Jeena Lee @theJeenaLee
Found one of the coolest vending machines in psu!!
KW5GP built a 40m JT65 transceiver powered by Arduino. You can too. #qsotoday bit.ly/1DGZ3E5
Jeena Lee @theJeenaLee
Found one of the coolest vending machines in psu!!
Here are the latest two videos in the One-Day Tech Class series:
Here are a couple more videos from the one-day Tech Class that I taught on January 30, 2016 at the University of Michigan.
I get occasional e-mails from MCM Electronics, pushing a variety of products, and every once in a while, something catches my eye. This morning, they were advertising a Four Element Directional Outdoor FM Antenna (see photo at right) for $25.
This seems like it would be a good deal, if it could be modified to operate on 2m. Have any of you ever tried this? It seems to me that all you’d have to do is shorten the elements a little bit.
By comparison, a four-element, 2m Yagi from ARROW Antenna costs about $80.
Last Friday night, I spoke about CW to the Central Michigan Amateur Radio Club. They have several members who are really interested in learning CW, and one of the things they plan to do is to set up a 2m CW net using modulated CW (MCW). I had just the perfect project for them.
Ten years ago, I purchased a little keyer called the PicoKeyer from a company called HamGadgets. The cool thing about this keyer is that it has an MCW mode that allows you to easily send CW with your FM transceiver. In MCW mode, the keyer’s output acts like a push-to-talk switch. I added a little circuit to bring out the audio and connected both of those signals to the packet connector of my ICOM IC-207.
I described all this to them and promised to send them links to the post here on my website. Before I e-mailed them, I thought I’d better check if HamGadgets was stlll in business and if they were still selling the PicoKeyer.
There’s some good news and some bad news about this, though. The bad news is that HamGadgets no longer sells the PicoKeyer. The good news is that they now offer a product called the Ultra PicoKeyer. It still has an MCW mode and comes in a little plastic enclosure. It now costs $29, instead of the $18 I spent for mine. So, you pay a little more and get a little more. It’s still a pretty good deal in my opinion.
One thing the new Ultra PicoKeyer is that it has an audio output. The original PicoKeyer did not. With the new keyer you don’t have to kludge something together like I did to operate MCW.
You still need to make up a cable with a couple of 3.5mm plugs on one end and whatever connector your rig needs on the other. Some radios, like the ICOM IC-208H actually has a packet port on the back that takes a 6-pin DIN connector. All of these connectors are available from HamGadgets at very reasonable prices.
I was thinking of purchasing one of these kits and some connectors and “upgrading” my current setup. What I have works just fine, though, and I don’t really need another project on my workbench. I do encourage any of you who are interested to give it a try, though. If you do, e-mail me and tell me how it goes.
The Tiny Radio Telescope wp.me/pk3lN-TZe
I found this in the June 2016 issue of the Eastern Michigan ARC Sparks…...Dan
If you want to use a repeater, make a legal transmission (see Section 97.119 Station identification).
If you want to “kerchunk” a repeater, just to see if it is working, don’t bother.
If you want to use it, go ahead and use it. If it is down, you will know right away.
If you are “just testing” and the control operator turns off the repeater because of your illegal transmission, then everyone loses.
-Mike AA8K
Recently, someone forwarded an e-mail from Rick, K1RJZ, to an amateur radio mailing list that I subscribe to. I found Rick’s comments to be so right on, I asked him if I could publish them here as a guest post, and he agreed. Thanks, Rick!
At Dayton this year, it was no surprise that digital technologies got a lot of attention, including HF software-defined radios (SDRs), like the ICOM IC-7300 and the FlexRadio 6000 series, and VHF/UHF digital radios, such as the Tytera DMR radio that sells for about $130. Hams are excited about digital radio because it is something new to explore. As you can see below, it was standing room only at the DMR Forum at Dayton this year.
One of the reasons for this excitement is that they are software-based, and unlike hardware radios, SDRs (some are really HF radio servers) are easily upgraded, and manufacturers can add compelling new features as technology changes. That means that you get a new radio every year without needing XYL approvals!
If you follow technology (smartphones, laptops, the internet, whatever), you know that there are certain common phases that all technologies must pass through. These include the pioneer stage, the early adopter stage, and then “the chasm.” Once a technology adoption has survived these three stages, it then reaches the mass adoption phase, and it begins to grow very quickly. Competing technologies then need to adopt. If they don’t, they will eventually fall by the wayside.
