[ARDF] Fun and Frustration

Charles Scharlau charles.scharlau at gmail.com
Tue Oct 6 10:05:21 PDT 2009

One brief update on my comments:

I'm seeing some strong evidence that it *might* be possible to create a
downloadable application that would turn an Apple iTouch into the "computer"
part of an SDR. So possibly taking an iTouch (or iPhone) loaded with the
right application, plugging an SDR front end into the microphone port, and
adding a directional antenna, you've got an all-mode ARDF receiver.

Not to go off the deep end with futuristic ideas, but if this were
implemented using an iPhone 3G (which includes a built-in digital compass,
lots of memory and the ability to display maps), you could have one device
that serves as receiver, map, and compass... not to mention music player,
web browser, cell phone, etc. etc. etc., with a Bluetooth interface to use
with your cordless headphones. The total cost could be well under $100 for
those who happen to already own the phone.

Just thought I'd mention that in case it motivates anyone else to more
closely examine the possibilities of an SDR ARDF receiver. Again, please let
me know if you might be interested in collaborating on an experimental
OK, I'll stop my monologue now.

On Sun, Oct 4, 2009 at 8:09 PM, Charles Scharlau <charles.scharlau at gmail.com
> wrote:

> 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

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