Twin Panadapters

Click above to enlarge.

This screenshot shows the simultaneous capture of panadapter views at WA5MLF and W4UOA this morning. A QSO at 3745 kHz had one station that was strong enough for Carl to hear as splatter in the 3740 pass band. See Carl's screenshots here for better views of the effects at his location.

The station was not strong enough to be heard at WA5MLF below 3742. John's screenshot (panadapter with waterfall) shows some other random noise below 3740 (we were not transmitting at that time). The wiggly line around 3742 on John's waterfall display is RFI from an APC UPS in the other room.

- John

Google Hangouts to W4BXI and W4UOA

This is a screen shot from my PC yesterday morning, showing simultaneous Hangouts -- one for the audio to/from W4BXI's rig and the other showing W4UOA's panadapter in operation. Each Hangout is in a separate web browser. I added labels in yellow italics to all windows. Click on the image for a full size view.

- John WA5MLF

Google Hangouts: Video + Phone

A recent update to the Hangouts app removed or lost the ability to add phone users to a video (computer-to-computer) hangout. Many Hangout users complained about this change, and a forum posting provided  a way to run the older Hangout app to regain the phone calling feature.

Here is a summary of the process:

1. In your web browser address (URL) box, type g.co/hangouts.

 

2. Add users by:

• email invite
• call a phone (use keypad icon)
• share hangout link (e.g. via chat session)

3. Enter a phone number (or a contact name)

 At any time after starting the Hangout using g.co/hangouts, computer or phone users can be added by clicking the "people+" icon to get the window shown in step 2 above.

Lightning damage to antenna

On July 14 my multi-band dipole antenna had a lightning encounter of some degree. Below are some photos showing damage to the feed point and the surge arrestor that is mounted on the outside wall of the garage.

 Here is a view of the feed point after I lowered it to eye level. The front part of the Ladder-Loc mount was blown away, but the electrical connections are intact.

Later I found two pieces of the front part and put them in place as shown in this photo. I have not found the other pieces.
The front part of a new unit might fit in place of the one that was damaged, if the dimensions have not changed much. I could simply secure the feed line and use the back part as is, without a front.

 This photo shows the inside of the balanced line surge arrestor, model AS-309H from Array Solutions. The referenced PDF file gives specs and explains the design features.
The feed from the antenna enters at the bottom, connected to the two long machine screws. At the top end of each screw a gas tube protector and a 1 Mohm resistor connect to a ground lug. The resistor provides a path for static charge to bleed off. A capacitor at the top of each screw connects to the balanced output lugs for the portion of feedline that enters the house.

Here is an annotated close-up of the area that shows the visible damage. Click on the photo for a better view. The two resistors have normal readings. I plan to replace both gas discharge tubes. The two capacitors are not shorted, based on ohmmeter readings, and don't appear to be open, based on transceiver operation and SWR readings. They may have changed somewhat in capacitance and should probably be replaced, too.

At the transceiver end of the feedline, I inspected the balun and found no visible damage. Ohmmeter readings revealed no shorts or grounds.







Update: In February of 2017, when adjusting the lengths of the dipole legs, I found additional evidence of the lightning hit at the southwest end of the dipole. See the two photos at the end of this posting.

John

LIGO

On June 18 I enjoyed a visit to the  Laser Interferometer Gravitational-Wave Observatory (LIGO) installation at Livingston, LA. You can see an aerial view of the facility at this page.
To learn about LIGO, see the links at this page.

I was part of a tour group arranged by the Baton Rouge Amateur Radio Club. Our tour started one hour ahead of the normal monthly public tours. Our tour guide was Dr. Amber Stuver, a research scientist who has been working at LIGO for the past 8 years. We started at the LIGO Science Education Center, viewing two video presentations and Dr. Stuver's presentation with Q and A. Then we walked over to the main building to visit the control center where staff members use a room full of computers and monitors to oversee and control the operation of the system.  The detection of a gravitational wave event is not recognized in real time by the system operators. Analysis of the collected data from this facility and the Hanford, Washington facility leads to the identification of events. Two have been announced as of this writing. This article in Science News includes an audio player (see "Chirp, Chirp") for hearing the waveforms associated with the two announced events.

