Return to KLUBNL.PL main page

rsgb_lf_group
[Top] [All Lists]

Re: LF: A test of cmsk on 8.97kHz

To: <[email protected]>
Subject: Re: LF: A test of cmsk on 8.97kHz
From: "Graham" <[email protected]>
Date: Sun, 2 Oct 2011 14:40:38 +0100
Importance: Normal
In-reply-to: <FA6C4AA653EF43EBB75BEC634A2598AC@AGB>
References: <FA6C4AA653EF43EBB75BEC634A2598AC@AGB>
Reply-to: [email protected]
Sender: [email protected]
I should  add
 
The  MF / EME  and   8Khz  AUDIO-BAND   modes  are  not  Spread Spectrum as   defined  by the  FCC  , and are  similar to  CMSK in deploying a  direct  sequencing  engine , the  expected  lowering  of the  minimum detection  threshold ,subsequently   may be observed in  both  modes,  
 
Reference   may  be made to  this months  Rad-Com Magazine  Data  coms article  , by  Andy ...
 
G..

From: Graham
Sent: Sunday, October 02, 2011 12:19 PM
Subject: LF: A test of cmsk on 8.97kHz

This   was  posted on the Digital mode  group  -yahoo-   http://groups.yahoo.com/group/digitalradio/message/40065
 
For  those  who can, the   ROS  direct  drive  8 Khz  sound  card  based system ,   with  optional   X2  Tx  frequency  to compensate  for  class  e/d  divide  by 2  , is still  available
for  use  , details  at  :-
 
 
 
__________________________________________________________________________________________________________
 
 
 
A test of cmsk on 8.97kHz


Hi all,

The last few days I've been doing some digi mode testing at 8.97 khz;
"dreamers band", mostly with use of the QRSS mode.

On the transmitter side, I have been using a 5 turn 10 x 10 m antenna
and an audio amplifier 100W. The system is feeded with a signal from the
program "Spectrum Lab".

On the receiver side, I have been using a 70 x 70 cm 60 turns loop,
tuned with a capacitor. The loop was connected to the microphone input
on my laptop and decoded with "Spectrum Lab".

The result has been interesting . With this simple arrangement, I have
reach a distance of 2.5 km.

Yesterday I tried out CMSK8 made by ZL1BPU Murray. I had to make some
changes in the ini-file to get the CMSK work om 8.97khz. The sampling
rate was adjusted with the program CheckSR and the transmitting
frequency was set to 8970Hz. Waterfall has a 2000Hz limit so this was
black and useless on 8790Hz.

It would makes it easier to track the signal if the developer could
extend waterfall to 10 kHz. Iam aware that one can get the view of the
waterfall by going down in frequency, but 8.97khz has become a de facto
water hole of VLF .

The result was exciting. A clean copy of the signal was received at
about 2 km.

I would also try to test out some of the VLF mode in multipsk ,
especially PSK10 and PSKAM10, but I have not find a way to fool the
program to work on 8.97Khz yet.

73 and good dx the VLF Steinar la5vna






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