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Regulatory Maximum .5 Second Lag Fdr

rob balsamo
post Jun 5 2007, 05:15 PM
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Calum Douglas from the UK (aka Snowygrouch) has been doing more research on the FDR work. He sent me a correspondence regarding buffer lags for FDR recording.

As im sure many of you know, one of the excuses/arguments govt loyalists try to use is that there is up to 2-6 or more seconds missing from the FDR.

Well, according to Ed Santana of L3 Communication (the manufacturer of the FDR), the maximum allowable lag on FDR recording is .5 seconds as noted in TSO-124 and ED-55, both regulartory documents. All of their recorders are built to that standard.


Therefore, if any govt loyalist says there is 2-6 seconds missing from the FDR, tell them they dont have a clue what they are talking about (but we already knew that..) and that recorders cannot have more than .5 seconds missing and are designed specifically under those guidelines. (which of course makes sense since these recorders are used to enhance flight safety and what good is a recorder that is missing 6 seconds of its crucial last moments).

Bottom line, the Animation and csv file data at 09:37:44 would have had to be recorded at a maximum .5 seconds from impact.. period. As we know, the aircraft is too high at that data point.

So, 1 of 2 possibilities exist.

1. The FDR is completely fabricated by the govt agencies involved

or

2. The FDR was "seperated" from an aircraft recording its parameters on the FDR at that point in time.

In other words, there is no way the aircraft could have hit the pentagon with a 480 feet recording at its last data point since L3 Recorders are built to standard of a .5 second or less lag between measurement and recording.

I also have Ed recorded with this information if anyone is interested. Ed was aware he was being recorded and was very helpful.

Cheers!
Rob
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Snowygrouch
post Jun 5 2007, 05:37 PM
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Good work on that phone call Rob,
Great to have audio and email.
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Cary
post Jun 5 2007, 06:11 PM
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Outstanding work to all involved. The noose just keeps tightening on the official story, don't it.
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awmatt
post Jun 5 2007, 08:17 PM
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I have made some progress on forensically analyzing the .FDR file, and this 0.5 second requirement makes sense. My guess is that it's much smaller than that in reality, that's just the "absolute worst case".

This is welcomed to be moved into a new thread; I'm not sure where it best fits. It does relate to this thread, though.

For future reference, I've created a file called NONHEADER.FDR. This is simply the original raw file with the first 0xAA (170) bytes removed. These bytes are NOT part of the flight data recorder's memory, but placed there later just to have a "cover page" for programs that read the data in (nothing unusual). The length of this file is exactly 24MB, or 24*1024*1024 bytes. All addresses will refer to THIS file, not the original.

The 24MB memory is split into 192 sections, each with two subsections (64kB each). The subsections are written in parallel in blocks of 0x80 (128) bytes. The two headers (each 0x80 (128) bytes long) of each of the two subsections contains this section number at offset 0x0A (10). Note that the section numbers have to do with the location in the memory, not the time the data was recorded. However, the word at offset 0x0E (14) in each header is the hourly timestamp, ranging from 0x1226 to 0x1244. It shows about 30 hours of recorded data, seemingly around ten flights (UT said 11-13 I believe?).

Most of the data in this file are on a 16-bit word basis, organized by little-endian (Intel-style as opposed to Motorola-style), which means the lower byte comes before the higher byte. For example, the first two bytes of NONHEADER.FDR as well as each header thereafter are 0x6B and 0xFE. This forms the value of 0xFE6B (65,131, just 405 short of 64kB, also interpreted as -405).

