I’m beginning to wonder just how the signals were detected, since the first reports expressed a mild amazement that the Chinese ship could hear them without the more sophisticated equipment available elsewhere. Could it be that their equipment is vulnerable to false positives?
As an example, I have a Canary WiFi detector. If I am near a WiFi signal, it reads the information and displays the channel, strength, digital name of the source, and status info such as “open,” “secure,” or “cloaked.” But there are other detectors that do nothing but light up a LED if they pick up RF. They do not read the data, they just react to a radio signal. That signal might not be a working WiFi channel. (For all I know, they might light up near a microwave oven, since some of the same frequencies are common to both.)
So I wonder if some detection equipment is so crude as to react to the very sounds we want to filter out, like whales or whatever?
You heard right. CBC reported the same. I think it’s safe to assume that at least one of the ping detections was attributable to something else. The way things have gone, it’s probably likely that all three reports were.
I’m also thinking that whatever took out the comms systems, either deliberate action or not, had a high probability of doing the same to the CVR/FDR. Maybe the FDR less so.
That doesn’t have any effect on the pinger mechanism but it’s cutting it really short by now. They need to find some debris and link it to the plane.
At least Angus Houston seems to be taking care of business quite nicely. Good show Australia.
There seems to be a lot of confusion around this. The signal has a frequency of 37.5 KHz. Meaning a 37.5KHz sound wave travelling in salt water. But the pulse is 1 Hz. Meaning a 10ms tone repeated over 1 second intervals.
There are no natural noise sources that can produce such a regular acoustic event.
I don’t doubt that. But the detectors that have found the sounds don’t seem to be the ideal kind for the job, and weren’t intended for this task. The ideal kind would be able to distinguish not only frequency, but pulse characteristics. Could these detectors be crude enough that bogus signals sound the same as real ones to them? Or are humans hearing just what they want to hear? (Consider the Canary analogy I posted in post #1261.)
The property that makes this sound unique is its regularity. That’s easy enough to detect. I believe the Chinese vessel was towing a hydrophone at very shallow depths. Don’t know if it is crude or not.
I don’t have any faith in this report but hopefully I’m wrong.
To expand further, yes, this is exactly like an LED that lights up when it detects 2.4GHz RF (typical WiFi frequency). If that LED blinks every one second, then you’ve got something that is very likely a 2.4GHz radio beacon.
Unfortunately, there are acoustic pingers made for divers that use 37.5khz such as this and this. The odds of them running across one of those has to be miniscule, but nothing would surprise me anymore.
The fact that the plane reached cruising altitude and there was contact with the pilots over 15 minutes later kind of rules out my subtle incapacitation by hypoxia theory. It indicates the plane was correctly pressurized during ascent to FL350. It could still be explosive decompression but then it gets harder to build a choesive story. Have to look into other failure modes for cabin pressure.
Also the fact that the blackout occurred just after signing off with malaysian ATC and entering vietnamese airspace is suspect. It points to the pilots directly as the most convenient time to divert the plane, unless someone was timing the flight, and even then it gives a window of a few minutes.
An Australian ship detected 2 separate signals consistent with a black box for 2 hrs and 20 minutes, then lost it. On the second pass, they heard it for 13 minutes. Two signals would fit with a FDR and a CVR. But the ocean is 4500-5000+ meters deep in that area, so getting something down to look could prove tricky.
This is in a different location than the Chinese report. I don’t know why I’m inclined to put more credibility into what Australia says, but I do.
I’d say that’s really promising. How many places in the ocean would have two pulse signals, if they mean two at once? Or could they mean something else?
They heard two signals at once and they heard them on two separate passes. The black box emits one for the flight data recorder and one for the voice recorder. So, yeah, it’s a good bet that they’ve found it.