Return to KLUBNL.PL main page

rsgb_lf_group
[Top] [All Lists]

Re: LF: WSPR sidebands

To: [email protected]
Subject: Re: LF: WSPR sidebands
From: DK7FC <[email protected]>
Date: Sun, 27 Mar 2016 23:14:43 +0200
In-reply-to: <[email protected]>
References: <[email protected]om> <[email protected]> <[email protected]> <[email protected]>
Reply-to: [email protected]
Sender: [email protected]
User-agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3
...AM key-clicks. Hasn't that been a quality title in the good old QRSS times, called dog-boning?
I've always been happy when i saw some of them in W1VD's captures :-)

73, Stefan

Am 27.03.2016 23:01, schrieb Graham:
Opera's AM key-clicks ,
 
VERY  True , there  has to be an associated  bandwidth, however ,  hard  non-conditioned on off  keying  of  a  carrier  will  produce , key-click's  , this was the  subject of a  e-mail , sent to  me some time  back, over my  TX bandwidth  on  477 /op8 .
 
Notably , the  email  enquired as  to  how  my Tx b/w  was  in the  order of  10 MHz or  less and not  the  mode usual  400 / 500 MHz
 
Its quite  simple,  I use  the  audio  drive  , via a  totally  linear  TX path  ma1723 > skanti amp
 
What appears to be a  simple  task,   is often quite  complex , as is the  use of the  R-PI as a  rf carrier  source
 
The  integrity of the  timing loops [ as before] are  compromised  by the  higher order  IRQ requests ,  hence  setting  a  flag high/low , with  a  executed code routine  to  generate a 'stable'  carrier  source  cannot be relied on.
 
In the  development of the  Opera  R-PI tx code ,  the  action  of the  IRQ's could be  observed as random  noise , acting   cycle  by  cycle , hence any  long persistence  in the  spectrum plot , simply  masked the  spurs , however , the  Opera  dsp  returned varying  s/n  levels  for the  same  test  set up , indicating the  channel  background noise varied. [ opera decoder  is a  sampling system running far faster than the  data  rate ]
 
The  project was  shelved , other than for  hard on-off  keying  of a  free  running  carrier ,  in this the  clock  jitter is  of no consequence.  
 
73-G,

Attachment: 02_Februar2012_DK7FC_to_W1VD.jpg
Description: JPEG image

<Prev in Thread] Current Thread [Next in Thread>