Hunting For NDBs In CLE260

ZQT-263 Thunder Bay, ON (ve3gop)

It's CLE time again!


'CLE's are 'Co-ordinated Listening Events, and NDB DXers around the world focus their listening time on one small slice of the NDB spectrum.


This time the hunting ground is the slice from 260.0 - 269.9 kHz and 440 - 1740kHz.
 

 

 

Propagation on MF has been excellent this past week and hopefully will continue to be good.

A worthy target for listeners in North America is ZQT - 263kHz in Thunder Bay, southern Ontario, on the western shores of Lake Superior. ZQT has been logged from coast-to-coast but it's a challenging target. Listen for ZQT's upper sideband on 263.392kHz with your receiver in the CW mode.

When tuning for NDBs, put your receiver in the CW mode and listen for the NDB's CW identifier, repeated every few seconds. Listen for U.S. NDB identifiers approximately 1 kHz higher or lower than the published transmitted frequency since these beacons are modulated with a 1020 Hz tone approximately.

For example, 'AA' near Fargo, ND, transmits on 365 kHz and its upper sideband CW identifier is tuned at 366.025 kHz while its lower sideband CW ident can be tuned at 363.946 kHz. Its USB tone is actually 1025 Hz while its LSB tone is 1054 Hz.

Often, one sideband will be much stronger than the other so if you don't hear the first one, try listening on the other sideband.

Canadian NDBs normally have an USB tone only, usually very close to 400 Hz. They also have a long dash (keydown) following the CW identifier.

All NDBs heard in North America will be listed in the RNA database (updated daily) while those heard in Europe may be found in the REU database. Beacons heard outside of these regions will be found in the RWW database. These databases have recently been re-vamped and are slicker than ever before!

From CLE coordinator Brian Keyte (G3SIA), comes the following CLE info:

Hello all,

Here’s our chance to forget all the current problems for a while – and get close and personal with OUR HEADPHONES! (?)

These are the final details for this weekend's Coordinated Listening Event which uses some challenging frequencies.

Any first-time CLE logs will also be very welcome, however modest.

 Days:    Friday 25 Sept. - Monday 28 Sept.

 Times:   Start and end at midday, your local time

 Target:  Normal NDBs  (not NAVTEX or amateur beacons)

      QRG:   260.0  -   269.9 kHz

      plus:    440.0  - 1740.0 kHz

Please log the NDBs you can identify that are listed in those ranges plus any UNIDs that you come across there.

North America has a modest number of active NDBs in both ranges.

For Europe listeners there are LOTS of targets in the hf range, but they are mostly well to the east, many of them also competing with strong Broadcasting Stations.

Australia has a few NDBs in both ranges.

You can find details of the beacons in these ranges, lists and maps, if you go to  http://www.ndblist.info/cle.htm  and click on the 'CLE SEEKLIST' link.

If you are disappointed by having very few likely targets, you could maybe listen instead via a remote receiver located nearer to the action?

See  kiwisdr.com  (previously available via sdr.hu) and please also see the important footnote below.

Send your final CLE log to the List, preferably as a plain text email, not in an attachment, with CLE260 and FINAL at the start of its title.

 Please show on EVERY LINE of your log:

  #   The full Date (or Day no.)  e.g. ‘2020-09-25’ (or just ‘25’) and UTC (the day changes at 00:00         UTC)

  #   kHz (the beacon's nominal published frequency if you know it)

  #   The Call Ident.

Other optional details - Location, Distance, etc. - go LATER in the same line (or in footnotes) Any extra details about new UNIDs, especially strong ones that may be near to you (maybe their approximate direction, etc.) will help us to discover more about them. 

Please make your log useful to old and new members alike by ALWAYS including your own location and brief details of the equipment and aerial(s) that you were using.

We will send an 'Any More Logs?' email at about 19:00 UTC on Tuesday evening so you can check that your log has been found OK.

To be included in the combined results your log must arrive at the very latest by 08:00 UTC on Wednesday 30 Sept.

We hope to complete making the Combined Results within a day or two.

Good listening

Brian and Joachim

---------------------------------------------------------------------

From:      Brian Keyte G3SIA       ndbcle'at'gmail.com

Location:  Surrey,  SE England    (CLE coordinator)

---------------------------------------------------------------------

 

If you are interested in some remote listening - maybe due to local difficulties - you could use any one remote receiver for your loggings,stating its location and with the owner’s permission if required.

A remote listener may NOT also use another receiver, local or remote, to make further loggings for the same CLE.

 

These listening events serve several purposes. They

• determine, worldwide, which beacons are actually in service and on-the-air so the newly-re-vamped Rxx online database can be kept up-to-date

• determine, worldwide, which beacons are out-of-service or have gone silent since the last CLE covering this range

• will indicate the state of propagation conditions at the various participant locations

• will give you an indication of how well your LF/MF receiving system is working

• give participants a fun yet challenging activity to keep their listening skills honed

Final details can be found at the NDB List website, and worldwide results, for every participant, will be posted there a few days after the event.


The NDB List Group is a great place to learn more about the 'Art of NDB DXing' or to meet other DXers in your region. There is a lot of good information available there and new members are always very welcome. As well, you can follow the results of other CLE participants from night to night as propagation is always an active topic of discussion.

You need not be an NDB List member to participate in the CLEs and all reports, no matter how small, are of much value to the organizers.

Remember - 'First-time' logs are always VERY welcome!

Reports may be sent to the NDB List Group or e-mailed to CLE co-ordinator, Brian Keyte (G3SIA), whose address appears above. If you are a member of the group, all final results will also be e-mailed and posted there.

Please ... give the CLE a try ... then let us know what NDB's can be heard from your location! Your report can then be added to the worldwide database to help keep it up-to-date.

Have fun and good hunting!

 

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.