locked Weird signal reports


Gary K6JAJ <k6jaj@...>
 

Hi Ron

AL throw I don’t use FT4 there is a real BUG in this software.  Some where there is a message from wsjt explaining a work around it, and there is a new version coming very soon to correct it

Gary K6JAJ

 

From: WSJTX@groups.io [mailto:WSJTX@groups.io] On Behalf Of Ron Grossl
Sent: Monday, May 06, 2019 3:25 PM
To: WSJTX@groups.io
Subject: [WSJTX] Weird signal reports

 

I have searched and found no one else with this problem, or maybe I didn't search the right way.  Anyway, I just installed the new RC5 version of WSJT-X.  I have made a few contacts and that part seems to be working just fine.  My problem is that all of the signals I receive are reported as being above 0db in strength.  The weakest signal I have seen has been 7db, not -7.  I have sent 35db as report to a station in England.  I know I have a good receiver, but not that good.  This only does this in FT4 mode, things are normal in FT8.  Did I miss something in the documentation or is something seriously wrong with my setup?

Thanks
Ron  N4RLG


Ron Grossl
 

Thanks guys.  I'll watch my filter settings closer and not worry too much about the really strong signals.

73
Ron


Herb Blue - WB8ASI
 

I got a +35 report the other day on FT4.  Crazy that I can ever get that kind of signal.  A fluke? cuz otherwise all is normal and working fine.

On May 6, 2019 at 6:24 PM Ron Grossl <grossl@...> wrote:

I have searched and found no one else with this problem, or maybe I didn't search the right way.  Anyway, I just installed the new RC5 version of WSJT-X.  I have made a few contacts and that part seems to be working just fine.  My problem is that all of the signals I receive are reported as being above 0db in strength.  The weakest signal I have seen has been 7db, not -7.  I have sent 35db as report to a station in England.  I know I have a good receiver, but not that good.  This only does this in FT4 mode, things are normal in FT8.  Did I miss something in the documentation or is something seriously wrong with my setup?

Thanks
Ron  N4RLG -=-=-=-=-=-=-=-=-=-=-=-
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Bill Somerville
 

On 07/05/2019 01:17, Bill Somerville wrote:
The reason for this mechanism is that FT4 is expected to be used on a busy channel
Hi Ron,

the same applies to FT8.

73
Bill
G4WJS.


Bill Somerville
 

On 07/05/2019 01:07, Ron Grossl wrote:
Thanks for the reply, Bill.  You're right about the filters.  I had been working CW and forgot to put the filter back to its widest position and I had my twin passband filters tightened up a little.  That certainly made my results much better.  I am now getting signals in the minus range now, but I am still getting signals as high as 26db.  Is that normal?

73
Ron
N4RLG
Hi Ron,

the SNR estimates rely on an accurate estimate of the noise energy, that is done using a baseline curve fitting algorithm across the waterfall bandwidth. The reason for this mechanism is that FT4 is expected to be used on a busy channel where overlapping signal may noise estimates within the width of a signal unreliable. Knowing that it should be clear that not matching the receiver bandwidth to the waterfall bandwidth may cause the true noise energy to be grossly underestimated.

26dB signals are not impossible but I'm not sure we expect much accuracy at high values like that.

73
Bill
G4WJS.


Ron Grossl
 

Thanks for the reply, Bill.  You're right about the filters.  I had been working CW and forgot to put the filter back to its widest position and I had my twin passband filters tightened up a little.  That certainly made my results much better.  I am now getting signals in the minus range now, but I am still getting signals as high as 26db.  Is that normal?

73
Ron
N4RLG


Bill Somerville
 

On 06/05/2019 23:24, Ron Grossl wrote:
I have searched and found no one else with this problem, or maybe I didn't search the right way.  Anyway, I just installed the new RC5 version of WSJT-X.  I have made a few contacts and that part seems to be working just fine.  My problem is that all of the signals I receive are reported as being above 0db in strength.  The weakest signal I have seen has been 7db, not -7.  I have sent 35db as report to a station in England.  I know I have a good receiver, but not that good.  This only does this in FT4 mode, things are normal in FT8.  Did I miss something in the documentation or is something seriously wrong with my setup?

Thanks
Ron  N4RLG
Hi Ron,

to get representative SNR reports the waterfall bandwidth must be roughly the same as your receivers bandwidth. Avoid using any filter on your rig that is narrower that the width extents of the waterfall.

73
Bill
G4WJS.


Ron Grossl
 

I have searched and found no one else with this problem, or maybe I didn't search the right way.  Anyway, I just installed the new RC5 version of WSJT-X.  I have made a few contacts and that part seems to be working just fine.  My problem is that all of the signals I receive are reported as being above 0db in strength.  The weakest signal I have seen has been 7db, not -7.  I have sent 35db as report to a station in England.  I know I have a good receiver, but not that good.  This only does this in FT4 mode, things are normal in FT8.  Did I miss something in the documentation or is something seriously wrong with my setup?

Thanks
Ron  N4RLG