Extra Class question of the day: meteor scatter propagation

February 21, 2012 by 2 Comments

Perseid meteor

Amateur radio operators use many different ways to get signals from one spot to another. Perhaps one of the most interesting is meteor scatter propagation.

Meteor scatter propagation is possible because when a meteor strikes the Earth’s atmosphere, a cylindrical region of free electrons is formed at the E layer of the ionosphere. (E3A08) 28 – 148 MHz is the frequency range that is well suited for meteor-scatter communications. (E3A09)

Unfortunately, these ionization trails are relatively short-lived, so to communicate via meteor scatter, you need to either be able to detect when these paths are available or be transmitting when the paths are available. All of these choices are correct when talking about  good techniques for making meteor-scatter contacts (E3A10):

  • 15 second timed transmission sequences with stations alternating based on location
  • Use of high speed CW or digital modes
  • Short transmission with rapidly repeated call signs and signal reports

For more information on meteor scatter, go to:

Filed Under: Extra Class Question of the Day, Propagation Tagged With:

Rugged Transistors, Designing Radio Systems

December 22, 2011 by Leave a Comment

Here are a couple of links to articles in electronics engineering trade magazines that I’ve run across lately that I think are of interest to amateur radio operators:

  • Some new transistors can withstand VWSRs up to 65:1.Gauging Ruggedness In RF Power Transistors. This article, written by editor Jack Browne, who is himself a ham, covers some of the new power transistors on the market. Some of them are capable of withstanding VSWRs on the output of up to 65:1!
  • The Radio Link: A Tutorial. This series of articles is a bit heavy on math for most radio amateurs, but the point of the series is to think of radio communication as a system whose behavior can be predicted. Thinking about how we use radio in this way could help us to become better radio amateurs.

And here’s something entirely out of left field. Scientists have published a paper that shows that random noise can actually make signals clearer. The process is called stochastic resonance, and while the article doesn’t explain the theory in much depths, and I’m not sure that it’s something that’s applicable to radio communication, it seems like it might be something to look into.

Filed Under: Books and Magazines, Building/Homebrew, Propagation

Gray Line Notifier

December 18, 2011 by 2 Comments

I’ve always been kind of fascinated by gray-line propagation. The gray line is a band around the Earth where night is turning into day and day is turning into night. Theories differ as to why, but radio propagation along the gray line is often very efficient. NA5N has one explanation of the phenomenon.

This morning, while walking to our ham radio club breakfast get-together, I got to thinking about how I might be better able to take advantage of gray-line propagation.Because this phenomenon is so short-lived, it’s easy to miss the gray line. How cool, I thought, would it be if I could come up with a program that would inform me when my QTH was beginning its transit through the grayline.

I thought up several ways to get my computer to do this. Then, it occurred to me that I should be able to write a Web application that hams could sign up for that would either send them an e-mail or send them a Tweet when their QTH was about to enter the gray line. And, coincidentally, I might be able to sell some advertising to pay for this and maybe make a few bucks off it.

I’m tentatively calling this application the Gray Line Notifier. I talked up this idea a bit at our breakfast this morning, and the guys noted that there are already may gray line maps on the Web, but none of them can be programmed to send you notices. We chatted a bit more about this, and came up with a couple of features for this app, including:

  1. Will send either an e-mail or a Tweet, when a ham’s QTH is about to enter the gray line.
  2. Include information about other countries/grid squares that are also along the gray line.
  3. Perhaps interface with a DX spotter to see if there is good gray line propagation at the time.
  4. Beam headings to take advantage of gray line propagation.
What do you think? Would you sign up for this service? Can you think of any other features that I might include?
Filed Under: Propagation, Software

Auroral flutter an interesting phenomenon

October 25, 2011 by 2 Comments
Aurora

An aurora over Alaska. Source: NASA

Last night, it was reported that there was a coronal mass ejection (CME) that resulted in an aurora being seen as far south as Atlanta, GA. The aurora, more commonly known as the Northern Lights, are usually only visible as far south as the northern tier of the United States.

I knew something was up as soon as I turned on my rig last night. Nearly every signal had some auroral flutter on it. Auroral flutter is caused by radio waves bouncing off the ever-changing aurora or passing through it. When severe, auroral flutter can make a signal nearly unreadable.

