Understanding Linux

The website How-To Geek published this article about 10 popular distributions of Linux. Of the ones listed, I have used, to various degrees, Ubuntu, Mint, Slackware and Puppy. I'm using one as I write this, but the web is (thankfully) agnostic.

The above article contains several links to other articles that can provide a better understanding of what all the Linux choices and piece-parts are about. If you are curious, I suggest browsing the following articles in this order:

What Is A Linux Distro
A brief discussion of the concept of a Linux distribution

8 Pieces of Software That Make Up Linux Systems
This one covers in more detail the components of a distribution.

Linux Desktop Environments
This one covers various desktop environments that may be part of a distribution or may be pulled into a Linux installation. A Linux user may choose from among several distributions that are identical except for the desktop environment. Those who wish to use or try Linux on older hardware are often advised in web articles or postings to consider the light-weight desktop environments Xfce or LXDE. Some Linux veterans have actually set up their installations to enable switching between two different desktop environments. Most users probably try out several distributions, running from a live CD (slow) or a USB flash drive before choosing one or more to install in some permanent fashion.

The web site Distro Watch is my favorite for finding and exploring different distributions. You can browse the main page or use the search filters to find candidate distributions for certain needs. You'll also note that the site catalogs BSD and Solaris, in addition to Linux. For those who are curious, this article explains the difference between BSD and Linux. The use of BSD as the base of Mac OS X is mentioned.

John

WiFi Tips & Tools

Episode 76 of the Know How show on TWIT.TV covered some good tips and tools for setting up and maintaining your 2.4 GHz WiFi system. (They promised to cover the 5 GHz band on a future show. I'll search for that after completing this post.) There's a brief summary in the show notes -- scroll down the page to the topics: WiFi Tools, AP/Router Setup, and Antennas.  I recommend downloading and viewing one of the video copies of the show. Jump ahead in your video player to 18:51 where the WiFi topic coverage starts. It runs about 13 minutes total.

Update: Now see this discussion of using multiple access points. 

Several WiFi tools are mentioned in the Know How show, to help with evaluating the coverage within your home or business. After viewing the show back in January I added the free WiFi Analyzer to my Android phone. I also like another program inSSIDer that is not mentioned in the show. I've used it with good results on my Windows laptop and my Android phone. The current version 4 for Windows and Mac is available here for $19.99, but the free version that I installed a while back is still available elsewhere. The Android version costs $9.99.

John

Microphone specs & equalization

Since obtaining my Flex-3000 transceiver months ago I've been using the supplied FHM-1 hand microphone.  Early reports from my ham friends said that my voice sounded muffled compared with how I sounded using the old desk microphone with my Heathkit SB-104A. Below is a copy of the microphone specs graph from FlexRadio.  A switch on the microphone has two positions for what they call "tone settings":

• Setting 1 has a flat frequency response of 60 Hz to 16 kHz.
• Setting 2 rolls off some of the low end frequencies (-6 dB at 300 Hz) and provides 3 dB of boost at 2 kHz for "optimum articulation needed for DX / communication quality audio".

On-air reports indicated no appreciable difference between these two settings.

I explored the transmit audio equalization settings in the Flex-3000 to compensate for the microphone's apparent poor high frequency response.  I tried several configurations to boost the treble, up to the available maximum of +15 dB. Although I thought I had all the right boxes checked and buttons clicked, the audio reports were still unsatisfactory. I began to test some quick and dirty arrangements to use either my Andrea NC-61 headset or my original dynamic desk microphone in place of the FHM-1 microphone. These efforts indicated a need for better impedance matching and better shielding to prevent hum. My most recent inclination was to build a microphone preamp circuit in a metal box to accomplish impedance matching, gain, and powering (for the Andrea's electret element). The Flex-3000 front panel jack has 5 V DC available along with PTT, ground, and a balanced microphone input. A rear panel line audio level input is also available.

While reviewing the transmit audio equalization settings early this week I observed the audio closely on the audio spectrum display of the PowerSDR program and listened to myself on the SB-104A. The saved audio profile that I created months ago was not doing what the equalizer curve said it should. I created a new profile from scratch and found that it really did improve the audio spectrum appearance and sound. On air tests the next day confirmed this.  Below is a screen shot of the equalizer settings I am now using.

Note that the audio is boosted 15 dB at the 2 kHz and 4 kHz bands of the equalizer, and is cut below 500 Hz. The little Enabled check box can toggle this equalization with one mouse click. I found that this box was unchecked on the profile I had previously created and saved. I don't know if I lost track of that box during multiple changes followed by multiple saves or if I toggled it off for working digital modes. For the latter, I am now using saved profiles that set frequencies, bandwidth, equalization and audio paths (virtual audio cables) to ensure correct operation while making it easy to return to voice modes.

