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Ric Gillespie

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Questions about Post-Loss Radio Analysis
« on: November 28, 2012, 08:10:03 AM »

This thread is for questions about the methodology and data described in the prelude to Catalog and Analysis of Radio Signals During The Search for Amelia Earhart in July 1937.

Questions should reference a specific statement in that document.
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Al Leonard

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Re: Questions about Post-Loss Radio Analysis
« Reply #1 on: April 27, 2013, 11:24:10 PM »


In the smoothed copy of Itasca's position 2 radio log I see several signals that, if I understand the log entries correctly, seem to suggest that Itasca was hearing transmissions originating from sources other than the Electra:

July 5, around 04:28 (page 16/22 of the pdf of the smoothed position 2 radio log): “HEAR CUPLE RUSSIANS STNS ON ICW CODE- RTM AND RNW- NOTHING ELSE ON 3105”

July 5, Around 21:40 to 21:44 (page 18/22): “HEAR S3 FONE SLITELY HIGHER IN FREQ THAN LAST ONE-ABT 3130 KC- MANS VOICE APPARENTLY TALKING IN FOREIGN TONGUE- CRM BREAKS IT UP SO UNABLE READ”

July 5, At 23:39 (page 18/22): “ …EAR S3 FONE ON 3105 MANS VOICE “AAA FIVE O’CLOCK AAA – VOICE DID NOT (sou)ND EXCITED, BUT NORMAL””

July 5, At about 23:42 (page 19/22): “ HEAR SAME S3 FONE ON 3105 AS AT 2339-VOICE MANS ES SOUNDS PLEASANT- APPARENTLY NOT FROM EARHART PLANE”

July 7, 05:23 (page 22/22): “ICW CODE SIGS ON OR NEAR 3105 KC UNREAD RUSSIAN OR JP CODE”

If these transmissions originated from sources other than the Electra, doesn't this suggest that some of the other, harder to characterize, signals that Itasca received could have originated from sources other than the Electra? If yes, what are the implications for the catalog of credible post loss radio signals?
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Andrew M McKenna

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Re: Questions about Post-Loss Radio Analysis
« Reply #2 on: April 28, 2013, 06:35:14 PM »

If the radio receptions were from random Russian and Japanese transmissions, the pattern should continue be pretty much constant, before - during - and after AE being lost.  Instead, we see we see the pattern of receptions essentially end July 7.  What we have is a surge of receptions between July 2-7, and then essentially nothing thereafter, despite the world carefully listening.  This leads me to think that there was some sort of unusual phenomena involved in creating the pattern of post loss signals, not a random pattern of foreign Russian and Japanese transmitters, whose pattern should be relatively constant both before (although no one was listening) and after July 2, 1937.

amck
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Al Leonard

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Re: Questions about Post-Loss Radio Analysis
« Reply #3 on: April 28, 2013, 10:47:30 PM »

If the radio receptions were from random Russian and Japanese transmissions, the pattern should continue be pretty much constant, before - during - and after AE being lost.  Instead, we see we see the pattern of receptions essentially end July 7.  What we have is a surge of receptions between July 2-7, and then essentially nothing thereafter, despite the world carefully listening.  This leads me to think that there was some sort of unusual phenomena involved in creating the pattern of post loss signals, not a random pattern of foreign Russian and Japanese transmitters, whose pattern should be relatively constant both before (although no one was listening) and after July 2, 1937.

Thanks for replying, Andrew. A few points:

-At present the “Possible Post-Loss Signal Sources” section of the Tighar Research Paper titled “Catalog and Analysis of Radio Signals During The Search for Amelia Earhart in July 1937” makes no mention of Russian and Japanese transmitters, yet the radio log entries I cited above suggest that Russian and/or Japanese transmissions could be heard. There was also a transmission described as being in a ‘foreign tongue’, suggesting a possible broadcast from some other country. If Tighar agrees that these signals were from foreign sources, it would be helpful for readers to have an updated Research Paper that clarifies this point.

-The log entry about 2 receptions from a man’s speaking in English, with signal strength 3, who the listener describes as calm and “not from the Earhart plane” seems worth some sort of discussion in the post-loss receptions story, yet as far as I know there has been none.

-I agree that there is an interesting temporal pattern to the post loss radio receptions, but not over the whole July 3-8 period (I’m going by GMT time/date axes on the plots in Tighar Tracks). It has been previously suggested, I think, that the correlation is with night time — listeners could receive signals from a much larger region, and thus they heard more signals. Is the correlation with night or with water height on the reef?  Night time and low water heights more or less coincided over the July 3-8 period, making it somewhat difficult to tell. I’d say that after July 5 there are so few receptions that there is no meaningful correlation. As for July 3-5, my statistically trained eyeballs tell me that on July 4 the receptions were evenly spread throughout the night so the data don’t cluster in the low tide part of the night. On July 3 and possibly July 5 the receptions do seem to cluster more around the low tide portion of the night. But of course, as previously discussed on another thread, waves only 9 inches in height during a the July 4 high tide would have permanently disabled the transmitter, according to Bob Brandenburg's tide reconstruction, thus precluding any July 5 radio signals from the Electra.

