Posts Tagged ‘Digital’

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Digital systems and amateur radio?

January 5th, 2015 | Author:

At the moment there seem to be several competing digital modulation schemes First there was ICOM’s D-star system, then C4FM from Yaesu, and of course DMR, which is gaining ground in the commercial PMR world.  There are even a few experimenting with TETRA, as used by the public services. Like Betamax and VHS, the best system may not win in the end.

At the moment, I am just not interested. I’ll wait to see who wins in the end. My bet is DMR will win in the end as there will be a plentiful second hand market from PMR. This will never be so with any proprietary system. DMR is an open standard, so there will be plentiful radios around and at decent prices before too long.

LHS Episode #136: Introduction to FreeDV

November 21st, 2014 | Author:

dv screen shotHello, everyone! We are back again with another fun and informative episode of Linux in the Ham Shack. In this episode, your hosts discuss solar flares, lots of space weather, stable and easy-to-install Linux distributions, H.R. 4969, Quentin Tarantino, dinner rolls and the amazing and fun new transmission mode for HF known as FreeDV. Don’t miss a second of this action-packed episode.

73 de The LHS Guys

NW Digital Radio

November 10th, 2014 | Author:

I keep waiting on the mythical Universal Digital Radio…

Despite the long wait, development seems to be ongoing and very interesting things are in the pipeline from NW Digital Radio. This interview with John Hays, K7VE begins at 48:50.

Filed under: Ham Radio Tagged: digital, udrx, video

1st Russian WW MultiMode Contest

November 2nd, 2014 | Author:

Dear Fellow Radio Amateurs,

The Russian Digital Radio Club has the honour to invite the radio amateurs all over the world to participate in the 1st Russian WW MultiMode Contest 2014. The objective of the contest is to establish as many contacts as possible between radio amateurs around the world and radio amateurs in Russia.

We invite all fans of digital modes to take part in contest from 12.00 UTC on Saturday 15th November till 11:59 UTC on Sunday 16th November, 2014. Types of modulation: BPSK63, CW, RTTY, SSB. The repeated contacts are permitted on different bands and different modes providing that a contact will be made not earlier than in 3 minutes. The output power should not exceed 10 watts on 160 meters and 100 watts on other bands. The operator may change the bands no more than 10 times within calendar hour (with zero on 59-th minute of each hour). Only one transmitted signal is permitted at any time.

Bands: 160 m, 80 m, 40 m, 20 m, 15 m, 10 m.

Prizes and certificates in all categories:

  • SOAB – BPSK63-CW-RTTY-SSB
  • SOAB – BPSK63-CW-RTTY
  • SOAB – BPSK63-CW-SSB
  • SOAB – BPSK63-RTTY-SSB
  • SOAB – CW-RTTY-SSB
  • SOAB – BPSK63-CW
  • SOAB – BPSK63-RTTY
  • SOAB – BPSK63-SSB
  • SOAB – RTTY-SSB
  • SOAB – CW-RTTY
  • SOAB – CW-SSB
  • MOAB – BPSK63-CW-RTTY-SSB

The certificate of the PARTICIPANT to all participants who have not borrowed prize-winning places, under condition of carrying out not less than 100 test (confirmed) QSOs.

You should send your log upload via the Web interface. All logs must be sent no later than 14 days after the contest (23:59 UTC on 30th November 2014).

73! de Russian Digital Radio Club

Filed under: Ham Radio Tagged: contest, digital

An Amazing Moment in Space Weather – Massive Solar Eruption June 2011

November 29th, 2013 | Author:

While many are talking about how Solar Cycle 24 is the weakest since the Maunder Minimum (the period starting in about 1645 and continuing to about 1715 when sunspots became exceedingly rare, as noted by solar observers of the time — see this Wiki entry), there are moments when activity on the Sun strongly increases, providing brief moments of excitement.

Here is a case in point, witnessed by the Solar Dynamics Observatory (SDO; see SDO Mission) on June 7, 2011, when the Sun unleashed a magnitude M2 (a medium-sized) solar flare with a spectacular coronal mass ejection (CME). The large cloud of particles mushroomed up and fell back down looking as if it covered an area almost half the solar surface.

SDO observed the flare’s peak at 1:41 AM ET. SDO recorded these images in extreme ultraviolet light that show a very large eruption of cool gas. It is somewhat unique because at many places in the eruption there seems to be even cooler material — at temperatures less than 80,000 K.

This video uses the full-resolution 4096 x 4096 pixel images at a one minute time cadence to provide the highest quality, finest detail version possible.  The color is artificial, as the actual images are capturing Extreme Ultraviolet light.

