Re: Topband: FT8 Observations

[VK3HJ]

Having no interest in FT8 or JT modes (for now), I don't have much to 
comment on that, but do have a few comments on the subsequent discussion.


My feeling is that, as mentioned already, many stations haven't made a 
decent job of improving their receiving capability, or are unable to do so. 
These stations may be 20 - 30 dB or more behind those who have, and 
therefore much of the receiving gain of FT8 is lost. In many cases, it's 
much easier to put out a decent signal, than to reciprocate by being able to 
receive decently.


I have three two-wire Beverages out of 280 m each in a quiet rural location. 
The nearest neighbour is several hundred metres away, and the nearest town 
is around 10 km away. I have used the design on Mike W0BTU's website, and am 
switching directions with 12 Vdc down each of the three feedlines giving me 
six switchable directions in the shack. I am pleased with the results, but 
haven't used the reverse directions much yet.


In the control box, I am just using a rotary switch, with mini coax carrying 
the RF. It would be interesting to devise a switching arrangement to allow 
diversity reception between any two Beverages. I currently can use diversity 
with by transmitting vertical in one receiver and one Beverage in the other.


We are well into Autumn here, but are still getting many evenings with 
thunderstorms in the region. Some call this an "Indian Summer". I was still 
able to work Dave K1WHS last evening despite a thunderstorm off our east 
coast.


See you on Top Band, on CW.

73,

Luke VK3HJ 


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Re: Topband: Wednesday 160m DX Activity Night

[Guy Olinger K2AV]

Hmm, this last week was still hitting RBN over there, and worked G3OLB
two different days a little before his sunrise. One of those was a
long lovely old time 599 QSO with Tom, like I was working someone in
Ohio on 80 meters.

It might be "season" over, but 160 sure isn't over, at least not yet.

I think a lot of people don't get on unless there is an "event". Or
unless they hear a lot of signals.

I remember when I was a kid and we had "marbles" season**. Everyone
started showing up at school with marbles in their pocket. Then one
day nobody had any and marbles season was over. We COULD have played
marbles for another month until school was out for summer, weather was
fine for such things most days. Just that nobody showed up at school
with any marbles after "marbles season" was over.

Waste of perfectly good propagation.

Hmm, CWops tonightlast ten minutes...

73, Guy.

** https://en.wikipedia.org/wiki/Marble_(toy)

On Mon, Apr 23, 2018 at 12:40 PM, Ed Sawyer  wrote:
> Roger.  My guess is that it is considered "season over" by most of the boys.
> I rarely get on 160M after early April unless there is a specific DXpedition
> on.  I don't think I am alone.
>
>
>
> In some cases, people even lose antenna options for the summer due to
> coexisting with farmers and other activities.
>
>
>
> 73
>
>
>
> Ed  N1UR
>
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Topband: FT-8 on 160m using DXE NCC-2

[Jason Pecora]

Good evening everyone. I just wanted to post a link to a video that I made
using the DXE NCC-2. I have had some high tension power line work done
about 1/8 mile from my qth over this summer, and since then I have been
subject to 10-20 over 9 noise floors on 160m. What used to be a S-2 S-4
band for me was now not so fun anymore. While I wait for the power line
crew to do repair work I decided to give the DXE NCC-2 a try. I have tried
other manufactures noise cancelers in the past and came to the conclusion
that all they do is attenuate both the noise and the signal. The DXE
version was a lot more money then the others, but everything I have ever
bought from them has worked beyond my expectations. Last year I installed
their DXE 4 square RX system and it worked great, but unfortunately this
noise I am hearing is coming from the NE direction (Europe) and it's loud
even on the 4 square. So I decided to buy the NCC-2 and I'm glad I did. I
did the comparison on FT-8 because it is very easy to see that with the
unit on, I hear stations 10-20 db stronger on FT-8 that without I would
never hear at all. I have consistently seen signals that are -25 db
increase to a average +2 db signal. So I will copy the link below so you
all can view it, I have yet to try and phase the 160m loop with the DXE 4
square. Maybe this weekend I will play around with that. If your looking to
improve your signal to noise this unit is defiantly something to look
into...

https://www.youtube.com/watch?v=ByBeSg9auCA

Jay KB8O
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Topband: Wednesday 160m DX Activity Night

[Roger Kennedy]

Yes, you're probably right Ed.