-You said “…If the radio receptions were from random Russian and Japanese transmissions…”. Without knowing what the source of these receptions was, why should we assume they were randomly transmitted in time? Just as there are reasons why a hypothetical Electra on a reef might have transmitted at certain times, there might be reasons why transmissions from foreign sources would have clustered at certain times. We can’t say without knowing more about these foreign sources. Does ‘RTM’ and ‘RNW’ in the log entry for the Russian sources tell us what/where stations those were?

Finally, since there is a lot of talk about ‘naysaying’ on the forum, I’d like to close by saying that there’s a difference between naysaying and attempting to offer constructive feedback. Tighar is taking a scholarly approach to the Earhart disappearance and part of the scholarly approach is to make a hypothesis, and then possibly refining it based upon input from others. My comments here and elsewhere are intended in the spirit of constructive feedback, as I am sure you understand.

---

As usual, in making the post yet another question has occurred to me: what do the Itasca radio logs tell us about radio receptions made after July 8?
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Steve Lee

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Re: Questions about Post-Loss Radio Analysis
« Reply #4 on: June 03, 2013, 07:17:05 AM »


In the smoothed copy of Itasca's position 2 radio log I see several signals that, if I understand the log entries correctly, seem to suggest that Itasca was hearing transmissions originating from sources other than the Electra:

July 5, around 04:28 (page 16/22 of the pdf of the smoothed position 2 radio log): “HEAR CUPLE RUSSIANS STNS ON ICW CODE- RTM AND RNW- NOTHING ELSE ON 3105”

July 5, Around 21:40 to 21:44 (page 18/22): “HEAR S3 FONE SLITELY HIGHER IN FREQ THAN LAST ONE-ABT 3130 KC- MANS VOICE APPARENTLY TALKING IN FOREIGN TONGUE- CRM BREAKS IT UP SO UNABLE READ”

July 5, At 23:39 (page 18/22): “ …EAR S3 FONE ON 3105 MANS VOICE “AAA FIVE O’CLOCK AAA – VOICE DID NOT (sou)ND EXCITED, BUT NORMAL””

July 5, At about 23:42 (page 19/22): “ HEAR SAME S3 FONE ON 3105 AS AT 2339-VOICE MANS ES SOUNDS PLEASANT- APPARENTLY NOT FROM EARHART PLANE”

July 7, 05:23 (page 22/22): “ICW CODE SIGS ON OR NEAR 3105 KC UNREAD RUSSIAN OR JP CODE”

If these transmissions originated from sources other than the Electra, doesn't this suggest that some of the other, harder to characterize, signals that Itasca received could have originated from sources other than the Electra? If yes, what are the implications for the catalog of credible post loss radio signals?


The Howland radio logs also record foreign receptions on the 3105 kHz frequency. There are four of them:

July 5, 0518: ‘DISTINCT JAPANESE MUSIC ON 3105’
July 8, 0200 :  'WEAK JAPANESE STATION'.
July 10, 0245 :  'MUSIC FROM JAPANESE STATION ON 3105'
July 12, 0330: 'WEAK CW CARRIER FROM JAP STATION’

There are an additional eight receptions listed as ‘WEAK CARRIER’ or some variant of this description, on the 3105 kHz frequency, all received AFTER the Lambrecht flyover, on July 9. Since we know the Electra wasn’t on Nikumaroro after the flyover, these radio signals clear did not originate at Nikumaroro. Here are those eight receptions.

July 9, 2210: ‘WEAK CARRIER 3105’
July 9, 2222: ‘CW SIGS’
July 9, 2238: ‘WEAK CARRIER’
July 10, 2227:  ‘WEAK CARRIER’
July 11 0030: ‘WEAK CW CARRIER’
July 11 0215: ‘WEAK CW CARRIER’
July 11, 2349: ‘WEAK CARRIER’
July 12 0515: ‘WEAK CW SIGS (CARRIER)’
July 13, 0300: ‘WEAK CARRIER 3105’

While Itasca and the Electra may have been the only possible central Pacific source of signals on Earhart’s frequency, as stated in the material accompanying the post-loss catalog, the 12 Howland receptions listed here and the Itasca receptions quoted above indicate that listeners in the central Pacific could have, and did, hear radio signals that weren’t from either of these sources.

