Adobe Flash blocked in Chrome 76

When you now run version 76 of the Google Chrome browser you will see the message shown in the screen shot excerpt below.

Click above to enlarge image.

If you click on Learn more at the right-hand side, you will see a 2017 message about the termination of Adobe Flash late next year.



 As explained in this article, Chrome now blocks Adobe Flash by default.  Flash support has been built into Chrome for a long while, thereby not requiring the user to download it separately from Adobe each time an urgent security update was needed.

Mozilla's Firefox browser will disable Flash starting in version 69.  I already have it disabled in my current version (68.0.1) of Firefox.

Based on what I see on the Adobe Flash Player download page, Flash is still supported in all versions of Windows, along with macOS and Linux. Web browsers other than Chrome may still support Flash, but the number of websites that still require Flash is rapidly shrinking.

If you still use a particular website for a service that is important to you and it will not run unless Flash is enabled, I recommend that you enable Flash only for that particular website.

John

Propagation Maps for 7 MHz

Using the VOACAP online program, I collected color-coded maps representing the predicted signal power (dB relative to 1 watt) centered on a designated transmitter site.  In the program this map is obtained from the SDBW button at the lower right corner of the main page.

I used the grid square location for W4UOA as the transmitter site and specified SSB mode, 500 W power and antenna at 33 ft (one of the limited menu selections).

The results are shown below for 1200, 1300 and 1400 UTC, encompassing the period of the RV Service net.  Below is the standard output from the program, for 1200 UTC -- covering the entire world. On the right side is a scale showing the relationship of color to the predicted received dBw signal level.

Since our area of interest for the RV Net is just the USA, I made a cropped version of each map. The results are below this one.

Click on image above for a full size view.

1200 UTC

Above is the cropped copy of the 1200 UTC map. The predicted low signal level within a few hundred miles of W4UOA is clearly seen and is consistent with the observed signal levels during the early part of the first hour of the Net.

1300 UTC

Above is the cropped version of the 1300 UTC map. The low signal (skip zone or doughnut hole) area is shrinking in size at the beginning of the second hour of the Net.

1400 UTC

Here is the 1400 UTC map, showing that good signal levels are now predicted closer to the W4UOA transmitter. This represents the end of the Net's second hour.

On a typical Thursday morning I am not able to copy W4UOA at 1300 UTC, but usually around 1330 UTC the signal comes up to a solid Q5 level. The distance from my station to W4UOA is 430 miles.

Many interesting reports and graphics are available from VOACAP, and I'm still getting acquainted with them. An excellent user guide for the online program is available at this web site. Another option for use is to download and install the program on your own computer. I may try that.

73,
John WA5MLF

AM broadcast received audio -- local and remote

Audio quality testing this morning involved reception of WWL-AM (870 kHz) on my Flex-3000 transceiver. I recorded audio samples from two places:

1. Flex-3000 speaker output
2. RCForb client program output

Below is a drawing that shows the arrangement of radio and computer software, and the software components that are involved in the two audio paths that I used for recording. I also showed the Ethernet connection to the Internet that provides the path to remote users. The testing reported here used only the data path internal to the PC and the external audio cable.

Click above to enlarge.

Here are audio recordings (about 18 seconds each) for the two audio paths. Click on each to hear the audio recording.

1. Flex-3000 speaker output via audio cable
2. RCForb client program output

Screen shots of the audio spectrum of each recording are shown below. Click on either for an expanded view.

Flex-3000 speaker output via audio cable

RCForb client program output

The RCForb graph shows high frequency content above 5000 Hz that may be due to the wide bandwidth of the Virtual Audio Channel and other data paths internal to the PC. It was not noticeable to me when listening via speakers.

John WA5MLF
 

Graphs of Maximum Usable Frequency from Ionosonde Data

In support of a forthcoming article on 40 m propagation during the daily East Coast RV Service Net, data has been collected for two ionosonde sites: one at Eglin AFB in Florida and one at Wallops Island in Virginia. The locations of ionosondes around the world can be seen at this web page. 

Thanks to Dan KC4GO for collecting data on

• critical frequency (foF2)
• MD = MUF(3000) / foF2
• Maximum Usable Frequency (MUF) 

from both sites, spanning 16 months. Data are available in plain text format from the Digital Ionogram Data Base.

