Greyline Propagation. Research Results

Transcription

1 Greyline Propagation Research Results With special thanks to: Johan ON5EX, Stan G3DSS, Alan G4ZFQ,, Mike VP8NO, Richard G3CWI, Chris G4IFX, Eric K3NA, 3Y0X, G3BJ, G3XTT and Gwyn G4FKH

2 What is Greyline Greyline propagation? The phrase was first coined in 1975 It describes the propagation of radio waves along the terminator separating night and day (sunrise/sunset) - this is the Greyline path (or Grayline in USA) The path is reported to be extremely efficient Some books vaguely refer to it as affecting the lower bands

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5 Using Grayline software by PA3CQR

6 The D Region : Is at an average height of about 60-90km It is mainly responsible for absorbing/attenuating signals on m. It can reflect signals at VLF This is why we don t hear much skip on the LF bands during daylight, especially in summer The actual level of absorption is dependent upon the frequency, time of day/year and solar/geomagnetic levels

7 D Layer Absorption: Absorption (db)= (10*log[flux (W m -2 )] + 65) 2 /f 2 That is, the lower the frequency, the more the absorption

8 Relative D Layer Absorption: According to the RSGB Amateur Radio Operating Manual, for a daytime path: 6db attenuation per hop on 21MHz (1 S-point) 40db attenuation per hop on 7 MHz (7 S-points) 100db attenuation per hop on 3.5MHz (17 S-points) (around 250db per hop on Top Band??? 41 S-points?) NB: Depends on time of year/time of day

9 Conventional Greyline wisdom At sunset, the lower D region is no longer illuminated, therefore absorption is reducing The higher F-layer(s) is/are still illuminated, so we still have ionisation to aid propagation At sunrise, the reverse occurs

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11 So what can we hear at sunrise? Theoretically, ZS6 (South Africa) in August ZL (North Island, New Zealand) in December LU/PY/VP8 (Argentina, Brazil, Falklands) in December And others according to the season

12 So what can we hear at sunset? Theoretically, JA (Japan) in August ZL (New Zealand) in September ZS6 (South Africa) in November LU/PY/VP8 (Argentina, Brazil, Falklands) in June And others according to the season

13 The purpose of Project Greyline To find better ways of modelling the greyline To find out if greyline paths actually exist in the way we currently model them To find out what frequencies are prone to greyline enhancements and by how much. To look at trans-terminator HF paths (skip focusing)

14 But, and it is a big but : Do we get greyline enhancements on concurrent sunrise/sunrise or sunset/sunset paths? Or is restricted to sunrise/sunset and sunset/sunrise paths? (Other side of the world)

15 G-VP8 40m sunrise/sunrise Nov and Jan/Feb Mike Harris VP8NO with a 40m dipole and a 12W Elecraft K2 Using slow Morse (QRSS) he transmitted his call on kHz Signals were received in the UK for three weeks using SpectrumLab software

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21 The G - VP8 40m sunrise/sunrise results Signals were received through the night A greyline enhancement of about 6-10db could be seen about 75% of the time. The enhancement occurred in the traditional twilight period - about 30 mins. before sunrise, dipping at sunrise This is probably due to a time lag on E/F layer build-up

22 The G<>VP8 40m sunset/sunset experiment Took place throughout May 2003 Signals were very poor, probably due to the season and high A/K indices. There was no confirmed greyline enhancement.

23 The G<>VP8 80m sunset/sunset experiment 05/03 and 11/04 sunrise/sunrise Took place in May 2003 and November 2004 There was a confirmed greyline enhancement of approx 6db corresponding with the onset of twilight at the sunrise/sunrise condition.

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26 Is there a twilight sweet spot? In the book Contesting in Africa Multi-Multi on the Equator Robert Ferguson, GM3YTS of the VooDoo Contest Group outlines several Top Band QSOs that took place minutes before/after the other stations sunrise/sunset.

27 The 80m Chirpsounder experiment By Richard G3CWI Looking for Round the World echoes Nothing heard

28 Trans-terminator paths or sunrise/sunset enhancements ON4UN suggests that 160m/80m signals are best at right angles to the terminator. Only 40m signals tend to follow a greyline path. N4KG says on 80 and 40 meters, signals ALWAYS peak AFTER SUNRISE to the west and BEFORE SUNSET to the east. On 160m, signals can peak at sunrise and sunset and can also peak during darkness. 160m is the LEAST predictable band in the amateur spectrum.

29 G4PEL<>VK2APG 80m 5th October 18:00Z

30 G3AB<>VK6HD 160m 21:23Z 4th October 2002

31 DL2FDL <> VK6HD 80m 22:52 12th August 2002

32 ZL2JR reception of 5MHz signals from the UK

33 The WWCR experiment (3210kHz) September 2005 Looking for sunrise enhancements at right angles to terminator Station transmits 100kW from Nashville, USA Also gives opportunities on 5765, 5935, 9975, 9985,12160 and 15825kHz

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38 3Y0X Top Band - contacts v sunrise

39 3Y0X 80m contacts v sunrise

40 3Y0X 80m reality (W6ELProp)

41 Greyline an alternative explanation Propagation on 160m is probably via a ducted mode for paths greater than 12,000km Propagation along or near (and parallel to) the terminator appears to be limited to about 6,000km Carl Luetzelschwab K9LA Greyline propagation on 160 could be due to ducting between the E and D layers Bob Brown NM7M

42 And what about skip focusing on HF - eg.. 10m? Does it always occur when operating near to the MUF?

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45 In conclusion - greyline paths Greyline paths above 40m on mutual sunrise or sunset may not be that much more efficient Greyline paths on 160m/80m on mutual sunrise are definitely more efficient The G-VP8 results showed around a 4-6db enhancement Greyline enhancements on 160m are more noticeable they are the ONLY likely possible times for antipodal contacts

46 In conclusion - trans-terminator terminator paths Look for skip focusing enhancements on 28Mhz as the terminator crosses the DX path and you are in daylight Worked at 14:55UTC on 1 st October 2006 VQ9JC, Diego Garcia on MHz (solar flux 78)

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48 By definition: Antipodal contacts on 160m WILL occur at greyline times as there will be no complete dark path before or after that time As 80m and 40m are less dependent on a full dark path you can work the antipodes slightly later or earlier.

49 You can read more at: qsl.net/g0kya

50 Web addresses for greyline greyline information Geoclock - D-layer absorption predictions Critical frequency (fof2) predictions SpectrumLab software - Beacon Time Wizard by Taborsoft RSGB Greyline Research Group -

51 References for greyline greyline information 1. Dale Hoppe, K6UA et al, "They Grayline Method of Dxing," CQ, Sept 1975, P J. G. Lee, "An Introduction to Radio Wave Propagation", Babani BP293, Ian Poole, G3YWX, "Your Guide to Propagation," RSGB, Jacobs, Cohen and Rose, "The New Shortwave Propagation Handbook", CQ Communications, John Devoldere, ON4UN, "Low-Band Dxing", ARRL, Roger Western, G3SXW et al, Contesting in Africa Multi-Multi on the Equator, Idiom Press. 7. Steve Nichols, G0KYA, The Twilight Zone just what is grey-line propagation, RadCom July available as PDF at