AmateurRadio.com

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.

I suspect there are probably a lot of Canadian amateurs still thinking that our new 630m is not very practical for anything other than local two-way contacts.



During the winter 'DX season', this is definitely not the case, as 630m shares many, if not all, of the propagation characteristics found in the lower end of our AM broadcast band. As well, a quick tune through the even lower NDB band on a normal night will reveal dozens of 25-watters, often from over a thousand miles away and with very robust signals.

With no 630m amateur activity yet coming from VE6, VE5 or VE4, it is difficult to get a sense of just how interesting the band could become on these normal nights, or how great it would be on a really good night of propagation. My recent CW contact with the nearest out of province station, VE3OT (Mitch), on a normal night, demonstrates that there is a lot of potential for some really effective two-way work over long distances.

So ... what do signals sound like between here and Ontario? Here is Mitch's CW beacon as heard here on the evening of February 11th, at around 2300 hours local time, using my 10' x 20' loop. I have heard Mitch at even higher levels than this, but his beacon is usually audible here on most undisturbed nights, sometimes as early as 2000 hours local time. His beacon signal runs 200 watts to a 340' circumference loop, from his London, Ontario, suburban backyard.


Even if you are not able to hear Mitch's signal audibly, it should be fairly easy to copy in one of the QRSS CW modes, such as QRSS3 or QRSS10 ... both of which could yield a reasonably quick two-way contact.

Judging from the reliability of the VE3 signal, any activity from the prairie provinces should be even easier to hear. Should any of you in the prairies take up the 630m challenge, I can assure you that you'll be very, very popular out west ... every night!

This blog also provides an opportunity for my initial use of the 'tunestotube' web site. It provides a nice online interface for posting audio files to Youtube, along with an image, or a slideshow. It seemed to work seamlessly and will save me having to link to audio files stored on my own web site, which really eat up what little space I have left.

courtesy: http://www.bing.com/mapspreview

Under most circumstances and on most bands, a contact between VE7 and VE3 would not be considered 'exciting' or 'challenging' ... but Saturday night's CW QSO between myself and Mitch, VE3OT in London, Ontario, met both of these criteria, as it was done on our new 630m amateur band on 475.0 kHz. As such, it represents the first-ever interprovincial contact as well as the furthest contact (2031 miles) between two Canadian stations on the 630m band. As usual, there's more to the story ...

Both Mitch and myself had been alerted to the excellent propagation earlier in the week, when VE3OT's CW beacon had reached S9 levels here for several hours on two consecutive nights ... but any late-night QSO attempts would have to wait until the weekend, when having to get up in the middle of the night would not conflict with Mitch's workweek schedule.

Our first attempt, late on Friday night and 3A.M. for Mitch, found that conditions had deteriorated from midweek's enhanced propagation and the low signal levels, combined with some unseasonal lightning noise, resulted in rescheduling for another shot on Saturday.

Late Saturday night found the band much quieter and propagation much improved, but not as good as it had been earlier in the week ... somehow Murphy always seems to have a hand in pre-planned events, and it's never a helpful one. Mitch's beacon signal was readable here but had a deep ten-minute fade cycle with a short-lived peak before fading out to nothing.

VE3OT at his loop's loading coil

Hoping to take advantage of one of the peaks, we began short two-by-two calls from both sides shortly after 0700Z. I eventually heard Mitch fade up and sending a '339' signal report but my response and '559' signal report to him went unanswered as he had faded away again. I continued the short calls, along with my signal report to him and on the next peak heard him responding with 'RRR and 'QSL'! This time his signal continued to build and we had several short exchanges, with Mitch upgrading my RST now to '549' and with me advising of his stronger '569' signal. As the fade cycle took its grip once again, we exchanged our '73's', 'TU's' and 'SK dit-dit's', while we still had the opportunity ... I can't speak for Mitch, but for me it was a truly exciting contact and one I'll not soon forget.

LF / MF station at VE3OT

I'm sure the opportunity to work again will present itself fairly regularly as we both know that Saturday's conditions were not the best. It will be interesting to try again when signal strengths reach the levels previously heard during the week.

For those of you that worked VE3OT during the recent 630m crossband event, Mitch has put together a very special QSL card!


As the solar cycle winds down, the 'good' nights will happen more often, as will the truly 'great' nights. Hopefully there will be more Canadians on the band to take advantage of what lies ahead.

Hopefully the U.S.A. will soon have the band as well, which will really spark nightly activity. What is really needed right now is more Canadian activity, especially in the western provinces, where nightly CW contacts could be readily made. Time to reach for the solder iron! There are several VE7's, and one VE3, waiting and wanting to work you!

courtesy: https://www.dvidshub.net/new

Well it seems as if the U.S. Navy has rediscovered something that most hams, especially older ones, have know for a long time ... CW is pretty darn handy!


After many years of abandonment by the various branches of the armed forces, the Navy has taken another look at the usefulness of knowing how to use CW and has been training a limited number of their Cryptologic Technicians (CTR's) each year, at the Center for Information Dominance (CID) based at Corry Station in Pensacola, Florida,

I've always absolutely loved CW, ever since first learning it at around twelve years of age, eventually using my new-found skill to help me get a ticket when I turned fifteen. A big stumbling-block for many, the requirement to send and receive CW was eventually eliminated with the introduction of the no-code licence and had many hams believing it would be the end of ham radio.

As the Coast Guard and maritimers around the world abandoned CW, somehow, it has managed to not only survive, but to seemingly flourish on the ham bands. Granted, operating habits and patterns may be changing and fewer stations are to be found, randomly CQ-ing, seeking a nice CW ragchew, but a short listen during any contest weekend or during a rare DX-pedition pileup will quickly reveal that the art of CW itself is still alive and well in 2016!

One of the reasons for CW's longevity, aside from the fact that it's just plain fun, is it's ability to be understood under the worst of conditions, unlike many other modes ... and it can be used with the simplest of equipment, without needing a computer.

courtesy: https://www.dvidshub.net/new

"In the updated course, sailors learn how to operate radio-receiving and associated computer-based equipment. From basic safeguards of security to communication procedures and systems theory to operation of communications equipment, the course teaches how to intercept Morse communications, as well as copy and send Morse code."

"Morse code continues to be an inexpensive and efficient means of communication for many states throughout the globe,” said Senior Chief Cryptologic Technician (Collection) (IDW/NAC/SW/AW) Tony Gonzales, CTR rate training manager for CID headquarters. “Manual Morse operators here at Corry Station are learning a skill set that has stood the test of time. Many of our most senior CTRs began their careers as Manual Morse operators.”

Somehow, it's very gratifying to see that the Navy is still keen on training sailors in the art ... affirming what hams have known since the earliest days of radio.

It's not clear if these folks are learning to actually send with a hand key or keyer but I rather suspect that their sending skills may be limited to how fast they can type as I don't see any keys in the training-center's photos ... but it's a start.

Maybe we'll hear a few of them on CW sometime in the future.