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From: "Andy" <actalbot@southsurf.com>
To: <rsgb_lf_group@blacksheep.org>
Date: Tue, 30 May 2006 11:56:11 +0100
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Subject: LF: Re: Re: Experimental MF Beacon test
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I turned it off this morning, not much point having it on in daylight hours.
My home QTH - IO90IV58

Andy  G4JNT  QTHR


-----Original Message-----
From: captbrian <captbrian@ukonline.co.uk>
To: rsgb_lf_group@blacksheep.org <rsgb_lf_group@blacksheep.org>
Date: 2006/05/30 08:57
Subject: LF: Re: Experimental MF Beacon test


>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
>>
>>
>>
>
>