Radio propagation - Revision history

Moleski: /* Skywave vs. Groundwave propagation */

2015-03-06T05:10:33Z

Skywave vs. Groundwave propagation

← Older revision		Revision as of 05:10, 6 March 2015
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	:: That's exactly my experience listening on the 20 meter ham band (except I was operating in Indiana). I had figured the polarization of the transmitted signal a lot to do with it, as well. Vertical polarization for ground wave, and horizontal polarization (e.g. a 20m beam) for skywave.		:: That's exactly my experience listening on the 20 meter ham band (except I was operating in Indiana). I had figured the polarization of the transmitted signal a lot to do with it, as well. Vertical polarization for ground wave, and horizontal polarization (e.g. a 20m beam) for skywave.

	:; [http://tighar.org/smf/index.php/topic,538.msg36178.html#msg36178 William G. Torgerson, ''Forum,'' 2015-02-18]		:; [http://tighar.org/smf/index.php/topic,538.msg36178.html#msg36178 William G. Torgerson, ''Forum,'' 2015-02-18; corrected.]

	:: Another factor affecting radio propagation is the Solar Cycle (because it affects the ionosphere). Solar Cycle 17, which started in September of 1933, and ended in January of 1944, reached a peak in April of 1937 (not so far from July). Although the effect of the solar cycle is generally considered 'negative', these cycles can cause unpredictable events, especially in the HF bands.		:: Another factor affecting radio propagation is the Solar Cycle (because it affects the ionosphere). Solar Cycle 8, which started in September of 1933, and ended in January of 1944, reached a peak in April of 1937 (not so far from July). Although the effect of the solar cycle is generally considered 'negative', these cycles can cause unpredictable events, especially in the HF bands.

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	[[Category:Radio considerations]]		[[Category:Radio considerations]]

Moleski: /* Skywave vs. Groundwave propagation */

2015-02-19T04:33:32Z

Skywave vs. Groundwave propagation

← Older revision		Revision as of 04:33, 19 February 2015
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	:: That's exactly my experience listening on the 20 meter ham band (except I was operating in Indiana). I had figured the polarization of the transmitted signal a lot to do with it, as well. Vertical polarization for ground wave, and horizontal polarization (e.g. a 20m beam) for skywave.		:: That's exactly my experience listening on the 20 meter ham band (except I was operating in Indiana). I had figured the polarization of the transmitted signal a lot to do with it, as well. Vertical polarization for ground wave, and horizontal polarization (e.g. a 20m beam) for skywave.

			:; [http://tighar.org/smf/index.php/topic,538.msg36178.html#msg36178 William G. Torgerson, ''Forum,'' 2015-02-18]

			:: Another factor affecting radio propagation is the Solar Cycle (because it affects the ionosphere). Solar Cycle 17, which started in September of 1933, and ended in January of 1944, reached a peak in April of 1937 (not so far from July). Although the effect of the solar cycle is generally considered 'negative', these cycles can cause unpredictable events, especially in the HF bands.

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	[[Category:Radio considerations]]		[[Category:Radio considerations]]

Moleski: /* Skywave vs. Groundwave propagation */

2015-02-16T22:35:21Z

Skywave vs. Groundwave propagation

← Older revision		Revision as of 22:35, 16 February 2015
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	:: I've never thought that the Itasca was receiving Earhart, at the strongest point, via ground wave propagation. Of course, that was the assumption by everyone at that time, and even still today by many people. But, just because the received signal was very strong was not an 'absolute' indication that she was close to the Itasca. Based on the fact that nothing was found in searching within the distance from Howland Island, that ground wave propagation would have existed, could indicate that she was much further away from Howland Island than was 'assumed' at the point of strongest received signals.		:: I've never thought that the Itasca was receiving Earhart, at the strongest point, via ground wave propagation. Of course, that was the assumption by everyone at that time, and even still today by many people. But, just because the received signal was very strong was not an 'absolute' indication that she was close to the Itasca. Based on the fact that nothing was found in searching within the distance from Howland Island, that ground wave propagation would have existed, could indicate that she was much further away from Howland Island than was 'assumed' at the point of strongest received signals.

