The Internet and Radio Propagation

I wanted to share with you three web sites that I am aware of that can show you how propagation is faring on the various amateur radio bands. These propagation tools don't attempt to explain the propagation modes, such as sporadic-E, tropospheric ducting, F₂ layer skip, etc. They just present the user with a map depicting the actual propagation.

Here are the sites:

• VHF Propagation Map
• PSK Reporter
• PropNet Project

I'm going to discuss the first one in this post and leave it to a future (but soon) post to discuss the other two sites.

The VHF Propagation Map can display a map of North America, Europe, Australia, Minnesota, Missouri, or the world. I understand the emphasis on Minnesota. If you examine the URL of the site you will notice that the VHF Propagation Map is hosted on a site for a Minnesota school system. I'm not sure why Missouri gets special emphasis. The map attempts to display various 2-meter radio paths with the different color-coded swatches (for lack of a better word). Yellow colors represent shorter paths; orange a little longer, and red being the longest paths. The data behind the map is obtained from the APRS-IS system. Basically in the early days of APRS, the packet-radio system was entirely RF-based, but then the Internet became commonplace, and the data from the RF side of things was fed to the Internet. The "IS" stands for Internet System. It is all of the APRS data traveling on the APRS-IS system that makes sites such as Findu and this propagation map possible. The VHF Propagation Map site does explain that some HF data may be mixed in, but I figure the percentage of HF data is pretty low. I don't pretend to know everything about APRS, but I believe earlier on, HF (and in particular, 30-meters) was used for long-haul transmission of APRS data. The Internet does that now. Anyway, this website looks at the APRS-IS data. It knows where each station is because position is reported as part of the packet, and it knows where the packets came from that the stations heard, because the transmission path is part of the packet. The website analyzes that data and plots the map.

From a practical standpoint, the user of the VHF Propagation Map, clicks on an area of interest, such as North America. If their geographical area is covered by a yellow, orange, or red swatch or blob, they can expect enhanced communications on 2-meters. If the patch is red, they should probably be able to hit distant repeaters, or communicate long distances on SSB, or CW. During the 2008 summer sporadic-E season, I visited this site a few times. Sure enough, large sections of the eastern U.S. where covered with red criss-crossing swatches. Why not the western U.S.? This site does rely on actual APRS stations. There are sections of the country (Rocky Mountain region, Nevada, Montana, and so on) that just don't have as many amateur radio operators.

So try out this site, and when color appears over your location, fire up your radio and try to hit a distant repeater, or see how far you can talk on simplex, or get out your all-mode rig and work on picking up some more grid squares. Although this site relies on data from the 2-meter band (specifically the 144.39 MHz APRS network), you might look at the higher bands such as 222 MHz, or 430 MHz, if 2-meters starts opening.

73

Back on APRS

After a little bit of a delay, I am back on APRS. APRS is an acronym for the Automatic Packet Reporting System. I've probably been on APRS off and on for about nine years. Nine years ago is about the time that Kenwood introduced their TH-D7A handie-talkie (HT). It was fairly groundbreaking at the time, and until recently was the only HT that could do APRS, let alone packet radio. Around the time of the 2008 Dayton Hamvention, however, Yaesu (Vertex Standard) announced the VX-8R, that promises APRS and packet capability.

Well, anyway, I was an early adopter of the TH-D7A, and used it quite a bit when I first acquired it. A few years later, Kenwood indicated that they were introducing a "G" version of the TH-D7A. I'm not sure what the letter "G" meant, but this new radio added some incremental features to the APRS capabilities. One of the more notably features, if I remember correctly, was the ability to do 9600 bps APRS and packet. Around the same time Kenwood said that for a fee, owners of the non-"G" version could ship their radios to a Kenwood Service Center for a firmware upgrade. I did not do that right away. I probably waited a year or so, but I eventually sent it off. I continued to use the HT off and on, but at some point my usage declined and the radio stayed in my carrying case. When I decided to start using it again, I first discovered that all of the batteries that I had wouldn't hold a charge anymore, so I had to buy a new battery. Sometime after buying the new battery, I used that radio and an Arrow Antenna to make my first contact through the AO-51 satellite. I talked about this in an earlier post. A little more time passed and the radio itself developed a problem. Everything was fine except for the display. The display is a dot-matrix type of display, but it was showing strange characters. They were characters from the ASCII set, but nonetheless I could not understand why they were there, and I tried everything to correct the problem including a full reset. At that point, I decided to sell the radio on Ebay. I fully disclosed its problems and the radio was sold.

Meanwhile, I had purchased a Kenwood TM-D700A at the Dayton Hamvention, I believe. I had every intention of installing the radio in my car, but that never happened and the radio never left the box. I eventually sold it on Ebay.

This spring, however, I was helping my local ARES (Amateur Radio Emergency Service) group, the COARES (Central Ohio ARES), provide communications support for the Tour of the Scioto River Valley (TOSRV). The COARES leaders indicated that APRS would be used this year, and that volunteers would space digipeaters about every two miles along the 100+ mile course (leapfrogging no doubt). I knew that my newer TH-D7A (G)--forgot to mention that I bought this radio brand new to replace my failing TH-D7A--would probably have problems in the hilly areas of southern Ohio. I decided that I would buy a Kenwood TM-D710A (the successor to the TM-D700) and become active in APRS. So I bought the radio a couple of weeks ago and got it set up last night.

I'm currently operating it as a base station under the callsign of N8OIF-9. You can view my position at the Findu site. The position is slightly off because at the present time, my position is hard-coded into the radio. I'm waiting on a GPS receiver to arrive that should provide better precision.

73

More Ham Radio Purchases

I've been doing quite a bit of buying and selling lately with regard to my amateur radio equipment. Last summer I bought a second HF rig, the Yaesu FT-897D. Actually, it is a MF/HF/VHF/UHF radio. It's a great little rig and includes features such as AF-DSP, a TCXO, and coverage of the 60-meter channels. I also bought an AT-897 autotuner made by LDG electronics. This tuner bolts to the left side of the radio. That rig is rounded out with LDG's FT-Meter. This adds an analog meter to the 897D. I placed my order for a second Tigertronics Signalink USB, that will interface this radio to my computer for sound card HF digital modes. I have recently sold three HTs. The first to sell was a Yaesu VX-7R. It was a great radio, but I had four HTs and that was too many. The second HT to go was my Kenwood TH-D7A. Again, a great radio with APRS and packet capabilities, but I have other plans. Finally, the HT that I sold most recently was my Icom IC-91AD FM and D-Star radio. The reason that it had to go was because I had purchased the IC-92AD (a beefed-up, submersible, more-versatile version of the '91). Another purchase that I made at the 2008 Dayton Hamvention was a new mobile rig, the Icom IC-2820H. A few weeks after the show, I added the UT-123 digital voice and GPS board. Earlier I mentioned that I had other plans for packet and APRS. In a couple of months, I plan to buy the Kenwood TM-D710A mobile radio. There are times when I would like to run APRS but I need more than five watts of power. Another purchase that I will make shortly is a third HF rig, the Icom IC-7000. I will talk more about these purchases in a future post. 73.