Posts Tagged ‘Digital’

LHS Episode #090: Purple Hays

Here we are at Episode #090, just 10 away from the century mark. Things have been rolling along fairly smoothly, and except for Russ being deathly ill for the last eight days, there’s not even a lot to complain about. In this episode, we have yet another interview. This time it’s with John Hays, K7VE, of Northwest Digital Radio. These guys are producing an entirely new purpose-built radio platform called the UDR56K. This technology promises to be a great advance in the amateur radio arena as well as in the computing arena. It’s a bit of kit that’s going to find a use in almost every radio amateur’s shack. If you want to find out why, please sit down and take a listen to this episode of LHS. We promise you will not be disappointed.

73 de The LHS Guys

Show Notes #088

Introduction:

  • A sticky, stormy night in Texas, just right for podcasting and Russ’ attempt to take over the MintCast.

Announcements:

Topics:

  • Pimpin’ the network: If you have a podcast and want to reach LHS listeners, please visit Black Sparrow Media and contact us to become a member! The Waveguides Podcast did and so can you.
  • Who is your hero in amateur radio, living or dead? Let us know! Richard is gathering information for his super-secret project.
  • Storm watchin and workin on radios. While a storm raged in Texas, Richard received an email about an IC-735 that would not power on reliably. Richard’s trouble-shooting philosophy: start with the things that are cheap to replace.
  • Richard is hoping to pursue a high-speed multimedia (HSMM) and mesh radio project using DD-WRT or OpenWrt for use in emergency communications. Used routers, such as the Linksys WRT54GL, are ideal and can be found for little money.

Feedback:

  • Leif, KC8RWR, wrote to clarify a comment to episode 86, explaining that he’d like to try using an NE602 frequency converter to an RTLSDR radio to receive ham bands.
  • Brian, G3XGY, heard Russ on the Mintcast and is looking forward to listening to episodes of LHS! Welcome, Brian.
  • Leif, KC8RWR, offers a suggestion for Grant, who was having difficulty with the LHS live Linux CD handed out at Dayton. He thinks it may have been due to Linux not recognizing Grant’s video card. Thanks, Leif.
  • Harrison, VE2HKW, a sometime participant in MintCast, expresses his appreciation for episode 85, our interview with David Rowe and discussion of Codec2. Thanks, Harrison. Speaking of Codec2, Russ reports that David Rowe has won the 2012 ARRL Technical Innovation Award for his work on Codec2. Congratulations, David!
  • Harrison, VE2HKW, wrote to ask for help with his Icom IC-735 (as mentioned above).
  • Claudio of the LinuxBasement podcast thanks us for the mention in episode 87.

Contact Info:

Music:

  • “The Television Song” by Bryan Dunn, from the album Vicious Waltz, courtesy of Jamendo.
  • “Total Breakdown” by Brad Sucks, from the album Out of It, courtesy of Jamendo.

LHS Episode #088: Total Breakdown

Hello, esteemed listeners. Welcome to the latest installment of Linux in the Ham Shack. Tonight, Richard and Russ take the first third of the podcast to get a few topics off their minds that they’ve been thinking about over the past several weeks, whether or not those topics have anything to do with amateur radio or Linux. Wedged in the middle, discussion of wireless networking comes up, using HSMM and inexpensive Linksys hardware to provide Part 15 and Part 97 based communications for local, regional and EMCOMM use. Then our cagey hosts finish up with a mad dash through feedback, giving useful advice to those listeners with enough mettle to write in. Thanks as always to our loyal followers. We appreciate each and every one of you, each and every fortnight.

73 de The LHS Guys

The $20 Software Defined Radio

Introduction:

Despite my interest in boat-anchors I do find myself peeking ‘over the wall’ from time to time and taking a look at new and emerging technologies. After several demonstrations from friends I had become convinced of the incredible potential of software defined radios and even found thinking about owning one … one day.

Perhaps the best known SDR in amateur radio circles are the FLEX rigs from FlexRadio. I had the chance to see a FLEX-3000 in use during Winter Field Day 2011 and had to admit that, barring the lack of knobs & dials, it was a very impressive rig!
One thing stopped me from running out and buying one straight away was the cost and perhaps the notion that once the new had worn off I would regret the significant outlay required to own the blue box. So, I shelved the idea of owning an SDR and found other things to occupy my time.
This changed when a post on www.reddit.com/r/amateurradio/ mentioned an unmodified digital TV receiving USB device that had been used as a software defined receiver in the 60MHz – 1.7GHz range. The best part was the cost, around $20 for most examples of this kind of device. Finally software & commodity hardware had come together to deliver useful receiver that everyone can afford.
The nuts and bolts:

There are specific parts required to put together your own $20 SDR but I will document what I used to get mine running and hopefully you can follow along.
Hardware: The device that I used was a Ezcap EZTV668 DVB-T Digital TV USB 2.0 Dongle purchased from DealExtreme. The part was shipped from Asia and I gather from reading else ware that DealExtreme is a middleman and not the actual supplier. Be prepared to wait a while if ordering from this supplier, my Ezcap took about 3 weeks to arrive but I have heard that a month or more is not uncommon.
The upside is that shipping is free and your purchase involves 0% tax, this really IS a $20 SDR.
This particular DVB-T dongle uses the RTL2832U chip which is required for use as an SDR, other dongles with this chip may work but if it does not have the RTL chip it will NOT work currently.

Software (Linux) : After poor results with the software running on MS Windows I moved across to Linux and got it working well there. I can’t point you to a single howto for this because I used several different guides and tried a few things before it started working. The most helpful, and probably all you really need, are the build-gnuradio script which gets hardware support and gnu-radio running and the “Getting Started With RTL-SDR” page by Tom Nardi which covers installing Gqrx. All the software used is in development and requires familiarity with the command line to install and use at the moment.

