Just One More dB!


 

*** The following blog was originally published in 2016 but is still very applicable in 2020! ***





How often have you struggled to pull a weak signal out of the noise? "Just give me one more db", you tell yourself.


A recent posting to the Topband reflector by Frank, W3LPL, sent me to the interesting webpage of Dave, AB7E. Dave had been pondering two antenna systems, one of which would provide a 2db improvement in forward gain but at a much higher cost ... he wondered if the extra expense would be worthwhile and could he even hear the difference that 2db would make? He created a series of CW files, incrementing the signal level in 1db steps to see for himself!

Now I've always been told that you need to increase signal strength by at least 3db before your ears can detect any difference ... but listen carefully and you may be in for a surprise, as AB7E discovered.

It's probably best to listen to this signal with headphones but, even on my I-Pad's tiny speaker, the demonstration is clear. The first recording starts at "zero db", which is sent twice while the next signal is "one db", sent twice. See if you can hear the difference between each 1 db increment as he steps up to "six db":

Try going the other way, from "six db" down to "zero db":

The following recording has two signals, one of which is one db louder then the other. Can you hear the difference?

Although I was able to hear one call slightly better than the other, it was difficult. How about two signals again, one of them being 2db louder this time ... this one is much easier:


Lastly, AB7E demonstrates the problem with sending too fast when conditions are very marginal. Here, several signals are sent at 20, 25, 30 and 35 WPM. Sending calls at high speed can often seem effective, even under poor conditions but this seems to demonstrate that slowing down just a bit would make it somewhat easier:


One of the more interesting comments posted regarding these recordings was from Bob, N6RW who cited his work in satellite communications:

"I spent part of my engineering career designing satellite command FSK
demodulators - including the deep space Pioneer Venus orbiter. To test
the performance of them, we would mix the test signal with white noise.
When you look at the FSK Bit-Error-Rate (BER) curve (bit errors versus
signal to noise ratio in a bandwidth equal to the bit rate), you can see
the BER improves by a factor of 10 to 1 for every dB in S/N ratio. In
other words, for every dB improvement, you get one tenth the errors."


Now Dave never did tell us if he bought the bigger antenna or not but I'm betting that he did ... it looks like "just one more db" may really be just enough after all.

Steve McDonald, VE7SL, is a regular contributor to AmateurRadio.com and writes from British Columbia, Canada. Contact him at [email protected].

Next Generation of Heroes Arrives…

News from QRP-Labs….

Homebrew Hero 2019 Hans Summers has been very busy and not from handling sales and QSX design efforts! The next generation of Homebrew Heroes has arrived in the form of Baby Atlas, another son in the Summers household. Hans writes:

Yes, new baby in the house! Born 30-Jun-2020, baby “Atlas”, his weight 3.7kg. My XYL is doing fine too thanks…Hope you enjoy the attached pics! I cuddled my son just a few minutes after he was born and as you see, wearing the homebrew hero T-shirt. The other occasions were when my XYL found a local photographer to do a photoshoot, she did two – one a couple of weeks before the birth and one a couple of weeks after. I was wearing my hero T-shirt in both because the photographer requested white 🙂

Hans Summers Hero 2019

After suffering a back injury last December, Hans has been slowed in the QSX development cycle what with continuing sales of current products being a strategic business revenue source and, ahem, a few family matters to stay attuned to! But progress is being made as he updates the marketplace via his QRP-Labs.com website.

The impact of the donated prizes by our sponsors has been significant:

Yes thanks the Benchduino PCBs did get here but I have not had much chance to think about what to do about them yet. The sponsor prizes that get absolutely DAILY use are the Siglent ‘scope and the Heil headphones which sound great on my QCX kits. I have also made good use of the MFJ antenna analyzer and the Analog Discovery2 pack, though less frequently as of this writing.

Hans Summers Hero 2019

It’s been a very fast-paced year for our 2019 Homebrew Hero. Next month in October, we will announce the Hero for 2020. Stay tuned!


Frank Howell, K4FMH, is a regular contributor to AmateurRadio.com and writes from Mississippi, USA. Contact him at [email protected].

LHS Episode #365: XLX Reflector Deep Dive

You have discovered the 365th installment of Linux in the Ham Shack. Due to new experiences with the D-STAR digital voice system, Russ has decided he wanted to set up a D-STAR reflector. XLX is a multi-protocol, open-source reflector system for D-STAR (and DMR and YSF) that anyone can run on a Pi, in a virtual machine or what have you. Tune in as we have an in depth discussion on downloading, building and running your own XLX reflector plus basic communication using D-STAR. We hope you have a wonderful and digital voice filled week.

