View source for Estimates of signal strength

== Signal Strength Quantifiers ==
Mike Everette, [http://www.tighar.org/Projects/Earhart/forum/Highlights141_160/highlights154.html October 22, 2001, Forum.]

As for reported signal strengths in terms like "S-5" this really does not have any relationship to the meter reading. In fact a signal reading high on the S-meter scale can still be covered up in strong noise.

The operator in those days used a scale of 1 to 5. 
*S-1 means "signal very weak, in the noise, barely intelligible if readable at all." 
*S-2 means "weak signal, still in noise, but readable, maybe with difficulty." 
*S-3 means "signal stronger, noise, but readable." 
*S-4 means "fairly strong signal, some noise, very readable." 
*S-5 means "very strong, clear signal."

This is SUBJECTIVE. There is a LOT of room for interpretation. An operator's ears might tell him/her that a signal is S-1 if any appreciable amount of noise is heard. Or, that a signal is NOT S-5 if there is ANY NOISE AT ALL heard. It's a judgment call. Different operators hearing the same signal may disagree. 

== Estimates of signal strength on the final flight ==
[[Ric Gillespie]], [http://www.tighar.org/Projects/Earhart/forum/Forum_Archives/199901.txt January 9, 1999, Forum.]

In the [http://tighar.org/Projects/Earhart/Archives/Documents/Cooper_Report/Cooper_Report.pdf report] submitted by [[Cooper|Air Corps Lt. Daniel Cooper]] on July 27, 1937, there is a summary of the strength of transmissions that the ''[[Itasca]]'' received from Earhart on the morning of July 2.  All times are local.
{| {{prettytable}}
|+
!Time
!Quality
!S-code
!Highlight of transmission
|+
|0345
|very faint
|S1
|"Will listen on hour and half on 3105..."
|+
|0445
|faint
|S2
| (not confirmed by log)
|+
|0600
|fair
|S3
| "Two hundred miles out..." (actually rec'd at 06:15)
|+
|0646
|good
|S4
| "About 100 miles out.."
|+
|0741
|very loud
|S5
| "We must be on you but can not see you..."
|+
|0750
|very loud
|S5
| "We are listening(?) but can not hear you..."
|+
|0758
|very loud
|S5
| "We rec'd your signals but unable to get a minimum."
|+
|0843
|very loud
|S5
| [["We are on the line 157 337"]]
|}
"The radio operator reported that from 0741 on, her signal strength was at a maximum and judging from her volume, she was practically over Howland.  All this seems to indicate that she passed close to Howland, probably within 50 miles" (Cooper).

This sounds like a steadily strengthening signal over a period of five hours.

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[[Category:Radio considerations]]