Below are additional views from our visit to the control room. The observatory is not currently operating, since it and the Washington state companion installation are undergoing  modifications to boost their sensitivity, to enable detecting more events. They are scheduled to resume operation in the 4th quarter of 2016.

I labeled the top 3 monitors to match the small label seen on each. They represent 3 different frequency ranges, corresponding to the types of vibrations that each displays. The graphs move from right to left, with new data added to the right side at 1-minute intervals.

System diagram displayed on a large wall monitor.

While looking at the various monitors in the control room, I recognized the presence of Apple and Linux desktop user interfaces. Our guide confirmed that those are the operating systems in use for the system. In a later question from a club member we learned that Matlab and Python are the main software environments used for data analysis. It would have been interesting to see some of the laser, optical, and detector hardware, but I don't know if those are ever included on public tours.

We returned to the Science Education Center to explore more of the hands-on exhibits there. Many of them involved aspects of wave behavior in various media.

Here is a photo of a Giant Slinky that is probably 25 ft long. It is suspended from vertical wires, allowing it to flex horizontally when the visitor moves a lever connected via a vertical pivot. This photo was taken before our tour started. The education center had many visitors when we returned from our tour as lots of folks were waiting for their tours that started every 20 minutes or so.
Below are additional photos showing other exhibits and the many afternoon visitors.

On our way out I took this photo where you can just see part of the concrete structure (near center, between trees) that houses the evacuated steel tube comprising one of the two 4 km (2.5 mile) tubes that form the laser paths of the interferometer. Many photos, graphics and videos are available on this gallery page.







Our guide encouraged us to return for another visit when the facility is operating.

Digital TV Resources

These are some links I collected over the years to help with using over-the-air Digital TV:

Find local broadcast channels:

• Antennapoint 
• Antennaweb 
• TV Fool

Other sites of interest:

• DTV Reception Maps
• Program Listings
• Digital TV Facts
• HDTV Info
• Accessories
• Home Entertainment Supplies

 John

Windows 10 Upgrade Topics

There is much discussion now about recent changes in the Windows 10 upgrade notifications and behavior, and the scheduled July 29 end of the free upgrade availability. Below are some recent articles that address these topics.

• Windows 10 Hits 300 Million Active Devices, Free Upgrade Still Ends July 29
• Microsoft Will Turn Off Windows 10 Upgrade Nagware In July
• The Ability to Cancel or Schedule the Windows 10 Upgrade is Not New

An alternative to upgrading in-place is to perform a clean install. This requires more work, but results in better performance and reliability by virtue of not carrying forward the baggage and debris accumulated by years of running Windows 7 or 8. Below are some articles about clean installation.They cover much of the same ground, with some variation in wording. The first link gives important details about the overall process, including how to handle your programs, files and settings. Note: in order to use the media creation tool you must be logged in with an Administrator account.

• How to clean install Windows the right way
• Microsoft instructions for media creation and clean install
• How to do a Clean Install of Windows 10, the Easy Way
• Revive a Windows 7 system with a clean install
• How to Clean Install Windows 10 on a Solid State Drive

Windows 10 Guides:

• Complete Guide to Windows 10 
• Understand and Configure Privacy Settings

Also see these two Youtube videos:

• 5 Things You Should Do After Upgrading to Windows 10
• Windows 10 Beginners Guide

Frequent Lightning Disrupting 75 m

Frequent lightning on the morning of 4/27/16 dominated my reception on 3740 kHz (and all of the 75 m band). The 24-hour map of lightning below shows where the activity was located. Yellow represents data that is up to 15 minutes old, relative to 0535 CDT. Orange is up to 2 hours old, and red through blue represent data that is 2 to 24 hours old.

From LightningMaps.org - Click to enlarge.

My SDR receiver display below shows that static crashes were very frequent and very broad-banded.The top part of the display is the panadapter format, with signal level represented on the vertical scale and frequency (kHz) on the horizontal scale. The bottom part of the display is the waterfall format, with time progressing vertically down the display, frequency on the horizontal scale, and average signal level represented by color.

