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Search: Posts Made By: auv-ee
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Forum: Tech Log
19th May 2011, 23:45
Replies: 2,546
Views: 937,377
Posted By auv-ee

Laser gyros and survival of a CSMU

Sorry to reply late to a couple of topics, but I've been either off the net or very busy the past few days.

--

Ring laser gyros measure changes in angular orientation, and, as previously...
Forum: Tech Log
16th May 2011, 19:32
Replies: 2,546
Views: 937,377
Posted By auv-ee

More Engine views

TurbineD, lomapaseo, Bear and others interested in the engines:

There are a lot more views of the engines now available in the latest video posted by BEA:
...
Forum: Tech Log
16th May 2011, 02:14
Replies: 2,546
Views: 937,377
Posted By auv-ee

ILE DE SEIN is about 700-800km from Dakar,...

ILE DE SEIN is about 700-800km from Dakar, heading toward it. I recall BEA said they would go in for some crew changes. 10.55206˚ / -22.03128˚...
Forum: Tech Log
13th May 2011, 13:28
Replies: 2,546
Views: 937,377
Posted By auv-ee

Pinger detection range

JD-EE:

I don't see where you accounted for either the spreading loss of the signal or the noise summed over the whole detection filter band (at least 100Hz). Remember that the noise figures I...
Forum: Tech Log
12th May 2011, 13:34
Replies: 2,546
Views: 937,377
Posted By auv-ee

I think I saw that figure in the Metron report. ...

I think I saw that figure in the Metron report. My estimate was 2-3km. I expect that Metron was intentionally conservative.

To answer your earlier question...

According to Urick, deep sea...
Forum: Tech Log
12th May 2011, 03:57
Replies: 2,546
Views: 937,377
Posted By auv-ee

I assume you are asking about the ambient noise...

I assume you are asking about the ambient noise of the ocean in the 100Hz-100kHz range. I don't have a copy handy of "Principles of Underwater Sound", Robert J. Urick. Over that wide a range the...
Forum: Tech Log
11th May 2011, 01:15
Replies: 2,546
Views: 937,377
Posted By auv-ee

Bloomberg: Recorder analysis

Air France Crash Analysis Reaches Lab as Black Boxes Return Home - Bloomberg (http://www.bloomberg.com/news/2011-05-10/air-france-crash-analysis-reaches-lab-as-black-boxes-return-home.html)

There...
Forum: Tech Log
10th May 2011, 19:28
Replies: 2,546
Views: 937,377
Posted By auv-ee

The figures for detection have been discussed...

The figures for detection have been discussed before, recently and a year ago. At 4km depth the probability of detection from Emeraude, even from directly above, was probably less than good. I...
Forum: Tech Log
10th May 2011, 13:30
Replies: 2,546
Views: 937,377
Posted By auv-ee

I was hoping you'd add some reality to this...

I was hoping you'd add some reality to this discussion. Agreed on all points. I was only pointing out that there is some room for improvement, given that the frequency spec is +/-1000Hz and the...
Forum: Tech Log
10th May 2011, 13:23
Replies: 2,546
Views: 937,377
Posted By auv-ee

Not really. For horizontal isotherms...

Not really. For horizontal isotherms (temperature changes with depth but not laterally; the usual case considered), there is no bending of the straight-down ray. As the angle of incidence increases...
Forum: Tech Log
10th May 2011, 01:51
Replies: 2,546
Views: 937,377
Posted By auv-ee

ULBs and recorders

An excerpt from the following article in Aviation International News:

Investigators Hope Recovered Flight Data and Cockpit Voice Recorders Shed More Light on AF447 Crash: AINonline...
Forum: Tech Log
10th May 2011, 01:23
Replies: 2,546
Views: 937,377
Posted By auv-ee

We speculated a long time back about whether the...

We speculated a long time back about whether the pingers have advanced to crystal oscillators or are still using RC or LC oscillators, and whether the ping rate is digitally divided or runs from a...
Forum: Tech Log
9th May 2011, 22:44
Replies: 2,546
Views: 937,377
Posted By auv-ee

Googleearth

Others may know better, but...