There is no question that DMR technology (Digital voice Mobile Radio) for hams has jumped the chasm and is now into the mass adoption phase, and may soon enter the low-priced commoditization phase. Inexpensive, mass-produced Chinese DMR digital voice + FM portable radios were being sold inside the Hara arena for as low as $109 with a color display and free programming software. Remember that these are Part-90 type accepted, commercial-quality radios, not low end junk with dirty transmitters and low quality RX audio.
In addition, there were many used, first generation Motorola DMR radios for sale in the flea area. These radios perform just as well as the current models, but have less memory. From what I saw at Dayton, I have no doubt that DMR is on a run and is now well into the low-priced mass adoption phase.
D-STAR, Fusion and to a lesser extent NXDN are all established and are not going away, but in many areas they are not experiencing any meaningful growth when compared to DMR. D-STAR repeaters in New England, for example, have been converting to DMR because DMR radios are far cheaper than D-STAR radios, have more features, and have far superior networking. ICOM D-STAR repeaters have not been highly successful in high-RF areas, such as you typically find on top of skyscrapers and busy mountaintop sites. The D-Star technology is way cool, the ICOM repeater hardware… much less so. Some repeater clubs have figured out ways to use non-ICOM RF guts for their repeaters, and those have been successful, but it also takes some smart techie-hams to pull that off. A tip of my hat to them!
Many clubs are wisely taking advantage of the subsidized Yaesu Fusion repeater offers but most in New England seem to be using them in either dual mode or FM-only Mode. Fusion in digital mode has been very slow to get traction in these parts of the world. It is not a bad format, but Yaesu got in the game very late, Fusion is proprietary and has far fewer working features than other technologies. As a big plus, Fusion in high-bandwidth mode can send pictures such as “ground truth” weather status pictures. Most other digital voice modes cannot do hat.
NXDN, another commercial digital voice format used by the railroad industry, has some pockets of ham activity such as in southeastern Massachusetts but nationwide adoption is very slow. I don’t want to sound biased, I’m just reporting what I am hearing from multiple face-face sources and Dayton presentations.
None of these digital voice technologies or FM will go away and all of the digital modes are generating a lot of interest in the hobby. They are all fun and if you are a ham, you will have a ball trying them out. I have used D-STAR and P25 digital voice for years, and though I have yet to try Yaesu Fusion, I am very much looking forward to it. But, from what I saw at Dayton, DMR now seems to be a serious leader the digital voice technology adoption curve.
For more information, check out a recent DMR podcast on the HamRadio360 podcast.
Only July 1, 2020, this post will become obsolete, as the new Extra Class question pool goes into effect. Click here to view the section from the updated study guide.
E2D – Operating methods: VHF and UHF digital modes and procedures; APRS; EME procedures, meteor scatter procedures
One of the most commonly misunderstood concepts in digital communications is the baud. A baud is not equal to a bit per second, except for very simple systems. Rather, the definition of baud is the number of data symbols transmitted per second, and a data symbol may represent multiple bits.
While modern Internet digital communication techniques can send and receive digital data at MBps speeds, digital communications over amateur radio links is much slower. Under clear communications conditions, 300-baud packet is the digital communication mode that has the fastest data throughput. (E2D09)
In the past ten years or so, the number of digital modes has just exploded. JT65 is one example. The type of modulation used for JT65 contacts is multi-tone AFSK. (E2D13) One advantage of using JT65 coding is the ability to decode signals which have a very low signal to noise ratio. (E2D14)
JT65 is a digital mode especially useful for EME communications. (E2D03) JT65 improves EME communications because it can decode signals many dB below the noise floor using FEC.(E2D12) One of the reasons that JT65 is such an effective method of establishing EME contacts is because it uses time synchronous transmissions alternately from each station. (E2D06) JT65 software organizes the timing of contacts by alternating transmissions at 1 minute intervals. (E2E03)
APRS
One of the most popular digital modes is the Automatic Packet Reporting System, or APRS. Most APRS operation takes place on the 2 m band around 144.39 MHz.