But the band is certainly still open to North America at this time of year,
and we rarely have any thunderstorms causing QRN on the band until August.

I'll certainly be on again tonight (from around 0100Z), and I'm sure other
Europeans will be too.

73 Roger G3YRO

--
Roger.  My guess is that it is considered "season over" by most of the boys.
I rarely get on 160M after early April unless there is a specific DXpedition
on.  I don't think I am alone.

In some cases, people even lose antenna options for the summer due to
coexisting with farmers and other activities.

73

Ed  N1UR


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Re: Topband: FT8 Observations

[K4SAV]

I'm not sure how many people have actually compared the new digital 
modes with CW as far as low signal level decoding.  I did that for a 
long time when JT-65 first became available.  Back then it was much 
easier to separate one station and compare the reported S/N to what I 
see on my receiver when using a very narrow passband.  There was always 
a huge disparity, usually 30 to 40 dB.  Most of those numbers were taken 
right off the main screen of a TS-990s, so the accuracy may not be a lot 
but it's a pretty good indication of how close the signal is to the 
noise floor.


Then I found this:
http://www.arrl.org/forum/categories/view/31/page:2
You have to sign in to the ARRL site and look for the article titled 
"JT65, JT9, FT8, SNR explained".


That article says that the S/N reported by JT-65 is actually 29.7 dB 
more than it should be and JT-9 is 31.6 dB more than it should be. That 
agrees pretty closely with what I have been observing although my 
measurement show a slightly larger difference than that, but that could 
be because my measurements didn't have enough accuracy.


I used to try to identify a signal at that was close to the noise floor 
and see if JT-9 would decode it.  It never did.  At a level where JT-9 
does decode the signal, it would have been easy copy on CW.  So for me, 
I see no low level signal advantage to these digital modes.  I continue 
to wonder why other people say there is.  I wonder if others are using a 
wide passband when making comparisons (if they really do make 
comparisons).  For low level CW I usually use 150 Hz, sometimes a little 
less if there is QRM.


Jerry, K4SAV
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Re: Topband: FT8 Observations

[Joe Subich, W4TV]

On 2018-04-23 12:08 PM, Tim Shoppa wrote:
On being able to hear signals at -12 to -17 dB on FT8, I do broadly 

> agree. A CW signal at those levels would be easily heard and copied
> by any decent CW operator.

-12 to -17 dB on FT8 (or any of the other "JT modes") is signal to noise
+ QRM in a 2500 Hz bandwidth.  "0 dB" in 'JT speak' is +22 dB S/N for
CW assuming a 100 Hz bandwidth (using the convention of total voltage
from the receiver vs. noise and QRM voltage).

That makes the -17 dB FT8 signal about +5 dB S/N on CW and the mythical
-24 dB (threshold) FT8 signal about - 2dB or -3 dB *below* the copyable
level for a CW signal.  JT9 has a threshold of -27 dB ... another 3 dB
more sensitive with its one minute cycle instead of the 15 second cycle
of FT8.

Since the 'JT mode' "threshold" represents a decoding probably of 0.50
(50%) and CW operators, particularly on 160 meters, often operate with
decoding probabilities as little as 10%, one can assume the ultimate
sensitivity for FT8 is 5 to 6 dB better than CW and JT closer to 10 dB
better than CW but it will take some time for experience to prove (or
disprove) those assumptions.  The nature of noise, fading and QRM will
also impact the relative sensitivities.

73,

   ... Joe, W4TV


On 2018-04-23 12:08 PM, Tim Shoppa wrote:

On being able to hear signals at -12 to -17 dB on FT8, I do broadly agree. A CW 
signal at those levels would be easily heard and copied by any decent CW 
operator.