			:; [http://tighar.org/smf/index.php/topic,538.msg36168.html#msg36168 Dave Ross Wilkinson, ''Forum,'' 2015-02-16]

			:: That's exactly my experience listening on the 20 meter ham band (except I was operating in Indiana). I had figured the polarization of the transmitted signal a lot to do with it, as well. Vertical polarization for ground wave, and horizontal polarization (e.g. a 20m beam) for skywave.

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	[[Category:Radio considerations]]		[[Category:Radio considerations]]

Moleski: /* 6210 Problems */

2015-02-15T21:02:42Z

6210 Problems

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 No transmissions were heard from [[Earhart]] on her [[Frequency,_wavelength,_and_antenna_tuning#Daytime.2Fnighttime_frequencies|"daytime frequency" of 6210 kcs]] until [[Transmission timeline|four hours after takeoff.]]  [[Chater|Chater attributed this to thunderstorms,]] but it also may be that this is evidence of a "donut" in the transmissions on that frequency.  The cause of such a big donut hole in the transmission pattern may lie in the [[antennas|history of modifications made to the antennas]] on [[NR16020]].  Each antenna has its own characteristic [http://en.wikipedia.org/wiki/Radiation_pattern radiation pattern.]
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 [[Category:Radio considerations]]

Moleski at 12:49, 10 December 2011

2011-12-10T12:49:29Z

← Older revision		Revision as of 12:49, 10 December 2011
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	== 6210 Problems ==		== 6210 Problems ==

	No transmissions were heard from [[Earhart]] on her [[Frequency,_wavelength,_and_antenna_tuning#Daytime.2Fnighttime_frequencies\|"daytime frequency" of 6210 kcs]] until [[Transmission timeline\|four hours after takeoff.]] [[Chater\|Chater attributed this to thunderstorms,]] but it also may be that this is evidence of a "donut" in the transmissions on that frequency. The cause of such a big donut hole in the transmission pattern may lie in the [[antennas\|history of modifications made to the antennas]] on [[NR16020]].		No transmissions were heard from [[Earhart]] on her [[Frequency,_wavelength,_and_antenna_tuning#Daytime.2Fnighttime_frequencies\|"daytime frequency" of 6210 kcs]] until [[Transmission timeline\|four hours after takeoff.]] [[Chater\|Chater attributed this to thunderstorms,]] but it also may be that this is evidence of a "donut" in the transmissions on that frequency. The cause of such a big donut hole in the transmission pattern may lie in the [[antennas\|history of modifications made to the antennas]] on [[NR16020]]. Each antenna has its own characteristic [http://en.wikipedia.org/wiki/Radiation_pattern radiation pattern.]

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	[[Category:Radio considerations]]		[[Category:Radio considerations]]

Thomas: correct TTracks URL

2011-02-23T03:06:15Z

correct TTracks URL

← Older revision		Revision as of 03:06, 23 February 2011
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	== 3105 Donut ==		== 3105 Donut ==
	[[File:3105 donut.png\|thumb]]		[[File:3105 donut.png\|thumb]]
	;[http://tighar.org/TTracks/2008Vol_24/1008.pdf TIGHAR Tracks 24 (2008) 3]		;[http://tighar.org/Publications/TTracks/2008Vol_24/1008.pdf TIGHAR Tracks 24 (2008) 3]

	:Recent software advances have made it possible to computer model the propagation properties of the [[Electra\|Electra’s]] transmitting antenna to an unprecedented degree of accuracy.		:Recent software advances have made it possible to computer model the propagation properties of the [[Electra\|Electra’s]] transmitting antenna to an unprecedented degree of accuracy.

