Topband: Diversity RX audio example

Wed Feb 6 18:46:15 EST 2019

I have received a few “off-list” comments and questions about my radio, RX set-up and the Flex so I thought I would respond to the list.

The Flex 6600 has been in use from the remote station since Oct 2018.  At first I was “underwhelmed” by the weak signal CW rx of the Flex.  Compared to the K3s, the Flex just didn't seem to lift the weak ones out of the noise. I ALWAYS have the APF engaged on the K3. (literally it is never turned off unless high QRN)  I am one of those guys who is addicted to an effective APF. The best APF ever was the original FT-1000d.  My FTdx-9000d APF was next best, and the K3s APF is also effective. In my opinion, without an effective APF to lift the weak ones out of the noise, there would be many QSO’s that never would have happened here at VE6WZ.  The important part of that last sentence was **the weak ones**.  For any signal above the noise, with or without the APF, copy will be ok.  When the signals are barley copiable…at or under the noise…almost no trace on the waterfall...then an effective APF will “lift” the signal above the noise because of the audio peaking effect.  (Some don't like the “ringing” artifact that can sometimes happen, but I listen to a 400Hz CW note, and I find that has less ringing than I higher tone.). There will be those that say they can copy everything without an APF, and I would say I can copy 80-90% of the signals without one, but there are maybe 10% of the signals that would not be copiable without an APF.
The Flex APF seemed mostly ineffective, much like most Icom radios (I have owned IC-746, 756, 756pro and IC-7800). There seems to be a lack of audio **peaking** at the centre frequency.  However, I discovered I can emulated the 400Hz audio peak by adjusting the RX equalizer on the Flex.  Using the rx EQ, I increase the 250 and 500Hz sliders and shut down all other frequencies since we don't need any other audio frequency data other than our CW note anyway.  This seems to come close to matching the K3 APF peak and allowed for comparable weak signal performance.  Lately the Flex has been the radio of choice vs the K3, mostly because of ergonomic reasons and the great SDR waterfall.  The Flex is also more functional when traveling and using the Laptop to access the remote.

The soundfile clip of Vlad RA4LW that I edited is NOT a typical EU signal here at VE6WZ, but rather an example of a **very weak** one.
I used it to show the diversity effect on those signals ***just at the noise***.
That is not at all “typical” of how I copy Vlad RA4LW.  I have had 23 QSOs with Vlad this season and most of the time he is much easier copy.  In fact, please visit my soundfile list at the link below where I have 12 recordings of Vlad, together with about 300 other EU recordings from this winter season.  My 160m EU QSO total since September 2018 is now over 730, so this is only about half of my EU QSOs. It is too much work editing and uploading every QSO.

My point with that edited recording is to show that if all I had for RX was the Beverage, or the 9 circle alone, I would NOT have copied his call, but somehow together in diversity he is Q5.
For signals much above the noise, often I would probably copy the signal on either the Beverages or the 9 circle by themselves without diversity.

Here is the link to my google drive 160m sound files.  You can sort by date, or callsign.  If you rx to a few of these you will get an idea of more “typical” EU here at ve6wz this winter….most (not all) of these recordings are stereo files of the diversity RX using the Flex or the K3.  Usually, the Beverage in left ear, 9 circle array in right ear.

https://drive.google.com/drive/folders/12GqZMPZ4R2nPLGbOVho6AHGkV9tD_MHf?usp=sharing <https://drive.google.com/drive/folders/12GqZMPZ4R2nPLGbOVho6AHGkV9tD_MHf?usp=sharing>

73, de steve ve6wz.

> On Feb 5, 2019, at 4:44 PM, VE6WZ_Steve <ve6wz at shaw.ca> wrote:
> 
> Today I decided to play with some of my recorded 160m QSOs from this season (I record almost all of my QSOs). 
> I did a few experiments with isolating my diversity RX antennas to try and hear the benefits of having a different antenna in each ear.
> 
> Because I record all of my QSOs in stereo, I was able to isolate each RX antenna and listen to them individually, and then together in diversity mode.
> 
> There are many other references to the benefits of using Diversity RX, but for those who have never tried it perhaps this one example will provide an example of the diversity magic.  However, this “magic” although almost always improves copy and intelligibility, it's only on the ***very*** weak ones….think ESP…when it really shines and this is the example I provide the audio link to.  Please be aware there is no point at all listening to this sound-file without headphones because you wont get the diversity “brain filling magic", and also the signal is so weak you wont hear anything.  This is a typical “just bubbling above the noise” 160m signal.
> 
> My edit method was to take the stereo recording and cut out the left channel (Beverage) and right channel (9 circle RX array) and splice them sequentially after the stereo recording of both channels.
> 
> The recording is of a QSO with Vlad RA4LW via the polar path and my edited clip goes as as follows:
> 
> CQ DX (vlad answers) RA4LW RA4LW (i respond) RA4LW 449.
> 
> This is repeated 4 times: 1.) Diversity, 2.) Beverage only, 3.) 9 circle only, 4.) Diversity again.
> 
> I have selected this example because it is one of the best I have were I do NOT think it is possible to copy Vlad's call on either of the RX individually, while somehow, when they are heard together, the call gets “put together” and is copiable.  google link below and your sound player should play it.
> 
> https://drive.google.com/file/d/1NbFLFw2BRHC9DGfxJVfhnrBOx5ViD_4b/view?usp=sharing 
> 
> On signals that are stronger, the diversity effect can help when one antenna goes way down below the noise and the other comes up.  Sometimes it can almost make you dizzy as the signal goes from ear to ear.  I have noticed this mostly on 80m when using the 2 el Yagi and Beverages in diversity.
> 
> 73, de steve ve6wz.
> _________________
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