Auroral flutter is usually limited to signals that pass over the North Pole. I first became aware of this phenomenon when I worked several stations in Northern Russia. Last night, though, even U.S. stations had this characteristic flutter. I was a little flummoxed by this. I’d never heard this on domestic QSOs.

I got to talking about this with Steve, N4LQ. He said that he was at first a little taken aback by the auroral flutter, because he had been fooling around with the receiver section of the HW-16 he was using and didn’t know if the odd sound he was hearing was the result of his experiments or band conditions. I assured him that it wasn’t the receiver. :)

Filed Under: Operating, Propagation

If the ionosphere has D, E, and F layers, what happened to the A, B, and C layers?

October 16, 2011 by 3 Comments

On Google+, Bob, K0NR posted,

Interesting question from a 10-year-old student in the ham radio class today: Why do we always talk about the D, E and F layers of the ionosphere…are there A, B or C layers? I don’t know the answer to that one.

Now, I’d always heard that the reason the lowest layer is the D layer is because when scientists first started studying the ionosphere, they found these three layers and postulated that they would find three layers below them, i.e. the A, B, and C layers. They did not find them, but never went back and relabeled ones that they did find.

I posted this as a reply, and Bob asked if I had a reference. Well, I Googled all over for one, but came up empty. Do any of you know if this explanation is true, or if this is a ham radio urban legend?

Filed Under: Propagation

Let the Sun Shine!

September 23, 2011 by 4 Comments

It looks as though solar activity is picking up, and with that propagation on the HF bands. The ARRL Letter reports:

Solar FlareTad “Somewhere the Sun is shining” Cook, K7RA, reports: Compared to the uneventful past few years, sunspot activity was truly remarkable this week. The daily sunspot number for September 16 was 173. We haven’t see numbers like this in more than six years, when the sunspot number was 181, way back on July 5, 2005 in Solar Cycle 23. The solar flux reached 150.1 on September 18. Just six months ago it was slightly higher, 153 on March 7 and 155 on March 8, but prior to that the only higher number was 157.3 on August 22, 2005, about 7 weeks after the sunspot number of 181. Currently, the solar flux and planetary A index forecast from USAF/NOAA calls for solar flux of 144 on September 22-23, 140 on September 24-25, 145 on September 26-28, 130 on September 29 through October 1, and 135 on October 2-5. The planetary A index is predicted at 5 on September 22-24, 8 on September 25, 5, 8, 5, 5, 15 and 8 on September 26 through October 1, and 5 on October 2-7. Look for more information on the ARRL website on Friday, September 23. For more information concerning radio propagation, visit the ARRL Technical Information Service Propagation page.

On Tuesday, I worked a guy on 40m, and he reported that 10m was wide open all day. Time for some DX!

Filed Under: Propagation

Space Weather Prediction Center to Continue Broadcasts on WWV and WWVH

July 3, 2011 by Leave a Comment

From the June 30, 2011 ARRL Letter:

In April 2011, the Space Weather Prediction Center (SWPC) informed the public that as of September 6, 2011, it would no longer broadcast its geophysical alert message on WWV and WWVH. The ARRL has now learned that the SWPC has changed its mind and will keep broadcasting these messages that inform listeners of the solar flux, the mid-latitude A and K indices and space weather storms, both current and predicted. Due to listener feedback, the SWPC is considering updating the broadcast; in addition to providing the current daily solar flux at 2800 MHz, the SWPC is evaluating adding more frequent observations at 2695 MHz. According to the SWPC website, other improvements to the message content will also be evaluated.

 

Filed Under: Propagation

Today in Ham Radio History: Moonbounce

January 10, 2011 by Leave a Comment

From Frank via the HamRadioHelpGroup mailing list:

Today in 1946, the United States Army Signal Corps at Fort Monmouth, New Jersey successfully conducted Project Diana, bouncing radio waves off the moon and receiving the reflected signals. 65 years later, ham radio operators all over the world conduct moon bounce or EME communications (Earth-Moon-Earth), with relatively inexpensive equipment.

Filed Under: Propagation, Satellites

No Sunspots for Decades?

October 6, 2010 by 2 Comments

Two solar scientists—Matthew Penn and William Livingston, with the National Solar Observatory (NSO) in Tucson, Arizona—are predicting that by 2016 there may be no remaining sunspots, and the sun may stay spotless for several decades. They’re basing their prediction on the measurement of the magnetic field strength of 1,500 sunspots since 1990. What they have found is that the average strength of the magnetic fields is declining. When the magnetic field strength falls below a particular value, sunspots are unable to form.