Moleski at 00:39, 23 December 2010

2010-12-23T00:39:32Z

← Older revision		Revision as of 00:39, 23 December 2010
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	** [[Betty\|Betty's notebook]] can only be authentic if the conditions were right for the signal to bounce off the ionosphere and reach her home in Florida. See [[Brandenburg\|Brandenburg's]] article, [http://tighar.org/Projects/Earhart/Research/ResearchPapers/Brandenburg/HarmonyandPower.pdf Harmony and Power: Could Betty Have Heard Earhart on a Harmonic?]		** [[Betty\|Betty's notebook]] can only be authentic if the conditions were right for the signal to bounce off the ionosphere and reach her home in Florida. See [[Brandenburg\|Brandenburg's]] article, [http://tighar.org/Projects/Earhart/Research/ResearchPapers/Brandenburg/HarmonyandPower.pdf Harmony and Power: Could Betty Have Heard Earhart on a Harmonic?]
	**[[Frequency\|daytime/nighttime frequencies]] The bands of the atmosphere that can and do reflect radio waves are higher in the daytime and lower at nighttime. The old maxim for best long-range transmission was, "The higher the sun, the higher the frequency." This is why the [[Radio equipment on NR16020\|transmitter on the Electra]] had two voice [[frequency\|frequencies]], 3105 kHz and 6210 kHz.		**[[Frequency\|daytime/nighttime frequencies]] The bands of the atmosphere that can and do reflect radio waves are higher in the daytime and lower at nighttime. The old maxim for best long-range transmission was, "The higher the sun, the higher the frequency." This is why the [[Radio equipment on NR16020\|transmitter on the Electra]] had two voice [[frequency\|frequencies]], 3105 kHz and 6210 kHz.
			* "You can see a graph of past solar cycles [http://www.wm7d.net/hamradio/solar/historical.shtml here.] Look for the "Monthly Sunspot Numbers 1900-1999" graph. The higher the sunspot number, the better for radio wave propagation" [http://tighar.org/smf/index.php/topic,244.msg2109.html#msg2109 (Brookner, Forum, 2010-12-22).]

	;Excerpts from [http://www.tighar.org/Projects/Earhart/Documents/Chater_Report.html "The Chater Report":]		;Excerpts from [http://www.tighar.org/Projects/Earhart/Documents/Chater_Report.html "The Chater Report":]
	:Local interference prevented signals from the plane being intelligible until 2.18 p.m. The Lae Operator heard the following on 6210 KC –“HEIGHT 7000 FEET SPEED 140 KNOTS” and some remark concerning “LAE” then “EVERYTHING OKAY”. The plane was called and asked to repeat position but we still could not get it. The next report was received at 3.19 pm on 6210 KC – “HEIGHT 10000 FEET POSITION 150.7 east 7.3 south CUMULUS CLOUDS EVERYTHING OKAY”. The next report received at 5.18 p.m. “POSITION 4.33 SOUTH 159.7 EAST HEIGHT 8000 FEET OVER CUMULUS CLOUDS WIND 23 KNOTS”.		:Local interference prevented signals from the plane being intelligible until 2.18 p.m. The Lae Operator heard the following on 6210 KC –“HEIGHT 7000 FEET SPEED 140 KNOTS” and some remark concerning “LAE” then “EVERYTHING OKAY”. The plane was called and asked to repeat position but we still could not get it. The next report was received at 3.19 pm on 6210 KC – “HEIGHT 10000 FEET POSITION 150.7 east 7.3 south CUMULUS CLOUDS EVERYTHING OKAY”. The next report received at 5.18 p.m. “POSITION 4.33 SOUTH 159.7 EAST HEIGHT 8000 FEET OVER CUMULUS CLOUDS WIND 23 KNOTS”.