The last addresses written were 0x003896F1 and 0x003994B9, each being a separate part of the compression "product", like a multiplier and multiplicand. It seems in the middle of nowhere, even in the middle of a 16-bit word. This suggests but certainly doesn't prove a small time delay. See the screenshot example:

http://www.egr.msu.edu/~mattes12/lastword.png

My notes:

http://www.egr.msu.edu/~mattes12/format.txt

The list of header information. By starting with HStamp 0x1226, you can follow it all the way to the power removal at 0x1244. Let me know if this is hard to understand, or needs clarification. Link:

http://www.egr.msu.edu/~mattes12/headers.txt

Note that what are called "255A" and "255B" are really supposed to be "029A" and "029B". When a new section is transferred to, 256kB is erased (in a nutshell). Erasing in EEPROM (floating gate) is accomplished by applying a voltage of about 15V to the appropriate memory sections. After data is erased, the result is all '1's. If bytes need to be written, the '0' bits will be cleared, but the '1' bits will not need to be touched. A '0' cannot be changed to a '1' unless the high voltage is applied to the entire section (true of the older memories, not necessarily the newer ones). I have personally designed a 15V on-chip CMOS supply for EEPROM/Flash memories for graduate school (brag, brag yes1.gif). Because of this mass erasure, we can tell exactly where the power was removed.

Assuming a 30-hour recording, about 200 seconds go by for each pair of 64kB subsections during flights. This gives around 300 bytes per second in each subsection, in parallel. This is after compression. It seems a power removal should be a very "magnifyable" event.

The 30-hour assumption may be wrong (also found farther above). I'll try to find this out soon. UT, know how much time was on the "tape"?


Great work on the 0.5 second thing, folks. Kudos.

- Arthur

This post has been edited by awmatt: Jun 5 2007, 09:22 PM
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UnderTow
post Jun 5 2007, 10:30 PM
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Here is an example of stoppage from another real investigation.
The loss of power and stoppage of the FDR was deteremined within 0.4 seconds of accuracy.

----------------------------
FDR Stoppage Time

Analysis of the last seconds of recorded FDR data indicate that power to the FDAU was interrupted. The FDR lost synchronization after word 54 of subframe 3, which corresponds to a time of approximately 0125:39.8. Two words containing 1s and 0s were then recorded, followed by 27 words, most of which contained only 0s. The FDR then regained synchronization, repeating subframe 3, although with updated values. The frame counter was incremented by one, and the recording continued for another partial subframe of 22 valid words (duration of 22/64 of a second), after which the recorder stopped. It was determined that a brief power interruption to the FDAU had occurred between word 54 and the pattern of 0s. When the FDR loses signal input from the FDAU, it continues to record for up to two words (duration of 2/64 of a second), based on tests carried out by the FDR manufacturer.

The FDR will coast through a power outage of up to 400 milliseconds, during which time no recording will take place, even though the recorder is still up and running.
When power was restored, a FDAU re-boot was initiated, as indicated by the 27 words of 0s (a duration of 27/64 of a second). The re-boot was considered to be a warm start, in that 0s were recorded without a resetting of the frame counter. A warm start re-boot implies a power interruption of anywhere between 10 and 400 milliseconds. The actual duration of the power interruption was not determined. However, it was most likely at least 2/64 of a second long, in order to have recorded the two non-zero words, representing a loss of FDAU signal. Therefore, following the loss of the FDAU signal, there was no recording of data for a maximum period of up to 0.37 seconds (0.4 minus 2/64).

Based on the pattern of the re-boot and the possible duration of the power interruption, the FDR stopped recording between 1.8 and 2.2 seconds after the FDAU power interruption (see above). The time of FDR stoppage would therefore be somewhere between 0125:41.6 and 0125:42.0.

The time reference for the FDR data is in UTC, which is synchronized to the radar time unless otherwise noted. Heading data is depicted in degrees with respect to magnetic north. Recorded pressure altitude is presented in feet and refers to altitude asl, assuming standard sea level pressure of 29.92 in. Hg. Derived indicated altitude is presented in feet above msl, corrected for pressure, based on the altimeter setting used for the specified segment of flight.