I think a lot of the FT8 “processing gain” claims, assumes a really poor CW 
operator. A 0dB FT8 signal is not at noise level, it is way way above noise 
level.

That said, this morning at my sunrise (noon in Europe) I was printing Italian 
stations on 40M FT8 and I was being decoded in Europe too, often at the -22 to 
-24 dB level. (I was barefoot and I’m assuming the italiAns too). Those are 
levels below what I can hear or copy on CW. I can work Europe midday on 40CW in 
winter but not so easy in spring or summer.

Tim N3QE

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Re: Topband: FT8 Observations

[Mike Waters]

I have no idea how FT8 compares with other weak-signal digital modes (such
as the ones that JT himself wrote), Dave. If no one knows here, then Google
is your friend. :-)

As for waiting until next fall and winter, keep in mind that we are
approaching the southern hemisphere's fall and winter. Since Topbanders
there have reduced or no lightning QRN, on occasion it's an opportunity for
us to work them!

73, Mike
www.w0btu.com

On Mon, Apr 23, 2018, 1:19 PM David Olean  wrote:

>  I guess I was just underwhelmed at what I could accomplish on FT8 vs
> CW on 160.  ...
>
> ... In the first evening I saw a huge improvement using diversity and it
> was nice having all the wires available too!  Too bad it won't get much use
> until next fall and winter!
>
> On 4/23/2018 3:50 PM, Mike Waters wrote:
>
> Hi Dave,
>
> I think it's safe to say that you're running Beverages in a very quiet
> location, and the hams that can't hear you are not. What is more, they
> might have a 20 over 9 noise level and are running non-directional antennas
> (such as verticals with no radials or low dipoles).
>
> 73, Mike
> www.w0btu.com
>
>
> On Mon, Apr 23, 2018, 10:36 AM David Olean  wrote:
>
>> I have been playing around with FT8 on 160M and am a bit puzzled. I have
>> made plenty of contacts, but with many stations, it seems to require an
>> inordinate amount of power to get their attention, or they do not respond
>> at all. I also have noted that I can hear in a 2.8 kHz passband, signals
>> that register from -12 to -17 dB. About the weakest that I see is a bit
>> more than -20 dB. Does this mean that FT8 is only a few dB better than CW?
>> I have ...
>
>
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Re: Topband: FT8 Observations

[David Olean]

  Hi Mike and all who responded.

    I guess I was just underwhelmed at what I could accomplish on FT8 
vs CW on 160.  I figured it would open up a whole new level of rare 
countries and places that were now workable to me. Working Kazakhstan on 
160 CW from my location is difficult, but doable on some nights in the 
winter. On FT8 I hear UN1L often, but I can never work him after many 
days of trying. I started out with 90 watts and ended up with 900 watts 
output, but never a response from him. I guess 160 is a special case 
where achieving a good receive noise level is very difficult.  FT8 must 
be a huge improvement for those, as you said, with few radials and 
smallish vertical radiators as their sole antenna. The extra 5 or 6 dB 
must be the difference of night and day for limited space or limited 
antennas in general.  It sure has fostered much activity on 160 with 
calls that are mostly unfamiliar to me.  I have worked a few regulars on 
FT8, like YO3APJ, and they seem to hear just fine. Unfortunately I am 
not QRV on other HF bands to try out FT8 there! I suspect the ALLIGATOR 
SYNDROME is not as evident on the higher HF bands.


On another subject, I ran out of room on my six position receive 
beverage coaxial switch. I had seven beverages, and one was not hooked 
up as a result.  I also have not been using diversity reception even 
though I am using a K3. So I finally worked out a plan to make a new 
switching box. It consists of two Grayhill 12 position rotary switches.  
The two switches have a set of the 12 positions wired in parallel 
between the two switches and each position connects to a rx input jack 
on the back, while the common terminal for each switch goes to the main 
rx jack or the diversity rx jack on the K3.  The 12 inputs are "F" 
fittings on the back of the switch box. I worried that the isolation 
would be poor, but it checks out at 55 to 65 dB on 160 and 80 meters. 
VSWR is pretty good too even with all the insulated wire used. I did not 
even try wiring it with coax! One switch selects any of 12 beverage 
antennas for the main receiver, while the second switch selects any of 
the beverages for the diversity receiver. It works very well and I 
wonder why I did not do this a long time ago. In the first evening I saw 
a huge improvement using diversity and it was nice having all the wires 
available too!  Too bad it won't get much use until next fall and winter!