Filed Under: Propagation Tagged With: ,

The KD8LWR Repeater Guide

August 2, 2010 by 24 Comments

“The KD8LWR Repeater Guide” is a database of analog FM repeaters across SE Michigan and parts of SW Ontario that is constantly updated based on my reception.

On a linked repeater system, “Activity” refers to the activity of that particular repeater being transmitted on.

PLs in parentheses mean the repeater sometimes requires the given PL. If you want to key up a repeater on this database with a PL in parentheses, key up the repeater with carrier access first; if that fails, use the given PL.

At the bottom of the post you will see when this repeater database was last updated and the last addition or change of a repeater.  This “change” refers to a frequency, PL, VOIP node, or callsign change as well as if a repeater goes down or back up.

Frequency Input PL Callsign Activity Comments
Ann Arbor area (Washtenaw)
145.150 144.550 100.0 N8DUY Medium  Skywarn/ARES
145.230 144.630 100.0 W8UM Medium Echolink node 301138
146.740 146.140 100.0 WB8UPM Inactive
146.920 146.320 100.0 KT8TD Active  RACES
146.960 146.360  (100.0) WB8TKL Medium  Owned by W8PGW
147.480 147.480 (100.0) KD8LWR Inactive Wide-coverage simplex repeater, at 100 watts ERP from 24 feet
224.340 222.740 W8UHW Medium
224.380 222.780  (100.0) W8PGW Inactive
224.780 223.180 100.0 K8RPT Down/Very inactive
443.050 448.050 107.2 N8LBV Inactive
443.500 448.500 (100.0) W8PGW Inactive
443.650 448.650 100.0 N8AMX Very inactive
444.075 449.075 82.5 WR8DAR Very inactive
444.975 449.975 107.2 WD8DPA Down Linked to 29.640
446.500 441.500 100.0 KD8LWR Testing Medium-coverage repeater, at 15 watts from 24 feet
51.740 51.240 88.5 W2PUT Down Linked to 927.9875 locally, and 444.100 and 927.4875 in Milan, IRLP node 4428
927.9875 902.9875 131.8 (use D025) W2PUT Inactive Linked to 51.740 locally, and 444.100 and 927.4875 in Milan, IRLP node 4428
29.640 29.540 114.8 WD8DPA Down Linked to 444.975
Chelsea area (Washtenaw)
145.450 144.850 100.0 WD8IEL Pretty inactive
146.980 146.380 100.0 WD8IEL Medium Programmed by KD8LWR
224.160 222.560 100.0 WD8IEL Medium
443.575 448.575 100.0 WD8IEL Active CMEN linked repeater system, Echolink node 41083, Allstar node 28236
Howell (Livingston)
145.410 144.810 162.2 K8JBA Very inactive
146.680 146.080 (162.2) W8LRK Active  Skywarn
444.525 449.525 100.0 W8LRK Inactive
Jackson area (Jackson/Ingham)
51.620 51.120 100.0 KA8ZXX Active Wide-coverage repeater, backup repeater programmed by KD8LWR
145.310 144.710 (67.0) K8YQP Inactive Part-time link to 147.360, 224.160, 443.875 and 927.0125, part-time link to 51.620, low-coverage repeater
145.470 144.870 114.8 W8IRA Medium Linked repeater system (linked to Lansing)
146.880 146.280 100.0 W8JXN Medium  Skywarn
147.360 147.960 100.0 KA8HDY Active Linked to 443.875 and 927.0125, Echolink node 644275, remote base, backup repeater programmed by KD8LWR
443.175 448.175 77.0 WD8EEQ Inactive
444.175 449.175 100.0 KA8YRL Inactive
443.875 448.875 100.0 KC8LMI Very active Linked to 147.360 and 927.0125, Echolink node 644275, wide-coverage repeater, remote base
444.950 449.950 KC8LMI Medium Low-coverage repeater, sometimes linked to the other related linked repeaters