It is interesting to compare the event in different wavelengths because they each see different temperatures of plasma.

Credit: NASA SDO / Goddard Space Flight Center

Video: http://g.nw7us.us/1aOjmgA – Massive Solar Eruption Close-up (2011-06-07 – NASA SDO)

Visit: SunSpotWatch.com

 

At 522,000,000 miles per watt, Voyager 1 might be the ultimate in QRP.

October 2nd, 2013 | Author:

At 522,000,000 miles per watt, Voyager could be the ultimate in QRP … if you have the right antenna.

For most HAMs the experience of seeing sub-one watt WSPR signals decoded from across the globe is enough of a thrill. However, the fine folks at the National Radio Astronomy Observatory have taken this a little further and used the Very Long Baseline Array radio telescope to precisely pinpoint the position of the Voyager 1 space probe.
While the layperson might see detecting the glimmer of 22 watts across the vastness of space miraculous, the amateur radio community can see this feat as the natural evolution and refinement of the technology and medium we know and love.
From nrao.edu:
Earlier this year, the National Science Foundation’s Very Long Baseline Array telescope turned its gaze to NASA’s famed Voyager 1 and captured an image of this iconic spacecraft’s faint radio signal. The Green Bank Telescope also detected Voyager’s signal, picking it out from the background radio noise in less than one second.

Astronomers using the National Science Foundation’s (NSF) Very Long Baseline Array (VLBA) and Green Bank Telescope (GBT) spotted the faint radio glow from NASA’s famed Voyager 1 spacecraft — the most distant man-made object.

According to NASA’s Jet Propulsion Laboratory (JPL), the VLBA imaged the signal from Voyager 1’s main transmitter after the spacecraft had already passed beyond the edge of the heliosphere, the bubble of charged particles from the Sun that surrounds our Solar System.

Using NASA’s Deep Space Network, JPL continually tracks Voyager and calculates its position on the sky, which is known as the ephemeris. Since the VLBA has the highest resolution, or ability to see fine detail, of any full-time astronomical instrument, NRAO astronomers believed they could locate Voyager’s ephemeris position with unprecedented precision. This is unrelated to Voyager’s distance from the Sun or position relative to the heliosphere.

The initial observations, which were made on February 21, placed Voyager very near, but not precisely at its predicted location. The difference was a few tenths of an arcsecond. An arcsecond is the apparent size of a penny as seen from 2.5 miles (4 kilometers) away. The second observations on June 1 produced similar results.

“It is possible that these observations are at the milliarcsecond [one-thousandth of an arcsecond] level, or better,” said NRAO scientist Walter Brisken, who led the observations with the VLBA. At 11.5 billion miles — Voyager’s approximate distance at the time of the initial observations — one milliarcsecond would be roughly 50 miles across.

Voyager’s main transmitter shines at a feeble 22 watts, which is comparable to a car-mounted police radio or — in visible light — a refrigerator light bulb. Though incredibly weak by the standards of modern wireless communications, Voyager’s signal is astoundingly bright when compared to most natural objects studied by radio telescopes.

“The ability to pinpoint the location of Voyager and other spacecraft is critical as we explore the inner Solar System and beyond,” said Brisken. “The NRAO’s VLBA has the capability to do this vital task with unprecedented precision.”

Voyager 1, which was launched in 1977, is now headed away from the Sun at a speed of about 38,000 miles per hour.

In a remarkably sensitive complementary observation, the NRAO’s Green Bank Telescope (GBT), which is the world’s largest fully steerable radio telescope, easily detected Voyager’s signal, picking it out from the background radio noise in less than one second.

“Voyager is the first man-made object to penetrate the interstellar medium, and we really want to be able to receive the data from this new frontier,” said NRAO scientist Toney Minter, who oversaw the Green Bank observations. “This information will provide many clues about how the interstellar medium behaves and how the Sun interacts with it.”

“NRAO’s instruments have the capability to provide the most accurate position information of distant spacecraft like Voyager,” said NRAO Director Tony Beasley. “The remarkable sensitivity of GBT and VLBA’s sharp vision are essential for discovery but also have unique capabilities that have enabled us to make this contact with one of humanity’s most ambitious missions of exploration.”

The VLBA is a system of radio antennas located across the United States from Hawaii to St. Croix. The antennas work together as a single telescope nearly 5,000 miles across, giving the VLBA its ability to see fine details. Only seven of the VLBA’s full complement of 10 antennas were used to make these observations.