Not much of the ocean bottom has been mapped at high resolution, and in many areas only by sparse tracks-of-opportunity from passing ships having deep fathometers. ...
Forum: Tech Log
9th May 2011, 22:31
Replies: 2,546
Views: 937,377
Posted By auv-ee

However, I should point out that an uncertain...

However, I should point out that an uncertain frequency is one problem that can be aided with improved signal processing. In the traditional detector one would make the filter bandwidth wide enough...
Forum: Tech Log
9th May 2011, 22:04
Replies: 2,546
Views: 937,377
Posted By auv-ee

I assume we are in agreement. That's another way...

I assume we are in agreement. That's another way to put the point I was trying to make.
Forum: Tech Log
9th May 2011, 20:37
Replies: 2,546
Views: 937,377
Posted By auv-ee

Noise

I think you are confusing wide-band vs. in-band noise. Note that I said in answer to DJ77 in post 1005, that a traditional detection starts with a narrow band filter. This accepts and compares only...
Forum: Tech Log
9th May 2011, 16:55
Replies: 2,546
Views: 937,377
Posted By auv-ee

If they were using a traditional detector, which...

If they were using a traditional detector, which consists of a narrow-band filter, a peak detector and a threshold comparison, then 20db would be about right. If they are doing more modern signal...
Forum: Tech Log
9th May 2011, 15:38
Replies: 2,546
Views: 937,377
Posted By auv-ee

May 9 update from BEA

Information, 9 May 2011 (http://www.bea.aero/en/enquetes/flight.af.447/info09may2011.en.php)
Forum: Tech Log
9th May 2011, 13:54
Replies: 2,546
Views: 937,377
Posted By auv-ee

I think that mm43 is referring to the photo that...

I think that mm43 is referring to the photo that BEA published of the CVR, showing the pinger half-buried. I am less sure than mm43 about the configuration of the transducer in the pinger case, and...
Forum: Tech Log
7th May 2011, 03:19
Replies: 2,546
Views: 937,377
Posted By auv-ee

Here is a different article that discusses a few...

Here is a different article that discusses a few of the topics that have been covered on this thread: that the events leading to the accident are more likely to be complex than simple, that airliners...
Forum: Tech Log
6th May 2011, 15:44
Replies: 2,546
Views: 937,377
Posted By auv-ee

Another good interview with Mike Purcell appears...

Another good interview with Mike Purcell appears in print here:

Air France 447: How scientists found a needle in a haystack - Boing Boing...
Forum: Tech Log
5th May 2011, 13:44
Replies: 2,546
Views: 937,377
Posted By auv-ee

BEA to investigate failure to detect pingers

This article discusses BEA's intent to study the reasons for not detecting the pingers in 2009. It also contains an initial comment from Honeywell.

BEA to examine why acoustic sweep missed AF447...
Forum: Tech Log
27th Apr 2011, 00:07
Replies: 2,546
Views: 937,377
Posted By auv-ee

It's not so much the depth and darkness as the...

It's not so much the depth and darkness as the basic properties of water. Water absorbs (or scatters, or both) light at the red end of the visible spectrum, and to a lesser extent at the blue end. ...
Forum: Tech Log
26th Apr 2011, 14:20
Replies: 2,546
Views: 937,377
Posted By auv-ee

The video that accompanies the latest BEA...

The video that accompanies the latest BEA announcement contains brief views of additional photos and sonar records, as well as some good shots of the Remora 6000. My French was never good enough to...
Forum: Tech Log
25th Apr 2011, 01:23
Replies: 2,546
Views: 937,377
Posted By auv-ee

One might fault PBS for repeating without...

One might fault PBS for repeating without independently checking, but that was originally a BBC production broadcast in the UK on 2010/05/30. I believe it was re-narrated (different accent of...
Showing results 1 to 25 of 25


 
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