73 de The LHS Crew


Russ Woodman, K5TUX, co-hosts the Linux in the Ham Shack podcast which is available for download in both MP3 and OGG audio format. Contact him at [email protected].

Perfect Straight-Key Morse Code? Can It Be Made Without Machines?

What is the proper (and most efficient) technique for creating Morse code by hand, using a manual Morse code key?
Ham radio operators find Morse code (and the CW mode, or Continuous Wave keying mode) very useful, even though Morse code is no longer required as part of the licensing process.
Morse code is highly effective in weak-signal radio work.  And, Preppers love Morse code because it is the most efficient way to communicate when there is a major disaster that could wipe out the communications infrastructure.
While this military film is antique, the vintage information is timeless, as the material is applicable to Morse code, even today.  This film has the answer to the question, “Can a person craft perfect Morse code by straight key, without the help of a computer or machine?
The International Morse Code (sometimes referred to as CW in amateur radio jargon because a continuous wave is turned on and off with the long and short elements of the Morse code characters) is a type of character encoding that transmits telegraphic information using rhythm. Morse code uses a standardized sequence of short and long elements to represent the letters, numerals, punctuation and special characters of a given message. The short and long elements can be formed by sounds, marks, or pulses, in on off keying and are commonly known as dots and dashes or, dits and dahs. The speed of Morse code is measured in words per minute (WPM) or characters per minute, while fixed-length data forms of telecommunication transmission are usually measured in baud or bps.
Why is it called Morse code? This character encoding was devised by Samuel F. B. Morse, the creator of the electric telegraph. This Morse code came in two flavors, in the beginning years of its usage. One was in use by the railroads of America, and is known as American Morse Code. And, there is a unified, internationally-used version (adopted by radio operators), now known as the International Morse Code. Now, when most people refer to Morse code, or CW, they mean, International Morse Code.
Currently, the most popular use of Morse code is by amateur radio operators, although it is no longer a requirement for amateur licensing in many countries. In the professional field, pilots and air traffic controllers are usually familiar with Morse code and require a basic understanding. Navigational aids in the field of aviation, such as VORs and NDBs, constantly transmit their identity in Morse code.
Morse code is designed to be read by humans without a decoding device, making it useful for sending automated digital data in voice channels. For emergency signaling, Morse code can be sent by way of improvised sources that can be easily keyed on and off, making Morse code one of the most versatile methods of telecommunication in existence.
More about Morse code, at my website: http://cw.hfradio.org
73 de NW7US dit dit

Visit, subscribe: NW7US Radio Communications and Propagation YouTube Channel

My first digi contest was very frustrating!

Last week while making some FT8 contacts I received a message from one of the contacts I had made and he asked if I was going to be taking part in the upcoming WW Digi contest? He told me if I used WSJT-X software it was a simple matter of a few mouse clicks and I was good to good for the contest. I do have WSJT-X on my desktop but I am a user of JTDX for my digital operation. I had to update my WSJT-X software to 2.2.2 and as I was advised it was just a few simple clicks to set the software up for the contest. As I began the contest and started to send my CQ WW on the waterfall I was met with frustrations. Here are some of the issues I had:

  • At first, the auto sequence was not working and as stations that were answering my CQ were going unanswered unless I did it manually. I don't have an issue with that but the auto sequence was turned on but not working. 
  • In the frequency drop-down menu, WSJT-X did not offer the contest frequency which was 14090 to 14092.8. When I tuned my radio manually to this frequency the software had the frequency in red and not the normal green. 
  • For some unknown reason and it was very random my rig would tune back to 14074. This had me calling CQ WW outside the contest frequency. 
The above things kept happening and it was very frustrating and I ended up just shutting down. I did try JTDX and it did have the contest frequencies in the drop-down menu. I had no auto sequence issues and the rig stayed on frequency. One might ask why I just didn't stick with JTDX and keep going in the contest? The main reason was frustration but also I needed to have a contest log of the contacts to send off at the end of the contest. Maybe I could have configured it in JTDX but as I said earlier I was very frustrated. 


Mike Weir, VE9KK, is a regular contributor to AmateurRadio.com and writes from New Brunswick, Canada. Contact him at [email protected].

Weekly Propagation Summary – 2020 Aug 31 16:10 UTC

Weekly Propagation Summary (2020 Aug 31 16:10 UTC)

Here is this week’s space weather and geophysical report, issued 2020 Aug 31 0137 UTC.

