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From: "captbrian" <captbrian@ukonline.co.uk>
To: <rsgb_lf_group@blacksheep.org>
References: <001101c6817e$4d9dafc0$2101a8c0@whitehead1> <001001c68263$71d5ad80$fe78a8c0@W1KW> <4479C3AA.7020104@freenet.de> <003501c68270$7fbc9050$fe78a8c0@W1KW> <005201c68335$ab37bd20$045bfea9@d4f8d8>
Date: Tue, 30 May 2006 08:42:03 +0100
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Subject: LF: Re: Experimental MF Beacon test
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Nothing heard 0800 . are you running continuously?
Where is the transmitter?

Bryan  Nr. Brighton

----- Original Message -----
From: "Andy Talbot" <actalbot@southsurf.com>
To: "LF Group" <rsgb_lf_group@blacksheep.org>
Cc: "API(Work)" <jfell@crydom.com>; "API(Home)" <jfell@tesco.net>; "WKL"
<g3wkl@btinternet.com>; "Alan Melia" <alan.melia@btinternet.com>
Sent: 29 May 2006 16:36
Subject: LF: Experimental MF Beacon test


> I am currently testing a low power experimental beacon on 1960.000kHz +/-
> 1Hz.
> It uses a transmission format similar to that of the 5MHz beacons,
> GB3RAL/WES
> and ORK, execpt that the sounder sequence is replaced by a PSK31 message.
>
> The sequence transmitted is :
> T+0s             CW     Callsign
> T+7 - T+15s  Nine power steps with the output reduced by 6dB each time
>                       for a total of -48dB
> T+16 - T+24  A repeat of the power steps.
> T+25 - T+30  Full power (level measurement reference period)
> T+30 - T+47  PSK31 data
> T+47 - T+59  Full power
>
> The reference time T starts at one minute past the hour and repeats every
15
> minutes, so transmissions occur at 01, 16, 31 and 46 minutes past the
hour.
>
> If the 'GB3RAL' monitoring software is used for logging this signal, the
> transmission will be shown and recorded as if it were that from GB3WES.
>
> The transmissions will continue overnight, and will hopefully be switched
on
> for
> subsequent evening & overnight  runs.   Power output is 3Watts to my 7m
high
> Tee antenna - esimated gain -9dBd
>
> The beacon hardware consists of an identical DDS and PIC controller to
that
> used on GB3VHF, although without the GPS locking; frequency is derived
from
> a TCXO alone.  A Motorola Oncore GPS module controls timing.  Completely
new
> PIC software uses the 12 bits of amplitude control possible within the
> AD9852 DDS chip to generate the power steps directly rather than having to
> use a separate programmable attenuator as was done for the 5MHz beacons.
> The PSK31 envelope is directly generaed at RF by looking up 250
> half-sinewave
> amplitude values for each 31.25 baud symbol at a sampling rate of
7812.5Hz.
>
> Full details of both the 5MHz beacon designs and the driver for GB3VHF can
> be
> found on the website below
>
> Andy  G4JNT
> www.scrbg.org/g4jnt/
>
>
>
> --
> No virus found in this outgoing message.
> Checked by AVG Free Edition.
> Version: 7.1.394 / Virus Database: 268.7.3/350 - Release Date: 2006-05-28
>
>
>