Notice that these 12 messages were all received during times of darkness. Somewhere in the forum there is a post by Gary LaPook where he pointed out that the post-loss receptions were best thought of as correlating with darkness rather than water levels at Nikumaroro. At night listeners in the Pacific were able to pick up radio transmissions fromgreat distances. LaPook argued that the post-loss receptions were fragments of transmissions from far away rather than fro the Electra, and the Itasca and Howland logs certainly show that those listening for Earhart did receive signals on her frequency from far away places.
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Ric Gillespie

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Re: Questions about Post-Loss Radio Analysis
« Reply #5 on: June 03, 2013, 08:58:06 AM »

While Itasca and the Electra may have been the only possible central Pacific source of signals on Earhart’s frequency, as stated in the material accompanying the post-loss catalog, the 12 Howland receptions listed here and the Itasca receptions quoted above indicate that listeners in the central Pacific could have, and did, hear radio signals that weren’t from either of these sources.

That's true. Itasca and the Electra were the only possible central Pacific source of signals on Earhart’s frequency.  Commercial aircraft on the U.S. west coast were also a potential source of faint voice signals on 3105. Weak unmodulated carriers on 3105 seem to have been not that uncommon and we have not listed any such reception as a credible post-loss signal from Earhart.

Notice that these 12 messages were all received during times of darkness. Somewhere in the forum there is a post by Gary LaPook where he pointed out that the post-loss receptions were best thought of as correlating with darkness rather than water levels at Nikumaroro.

The water level charts at the end of Bob Brandenburg's paper clearly show that the credible transmissions were not randomly distributed during the hours of darkness but correspond quite precisely to periods during the night when the water level was low enough to run an engine.
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Steve Lee

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Re: Questions about Post-Loss Radio Analysis
« Reply #6 on: June 03, 2013, 11:30:12 AM »

The receptions I listed, and the ones Al listed, fall somewhere in the spectrum between a fragmentary voice reception and a reception of a weak carrier signal. I looked at the post loss catalog and it seems to me that a number of the credible receptions listed  there also fall in this range. I list some of these receptions below:

Cat #55, July 4 Mokapu Point. “Immediately following the KGU broadcast at 0833Z, the Pan American station at Mokapu heard a faint carrier on approximately 3105 kHz, but the signal was too weak to distinguish any words.”

Cat# 102 July 5 Midway. “A faint, wobbly, short duration voice signal was heard and a bearing of approximately 201°was obtained. The frequency was checked with that of Itasca’s 3105 kHz transmitter and found to be “just a hair higher.” A man’s voice was distinctly heard but was too weak to be understood or identified.”

Cat # 114 July 4 Itasca Detachment, Howland.  “A man’s voice, very weak, was heard.”

Cat # 121 July 5 Wake Island. “At 0948 a voice signal of good intensity and well modulated but wavering badly suddenly came on 3105. While the carrier frequency of this signal did not appear to vary appreciably, its strength did vary in an unusually erratic manner and at 0950 the carrier strength fell off sharply with the wavering more noticeable than ever. At 0952 it went off completely.”

Cat # 123 July 5 Itasca Detachment, Howland. “An unidentified continuous wave signal was heard. No call sign was heard. A direction finder bearing of either south-southeast or north-northwest was obtained using a magnetic compass. The bearing ambiguity was due to ionospheric multipath interference – “night effect.” The frequency was reported as “slightly above” 3105 kHz.”

Cat# 129 July 5 Wake Island. “A very unsteady voice modulated carrier was observed at 1223Z, which lasted until 12:36 Z. Wake was able to get an approximate bearing of 144 degrees, believed to be reasonably accurate. The signal began at QSA 5 (a very strong signal) and gradually reduced to QSA 2 (moderate strength) by 12:36Z.”
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Ric Gillespie

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Re: Questions about Post-Loss Radio Analysis
« Reply #7 on: June 03, 2013, 11:50:10 AM »

The receptions I listed, and the ones Al listed, fall somewhere in the spectrum between a fragmentary voice reception and a reception of a weak carrier signal. I looked at the post loss catalog and it seems to me that a number of the credible receptions listed  there also fall in this range.