Panafall display at 0623 CDT - click to enlarge

Compare this display with the one in my earlier post that showed less frequent lightning activity compared with a nice strong signal from W4PRE.

Static crashes vs W4PRE

W4PRE signal at 0614 CDT, interrupted by static crashes from storms in Texas. Phil was S9+18 when captured.

Below is a wider view showing static crashes.

Weather Sites

The web offers us many richly-detailed web sites devoted to weather. Here is a list of many of the best known, and a few others, in no particular order:

• National Weather Service
• Storm Prediction Center
• The Weather Channel
• WeatherSpark
• Intellicast
• Weather Underground
• AccuWeather
• WeatherBug
• Alabama Weather Blog

Lightning data maps:

• LightningMaps
• StrikeStar
• Vaisala
• Blitzortung

Linux Distributions and Desktop Environments

We've had recurring discussions on HF radio about Linux, especially following the end of Microsoft support for Windows XP and the arrival of Windows 10. For some Windows users, Linux offers an effective alternative to upgrading or replacing older hardware. I've used Linux for many years on an alternating basis with Windows. Currently I use only two applications at home that do not have Linux versions or equivalents, and my understanding is that they do not run under the Wine software that enables many Windows programs to run on Linux. At my part-time job I am supporting Windows 7 computers, so it is helpful to maintain familiarity with that environment.

Linux provides many opportunities to learn more about computers and networking, and has many capabilities that are less common or are absent from Windows. Occasionally these have been helpful for me to troubleshoot computer hardware and network connections, and have helped to distinguish between hardware and operating system software troubles.

Most users of personal computers can accomplish the majority of their routine tasks with software applications on Linux. System maintenance does require some new learning, but all who use and maintain Windows today had to learn to use it, too.

For my friends who are curious about Linux and want to try it out or even use it part time or full time, I assembled this collection of web links that address the following topic areas:

• Linux challenges & tips
• Choosing a Linux distribution
• Choosing a desktop environment
• Trying Linux without installation 

____________________________________________________

 Linux Challenges & Tips

• Why it's not mainstream - This article explores some of the issues that inhibit greater adoption for desktop computers. As noted above, you need to be willing to learn if you want to install and use this operating system. Most Windows users are using computers with Windows pre-installed. There are a few computers available for purchase with Linux pre-installed.
• Rules for a new Linux user - The author gives some tips for the new user. Her recommendation of carefully choosing your first distribution relates to my second topic area below. She includes a link to a separate article to cover the question "should I use Linux".
• Helpful Communities - This lists some of the communities that are good resources for finding resolutions to problems encountered. There are general Linux communities as well as distro-specific communities. 
• Tips & how-to articles: 
• Linux collection from How to Geek
• Tips & Tricks collection from Make Tech Easier

Choosing a Linux Distribution

• Best Linux Distributions for Beginners
• 10 Linux Distributions Compared
• The Best Linux Distributions 
• DistroWatch provides a comprehensive catalog of distributions (BSD and Solaris in addition to Linux) with details, applications, reviews and download links for each. You can browse, list the major distros or search based on your criteria, such as older hardware. 
• Windows 7 >> Elementary OS

Choosing a Desktop Environment (DE) (e.g. GUI)
You select a distribution and use its included default DE or change the DE after installation.

• Environments for Ubuntu - Be sure to see the How To Get It section under each DE description.
• 5 Best Desktop Environments  - with pros and cons of each
• Another 5 Best Desktop Environments list 
• Top 10 Desktop Environments 

Trying Linux Without Installation
Many computer hobbyists like to download a Linux distro and try it out before installing. There are two options for this

• CD /DVD - After downloading the chosen Linux distro ISO (disk image) file you use a program that can burn a CD  or DVD with the ISO file. You can then boot the computer from this disk, but the performance is limited by the slow speed of the optical drive.
• USB Flash Drive - Better performance is obtained by running Linux from a USB flash drive, but not all computers can boot from USB. Here are some of the available programs for making a bootable USB flash drive with your chosen Linux distro:
• UNetbootin
• LinuxLive USB Creator
• Universal USB Installer

 A bootable Linux CD or DVD is a good tool to keep for troubleshooting on any computer.