to know anyway. Further, while radar and sonar detection shares many similarities, there are many divergences and my specialty was in radar and general avionics..

Who was stroking his ego?
You questioned my comment in the first place by using blunt words and showed off your knowledge.
Anyway, I am glad you had radar/avionic background and that helped a lot in our statements.

If you are that keen on 'proving' to the Iranians that they have supremacy in submarine warfare in their backyard, I have no doubt you can manipulate any and all data points to suit your intent.

It is related to your first comment where you claimed that I have said something without even doing a simple Google search, not Iranian supremacy . remember?
You did a simple Google search and found "variable Depth Sonar", and thought I was dumb and "variable Depth Sonar" is the answer to any problem in shallow waters. You did not know "how it works" and you still lack a deep understanding of its fundamentals.
You never provided a statistical analysis in an article that proves your point. I am looking for accuracy, reproducibility, sensitivity, and specificity in a defined setup of experiment by known acoustic parameters. Finally, I want to see the analysis for different object geometric location with respect to natural boundaries.

 

[RayKalm]

I say we order some of the other midget boats and ships Iran has, they may seem useless, but at least they will increase our presence in the water!

 

[Hack-Hook]

I say we order some of the other midget boats and ships Iran has, they may seem useless, but at least they will increase our presence in the water!

well , you need ocean going submarine , our submarines are not suited fr your needs

I say we order some of the other midget boats and ships Iran has, they may seem useless, but at least they will increase our presence in the water!

well , you need ocean going submarine , our submarines are not suited fr your needs