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Title: 20 meters during the morning and mid-day hours question Post by: steve_qix on September 09, 2014, 06:09:52 PM Hi !
I don't have any experience with 20 meters, but how reliable is 20 meters during the morning (about 8:30 Eastern time) to about 3:00PM Eastern for working G.B.? This would be part of a scientific experiment associated with a local school. We would need to send a signal to G.B. during the school day. Any information would be much appreciated ! Thanks and Regards, Steve Title: Re: 20 meters during the morning and mid-day hours question Post by: Pete, WA2CWA on September 09, 2014, 07:16:14 PM Simple to do. Tomorrow and/or mid day, check this link:
http://www.dxmaps.com/spots/map.php?Lan=E&Frec=14&ML=M&Map=W2L&DXC=N&HF=S&GL=N It's in real time. Title: Re: 20 meters during the morning and mid-day hours question Post by: SM6OID on September 10, 2014, 01:18:39 AM Hi!
You can use this tool to make predictions, but remember it is only a prediction. Actual propagation can be al lot different... http://www.voacap.com/prediction.html Title: Re: 20 meters during the morning and mid-day hours question Post by: W1RKW on September 10, 2014, 04:35:58 PM my experience with 20m in that time frame has been good. Not consistent but more so than 10m by far.
Title: Re: 20 meters during the morning and mid-day hours question Post by: Ralph W3GL on September 10, 2014, 07:07:23 PM Hey Steve,
This is off topic but for some reason my confuser has deleted my ability here to start a new topic. Did I miss something or what happened to the 2014 AMTR results? Thanks, Ralph... Title: Re: 20 meters during the morning and mid-day hours question Post by: K4RT on September 10, 2014, 08:45:59 PM Steve,
Good luck with your experiment. Good to hear you will be exposing students to ham radio. Just a thought: In case 20M propagation is in the dumpster you might want to have a Plan B (if appropriate) such as alternative bands or demonstrating ham radio generally for your students ... perhaps QSOs with other DX, stateside, different modes, etc. 73, Brad Title: Re: 20 meters during the morning and mid-day hours question Post by: steve_qix on September 10, 2014, 11:04:49 PM This is more of a physics experiment than specific ham radio. The goal is to measure, with a reasonable degree of accuracy, how long it takes for a radio signal to go from a specific location in the U.S., across the "pond" to G.B.
Title: Re: 20 meters during the morning and mid-day hours question Post by: K1JJ on September 11, 2014, 12:16:04 AM This is more of a physics experiment than specific ham radio. The goal is to measure, with a reasonable degree of accuracy, how long it takes for a radio signal to go from a specific location in the U.S., across the "pond" to G.B. I'll save ya the trouble.... ;D It will take about 21.5 milliseconds to travel from the east coast to the UK. (Based on 4,000 miles distance at 186,000 miles / second) Actually measuring it will be an interesting challenge, however. How do they intend to do it, with a GPS time reference and trigger of some kind? T Title: Re: 20 meters during the morning and mid-day hours question Post by: WD8BIL on September 11, 2014, 11:40:47 AM The velocity factor of pure air is something like .99995. It's probably something less in real life with humidity, altitude, pollution and any other variable you can add.
Title: Re: 20 meters during the morning and mid-day hours question Post by: KL7OF on September 11, 2014, 11:55:08 AM You should try to bounce off the moon....you could hear your own signal and time it easily...Gud Luk
Title: Re: 20 meters during the morning and mid-day hours question Post by: steve_qix on September 11, 2014, 11:05:08 PM This is more of a physics experiment than specific ham radio. The goal is to measure, with a reasonable degree of accuracy, how long it takes for a radio signal to go from a specific location in the U.S., across the "pond" to G.B. I'll save ya the trouble.... ;D It will take about 21.5 milliseconds to travel from the east coast to the UK. (Based on 4,000 miles distance at 186,000 miles / second) Actually measuring it will be an interesting challenge, however. How do they intend to do it, with a GPS time reference and trigger of some kind? T Right! We know how to calculate it, but it's another thing to prove it 8) That's the whole idea - to prove it and also to get accurate measurements. GPS is probably the most practical way to measure absolute time without spending a fortune. Title: Re: 20 meters during the morning and mid-day hours question Post by: W1RKW on September 12, 2014, 03:40:45 PM Steve,
This is a very curious, intriguing and interesting experiment. Back in the 18th century, I think, the speed of light measurements were done over approximately 5 miles with rotating mirrors and were line of sight. the rotating mirrors introduced a constant/variable that allowed for the time/distance calculation. How will you account for distance over the pond? It's not a direct path and will probably vary to some extent on atmospherics. How will you determine time for sent and received or returned signal? This is a cool experiment. Title: Re: 20 meters during the morning and mid-day hours question Post by: Pete, WA2CWA on September 12, 2014, 04:07:36 PM Propagation time delays between two locations can be quite variable and are probably dependent on a number of atmospheric anomalies at any time of day. One probably also has to consider the angle(s) of incidence into a specific atmospheric layer(s) and the angle of refraction on the receiving end.
Title: Re: 20 meters during the morning and mid-day hours question Post by: AJ1G on September 13, 2014, 06:12:59 PM Hopefully you will have no/minimal digital signal processing in the signal path end to end to throw in timing errors, AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
Would be interested in seeing details of the experiment and how it comes out. |