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LF: ROS VLF 0.8 and 0.4 Baud

To: <[email protected]>
Subject: LF: ROS VLF 0.8 and 0.4 Baud
From: "Graham" <[email protected]>
Date: Mon, 1 Nov 2010 17:05:40 -0000
Importance: Normal
Reply-to: [email protected]
Sender: [email protected]

ROS VLF    0.8  and  0.4 Baud

 

Outline

 

Based  on the  ROS MF- 1  and MF-7   narrow  band  data  modes , ROS VLF is a free  running   live  key  board qso  mode , not  requiring internet  connection  or  accurate  time or  frequency control , AFC of  78 Hz    is  provided  for  receive and once locked , the  overall  circuit stability  must  exceed   5 Hz during the  tx period.

 

Configured for  operation  within the  8 KHz  experimental  band , using  phase  continuous  multi  tone  frequency shift  keying , with in a  bandwidth  of  25 Hz , allowing  for  a system Q of over  300  with out degradation and may  be  transmitted  using  non   linear  amplifiers.

 

Provision is made for the  drive  frequency  division, inherent  in some  Class E/D  amplifiers,  by the  ability to  select  ?normal or ? Class E/D? , this  selection  causes  the  transmit  tones and  modulation bandwidth to  be  multiplied by a  factor  of  -2- to  16K / 50Hz  , thus after  amplification , the  signal  is reverted to  8k / 25 Hz

 

Rx frequency is fixed and not affected by the Tx select function

 

All  normal  functions are  retained, including the  ROS-Chat , allowing  text  messages to  be  broadcast to  ?all?  or  individual ROS  users, via the  internet . The Beacon timer cpu and Rx monitor?s have been disabled to facilitate tx only operation.  If connected to the  www, reception  reports will  be uploaded to  :-

 

http://pskreporter.info/pskmap.html

 

As in MF , spots will  show as   band ?unknown?

 

The  system  utilises the   soundcard to  produce in effect a  SDR  radio  operating at   8KHz . it is  estimated that  the  0.4 baud  version  will  give a  noise  floor  of  some -38 dB , the  0.4  baud version ,  produces  a  higher  CPU load than  0.8 , showing  round  20% on a  dual  core  lap-top

 

Data  summery

 

Frequency  tx/rx           8950-8975  Hz           

Bandwidth                    25 Hz

Baud rate                     fixed  0.4   /  0.8

Rx AFC range              78 Hz

Drift tolerance               5 Hz

S/N  0.4  Baud             -38 dB

 

 

Two  exe  files  are  available  , one  0.4  band  , the  other  0.8  baud. for  testing 

 

73 - G ..

 

 



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