I disagree. All of the credible signals you cite have positive factors , i.e. apparent direct response to KGMB, definite modulation, a bearing indicating possible origin in the Phoenix Group.  The weak carrier receptions you cite are just that - weak carriers.  I see no basis for saying they "fall somewhere in the spectrum between a fragmentary voice reception and a reception of a weak carrier signal."
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John Ousterhout

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Re: Questions about Post-Loss Radio Analysis
« Reply #8 on: June 29, 2013, 08:28:40 AM »

In trying to evaluate some of the post-loss radio signal reports, and specifically DF signals, it would be nice to know how uncommon were such signals to be heard at Wake, Midway and Mokapu*.  That is, how common were DF signals on 3105 that aligned with the Phoenix group at times other than Amelia's flight?  Knowing this would establish a baseline.  Were the reported signals from there on 4 and 5 July the only such incidents, ever?  The reports I've seen are only compelling if they indicate an abnormal occurrance of such signals seeming to originate there.  The Pan Am station at Mokapu would seem to be an especially likely source for a baseline data set, since they were in the job of recording aircraft DF signals on 3105.
Records of 3105 signals DF'd from sources other than the Phoenix group could be used to evaluate the probability of the Phoenix group being the true source.  In effect, such data could tell us how likely a DF signal could fool an analyst.
*(Itasca logs go as far as 14 July, and indicate that 3105 had gone practically silent)
Cheers,
JohnO
 
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Dick Jansen

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Re: Questions about Post-Loss Radio Analysis
« Reply #9 on: February 06, 2016, 03:24:39 PM »

Waking an old thread...

Wondering if there is any documentation of what the Pacific transport "route frequencies" actually were for Tx, if not 3105/6210?

(Google wasn't helpful)
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Ric Gillespie

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Re: Questions about Post-Loss Radio Analysis
« Reply #10 on: February 06, 2016, 03:30:44 PM »

Wondering if there is any documentation of what the Pacific transport "route frequencies" actually were for Tx, if not 3105/6210?

Of course, in July 1937 there were no Pacific transport aircraft other than the Pan Am Clippers and they communicated only code.  I'll ask Bob Brandenburg if we know what frequencies Pan Am was using.
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Neff Jacobs

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Re: Questions about Post-Loss Radio Analysis
« Reply #11 on: February 06, 2016, 09:20:12 PM »

Anne Lindbergh relied heavily on Pan Am for communication on the North to the Orient flight in 1931.  Her transmitting frequencies were:
333 KC   now kHz
500 KC
3130 KC
5615 KC
8450 KC
13240 KC
All 15 watts CW to a trailing wire antenna.   Her Pan Am standard transmitter and receiver are on display at the Smithsonian. 
In addition to contact with Pan Am she also contacted JOC Japan

Various Supplements to the List of Fixed and Land Stations show in the 1930s
Boeing
North West Airlines
National Air Transport  and
American Airlines
were assigned 3106 KC.
There appears to have been nothing unique about AE's 3105 KC assignment.   It was an Aeronautical Mobile frequency.
The Smithsonian also has Anne's cut down copy of Fixed and Land Stations 1930 used on the flight.
Neff
« Last Edit: February 06, 2016, 09:24:57 PM by Neff Jacobs »
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Ric Gillespie

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Re: Questions about Post-Loss Radio Analysis
« Reply #12 on: February 07, 2016, 08:12:02 AM »

There appears to have been nothing unique about AE's 3105 KC assignment.   It was an Aeronautical Mobile frequency.

Exactly.  3105 was the standard calling frequency for aircraft in the U.S.  By international agreement voice communication on 3105 could only be used by U.S. registered aircraft calling ground stations.  The ground stations replied on a different frequency.  Itasca had to get special permission to transmit on 3105.

See "Radio Frequency Allocation and Usage" in the Post-Loss Radio Signals Analysis and Catalog
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Dick Jansen

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Re: Questions about Post-Loss Radio Analysis
« Reply #13 on: February 07, 2016, 09:30:26 AM »

Just opinion of course but it seems reasonable to think that the Pan Am M-130's, by International agreement and being home based in Alameda, would very likely comply with the quoted regulations by having 3105 transmit capabilities (in addition to whatever the "route frequencies" were)
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Ric Gillespie

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Re: Questions about Post-Loss Radio Analysis
« Reply #14 on: February 07, 2016, 10:07:32 AM »

Just opinion of course but it seems reasonable to think that the Pan Am M-130's, by International agreement and being home based in Alameda, would very likely comply with the quoted regulations by having 3105 transmit capabilities (in addition to whatever the "route frequencies" were)

The Clippers may have had 3105 transmit capability.  I don't know.  But nobody reported hearing a transmission from a Pan Am Clipper on 3105 and the Pan Am stations on Oahu, Midway and Wake were heavily involved in listening for and taking bearings on possible post-loss signals from Earhart. It's not likely that they mistook a transmission from one of their own aircraft for a transmission from Earhart. 

The Pan Am memos documenting their involvement are on the TIGHAR website.  We've examined them closely.  All of the post-loss receptions that we consider to be credible are cataloged in detail in the Post-Loss Signals Catalog.  If you see any messages we have listed as credible that you think might have been sent by a PanAm Clipper please point it out and we can discuss it.
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