446.800 446.800   KC8LMI Down Low-coverage simplex repeater programmed by KD8LWR
927.0125 902.0125 131.8 N8URW Active Linked to 147.360 and 443.875, Echolink node 644275, remote base
Lansing area (Ingham/Eaton)
145.390 144.790 100.0 W8BCI Active
145.470 144.870 107.2/100.0 W8IRA Active Linked repeater system (linked to Jackson)
146.700 146.100 107.2 W8BCI Medium
146.940 146.340 100.0 W8BCI Active
147.080 147.680 103.5 K8CHR Inactive
147.280 147.880 100.0 KB8LCY Active CMEN linked repeater system, Echolink node 41083, Allstar node 28236
224.820 223.220 107.2 W8FSM Down
224.980 223.380 100.0 W8BCI Inactive
442.025 447.025 N8JI Inactive
442.050 447.050 100.0 N9UV Inactive
442.425 447.425 100.0 KD8PA Usually medium
442.525 447.525 107.2 KC8QYW Inactive? CMEN linked repeater system, Echolink node 41083, Allstar node 28236
442.725 447.725 100.0 KB8SXK Medium
442.900 447.900 77.0 W8MSU Very inactive
443.000 448.000 107.2 KD8IFI Inactive CMEN linked repeater system, Echolink node 41083, Allstar node 28236
443.525 448.525 100.0 W8CLI ???
443.625 448.625 100.0 N8HEE Medium
443.700 448.700 WB8RJY Medium Does not identify itself
444.125 449.125 107.2 N8DEF Inactive
444.575 449.575 107.2 N8OBU Pretty active CMEN linked repeater system, Echolink node 41083, Allstar node 28236
444.700 449.700 (DPL 073) KB8FUN Medium
444.850 449.850 141.3 WC8CLI Inactive
51.700 51.200 192.8 WB8RJY Very inactive Wide-coverage repeater
52.960 52.460 KD8PA Down
910.250 439.250 N8OBU ??? ATV repeater (LSB input, AM output)
927.525 902.525 131.8 (use D073?) KB8FUN ???
Flint area (Gennessee)
145.190 144.590 100.0 W8YUC ???
145.410 144.810 91.5 W8YUC Inactive CMEN linked repeater system, Echolink node 41083, Allstar node 28236 (also used in West Branch, but still inactive, and not linked up)
146.780 146.180 (67.0) W8FSM Very active Echolink node 146780
147.060 147.660 100.0 N8NJN Medium
147.100 147.700 100.0 KC8KGZ Active Linked to 224.180
147.260 147.860 100.0 KC8KGZ Very active  Skywarn
147.340 147.940 100.0 W8ACW Medium
147.380 147.980 100.0 N8NE Inactive
224.060 222.460 100.0 N8NJN Inactive
224.180 222.580 88.5 KF8UI Active Linked to 145.310 N8BBR repeater in Bay City (131.8 PL)
224.480 222.880 100.0 KC8KGZ Inactive
224.620 223.020 100.0 W8FSM Inactive
224.960 223.360 W8YUC Down
442.250 447.250 100.0 KA8ZAU Inactive
442.300 447.300 91.5 W8YUC Inactive
442.350 447.350 107.2/88.5 W8FSM Active CMEN linked repeater system, Echolink node 41083, Allstar node 28236
443.925 448.925 151.4 W8FSM Medium
443.975 448.975 67.0 W8VHB Down
444.200 449.200 107.2 W8ACW Inactive?
444.375 449.375 W8JDE Inactive?
444.600 449.600 W8JDE Inactive
444.650 449.650 100.0 KC8KGZ Inactive
1253.250 439.250 KC8KGZ ??? ATV repeater, input on LSB mode, output on AM mode
South Lyon (Oakland)
147.040 147.640 110.9 K8VJ Active
White Lake (Oakland)
145.490 144.890 67.0 N8BIT Usually inactive
Clarkston (Oakland)
146.840 146.240 100.0 K8NWD Medium/active
Detroit area (Wayne/Oakland/Essex, ON)
145.110 144.510 100.0 W8DET Inactive
145.170 144.570 100.0 KA8SPW Inactive Currently still identifies as K8RUR
145.210 144.610 123.0 WW8GM Down
145.270 144.670 100.0 K8UTT Medium Linked to 224.520
145.330 144.730 100.0 WR8DAR Very active  Skywarn
145.350 144.750 100.0 K8UNS Active
