[ARDF] ARDF Digest, Vol 76, Issue 12

[Charles Scharlau]

In an earlier post I suggested that ARDF needed to evolve, including the
equipment we use. I hadn't commented with thoughts about equipment
evolution, but I thought I'd go ahead and post some thoughts... even if no
one asked :-) I think the subject fits the original subject because the
current situation with receivers contributes to the frustration of the sport
for both newcomers and those who have been playing the sport for years.

I see three problems that need to be addressed: 1) availability - where to
find quality ARDF receivers in particular, 2) cost 3) complexity. Yes, I
know one can put out feelers and others will gladly identify someone,
somewhere who is selling a receiver. But that only serves to illustrate the
frustration of obtaining equipment: it is very much a treasure hunt, and a
buyer beware activity. When searching for a quality receiver one must
either buy a used receiver of uncertain condition, sans warranty, and sans
manual, or contact a foreign builder with uncertain product availability
(often uncertain product specs!), and all the problems that can go
along with communicating and remitting payment to an overseas entity. After
being in the sport for a while one tends to get numb to this situation, but
I'm always reminded when I must explain to a newbie the hoops that he/she
must jump through to purchase ARDF equipment.

Loaner receivers are great, and shifts the issues of availability and cost
to the one doing the loaning, but it does nothing to reduce the complexity
of the sport... especially for the technology challenged.

I believe that receiver evolution is needed sooner than later, especially in
countries where the sport has little or no history, and no domestic receiver
suppliers exist. But I think there might be the beginnings of a solution to
the receiver situation beginning to take shape: SDR or Software Defined
Radio.

There is a cottage industry of SDR front ends. See
http://groups.yahoo.com/group/softrock40/ for links to information on how
the concept works and sources of kits. The remarkable things about the SDR
concept are the low parts count (ignoring the computer for now), the high
performance (including huge dynamic range, and high selectivity), and the
ability of the radio to gain new capabilities or
performance improvements with just a change to its software.

Currently, the need to lug along a laptop makes an SDR totally impractical
as an ARDF receiver. One solution would be to substitute a handheld computer
instead of a laptop. But so far I've yet to identify a suitable handheld
with the requisite two-channel sound card. Another solution would be to
build a stand-alone SDR by interfacing the SDR front-end with a high
performance digital signal controller (i.e., an all-in-one DSP +
microcontroller IC). Such a stand-alone SDR holds the promise of an overall
parts count (and parts cost) well below any similarly capable receivers
available today. Also, with the appropriate software installed, it could
operate on any mode (AM, FM, CW, etc.), and possess features specifically
for the sport of ARDF (or for any other purpose that one can imagine). Come
up with your own whizzbang feature set for simplifying ARDF receiver
operation, or gaining an edge in ARDF competition, and most likely it can be
supported in the same SDR hardware in combination with the right software.

I believe that a publicly-available hardware design using standard parts,
and an open source software effort, could eventually resolve all three of
the ARDF equipment issues I've listed - in the USA and elsewhere.

Others more knowledgable than myself have probably considered the SDR
possibilities. I would be interested to hear/read your thoughts and ideas. I
would be especially interested to hear from anyone with DSP or hardware
design experience who might be interested in collaborating on an
experimental design. Feel free to contact me offline if your post doesn't
seem of general interest: charles.scharlau at gmail.com.

73,
NZ0I