The Eglin ionosonde provided 96 data sets for each day, and the Wallops Island ionosonde provided even more. Data were collected for propagation distances of 300 and 500 miles, which were chosen to represent some common distances among regular RV Net participants. The longest distance among regular participants appears to be about 1200 miles.  A review of past ionogram data shows that the MUF at 900 miles or beyond is typically about 7 MHz at the start of the 2-hour net. Shorter distances are likely to have poor to marginal propagation that improves gradually during the Net time frame.

Eglin Graphs

Below are some graphs developed from the Eglin ionosonde data. Click on any graph for a full size view.

The above graph shows the variation of MUF(300) [MUF at 300 miles] over the past 5 months, using data from 1200 UTC each day.

The above graph shows the MUF(300) at 1300 UTC on each of the dates.

 The above graph shows the MUF(500) at 1200 UTC on each of the dates.

 The above graph shows the MUF(500) at 1300 UTC on each of the dates.

 The above graph presents the variation of MUF(500) values during the 2-hour time frame of the RV Service Net.  The data points are taken from the same calendar period as the previous four graphs: 9/1/2019 thru 1/15/2019. The bottom curve shows the minimum value of MUF(500) for each time-of-day point among the 137 days.  The middle curve shows the average or mean value (across the 137 days) of MUF(500) for each time-of-day point. The top curve shows the maximum value of MUF(500) for each time-of-day point among the 137 days.

I plan to produce the same type of graph for MUF(300) [MUF at 300 miles].


Wallops Island Graphs

The above graph shows the MUF(300) at 1200 UTC on each of the dates.

The above graph shows the MUF(300) at 1300 UTC on each of the dates.

The above graph shows the MUF(500) at 1200 UTC on each of the dates.

 
The above graph shows the MUF(500) at 1300 UTC on each of the dates.



John WA5MLF

Hidden Damage to 450-ohm Balanced Line

Recently I installed new coax cable from my rig to the outdoor surge protector on the back of my garage, where the balanced feed line terminates from my multi-band dipole. This is the latest evolution of the dipole from its initial design based on pages 7 - 10 of the article Choosing the Correct Balun.  The current configuration has adopted some characteristics of a G5RV design.

While handling the 450-ohm window line I noticed that a short (1.25") section of one side of the line was able to bend at a much sharper angle than other parts of the line. Since this was part of the length I cut off, I examined it more closely by slicing away some of the insulation. The photo below shows what I saw.

Click to enlarge

It appeared that one strand of the stranded wire was still connected. I can't tell if this localized damage relates to the lightning strike in 2016 or the recent lightning strike to a nearby tree or high-power operation on 40 m or a combination of these events.

I am continuing to use and modify this antenna.

73,
John

Lightning - Sunday night

Here's a screen shot of the real time display from LightningMaps.org during a 15-minute period last night. The yellow and orange dots are the lightning detections. The blue dot is my home location.

My rain gauge collected 1.3" last night.

John

Joining Google Hangout from shared link

Here are some notes from my recent testing of joining a group Hangout on an Apple iOS device via shared link.

First, install the Google Hangouts app. The screen photo below shows the correct app to use, from the Apple App Store. There are 3 other Hangouts apps published by Google.

In order to use the app you must log in with your Google account.

My ham radio friends who meet on 3740 kHz have often used a group Hangout to supplement voice communication with live video and sharing of photos or software demonstrations / assistance. One of the group members starts a Hangout from the app on a mobile device or from a desktop / laptop computer by directing the Google Chrome web browser to hangouts.google.com.  The person starting the Hangout then copies the link for sharing (see image below) with other group members via the chatroom.  The group members can then click on the shared link to launch their Hangout apps and join the Hangout in progress.

This process works smoothly on Windows PCs, using the Google Chrome browser.  Some iPad users are able to join a group Hangout by clicking the shared link in the chatroom, viewed from the Safari browser. I have tested this multiple times successfully with a model A1474 iPad running iOS 11.4.  It is not clear whether older iPad models are able to "join via link" easily or consistently.  I've seen some indication that cookies must be enabled for the Hangouts app to work properly.

A member of a group Hangout can also send a direct invitation to another person via email, using the window shown below. Also, the copied link can be emailed to another person.

Communication between two individuals via Hangout can be initiated from the app by one person simply inviting the other.

Send me a reply if you have questions or comments.

John WA5MLF