AX.25 is the digital protocol used by APRS. (E2D07) AX.25 is more commonly known as packet radio. Unnumbered Information is the type of packet frame used to transmit APRS beacon data. (E2D08)
APRS stations can be used to help support a public service communications activity. An APRS station with a GPS unit can automatically transmit information to show a mobile station’s position during the event. (E2D10) Latitude and longitude are used by the APRS network to communicate your location. (E2D11)
Amateurs that enjoy satellite communications also use digital modes. For example, store-and-forward is a technique normally used by low Earth orbiting digital satellites to relay messages around the world. (E2D05) The purpose of digital store-and-forward functions on an Amateur Radio satellite is to store digital messages in the satellite for later download by other stations. (E2D04)
Meteor scatter
Digital modes can also be used to make meteor scatter contacts. FSK441 is a digital mode especially designed for use for meteor scatter signals. (E2D01) All of these choices are correct when talking about good techniques for making meteor scatter contacts: (E2D02)
NOTE! On July 1, 2020, this post will become obsolete as the 2020 Extra Class question pool goes into effect. Please refer to the post from the 2020 No Nonsense Extra Class Study Guide instead.
E2B- Television practices: fast scan television standards and techniques; slow scan television standards and techniques
Although we are called “radio” amateurs, we can also transmit and receive television signals. There are several ways that amateurs communicate by television. Perhaps the two most popular ways are standard fast-scan television and slow-scan television (SSTV).
The video standard used by North American Fast Scan ATV stations is called NTSC. (E2B16) The NTSC, or National Television Systems Committee, is the body that set standards for the analog television system that was used in the U.S. and many other parts of the world. After nearly 70 years of using the analog NTSC system, U.S. broadcasters switched over to a digital broadcasting system on June 12, 2009.
A fast-scan (NTSC) television frame has 525 horizontal lines (E2B02), and a new frame is transmitted 30 times per second in a fast-scan (NTSC) television system. (E2B01) NTSC systems use an interlaced scanning pattern. An interlaced scanning pattern is generated in a fast-scan (NTSC) television system by scanning odd numbered lines in one field and even numbered ones in the next. (E2B03)
In order for the scanning beam to only show the picture, a technique called blanking is used. Blanking in a video signal is turning off the scanning beam while it is traveling from right to left or from bottom to top. (E2B04)
NTSC signals are amplitude modulated (AM) signals, but use a technique called vestigial sideband modulation. Vestigial sideband modulation is amplitude modulation in which one complete sideband and a portion of the other are transmitted. (E2B06) The reason that NTSC TV uses vestigial modulation is to conserve bandwidth. Even using this technique, an NTSC signal is 6 MHz wide. One advantage of using vestigial sideband for standard fast- scan TV transmissions is that vestigial sideband reduces bandwidth while allowing for simple video detector circuitry. (E2B05)
Amateurs can transmit color TV as well as black-and-white TV. The name of the signal component that carries color information in NTSC video is chroma. (E2B07)
There are a number of different ways to transmit audio with an NTSC signal. The following are common methods of transmitting accompanying audio with amateur fast-scan television:
All of these choices are correct. (E2B08)
Because of the bandwidth requirements, amateurs can only transmit fast-scan TV above 440 MHz. FM ATV transmissions, for example, are likely to be found on 1255 MHz. (E2B18)
Because SSTV is normally found on the HF bands where bandwidth is at a premium, one special operating frequency restriction imposed on slow scan TV transmissions is that they are restricted to phone band segments and their bandwidth can be no greater than that of a voice signal of the same modulation type. (E2B19) The approximate bandwidth of a slow-scan TV signal is, therefore, 3 kHz. (E2B17)
SSTV images are typically transmitted on the HF bands by varying tone frequencies representing the video are transmitted using single sideband. (E2B12) The tone frequency of an amateur slow-scan television signal encodes the brightness of the picture. (E2B14)
128 or 256 lines are commonly used in each frame on an amateur slow-scan color television picture. (E2B13) Specific tone frequencies signal SSTV receiving equipment to begin a new picture line. (E2B15)
There are a number of different SSTV modes. The function of the Vertical Interval Signaling (VIS) code transmitted as part of an SSTV transmission is to identify the SSTV mode being used. (E2B11)
Digital Radio Mondiale is one way to send and receive SSTV signals. No other hardware is needed, other than a receiver with SSB capability and a suitable computer, is needed to decode SSTV using Digital Radio Mondiale (DRM). (E2B09) Just like any SSTV transmission, 3 KHz is an acceptable bandwidth for Digital Radio Mondiale (DRM) based voice or SSTV digital transmissions made on the HF amateur bands. (E2B10)