Software (Windows) : I had another shot at getting the MS Windows software running and stumbled across the excellent website http://rtlsdr.org. Rtlsdr.org mentions using a new version of SDR# software which worked very well! 
I would recommend following the instructions under the Windows Software section, this had me up and running in a matter of minutes. Follow the instructions EXACTLY, I made life hard on myself by not paying attention to details and I think was responsible for my earlier issues.
Going further – Antenna : The stock antenna that is supplied with the Ezcap EZTV668 is sufficient for testing but you’ll want to add something a bit more substantial for regular use. You may even want to remove the existing (hard to find) antenna connector from the board and install a standard connector and a less flimsy metal casing. This will help with RF shielding and temperature stability. 
If you are going to use a larger antenna, especially an outside antenna, you’ll want to check to make sure a protection diode has been fitted to the input. The Ezcap EZTV668 is a very inexpensive device and others have found units in which the protection diode was not fitted to save costs.
Going further – 160M – 6M ? : I’ve just seen an interesting blog post titled FunCube Upconverter where the author, George Smart, has built a converter allowing the reception of 160M – 6M using the FunCube dongle. The FunCube is functionally the same as the RTL dongles available for $20. For any home brewers out there this could be a great project as George has included all the details including schematics and board artwork required to build the converter.


Update : Thanks to a link from Neil W2NDG to an EBay sale I’ve been able to track down a pre-assembled HF up-converter on this page : New HF Converter Kit for the SDR Fun Cube Dongle The price seems to be 45 euros, or about $55 US.

I’ve had a lot of fun using the $20 SDR to listen to AM aircraft traffic, local repeaters, emergency services and amazingly good quality broadcast FM stereo programming. Its easy to see, with an SDR, just how wide a radio broadcaster is transmitting and move your filter bandwidth to match.

Hopefully this is just the beginning of inexpensive SDR hardware that the radio community can re-purpose and re-engineer. 

Show Notes #085

Introduction:

  • “You know it’s summer in Texas, because all the truck tires shed their winter coats.”
  • This episode, an interview with David Rowe, VK5DGR.

Topics:

  • Our hosts conduct a lively conversation with David Rowe, VK5DGR, from Adelaide, South Australia.
  • David is the author of Codec 2,, an open source speech codec designed for communications quality speech.
  • You can find more information about David and his project on his blog.
  • Powerpoint presentations and Youtube videos of how Codec 2 works are available on his Codec 2 blog page.
  • You can see David’s presentation of Codec2 at linux.conf.au here.
  • David then describes the Mesh Potato project, an open hardware product designed specifically to build telephone networks without infrastructure like cell phone towers or land lines.
  • The Mesh Potato is available for purchase.

Contact Info:

Music:

  • None.

The unfortunate & epic saga of the perfect military radio

The long awaited but ultimately unwanted GMR radio

As my day job starts to include more long term projects & project management I was particularly intrigued by an article in arstechnica.com. The article is, “How to blow $6 billion on a tech project“, although the title may be more inflammatory than technically accurate.

The article covers the 15 year development of an advanced & unified military radio communications system that suffered from multiple issues including scope-creep & a rapidly changing underlying technology.

If you are involved with a group that is working to develop a product or service you’ll really get something from this article. If you interested in radio systems, military or otherwise, you’ll find this interesting as well.

Its hard to image the frustration people suffer when contributing to a project that is mismanaged unless you have been there yourself. I hate to think of the wasted effort that resulted when people found out How to blow $6 billion on a tech project

Show Notes #083

Introduction:

  • Back from Dayton and ready to go.

Topics:

  • Dayton Hamvention 2012
    • LHS had the same booth as last year at North Hall #131. Estimated attendance was 25,000 individuals. Russ recounts the experience. Thanks to Matt, KC8BEW, who stopped by and helped out at the booth. The LowSWR podcasters stopped by, too.
  • FCC Dismisses Texas Ham’s Fourth Petition, Calls it “Repetitive”
    • Our hosts discuss.
  • Contest logging for Linux.
    • Several people at Hamvention asked about contest logging software for Linux, but Russ was at a loss for a recommendation. Upon his return, he discovered…
    • SO2SDR Contest Logging Software
    • Stefano, IZ3NVR/KD2BGM was trying to get so2sdr to work under Linux Mint and while it would compile, it did not run, so Russ set about trying to get it going.
    • It’s not packaged for Debian or Fedora, so it must be built from source, available at the link above.
    • The program is written in Qt, so it can be run on devices which support that environment, including Linux and Windows. Of course, Qt must be installed in order to compile so2sdr.
    • Russ also had to install the following packages on his Linux Mint machine: portaudio19-dev (NOT libportaudio-dev; apparently, libportaudio-dev is too old), fftw3 and fftw3-dev
    • The compilation procedure consists of:
                    qmake
                    make
                    sudo make install
    • so2sdr compiled and ran fine. It did complain that it wanted a parallel port for switching between radios, but you can ignore that if you don’t need to do that.
    • Russ gives an overview of the features and capabilities.
    • There are a few drawbacks:
      • An apparent lack of SSB support? It seems to be CW-only.
      • Frequency input checking is broken.
      • Keystrokes are not intuitive, but are well-documented.
    • However, the built-in help file is quite useful.

Feedback:

  • E-mail from Larry, KG4Q, extolling fldigi and JT65-HF. He wishes there was a version of JT65-HF for Linux. Well, Larry, there is! You can download the source here. Also, WSJT does JT65, too.
  • Chris, K4FH, caught up with Russ at Hamvention and talked about his Linux in the Ham Shack presentation. He managed to put together a fine bunch of slides completely without our help. Sorry, Chris!

Contact Info:

Music:


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