--------------
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Thous
post Jan 22 2009, 01:34 PM
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QUOTE (johndoeX @ Jun 5 2007, 06:15 PM) *
Calum Douglas from the UK (aka Snowygrouch) has been doing more research on the FDR work. He sent me a correspondence regarding buffer lags for FDR recording.

As im sure many of you know, one of the excuses/arguments govt loyalists try to use is that there is up to 2-6 or more seconds missing from the FDR.

Well, according to Ed Santana of L3 Communication (the manufacturer of the FDR), the maximum allowable lag on FDR recording is .5 seconds as noted in TSO-124 and ED-55, both regulartory documents. All of their recorders are built to that standard.


Therefore, if any govt loyalist says there is 2-6 seconds missing from the FDR, tell them they dont have a clue what they are talking about (but we already knew that..) and that recorders cannot have more than .5 seconds missing and are designed specifically under those guidelines. (which of course makes sense since these recorders are used to enhance flight safety and what good is a recorder that is missing 6 seconds of its crucial last moments).

Bottom line, the Animation and csv file data at 09:37:44 would have had to be recorded at a maximum .5 seconds from impact.. period. As we know, the aircraft is too high at that data point.

So, 1 of 2 possibilities exist.

1. The FDR is completely fabricated by the govt agencies involved

or

2. The FDR was "seperated" from an aircraft recording its parameters on the FDR at that point in time.

In other words, there is no way the aircraft could have hit the pentagon with a 480 feet recording at its last data point since L3 Recorders are built to standard of a .5 second or less lag between measurement and recording.

I also have Ed recorded with this information if anyone is interested. Ed was aware he was being recorded and was very helpful.

Cheers!
Rob



If one frame of data is recorded at 09:37:44 what time should the next set of data be recorded? I guess Iím just looking for the elapsed time between sets of data.
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rob balsamo
post Jan 22 2009, 02:46 PM
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http://pilotsfor911truth.org/forum//index....showtopic=13846
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Thous
post Jan 22 2009, 03:18 PM
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QUOTE (rob balsamo @ Jan 22 2009, 03:46 PM) *


I understand what TF is saying, but I didnít really see the answer to my question. I really wanted to know what time elapsed between each sample.

Iíve been able to track down the CSV file and it looks like the answer to my question is .01 seconds. What I was going to bring up (especially if the .01 second value was higher) was that when a simulation is made we really donít know if the digital reading was taken at the beginning of the frame or at the end.

An example of what I am referring to would be the first ALT reading in the CSV file; all we know is that it occurred between 8:19.00 (inclusive) and 8:19.01 (exclusive).

I now see the value I was looking for is a bit smaller then expected, but I still have a question you may be able answer easily. If we ran two versions of the simulation: one assuming the readings were taken at the beginning of the frame and the second where we assume the readings were done at the end of the frame, what difference would we see?

I am also assuming that each line in the CSV file represents an instant in time, in a give frame, and that each line does not necessarily represent 1/8 of a second. Do you agree?

Thanks for your patience!
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rob balsamo
post Jan 22 2009, 03:56 PM
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QUOTE (Thous @ Jan 22 2009, 02:18 PM) *
I understand what TF is saying, but I didnít really see the answer to my question. I really wanted to know what time elapsed between each sample.

Iíve been able to track down the CSV file and it looks like the answer to my question is .01 seconds. What I was going to bring up (especially if the .01 second value was higher) was that when a simulation is made we really donít know if the digital reading was taken at the beginning of the frame or at the end.


Cross check csv file altitude with the animation altitude also made by the NTSB. They are made from the same file allegedly. According to this method, Alitude was recorded in the first third of a second/frame. Record time depends on interval of certain parameters. Some are recorded 4 tmes a second, some 8, some once every 4 seconds.. etc. Depends on the parameter.


The rest of your questions i'll let TF explain.

Bottom line, the data as plotted and provided by the NTSB does not support the govt story regarding the physical damage at the pentagon. The NTSB/FBI refuse to comment.
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