RV Service Net - 11 April 2019

During the second hour of Thursday's net I captured some audio and screen shots of the activity. The net control station, Sam WA4ICK, was S9+10 to me (in Baton Rouge) and painted a strong image on my FLEX-3000 SDR waterfall/panadapter view as shown below.

Click on image for an expanded view.

Improved propagation noted by several net participants can be attributed to an active region (with sunspots) on the Sun that has rotated back into Earth view and is raising the solar flux. On April 11 the sunspot number was 13.

A sample of the audio recording from around the middle of the second hour illustrates the reception here of signals from WA4ICK and W3TOM. Below is a screen shot of a portion of the audio waveform. You can see how the signal-to-noise (S/N) ratio changes after the hand-off from WA4ICK to W3TOM at about 1/3 of the way from the left.

Click on image for an expanded view.

The first third has a narrow baseline between syllables, indicative of my receive AGC turning down the gain in the presence of the strong signal. The remainder of the waveform has a lower S/N ratio as indicated by the thick baseline. Some fading is evident. The signal improved after the first few seconds. In this later 2/3 of the waveform the AGC opened up to allow more signal, but the noise was also higher. Click here for a 47-second recording that includes the portion represented by the above waveform.

 I have two longer recordings that I can share with interested parties upon request.

73,
John WA5MLF

RV Service Net Reception at WA5MLF

During the last half-hour of yesterday's RV Service Net the signal from W4UOA was solid at Baton Rouge. The distance from my station to W4UOA is 430 miles.

Below is a screen shot captured at 0751 CDT, while W4BXI was transmitting on 7191 kHz  from W4UOA. Another strong signal can be seen below 7188 kHz.

Click to enlarge view.

A little earlier (0728 CDT) I recorded KB0BH checking into the Net and acknowledged by W4BXI. The recording (click here) was made from my Flex-3000 transceiver in Baton Rouge.

73,
John WA5MLF

Sampling of Group Videos & Screen Shares

While browsing through some files on an older hard drive I found some collected screen shots of some past group videos and screen shares that were common among our group members on morning QSOs. Below is a sampling of these, in order by date, starting in 2009.  The file name of each image shows the date of capture. The newest screen shot is from July of 2017.

Our group sessions made use of three services: Adobe ConnectNow (free for a limited time), Skype and Google Hangouts. Some of the later screen shots show that it is possible to participate in two separate sessions simultaneously on the same computer. In that case it is good to keep track of the microphone muting in each session window.

I added text notations to some of the views. Click on any image below to see an expanded view.

73,

John WA5MLF

SDR Screen Shots of Received Voice Transmissions

During this morning's QSO on 3740 kHz, Jim K4JPM shared his Flex Radio screen via Google Hangout. He had good reception of the lower sideband voice transmissions from W4BXI and W4UOA. The screen shots below show an abnormal property of each signal. Jim activated the peak mode on his receive display to hold the peak value at each frequency over a period of many seconds of voice transmission. The displays show a panadapter view (amplitude vs frequency) on top with a waterfall display (amplitude [brightness] vs frequency and time) below. The light-shaded box on the panadapter indicates the receiver's audio bandwidth setting. Signals outside of this box are not heard in the speakers.

W4BXI signal at K4JPM

Above is the view of W4BXI's signal on Jim's Flex Radio. Click on the image for a full-size view. The notable detail here is the presence of carrier at 3740 kHz (red vertical line). The LSB voice band shows the fairly typical male voice with more energy at the lower audio frequencies.

W4UOA signal at K4JPM

Above is the view of W4UOA's signal on Jim's Flex Radio. Click on the image for a full-size view. Note the presence of energy in the upper sidebands (to the right of the red line).

- John WA5MLF

Spectrum waterfall views on 60 m

During this morning's QSO I captured screen shots of the waterfall display of received signals on my Flex-3000. Below are the views with stations identified, as heard during the 0755 to 0810 CST time frame. (Click on any image for a larger view.)

Above is the display while WA4PTZ was transmitting. The vertical dimension is about 30 seconds of elapsed time. The 60 m channel 1 bandwidth is represented by the gray shading on the top edge. The carrier frequency is marked with a red line. The lighter patches show the received SSB signal level compared with background noise. Some persistent signals (or artifacts) are seen around 5.328 MHz.

Above is the signal display for W4PRE.

Here is the signal view for W4UOA.

Above is a view showing transmissions from KB4XX and W4UOA.

Here is a longer transmission from KB4XX.


For a different view, see the screen shot below from 40 m (7.143 MHz) at about the same time of the previous morning. This shows transmission from KB4PYR with a strong QSO in progress "next door" at 7.140. The yellow and red colors signify much stronger received signals, compared with the 60 m views above.

-- John