Message-ID: <001301c09496$c124e600$0a00a8c0@ThreeLakes.ca>
From: "Larry Kayser" <kayser@sympatico.ca>
To: rsgb_lf_group@blacksheep.org
References: <2001021200082868199@zetnet.co.uk>
Subject: LF: DDS Frequency setting requirement
Date: Sun, 11 Feb 2001 20:49:46 -0500
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Greetings:

I suggest it has come to the time when we need to have all DDS units be
programable frequency wise down to the integer steps of DDS unit rather than
in the steps of 1 Hz and higher.  1 Hz steps are inadequate for the
operations currently in progress in the LF community.

In case anyone is not familiar the DDS units commonly available now have
very small steps available to them.  The basic is this, if you have a
Reference oscillator of 30 MHz, or what ever, divide the reference in Hz,
say 30000000 for a 30 MHz reference by the normal 32 bit value for most of
the DDS devices available to us today.

The simple math is this, 30000000/2^32 results in 0.006984919 or more easily
presented as steps of 6.98 milliHz per step at the DDS level.

The DDS VFO devices we are buying are programmed to step in approximately 1
Hz steps, what we need is a selectable setting so we can also select the
milliHz steps.  There are just over 143 steps of 6.98 MilliHz in a single
Hz, this will let us move in tighter for intercontinental work at 60 second
bits and higher.  We should be able to have between 7 and 10 stations in a
single Hz.

The problem is the application layer software in the DDS unit, all we need
is an upgrade to allow significantly better frequency control than we have
now.

The day of DDS units with 1 Hz steps is long over, we need the next level
and I suggest we need this capability now.  Thgis isnt rocket science, it is
just making use of what already exists if you have a DDS frequency control
system.  I suggest the time has come to make this a requirement for all of
us experimenting on LF.

Comments etc.

Larry
VA3LK