Highlights of Solar and Geomagnetic Activity 24 – 30 August 2020

Solar activity was very low for the highlight period. No spotted regions were present on the visible disk. There were no Earth-directed CMEs observed during the period.

No proton events were observed at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit was at normal to moderate levels on 24-29 Aug. High levels were observed on 30 Aug with a peak flux of 2,800 pfu observed at 30/1845 UTC.

Geomagnetic field activity was at quiet levels on 24-26 Aug under a nominal solar wind environment. Activity levels increased to unsettled on 27 Aug as a positive polarity CH HSS moved into a geoeffective position. G1 (minor) storm levels were observed on 28 Aug with unsettled to active conditions observed on 29-30 Aug, all due to positive polarity CH HSS influences. During this period of activity, solar wind speeds reached a peak of 530 km/s at 29/0631 UTC, total field reached a maximum of 11nt on mid to late 28 Aug while the Bz component reached a maximum southward extent of -8 nT during that same time frame. Phi angle was in a mostly negative solar sector through about midday on 25 Aug when it switched to a predominately positive orientation through the remainder of the period.

Forecast of Solar and Geomagnetic Activity 31 August – 26 September 2020

Solar activity is expected to be very low for the outlook period.

No proton events are expected at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit is expected to be at moderate to high levels on 31 Aug – 07 Sep and again on 26 Sep due to recurrent CH HSS influences. The remainder of the period is expected to be at normal to moderate levels.

Geomagnetic field activity is expected to be at unsettled to active levels on 31 Aug – 02 Sep, unsettled levels on 18-19 Sep and unsettled to active levels on 23-26 Sep, all due to recurrent CH HSS influences. The remainder of the outlook period is expected to be at quiet levels.

Don’t forget to visit our live space weather and radio propagation web site, at: http://SunSpotWatch.com/

Live Aurora mapping is at http://aurora.sunspotwatch.com/

If you are on Twitter, please follow these two users: 1. https://Twitter.com/NW7US 2. https://Twitter.com/hfradiospacewx

– – – – – – – – – – – – –

Be sure to subscribe to our space weather and propagation email group, on Groups.io

https://groups.io/g/propagation-and-space-weather

Spread the word!

– – – – – – – – – – – – –

Links of interest:

+ Amazon space weather books: http://g.nw7us.us/fbssw-aSWSC
+ https://Twitter.com/NW7US
+ https://Twitter.com/hfradiospacewx

Space Weather and Ham Radio YouTube Channel News:

I am working on launching a YouTube channel overhaul, that includes series of videos about space weather, radio signal propagation, and more.

Additionally, I am working on improving the educational efforts via the email, Facebook, YouTube, Tumblr, and other activities.

You can help!

Please consider becoming a Patron of these space weather and radio communications services, beginning with the YouTube channel:

https://www.patreon.com/NW7US

The YouTube channel:
https://YouTube.com/NW7US

..


Visit, subscribe: NW7US Radio Communications and Propagation YouTube Channel

Why I signed with Google Adsense.

For years I had tried to get an Adsense account accepted on this blog but for some unknown reason it was rejected? I didn't understand the complicated email reply they sent back at the time, even others I showed  the email to were also puzzled? But I came to the conclusion, that in the blog's early days of it's birth, there wasn't enough content on here for them to entertain an Adsense account, so I never really bothered pushing again until now.


 During last week I had some spare time available  (very rare at the moment) so I applied again,  this time I was accepted and the Adsense account was opened. Nothing different had changed on my part or had the blog been altered in anyway?



If folk don't understand what Adsense is, it is a system that places adverts around the blog's spare unused space. Down the sides, along the top or bottom, or sometimes within the content. It can either be setup manually, or auto. The latter is how I have set it up, because I have little spare time to mess around, adverts will be automatically placed in the areas it thinks best.
 
Yes I get paid a small amount in return, mainly if someone clicks on the advert and goes off and views it.

I have tried to set it up that it will show advertising from things that will be of interest to you the person that comes here and that reads the blog. Although this cannot be guaranteed the adverts will be applicable to its content?
 
How will this help me?

I don't expect I will be riding around in a Ferrari! But it may help fund the purchase of small items, which may be of interest to the hobby to test out and review in the future and make the blog more exciting with content.

So it is a win win situation for us all, get clicking!




Steve, G1KQH, is a regular contributor to AmateurRadio.com and writes from England. Contact him at [email protected].

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