145.410 144.810 118.8 VE3EOW Medium
145.430 144.830 100.0 W8JIM Pretty inactive
145.470 144.870 118.8 VE3RRR Medium
146.640 146.040 100.0 W8HP Very active
146.760 146.160 100.0 KE8HR Very active  Skywarn
146.860 146.260 100.0 KK8GC Medium
146.900 146.300 100.0 W8OAK Very active  Skywarn
147.000 147.600 118.8 VE3WIN Active
147.060 147.660 118.8 VE3III Medium
147.080 147.680 100.0 N8LC Active
147.140 147.740 (100.0) N8KD Very active
147.160 147.760 100.0 WR8DAR Active
147.180 147.780 100.0 K8UO Very active
147.240 147.840 WY8DOT Medium
147.330 147.930 151.4 KC8LTS Inactive APCO-P25 repeater, can key up with FM transceivers
224.360 222.960 103.5 KC8LTS Very inactive?
224.420 222.820 77.0 W8JIM Very inactive
224.520 222.920 100.0 K8UTT Very inactive Linked to 145.270
224.700 223.100 100.0 K8PLW Medium
224.740 223.140 100.0 W8PMN Inactive/down
442.175 447.175 123.0 KC8LTS Very active CMEN linked repeater system, Echolink node 41083, Allstar node 28236
442.275 447.275 100.0 W8TX Very inactive
442.475 447.475 88.5 W8JIM Inactive?
442.500 447.500 107.2 WB8NXP Active  IRLP node 4460
442.575 447.575 88.5 K8ZKJ Very inactive
442.775 447.775 107.2 N8BK Very inactive Echolink node 331551
442.800 447.800 107.2 WR8DAR Medium
443.075 448.075 123.0 WW8GM Medium/inactive
443.100 448.100 82.5 WR8DAR Medium
443.125 448.125 107.2 N8DJP Medium
443.225 448.225 107.2 W8HP Inactive/medium
443.275 448.275 107.2 N8ISK Inactive
443.425 448.425 107.2 K8UTT Very inactive
443.475 448.475 88.5 WR8DAR Active
444.000 449.000 100.0 WB8CQP Inactive
444.225 449.225 107.2 N8XN Medium
444.300 449.300 118.8 VE3RRR Inactive
444.325 449.325 107.2 W8OAK Medium
444.350 449.350 100.0 WR8DAR Inactive/medium
444.400 449.400 118.8 VE3UUU Medium
444.425 449.425 118.8 WR8DAR Very inactive
444.600 449.600 118.8 VE3WIN Inactive?
444.800 449.800 110.9 WA8UMT Inactive/medium
445.500 440.500 136.5 KD8NNY Very active Linked to Echolink’s *USA* conference server
927.4875 902.4875 131.8 (use D025?) KC8LTS Inactive? CMEN linked repeater system, Echolink node 41083, Allstar node 28236 (connected to links or not?)
927.6875 902.6875 131.8? (use D025?) K8UH Medium/Active Echolink node 71379, scans other repeaters around the Detroit/Ann Arbor/Toledo/Monroe area
Monroe area (Monroe/Washtenaw)
145.310 144.710 W8YZ Inactive?
146.720 146.120 100.0 K8RPT Very active  Skywarn
442.650 447.650 100.0 K8RPT Inactive?
442.825 447.825 100.0 K8RPT Medium
444.100 449.100 82.5 W2PUT Very active Linked to 927.4875 locally, and 51.740 and 927.9875 in Ann Arbor, IRLP node 4428
444.550 449.550 100.0 N8OSC Inactive
927.4875 902.4875 131.8 (use D025) W2PUT Medium? Linked to 51.740 and 927.9875 in Ann Arbor, and 444.100 locally, IRLP node 4428
Lapeer area (Lapeer)
146.620 146.020 100.0 W8LAP Very active Linked to 443.450, Skywarn
224.800 223.200 100.0 W8LAP Inactive
442.700 447.700 100.0 W8LAP Medium
443.450 448.450 100.0 KG8ID Medium Linked to 146.620

Last updated:
05/31/2013

Last updates:
Removed KD8LWR cross-band repeater and 147.420 simplex repeater (don’t worry, my 147.480 simplex repeater and 446.500 repeater will use Don’s (AE5DW) voice!).

Filed Under: Mobile/Portable, Operating, Propagation, VHF/FM/Repeaters Tagged With:
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