73

Dave K1WHS


On 4/23/2018 3:50 PM, Mike Waters wrote:

Hi Dave,

I think it's safe to say that you're running Beverages in a very quiet 
location, and the hams that can't hear you are not. What is more, they 
might have a 20 over 9 noise level and are running non-directional 
antennas (such as verticals with no radials or low dipoles).


73, Mike
www.w0btu.com 


On Mon, Apr 23, 2018, 10:36 AM David Olean > wrote:


I have been playing around with FT8 on 160M and am a bit puzzled.
I have
made plenty of contacts, but with many stations, it seems to
require an
inordinate amount of power to get their attention, or they do not
respond at all. I also have noted that I can hear in a 2.8 kHz
passband,
signals that register from -12 to -17 dB. About the weakest that I
see
is a bit more than -20 dB. Does this mean that FT8 is only a few dB
better than CW?  I have my time set accurately and I try to place
my TX
signal away from whomever I am calling on a clear spot on my
waterfall.

Some stations are easy to work, and I have worked across the country
(FN43 to a CM grid) running just 1 watt. It just seems that there are
many stations that are not hearing much, but are making plenty of
noise.  Am I wrong?

I am working on cleaning up my 160 setup and have 8 beverages running
and they are all pretty quiet now that I installed plenty of ferrite
chokes around on the RG-6 feed lines.  I am looking forward to
next fall
and winter.

73

Dave K1WHS

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Re: Topband: FT8 Observations

[Grant Saviers]

Dave,

Remember that the reported S/N is relative to the receive station noise 
+ QRM level.   Since many TB stations don't have your antennas and have 
high noise, they can't decode you or report a poor S/N.  I get +9 and 
-18 reports from YB stations a hundred KM apart.  It's not spotlight 
prop.  So more power helps. Often I find I need to move TX freq, 
especially way into the FT8 band edges when well heard stations don't 
decode me, but that is more my experience on 80m long path.   The EU QRM 
level is clearly a limiting factor.   I think the latest release decodes 
to -24, I see that sometimes but rarely does the other station respond.  
It is always worth calling since their noise level might be a lot lower 
than mine.  That is clearly the case for some of the skimmer posted 
signal reports by great hearing stations that are not on the air.  I 
will get a -17 report but no other station in that country decodes me 
(or decides to answer my CQ DX).


Grant KZ1W

On 4/22/2018 7:17 AM, David Olean wrote:
I have been playing around with FT8 on 160M and am a bit puzzled. I 
have made plenty of contacts, but with many stations, it seems to 
require an inordinate amount of power to get their attention, or they 
do not respond at all. I also have noted that I can hear in a 2.8 kHz 
passband, signals that register from -12 to -17 dB. About the weakest 
that I see is a bit more than -20 dB. Does this mean that FT8 is only 
a few dB better than CW?  I have my time set accurately and I try to 
place my TX signal away from whomever I am calling on a clear spot on 
my waterfall.


Some stations are easy to work, and I have worked across the country 
(FN43 to a CM grid) running just 1 watt. It just seems that there are 
many stations that are not hearing much, but are making plenty of 
noise.  Am I wrong?


I am working on cleaning up my 160 setup and have 8 beverages running 
and they are all pretty quiet now that I installed plenty of ferrite 
chokes around on the RG-6 feed lines.  I am looking forward to next 
fall and winter.


73

Dave K1WHS

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Re: Topband: FT8 Observations

[Mike DeChristopher]

Hi Dave,

In my [very, very, extremely] limited experiences with any of the JT
modes, it has always seemed to me that many are alligators. I think
the FT8 craze has inspired a lot of people to get on 160 with
compromise tx antennas -- this is a good thing -- but I'm not sure
they realize how much they're missing on RX. I'm currently writing an
article for a local club on simple RX antennas for this very reason
(big ft8 crowd). If you try it on other bands, even 80 for example,
you'll find your mileage *magically* improves. The program hears so
well that even a stoopid rx antenna that only slightly pares down the
noise would be fb for most.

