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Re: LF: 'JNT Dual purpose beacons

To: <[email protected]>
Subject: Re: LF: 'JNT Dual purpose beacons
From: "Graham" <[email protected]>
Date: Sat, 19 Sep 2009 14:02:46 +0100
Importance: Normal
In-reply-to: <[email protected]>
References: <[email protected]>
Reply-to: [email protected]
Sender: [email protected]
Andy,
 
As the  502.4 dial frequency looks to  be  accepted , with other stations moving in to  the  capture area when running  wspr and as it would seem, AA1A is monitoring this dial setting  a frequency in the lower  part of the wspr section would  ensue a clear frequency, activity looks to  be  centred in the  higher portion of the  band ?
 
These look to be the  first wspr spots , of which I assume to be the  'first established permanent wspr  beacon' ?
 
2009-09-19 12:06   G4JNT   0.503855   -9   0   IO90iv   0.2   G3XVL   JO02nb   212   51 
 2009-09-19 12:06   G4JNT   0.503850   -23   0   IO90iv   0.2   M0LMH   IO93gx   343   358 
 2009-09-19 12:06   G4JNT   0.503850   -1   0   IO90iv   0.2   M0BMU   IO91vr   119   39 
 
Power wise , during daylight , your ground wave looks to  be  simply a function of  power , at  -23  at 343 k with 100 watts ? , you  could reduce by  10dB to  10 watts and still provide ground wave data ? , in tests last  year  with  Rick ON7T , carrier levels below 1 watt still decoded at  range.
 
I will up date the beacon page on uk500khz to  include the  new mode
 
73 - G .
 
 

Sent: Saturday, September 19, 2009 12:06 PM
Subject: LF: 'JNT Dual purpose beacons

I'm in the last stages of modifying my beacon to include a WSPR transmission that will run pseudo-simultaneously with the 15 minute regular one at 503.7kHz
 
It has turned out to be posible to fit all the code into one controller PIC which simplifies the hardware considerably - the only downside is that the PSK31 message length has had to be shortened by a few characters to be able to get the additional WSPR symbol and frequency information into the EEPROM area of the PIC.
 
I've included to option to be able to transmit the WSPR signal at a lower amplitude than the 15 minute beacon, and the pseudo random timing is anything but - it has been chosen to fit round the 15 minute intervals, and preferably not adjacent to them.  
 
Before I programme-up the actual beacon Tx, can I have some suggestion on the frequency that would be best to avoid existing users, and what sort of power to adopt, bearing in mind the main Tx runs at about 100 Watts of RF giving somewhere in the region of 24dBm ERP.  Also some idea of a duty cycle to use - 50% is the maximum I've allowed for.

Andy
www.g4jnt.com

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