Tuesday, December 15, 2009

NIST will re-test P25 radio under high-noise scenarios in 2010


A while back (July 2008) I discussed a report from the International Association of Fire Chiefs on NIST/NTIA testing of digital vocoder performance in high-noise environments such as firegrounds.

NIST has announced that they'll be re-testing in 2010 with new DVSI vocoders. Urgent Communications reports that next year’s tests will be similar to the previous tests, in that the same noise environments will be explored. Key differences include the use of a mask with an internal microphone, use of radio reference systems to avoid manufacturer settings and the addition of "radio-channel impairments" that are designed to emulate the impact of a firefighter receiving a weaker signal when entering a building. This latter aspect (effects the so-called "digital-cliff" in low signal or degraded propagation environments) was a key component missing from the 2008 tests and I'm glad to see it being included on this round.

I'm still not sure about the wisdom of using proprietary vocoders (DVSI) for radio systems. We have enough interoperability challenges as it is; do we really want to tie next-gen radio systems to licensing from a single manufacturer? The digital radio world really needs to come up with a viable open-source vocoder.

Saturday, December 12, 2009

An example of why amateur radio is failing to attract young people

I follow various hams on Twitter and in blogs. Some because they're friends, some because they're part of my local radio community, and some just because I like what they have to say. There's another smaller group I follow, which is people I tend to not agree with. In the same way that conservatives will listen to NPR and watch CNN as a way to better understand and counter the liberal/socialist viewpoint, reading these people's tweets and blogs helps me understand why amateur radio continues to slide into obscurity.

Mike WA4D's "MEWCOMM" blog and Twitter commentary is one which I typically don't agree with. His position on matters relating to amateur radio are highly representative of a mindset which pervades the hobby, and which I believe is ultimately counter-productive to the hobby's evolution. I will use Mike's writings as proxies for opinions held by others, so apologies to Mike in advance; this is not intended to be a personal attack at you. To be fair; I like and agree strongly with Mike's perspectives on politics and foreign policy, but his judgmental attitude towards no-code hams (i.e. those who have not learned Morse Code or "CW" in the parlance) happens to be a perfect example of why amateur radio is failing to attract young people into the hobby. A sampling of Mike's comments include:
  • People who don't know how CW "are not real hams".
  • Removal of the CW testing requirement was equivalent to "affirmative action" or a "back door".
  • CW defines the "soul of the hobby" and "defines what a real ham is in the 21st century".
In 2006 the FCC was in the process of implementing WRC-03 recommendations which would later eliminate CW testing as a requirement for amateur radio licensing. I filed comments with the FCC during the comment period in support of this decision, in which I asked "Is the true measure of technical prowess the ability to understand what amounts to a language?" Indeed; my experience is that hams who know code are no better or worse operators or technologists than hams who don't know code. Some of the smartest hams I know -- hams who have contributed real value in the application of computing technology to radio -- are Extra-class hams who never learned Morse Code. My opinion? These people, and the technology they're developing, will truly define amateur radio in the 21st century.

Mike recently wrote that no-code hams "know not of the 'thrill of recognition'", which I infer to mean that they're not real hams because they're never experienced the "satori" moment of completing their first Morse Code contact. Having experienced the "thrill of recognition" for CW and other modes I can say that while the satori moment for CW is indeed exciting, it's no stronger or more "real" than the satori moment I had when I made a 10,000+ mile contact using JT65A on HF at 50 watts of power into a hand-made antenna cobbled from $2.00 worth of spare parts and wire. I remember both experiences equally well, and yet the JT65A contact is more memorable (and a source of greater pride for me) because I did it using a new (at the time) mode on jury-rigged hardware. But following Mike's logic I guess this wasn't a real accomplishment because it involved use of a computer, and at the time I didn't know how to send & receive CW..?

Amateur radio is a "big tent" hobby which offers something for everyone. If the hobby were healthy, growing, and not in danger of obsolescence I would say "Live and let live" and be done with it. But opinions such as "people who don't know or use CW are not real hams" are too prevalent among a majority of hams, with the end result being that bright young people who might want to explore amateur radio's application to computers and digital communication are scared away by older hams who insist on defining "real radio" in terms that they can understand.

The danger is that, as older hams pass on and are not replaced by younger hams, we will reach a point where the government decides that amateur radio spectrum can be put to better use. ARRL or not, the ham population will be too small to defend our allocation, and combined with decreasing relevance and value to emergency communications we will eventually lose our spectrum. Proficiency in CW and adherence to traditions will not solve this problem and help us keep our spectrum. The only solution is to open our minds, embrace change, and get over this self-defeating need to hold up 100+ year old technology as the gold standard against which new technology must compare.

The crux of the problem is that the prevailing majority has defined amateur radio and its reverence of traditions as an immutable core. This is horribly wrong and ultimately self-defeating. We should instead be seeking ways that encourage the applying of amateur radio to new technologies, and in doing so continuously finding new relevance and recruiting new hams. "Real hams" are those that are creating innovative technology which applies amateur radio to technology, such as Chris K6DBG's hack that converts a Wi-Fi router into an APRS receiver. Speaking the "language" of Morse Code isn't proof of technical ingenuity, doesn't prove that a ham is innovative or intelligent, and arrogantly judging hams based on their ability (or not) to use CW drives away new recruits and will NOT save our hobby.

Saturday, December 5, 2009

Drinking the Kool-Aid

A while back I set up a Twitter account for the Wireless Communications Alliance (http://twitter.com/wcaorg) and have, on occasion, tweeted from it about non-WCA events. Not a problem, but I thought it was time to set up a personal account so if you like please follow me via http://twitter.com/w6dtw

in reference to: David W6DTW (W6DTW) on Twitter (view on Google Sidewiki)

Saturday, November 28, 2009

TV repair tools: screwdriver, wrench, drill...Did you say "drill"?


