Re: LF: GPS Locked test transmission

["Andy Talbot" <andy.g4jnt@googlemail.com>]

I am using th3 AD9852 DDS for this transmission with its 48 bit tuning word, so frequency setting is to within 10^-14 - in other words exact ;-)

 

I have only just subscribed to the reflector on my home email account, so would otherwise have missed  this thread.   I was hoping to go to bed early tonight for a early start walking tomorrow, so will do a shorter off period than Uwe suggested.  I'll drop power at 2100z , go off at 2130z then on again at 2200z

 

Andy  G4JNT

 

On 14/10/06, Scott Tilley <sthed475@telus.net> wrote:

Hi Alan and other clicklockers...

All should be fine if the CFH stuff is not exactly on 137.00000000ish

The clicklock alg. can easily resolve in the sub mHz region so seeing
around QRM should be easy.

Even the Russian loran line shouldn't really cause QRM if your careful
in the interpretation of the data if you switch phase on the amateur
signal for the same reason a PSK31 signal produces two lines in its idle
mode.  Our early experiments used this feature to produce unique
sequences based on the phase switching time so that QRM such as loran
lines could be excluded and the real amateur signal identified.  I
modified my DDS software to allow phase switching in 11 degree ish
increments to play with this concept and had lots of fun pulling my clip
leads radiated signals from across the yard out of the noise.  I believe
the ZLs also evolved this to a higher degree in their experiments.

Depending on the version of the alg you're using they may need to use
certain freq that the DDS can produce which are rational numbers.
Peter's 'spinfreq' adaption allowed for using irrational numbers but the
absolute GPS phase reference gets lost if I recall.  Of course Peter had
a solution to that as well involving some real fancy stuff to get it
back using the loran pulses if my memory serves me well...

I'd suggest breaking out Excel and play with the FFT feature and create
your own methods to extract the signal and you may be surprised.  I have
a template around here somewhere that could be used for experimenting if
you need something to start off with.  Peter may have something more up
to date...

73 Scott


Alan Melia wrote:
> Hi Uwe, i would think it would be better fot Andy to avoid exact frequecies
> like that also I wonder if you were receiving a line from CFH which is
> centred there and has been active the last few nights. It is not so strong
> at the moment but is visible on Spectran here, as a noisy 200Hz wide band.
> (GMSK)
> Cheers de Alan G3NYK
>
> ----- Original Message -----
> From: <uwe-jannsen@versanet.de>
> To: <rsgb_lf_group@blacksheep.org>
> Sent: 13 October 2006 23:51
> Subject: Re: LF: GPS Locked test transmission
>
>
>
>> Zitat von Alan Melia <alan.melia@btinternet.com >:
>>
>>
>>> Hi Uwe, you are receiving this through the CFH "noise" as well??
>>> Cheers de Alan G3NYK
>>>
>>>
>> Yes, Alan, I did. but, but, but, home agn at midnight I switched on the
>> equipment and do see nothing. possibly I registrated the carrier Markus
>> mentioned and not the transmission of G4JNT.
>>
>> Andy, is your transmission off the air?
>>
>> regards
>> Uwe/dj8wx
>>
>>
>>
>
>
>
>