Moleski: /* 6210 Problems */

2010-08-12T15:56:45Z

6210 Problems

← Older revision		Revision as of 15:56, 12 August 2010
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	== 6210 Problems ==		== 6210 Problems ==

	No transmissions were heard from [[Earhart]] on her [[Frequency,_wavelength,_and_antenna_tuning#Daytime.2Fnighttime_frequencies\|"daytime frequency" of 6210 kcs]] until [[Transmission timeline\|four hours after takeoff.]] [[Chater attributed this to thunderstorms,]] but it also may be that this is evidence of a "donut" in the transmissions on that frequency.		No transmissions were heard from [[Earhart]] on her [[Frequency,_wavelength,_and_antenna_tuning#Daytime.2Fnighttime_frequencies\|"daytime frequency" of 6210 kcs]] until [[Transmission timeline\|four hours after takeoff.]] [[Chater\|Chater attributed this to thunderstorms,]] but it also may be that this is evidence of a "donut" in the transmissions on that frequency. The cause of such a big donut hole in the transmission pattern may lie in the [[antennas\|history of modifications made to the antennas]] on [[NR16020]].

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	[[Category:Radio considerations]]		[[Category:Radio considerations]]

Moleski at 15:54, 12 August 2010

2010-08-12T15:54:29Z

← Older revision		Revision as of 15:54, 12 August 2010
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	:At 08:43-55 local time Itasca heard Earhart say, [[the line\|“We are on the line 157 337.]] Will repeat message. We will repeat this on [[frequency\|6210 kcs]]. Wait. We are running on line north and south.” The message came in at maximum strength. Given a newly discovered anomaly in the propagation pattern of the aircraft’s transmitting antenna, to have even a 10% chance of being heard at maximum strength, the Electra had to be somewhere within the “donut” shown. If on the line southeast of Howland, the plane was much closer to [[Niku\|Gardner Island (Nikumaroro)]] than previously assumed.		:At 08:43-55 local time Itasca heard Earhart say, [[the line\|“We are on the line 157 337.]] Will repeat message. We will repeat this on [[frequency\|6210 kcs]]. Wait. We are running on line north and south.” The message came in at maximum strength. Given a newly discovered anomaly in the propagation pattern of the aircraft’s transmitting antenna, to have even a 10% chance of being heard at maximum strength, the Electra had to be somewhere within the “donut” shown. If on the line southeast of Howland, the plane was much closer to [[Niku\|Gardner Island (Nikumaroro)]] than previously assumed.

			== 6210 Problems ==

			No transmissions were heard from [[Earhart]] on her [[Frequency,_wavelength,_and_antenna_tuning#Daytime.2Fnighttime_frequencies\|"daytime frequency" of 6210 kcs]] until [[Transmission timeline\|four hours after takeoff.]] [[Chater attributed this to thunderstorms,]] but it also may be that this is evidence of a "donut" in the transmissions on that frequency.

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	[[Category:Radio considerations]]		[[Category:Radio considerations]]

Moleski: /* 3105 Donut Hole */

2010-07-03T23:41:07Z

3105 Donut Hole

← Older revision		Revision as of 23:41, 3 July 2010
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	:Hue Miller, 23 February 2009 [[AESF\| Forum]]		:Hue Miller, 23 February 2009 [[AESF\| Forum]]

	== 3105 Donut ~~Hole~~ ==		== 3105 Donut ==
	[[File:3105 donut.png\|thumb]]		[[File:3105 donut.png\|thumb]]
	;[http://tighar.org/TTracks/2008Vol_24/1008.pdf TIGHAR Tracks 24 (2008) 3]~~<nowiki>:</nowiki>~~		;[http://tighar.org/TTracks/2008Vol_24/1008.pdf TIGHAR Tracks 24 (2008) 3]

	:Recent software advances have made it possible to computer model the propagation properties of the [[Electra\|Electra’s]] transmitting antenna to an unprecedented degree of accuracy.		:Recent software advances have made it possible to computer model the propagation properties of the [[Electra\|Electra’s]] transmitting antenna to an unprecedented degree of accuracy.