The 100-meter GBT is located in the National Radio Quiet Zone and the West Virginia Radio Astronomy Zone, which protect the incredibly sensitive telescope from unwanted radio interference. The GBT observations were made by NRAO scientists Toney Minter and Frank Ghigo, and Green Bank Director Karen O’Neil.

Show Notes #097

January 3rd, 2013 | Author:

Introduction:

  • Welcome to another episode of Linux in the Hamshackedness, where the Chocolate Shake Fairy visits Richard.

Announcements:

  • LHS now accepts micropayment donations via Flattr. It’s been successful for the Linux Outlaws guys, so we’re giving it a try here.
  • We now have a countdown timer on the Web site that shows the time remaining until the next live recording. Of course, now that we’re recording on Wednesdays, we’ve decided to move back to Tuesdays. That will happen in January. Keep an eye on the web site for the dates. (Tuesday, January 8, 2013, as of this moment.)
  • We also have a Google Community for Linux in the Ham Shack. It’s a great method for leaving feedback, show suggestions, questions, hate mail or anything else.
  • The Dayton Hamvention 2013 will be coming up soon, so we’ve added the donation thermometer to the website. Please make a donation and help send LHS to Dayton again in 2013.
  • Sign up for the LHS mailing list, too.
  • Gnorman has a bio on the LHS About Us page.

Topics:

  • Raspberry Pi in the Ham Shack
    • Russ has been working on getting an Echolink node running on his Raspberry Pi.
    • He’s chosen Raspbian as the operating system, which is based on Debian Wheezy.
    • Installation consists of downloading the iso, using dd to copy it to a secure digital card (SD flash memory card), booting the Raspberry Pi with the SD card, and following the prompts to install.
    • VK2MEV has posted instructions for configuring a Raspberry Pi as an Echolink node.
    • So far, Russ has Raspbian installed, as well as svxlink and qtel, but has not yet connected it to the usb sound card or attached it to his Rascal GLX interface to control the radio. Another option would be to use the Pi’s GPIO bus to control the radio instead of a digital mode interface.
    • VK2MEV also has a page describing WSPR on a Raspberry Pi. (Another page is VK2MEV’s blog on WSPRnet.)
    • Ted, WA0EIR, says he thinks some folks have his PSK31LX program running on a Raspberry Pi.
    • Russ mentions that there is a Slackware build for the Raspberry Pi.

Feedback:

  • Cory, KD0QEA, asks if there are any “hangout” radio frequencies for LHS hosts and listeners. Well, Cory, there are none due to lack of time for the hosts to get on the radio. However, perhaps our listeners would like to establish an LHS net. Email your suggestions for bands, frequencies and times and we’ll announce them on the podcast. When Russ gets his Echolink node/Raspberry Pi running, he’ll be there more often. The node number will be 54711 (LHS11 on the telephone pad).
  • Doug, N6LMX, left a voice mail about the Raspberry Pi. He has one and wonders which ham radio apps can be used on the Pi. He’s also using Raspbian as the operating system. Doug will be attempting to create a media center with his, as well as ham radio applications. Russ suggests running the Pi headless and using ssh from a smartphone or tablet to access it. That would avoid having to carry a monitor and keyboard around with the Pi. It’s likely that most of the popular Linux ham applications, such as fldigi, would work fine with the Pi, though you may need to compile them yourself. As for the media server idea, the Pi may not be quite powerful enough. Raspbmc is based on XBMC, and might be the best option. Ted, WA0EIR, has several Linux ham radio applications that should work quite well on the Pi. Richard also wonders if there are folks running APRS on the Pi, and there’s at least one. Thanks for the voice mail, Doug. We appreciate it.
  • Dave, M0DCM, has been catching up on the show, and responds to episodes 95 and 96. He uses 75-ohm coax as a feedline with a 1:1 balun to horizontal and vertical dipoles, and is able to bypass his tuner on 21 and 24MHz. He goes on to describe his Linux and radio activities. Thanks, Dave.
  • Thanks to everyone who sent happy birthday messages to Russ.
  • Gorkon, aka Joel, says there may have been a problem with the ogg version of episode 96. Russ will take care of it if he finds the problem.
  • Mike, from Sugarland, TX, has been trying to use N3FJP’s Amateur Contact Log (ACLog) program for logging, presumably under WINE, but it crashes and he wonders if anyone else has had any experience with this. If any of our listeners have tried ACLog under Linux, let us know, or respond on the Google+ LHS community. Russ suggests forcing WINE into 16-bit compatibility mode.

Contact Info:

Music:

  • None this episode.
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