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SDR USB radio: GWRX. Cubic SDR

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For a couple of months, the audio of today’s show is here. Recent shows are here.

The intro and outro music was by Pentatonix.

 

Both Paul and Glenn were in the studio today.

 

Paul mentioned that archive.kvmr.org has the audio from recent KVMR shows and that one can listen to a live stream of the shows by going to kvmr.org click on Listen Live.

Forgetting that there was a Community Calendar to present, Paul continued to explain that over the air digital broadcasting <not over internet, but similar to digital TV> has a sub-carrier to carry information such as station ID, weather info, amber alerts, etc.

Paul said he’s had experience as a radio amateur in his teen years when enthusiasts would often build their own radios transmitters. That’s not done much anymore as there are many inexpensive off the shelf transmitters. One lowest cost 2-meter transmitter is from a Chinese company called Baofeng with a digital display and keypad.

The test for a basic level 3 amateur license is no longer about constructing a transmitter, but more about what frequencies you can transmit on, how antennas work, what to do about interference or an emergency, etc.

Paul said he’s thinking about getting back into amateur radio by getting a license, He’s already found a radio for $22 <he gave no details>. Generally, no license is required for listening to radio broadcasts, he added.

Paul bought a Chinese USB device called an SDR, software defined radio. You can plug it into a PC, Linux or Mac computer with one end, and plug an antenna into its other end. The SDR takes the analog radio signal that comes in over the antenna, converts it to digital and then sends it to the computer. It’s the computer that decides what to with it. At this point, Glenn insisted on doing the Community Calendar, which took a few minutes.

After the Community Calendar, Paul announced that Sierra Roots is opening up a cold weather shelter this Sunday and Monday at 4pm at the veteran’s building located at 415 North Pine Street Nevada City.

Paul continued talking about SDR, software defined radio. He said he was aware of 2 SDRs — google either GWRX or Cubic SDR. He thought GWRX can work on PC, Linux and the Mac computers. The documentation that comes with it will get you started.

For radio, the antenna is cheapest part and the weak link, he said. It’s worth the trouble and attention you give it. For shortwave listening it’s simply a spool of wire strung out in such a way so as not to lose current down to ground. This is done by insulating the ends at the point of suspension. It’s not necessarily true that the longer the wire the better. The direction the wire faces and how it’s connected is more important.

GWRX will show you a spectrum of what’s being transmitted, on your screen. You can see all sorts of weird stuff depicted by bumps along the spectrum. He found that 121.5 FM is a frequency used by a local airport.

Paul clarified that no license is required to use an SDR because it’s incapable of transmitting. It’s only a receiver. You “hack and freak and do anything and tune anywhere” with an SDR.

Paul tried to receive the station WWV, which provides precise time signals. It’s the oldest continuously transmitting radio station in the US.

Call letters for radio stations West of St Louis generally start with a ‘K’ (KVMR) and those East with a ‘W’. It got started in the East, around Washington in the 1920s. It’s now in Colorado but retained the ‘W’. Funding for WWV is being threatened in part due to new technology — computers & mobile devices get their time synched over the internet.

Glenn mentioned that he bought a refurbished iPhone 8 (a late 2017 model) with 64 gigs of memory. He found that it’s exactly the same size as his iPhone 6S and fits into the Otter Box that he is currently using.

He said iPhone 8 from Oct 2017 and later models have Qi (chee) charging, meaning it can charge wirelessly. The charging is done inductively.
<More info about Qi here.
Qi was first mention during the 11-26-14 show>

Glenn bought a charging case for his iPhone 6, which does not use Qi charging. It’s from Patriot called a Fuel Ion and it’s $5 at Fry’s. It’s still on sale, he said. When the iPhone 6 is plugged into the case, the case itself can charge the phone. <At first I thought he meant it uses the Qi charger. But Paul pointed out, in a way I couldn’t follow, that it uses some concentric gold plated circles to do contact charging, it’s not inductive.>

When Glenn turned on his iPhone 8 and it got past the ‘language greeting’, it said “if you would like to change over from your previous iPhone to this iPhone, put the two of them next to each other.” Paul said you have to be using at lest IOS 11 to migrate one to the other. Glenn said it did an excellent job with the settings, alarms and the pre-entered wi-fi information. And it was quick. It didn’t migrate the apps. He had to use iTunes for that.