As for your tribulations, I don't know enough about the mode to say
too much, but it should be regularly better than CW, even factoring in
the alligators. A local fellow here in WMA probably has 60+ cty on FT8
with only a compromise inverted-L and no RX. I know he's running >10
or 20W -- not sure if that's considered inordinate or not.

Glad to hear your beverage noise is straightened out.

73
Mike N1TA



On Sun, Apr 22, 2018 at 10:17 AM, David Olean  wrote:
> I have been playing around with FT8 on 160M and am a bit puzzled. I have
> made plenty of contacts, but with many stations, it seems to require an
> inordinate amount of power to get their attention, or they do not respond at
> all. I also have noted that I can hear in a 2.8 kHz passband, signals that
> register from -12 to -17 dB. About the weakest that I see is a bit more than
> -20 dB. Does this mean that FT8 is only a few dB better than CW?  I have my
> time set accurately and I try to place my TX signal away from whomever I am
> calling on a clear spot on my waterfall.
>
> Some stations are easy to work, and I have worked across the country (FN43
> to a CM grid) running just 1 watt. It just seems that there are many
> stations that are not hearing much, but are making plenty of noise.  Am I
> wrong?
>
> I am working on cleaning up my 160 setup and have 8 beverages running and
> they are all pretty quiet now that I installed plenty of ferrite chokes
> around on the RG-6 feed lines.  I am looking forward to next fall and
> winter.
>
> 73
>
> Dave K1WHS
>
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Re: Topband: Wednesday 160m DX Activity Night

[Ed Sawyer]

Roger.  My guess is that it is considered "season over" by most of the boys.
I rarely get on 160M after early April unless there is a specific DXpedition
on.  I don't think I am alone.

 

In some cases, people even lose antenna options for the summer due to
coexisting with farmers and other activities.

 

73

 

Ed  N1UR

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Re: Topband: FT8 Observations

[Tim Shoppa]

On being able to hear signals at -12 to -17 dB on FT8, I do broadly agree. A CW 
signal at those levels would be easily heard and copied by any decent CW 
operator.

I think a lot of the FT8 “processing gain” claims, assumes a really poor CW 
operator. A 0dB FT8 signal is not at noise level, it is way way above noise 
level.

That said, this morning at my sunrise (noon in Europe) I was printing Italian 
stations on 40M FT8 and I was being decoded in Europe too, often at the -22 to 
-24 dB level. (I was barefoot and I’m assuming the italiAns too). Those are 
levels below what I can hear or copy on CW. I can work Europe midday on 40CW in 
winter but not so easy in spring or summer.

Tim N3QE

> On Apr 22, 2018, at 10:17 AM, David Olean  wrote:
> 
> I have been playing around with FT8 on 160M and am a bit puzzled. I have made 
> plenty of contacts, but with many stations, it seems to require an inordinate 
> amount of power to get their attention, or they do not respond at all. I also 
> have noted that I can hear in a 2.8 kHz passband, signals that register from 
> -12 to -17 dB. About the weakest that I see is a bit more than -20 dB. Does 
> this mean that FT8 is only a few dB better than CW?  I have my time set 
> accurately and I try to place my TX signal away from whomever I am calling on 
> a clear spot on my waterfall.
> 
> Some stations are easy to work, and I have worked across the country (FN43 to 
> a CM grid) running just 1 watt. It just seems that there are many stations 
> that are not hearing much, but are making plenty of noise.  Am I wrong?
> 
> I am working on cleaning up my 160 setup and have 8 beverages running and 
> they are all pretty quiet now that I installed plenty of ferrite chokes 
> around on the RG-6 feed lines.  I am looking forward to next fall and winter.
> 
> 73
> 
> Dave K1WHS
> 
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