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Re: LF: DK7FC WSPR bad quality problem

To: <[email protected]>
Subject: Re: LF: DK7FC WSPR bad quality problem
From: "Markus Vester" <[email protected]>
Date: Sun, 27 Mar 2016 20:20:32 +0200
Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mx.aol.com; s=20150623; t=1459102837; bh=OkyUV9+l+ohId772zGLrwItP0C0pRq9SXzI21hI6ZOA=; h=From:To:Subject:Message-ID:Date:MIME-Version:Content-Type; b=UAcqxo6lkK+N8670IoCjkIGZuwn/ovH5BzcAVMaW93n8vq5/50/I9J9z51RbsTw1N XcnI4YEKSW1D56OWx5yCeB30MamT9Rbgrgd761uCF3elrGHSR9psUojiPHobfyQIJu aMfrWCLL8dz06oDcWNtA2uT/Nau2D8NMwxe/722A=
Importance: Normal
References: <779E45249B3045B8ACB0E9A1E32CC15F@pcn5> <FD981C55753B463C9C041B07D5BAAF36@AGB>
Reply-to: [email protected]
Sender: [email protected]
Don't blame the little RasPi, it's not its fault either. Stefan's signal actually looks quite pure from here (180 km). Though there exist -38 dB AM sidebands at +- 100 Hz caused by the rectified mains ripple, these shouldn't cause a significant problem except for an occasional extra decode. However note that a strong and clean signal can be widened up by the receiver if noiseblanking is enabled.
 
73, Markus
 

From: Graham
Sent: Sunday, March 27, 2016 7:14 PM
Subject: Re: LF: DK7FC WSPR bad quality problem

Andy,
 
This time its not really Stefan's  fault  :-,)
 
This is a  problem , using the  raspberry PI ,  the  Pi processor uses  interrupts, which, cause the  execution  time  of the  timing  loops to  vary  slightly ,
the 'small' time  variations , produce side bands .
 
This was evident  during  the  development of  a  R-PI  routine  for  sending  Opera , as the  R-Pi support documentation is not  particularly  comprehensive, its  'not' possible to  fully address the  i/o  functions and as such there exists  a conflict  with higher order irq   requests .  Producing  seemingly  random widening  of the  spectrum,  depending  on the  irq  deployments.
 
Ie the  pulse train suffers  from  timing  jitter
 
The  alterative of the  U3 beacon  key'er , driving  the  DDS 'oscillator' is  a more  elegant  solution,  but as noted by  Andy [rad-com]  some time  back, the  later  U3 with the  PPL  suffers from  settling  time issues ,  when  commanded with , step  frequency changes.  these sever to produce sidebands , at the  step changes.
 
73-G,
 

Sent: Saturday, March 26, 2016 8:36 PM
Subject: LF: DK7FC WSPR bad quality problem

Hello Stefan.

 

I am sorry, but this evening you have a very poor quality WSPR signal on MF with many splatters, I think it is perhaps due to an overload TX AF level.

 

That is not in phase with the normal ham spirit. So, please be kind to stop now your transmission and correct this problem.

 

On the way, can you say honnestly if your power is not over the legal limit ?

 

Sincerly yours and  my best 73 de Andy.

 

P.S.

 

Have a look below at some reports last hour showing the problem :

 

 

2016-03-26 19:00

DK7FC

0.475683

+12

0

JN49ik

1

PI4THT

JO32kf

336

338

2016-03-26 19:00

DK7FC

0.475783

-25

0

JN49ik

1

PI4THT

JO32kf

336

338

2016-03-26 18:50

DK7FC

0.475783

-23

0

JN49ik

1

PE1RKT

JO22fb

418

316

2016-03-26 18:50

DK7FC

0.475683

+14

1

JN49ik

1

PE1RKT

JO22fb

418

316

2016-03-26 18:40

DK7FC

0.475683

+12

0

JN49ik

1

LA8AV

JO59cs

1153

4

2016-03-26 18:40

DK7FC

0.475783

-24

0

JN49ik

1

LA8AV

JO59cs

1153

4

2016-03-26 18:50

DK7FC

0.475783

-28

0

JN49ik

1

LA3JJ

JO59bh

1102

4

2016-03-26 18:50

DK7FC

0.475683

+10

0

JN49ik

1

LA3JJ

JO59bh

1102

4

2016-03-26 18:40

DK7FC

0.475780

-28

1

JN49ik

1

G3KEV

IO94sh

829

314

2016-03-26 18:40

DK7FC

0.475679

+10

0

JN49ik

1

G3KEV

IO94sh

829

314

2016-03-26 19:10

DK7FC

0.475682

+13

0

JN49ik

1

F6CNI

JN19qb

389

266

2016-03-26 19:10

DK7FC

0.475782

-27

1

JN49ik

1

F6CNI

JN19qb

389

266

2016-03-26 18:30

DK7FC

0.475682

+15

0

JN49ik

1

F5WK

JN18hp

452

261

2016-03-26 18:30

DK7FC

0.475782

-22

0

JN49ik

1

F5WK

JN18hp

452

261

2016-03-26 18:00

DK7FC

0.475680

+19

0

JN49ik

1

DL6II

JO30nx

205

327

2016-03-26 18:00

DK7FC

0.475780

-18

0

JN49ik

1

DL6II

JO30nx

205

327

2016-03-26 18:50

DK7FC

0.475682

+17

0

JN49ik

1

DL4RAJ/2

JN68kj

326

109

2016-03-26 18:50

DK7FC

0.475782

-22

0

JN49ik

1

DL4RAJ/2

JN68kj

326

109

 

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