A few weeks back my Samsung DLP TV went on the fritz; showing a green tile pattern when playing analog sources, and randomly freezing when playing HDMI sources. After doing some research I found that this is known problem in the digital board on the HLR5067WAX/XAA and other TVs in the series where the DNIe chip (which is a BGA-type package) develops a loose connection. (Root cause was probably a mistake in the solder mask or poor QC on application of the solder paste prior to chip placement.)

The problem can be resolved by (of course) purchasing a new digital board for hundreds of dollars. Some of the sharp minds in the peer forums over at Home Theater Shack have found that if you can apply pressure to the DNIe chip, the problem goes away. So I opted to follow the process outlined by Leonard and Tito over at HTS for installing a mechanical pressure arm to push on the DNIe chip. I figured it was a few bucks, a trip to the hardware store, and some of my time.

I built the arm into the digital board's RFI/EMI cover, adjusted it to apply just a bit of pressure, and re-assembled the TV. Works 100%. Saved myself a few hundred dollars and now I can say I once fixed a TV with a drill and a tube of Loctite.

Sunday, November 22, 2009

SO2R -- The hard way


This past weekend I had the privilege to be a guest operator for the Radio Club of America on their special event station W2RCA, celebrating the 100th anniversary of the RCA. The station was co-located with the anniversary event in Washington DC, and I wasn't able to attend in person, so the operation was handled using remote PC access and VOIP software, similar to the setup which I described back in late 2007.

A problem with remote setups is that they require a fast Internet connection to work well; the primary challenge being the speed (or lack thereof) at which you can switch from receive to transmit and back again. Because the W2RCA special event station was scheduled to happen during the ARRL's November SSB Sweepstakes, it was decided that we would work the contest as W2RCA. Being in a contest situation meant that rapid TX/RX switching would be a must.

As it turned out the network connection between my home and the RCA event location wasn't quite fast enough for the furious pace of the contest. I was having a hard time getting the remote radio keyed quickly enough to bust the pileups. In some cases I would bust the pileup only to have the target station get frustrated because I wasn't coming back to him fast enough. Not good, not good...

Out of curiosity I turned on my home station and tuned to the same frequency as the W2RCA remote. I found that despite being separated by 2,500 miles I could hear the target station well on both radios! Not wanting to give up on the contest for lack of fast TX/RX switching I decided to try an odd twist on SO2R (Single Operator-Two Radios) setup. I activated transmit on the W2RCA remote station, muted my microphone, and plugged my headphones into my home station. Because SSB is carrier-less mode the remote radio would not transmit any power with the microphone muted.

The next time the target station called QRZ I unmuted my microphone and called him, and heard him come back to me on my home station! I was able to work several stations this way, although there were still a few challenges. First was the effort of keeping the frequency of ftwo radios in sync. Second was some of the stations I could hear clearly on my home station were outside the range of the W2RCA remote station. But in general it worked and was an interesting way to get around the slow TX/RX switching issue.

Thursday, September 10, 2009

..-. .. .-. ... - -.-. --- -. - .- -.-. - <= (First Contact)


This week marked a big milestone for me; I successfully completed my first radio contact using CW aka Morse Code. It was a tough contact; conditions were bad but the guy I worked was polite and patient with me so we managed to pull it off.

I had always believed that I simply did not have an "ear" for code; it sounded like noise to me and I was never able to get past a basic understanding of the mechanics. After the amateur radio code requirement was lifted I was thankful and quickly upgraded to the highest level license. Still, in the back of my mind I felt I should make a real effort to learn code; if for no other reason than to overcome a personal limitation. (If you think I have a strong aversion to being told what to do; I have an even stronger aversion to being told what I can't do -- even if I'm the one doing the telling.) So my 2009 resolution was to learn enough code to complete a radio contact. It took me nine months, but I made it. I don't know that I will ever be a "real" CW operator, but right now I'm having fun and feeling good about my accomplishment.

I would like to thank the following people who helped make this happen for me:
  • Gerald Wheeler (W6TJP) - Author of the Code Quick learning method. A great basic foundations course.
  • Fabian Kurz (DJ1YFK) - Developer of the LCWO.net website. An awesome online Koch-method trainer. Did I mention it's free?
  • Leon "Skip" Stem (WB4DAD) - CW operator, FISTS member, and the first entry in my CW contact logbook. Thanks for being patient with me.

Wednesday, August 26, 2009

You, um, expecting trouble? BIG Batteries...


Through a contact at an SF Bay Area web hosting company I recently obtained for free a set of used -- but still very strong -- UPS batteries; the Deka/Unigy 31HR5000. This hosting company offers their customers a 100% uptime guarantee which means that they can't wait for their UPS batteries to fail; they are used for a number of months and then they're replaced. Since the hosting company has to pay someone to come haul them away they're happy to see them repurposed.

These batteries aren't the typical deep-cycle marine variety you see on Field Day. They weigh 95 lbs each. Fresh from the factory they're rated at 135 amp-hours, which is about 1,800 watt-hours. My main HF rig (Kenwood TS-2000) consumes about 200 watts worst-case (when keyed on 2 meter FM, set for 100 watts) which means that using one of the Deka batteries I could leave my rig keyed-down on 146.520 FM @ 100 watts and it would remain on the air for about 9 hours.

I now have 3 of these monsters running in parallel on my home station. That's over a full day of continuous talk time. Left in receive-only mode my station will run off-grid for about 8 days.

Total cost? About $40 for some 4-gauge jumpers and misc hardware.

Bring on the zombie attack. I'm ready.