Saturday, May 9, 2020

Are You a Code Warrier?

As of February 2007 the Federal Communications Commission removed all requirements for Morse code proficiency on amateur radio license exams. Many were sad to see the end of the Morse code requirement as hams have sustained this specialized communications language for many years. Known to hams as CW or Continuous Wave transmission, it is the most fundamental of radio transmission technologies in which a carrier wave is turned on and off to form dots and dashes with a telegrapher’s key. Given the technology advancements at the time everyone had to admit that the CW mode of operation had given way to modern text messaging, email and voice data. Ham radio evolved to include RTTY (Radio Teletype) and automated PSK31 and FT8 digital data/text modes effectively rendering Morse code obsolete. These facts aside, CW remains a highly reliable mode of communications when others might fail and is still popular with hams the world over.

I obtained my novice license in 1967 when the Morse code requirement was five words per minute with thirteen words per minute for the General and Advanced class exams. A Novice license term was one year and without an overlapping General Class upgrade you were off the air. No way.  Several months into my Novice term I obtained my General ticket and shortly afterward my Advanced Class license. The Extra Class exam required twenty word per minute proficiency and having obtained an Advanced Class license (my current license) I decided to defer an Extra Class license upgrade till my retirement years. My retirement years have arrived, the Morse code requirement is gone and I’m planning an Extra Class upgrade soon.

That said, I’ll recount some valuable Novice experience as insight to newer hams pondering the craft of CW. When other voice and data modes might fail, a skilled and persistent CW operator will succeed. Upon passing my Novice license exam I immediately ordered three quartz crystals from Texas Crystals (a forerunner of today’s Texas Instruments).

FCC rules required Novice operation with crystal control, no VFOs (Variable Frequency Oscillators) allowed. Note that in the 1960s frequencies were designated in Kilocycles and Megacycles until the NBS (National Bureau of Standards) became the NIST (National Institute of Standards and Technology) and Hertz (cycles per second) replaced the Kilo-Megacycle convention.

Anticipating operation on the Novice 40 Meter band; 7.150 to 7.200 MHz, I ordered crystals for 7.153, 7.155 and 7.158 MHz. The crystals arrived in the mail and that evening I went on the air as WN4JVJ, a CW Novice. DX propagation was excellent as the sun was at solar maximum. The 40 Meter band was packed and a very large AM broadcast signal occupied 7.150 MHz. It was Radio Moscow [1] whose typical power output peaked at one Megawatt. Radio Moscow’s AM bandwidth spilled well above and below 7.150 and appeared to render my selection of 7.153 a poor choice. During the 1960s many Short Wave broadcast stations took residence in the ham bands and my other crystal frequencies provided no clear channel advantage. Recalling the old adage “Work with what you’ve got”, I went on the air. With my brass pounder’s key I tapped out a CQ on 7.153. Because Novice’s operated on fixed crystal frequencies you would rarely hear a response on your own transmitter frequency. Operating technique required calling CQ on your crystal frequency and then listening for a response, searching adjacent frequencies and acrossed the band for someone keying your call sign. After calling CQ several times I thought I heard a response near my own frequency. I chuckled to myself thinking another ham had made a poor choice of crystal frequency, but within the envelope of Radio Moscow’s one Megawatt upper sideband I could hear the faint heterodyne of a CW station calling me. It was another Novice station in Virginia, closer than Radio Moscow but almost overwhelmed in the QRM (interference). Novices were limited to 75 watts of transmitter power output but physics intervened to make the signal readable.  When two radio carrier waves are close enough in frequency and overlap they heterodyne to form a tone known as a “beat” frequency.  Early ham radio receivers were designed to receive AM (Amplitude Modulated) voice signals but were also equipped with a BFO or Beat Frequency Oscillator. The BFO could be switched on to inject a receiver generated carrier signal which would beat against selected CW reception.  An audible interference tone resulted from the opposing carriers providing the familiar CW tone/note we hear in our headphones or speaker. A good CW operator can copy signals through seemingly insurmountable interference.

The human brain is a remarkable signal processor. A good CW operator can focus the mind to sift through static noise and interference to copy CW messaging with great accuracy. During the last months of my Novice term I logged for a veteran CW operator on Field Day. During the contest Arnie worked CW exclusively averaging 25 words per minute (my estimate). I improved my CW speed significantly by copying and logging the contacts he made and gained valuable operating experience along the way. After a few hours Arnie seemed to sense this and began to point to the left or right above the Drake Twins (radios T4X and R4B). Not sure what he meant I removed my headphones and asked. "What are the hand signals for?" He laughed and explained he was spotting signals for me to pre-log. As he was working one CW station he would simultaneously copy another he could hear within the receiver’s bandpass. If I could log them in advance we would save time and work more contacts in the contest time allowed. If he pointed left it meant the station he wanted pre-logged was below the tuner curser. If he pointed right the target station was above the tuner curser. Laughing out loud I asked, “How do you know if they’re above or below?” He laughed in return explaining the pitch of the heterodyne note made by his intended target was either higher or lower in tone indicating its position above or below our dial frequency. I laughed again in amazement and began following hand signals while listening high and low.  While Arnie would listen to the tone of a CW signal to determine its location within the bandpass, today's SDR displays enable us to see the RF spectrum above and below our operating frequency. 

Note the vertical curser mark above the spectral display shown below.  You can visually spot the Single Sideband traffic +/- 20 KHz on either side.

I'll pause here for a side note: A frequent curiosity is how Morse code speed might equate to a bps data rate.  As explained by N2EY, [2] (scroll down the linked page)  "Paris" is used as a five letter test word to compute per minute code speed; Paris sent fifty times in one minute equals fifty words per minute. By totaling the dit times, (that is the dahs (three dit lengths) dits and spaces between words), this fifty word per minute CW speed represents 2500 dit times or 41.66 bps.  By extrapolation we can surmise a ham who copies CW at 25 words/min copies an approximate data rate of 20.83 bps. Machine code for the mind?

After several hours our CW shift concluded and another Field Day operator/logger team relieved us. I shook hands with Arnie and thanked him for a great lesson in CW operating skills. We departed with another great laugh as we exited the mobile van housing our Field Day station. It was three or four AM as I began walking toward my car when I stopped in my tracks to copy CW traffic. Had I left my headphones on? No. I listened again intently and realized I was trying to copy the crickets in the woods. Another great laugh (at myself). My mind had become so conditioned to copy CW that everything, every noise I heard was being processed as Morse code. Enough ham radio for one weekend. Time to go home. My girl friend awaited.

We might think CW a lost art but a few weeks ago I tuned around to hear new General and Extra Class operators QSO on CW at five to ten words per minute. Using straight keys they brought back memories of the not so old days. CW has regained popularity as hand held decoders can now scroll received data.  Computer based software is available for contest logging and the automated send/receive of CW.  If you've been to a recent Hamfest you might have seen the new product lines of straight keys, semi-automatic and Iambic electronic keyers.

Many new technology toys await hams as the spring season draws near. What was old becomes new again.  Wishing you good DX.  Be safe everyone.

Have a great weekend!

Best regards,
Thomas D. Jay

W4TDJ  Member ARRL
TDJ Technology
Thomas D. Jay YouTube Channel

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References and acknowledgements:

[1] Radio Moscow

[2] N2EY

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