Paul said there’s some indication that Google is trying to change Android into a platform independent OS so its apps will work on more platforms.

Paul mentioned that SSDs (solid state drives) are replacing the spinning drive market. Their price keeps coming down and one day soon, if not already, the number of machines sold with SSDs will exceed those with mechanical drives. Glenn noted that they use less electricity. Paul said it’s typically 1.5 to 2 watts, judging from the one he bought. And they work much faster. If Paul has to repair someone’s computer, he’ll often replace a spinning drive with an SSD. Paul said he tends to stick with brand names for SSDs like Samsung, Sony or San Disk. <SSDs were mentioned on the 8-9-17 show.>

Glenn spoke more about the refurbished iPhone 8 he just bought. It comes with a 1-year warranty. And you can buy Apple Care for it for $130, which adds an additional year. But Glenn contacted customer service for his Citi Costco Credit Card to ask about, what he thought, a 1-year extension on the warranty. He found out that they now offer a 2-year extension. So he didn’t get the Apple Care. However, Paul pointed out that Apple Care covers more than his credit card would.

Glenn invited listeners to call 530-265-9555 with their questions and comments.

Ellen called. She had to get a new phone along with a new number, and ported her old number to Google Voice. Her phone now rings “when it comes in to the other number”, but when she answers it, the call is cut off. Glenn said that he also has Google Voice and he’ll have Paul call him to see if he has the same problem. He’ll report the results in the show notes.

Paul said there are a bunch of setting for Google Voice. Go to google.com/voice. One of the settings Paul likes requires the caller has to say their name. He thought she might have it turned on in her settings and it’s causing the problem. She can test it, but not by using her own phone — she should call her Google Voice number from an unrelated phone line and see what happens.

Scott called about the 121.5 airport frequency that Paul talked about. He said it is the emergency frequency. He thought that particular frequency might soon be decommissioned. The aircraft band goes from about 108 megahertz up to 135. The lower half, up to about 118, is generally for navigation. The rest is for voice. And it mostly uses AM, not FM.

Scott expressed his surprised that it’s taken so long for inductive charging to come to phones. His toothbrush uses it, and it’s 10 years old. Paul said the reason might because of the need to insure the rest of complicated phone circuitry isn’t adversely affected.

Glenn had been charging his iPhone 8 inductively during the show. He reported that it just now hit 100%. It took 53 minutes to go from 81% to 100% charged. The iPhone 6S, where he “added the inductive charge”, it went from 78% to 95% charged.

Paul said induction charging side steps the potential problems of using a large current of around 2 amps to charge a phone, which can shorten the lifetime of the battery and possibly damage the contacts.

Battery life can also take a hit if it’s much above room temperature — nearing 90 degrees F. Battery “age stars to degrade and the number of cycles available decreases with temperature over time.”

Paul said he’s been using Ubuntu Linux for many years. Others have espoused Mint Linux. He’s now found out that Mint is based on Unbuntu and uses the same upgrade path. It’s much more lightweight and uses the Cinnamon desktop. The Cinnamon desktop is also very lightweight and it’s “the most efficient distribution of Linux” Paul has seen for old machines with limited hardware. It should be a good replacement for Windows XP. It’s also available for 32bit machines. If you’re about to turn you computer over to the recycler, give Mint a try.

Paul mentioned an internet of things (IOT) alarm system for around $50-$60 from China. The Nest thermostat learns your behavior, Glenn added. There’s a potential to save energy and money as products get smarter.

Last Updated 12:29 AM 11-29-2018