Thanks to all for their helpful signal reports!

John

80 m Loop Feedpoint SWR

As an aid to recent discussions of whether to use 300-ohm or 450-ohm balanced line to feed a loop antenna for 80 m, I ran an updated antenna model for a square loop, 68 ft per side at 40 ft above average ground, 12-ga copper wire.

Below is a superimposed version of the plot of SWR for a series of 44 frequencies (that I keep in a file for frequent use) to cover the ham band frequencies. The dots on the plot are the discrete frequencies where model calculations are done. The pink plot shows the SWR results for a 300-ohm source connected to one corner of the loop. The blue plot represents a 450-ohm source. Click on the plot to expand the view.

The combined plot shows that the 300-ohm source gives slightly lower SWR on the lower bands (80 and 40 m) while the 450-ohm source gives slightly better SWR on the high bands. (60 m is, of course, the odd-ball.) The differences in SWR are not too significant and either case should be manageable by a decent antenna tuner.

Additional analysis can include a selected length of feedline from the loop to the source (transmitter). The impedance seen at the transmitter end will likely be transformed to a value different from what is seen at the loop's feed point. We know that odd multiples of 1/4 wavelength will transform impedance from low to high or vice versa, while even multiples will present an unchanged impedance at the transmitter. Other lengths will present some other impedance. With some care in feedline length selection we will (hopefully) avoid extreme values of impedance at the transmitter end.

Google+ Notifications

Google+ users may not be aware of the settings that allow you to select which notifications you receive for various postings or other activities. I became aware of this when I first started using Google+ and noticed I was getting many email notifications. I customized my settings to reduce this email traffic. Below are two screen shots showing where to find the settings.

First get the menu by hovering your mouse pointer over Home under the colorful Google+ at the upper left corner. Click on Settings near the bottom of that menu.










A new window opens with lots of settings to manipulate. Scroll down to the area shown in the screen shot below where you see Notifications.

Each category under Notifications will expand when you click on it. There you can choose which notifications to receive and which communication path they should use.








The topic of Notifications is also covered in this Google posting.  Be sure to browse the other settings for other things you may like to customize.

- John

PowerSDR on iPad via TeamViewer

I tested this arrangement this morning on an iPad Air (iOS 7).  With Power SDR software running my Flex-3000 and accessed via TeamViewer I was able to control the radio using a little mouse pointer on the iPad screen. I also verified the ability to zoom in using the two-finger pinch gesture. Below are two views captured with a digital camera.

Normal full window view of PSDR. Other PC taskbar icons are visible at bottom of screen.

Zoomed-in to the maximum amount.

I also had the receive audio playing from the iPad since I activated a virtual audio cable connecting the Flex-3000 audio to default playback. At times the audio would go choppy for several seconds and then settle out for a few minutes. I also heard audio in the background from the web link I still had open to a Flex-6700.

A few weeks earlier I tested the equivalent remote control capability from my Android smartphone using TeamViewer. Of Course, that screen is much smaller, but I was able to zoom in, albeit requiring a lot of panning to navigate.

-John

Microphone level setting in Windows 7

In recent Google Hangouts and tests of patching a Hangout to an HF transceiver, the need for adjusting microphone gain was noted. Many of us were familiar with how to set microphone gain in Skype, since it provides an explicit setting option for this. (The Google Hangout app does not.) Some are familiar with how to set this in Windows XP via its audio mixer settings, but those settings seemed to be absent in Windows 7.

After a little digging around this morning I found where to set microphone gain in Windows 7.
This is also documented in a Microsoft Support article. Start by right-clicking the familiar speaker icon in your lower right desktop corner (task bar on bottom). You'll get the menu shown below.

Click on Recording devices and see the window shown below.

Click on the Recording tab, verify the microphone device you want to use is designated as default, click on it to select and then click Properties. Next you'll see the window below.

Click on the Levels tab and you'll see slider controls for Microphone and Boost, or possibly just Boost. Here you can adjust the level for your microphone. I've verified this on three different Windows 7 computers, and noted that the microphone level defaults to 100%. If your audio app, such as Google Hangouts, is getting too much audio you can reduce it here.

While digging around in these settings I also found an option that should let me try my headset microphone with the Flex-3000. The Listen tab on the Microphone Properties page has an option to "Listen to this device" and choose "Playback through" a device selected on a pull-down menu. There I can choose the virtual audio cable for my transmit audio. I'll try this on an upcoming QSO.

JK