Discover New Applications For Low-Cost Solutions Discover ... - Xilinx

ands on the market. We use a 73.768 KHz
watch oscillator followed by a Xilinx
CoolRunner-II device to generate the
timing signals (Figure 2). This provides an
optimal solution, saving on both power
consumption and PCB real estate.
Figure 1 – Training transmitter
I/O Port Expanders
The best practical training application for
beacons is, of course, to bury the transmitters
into mountain snow. However, changing the
location of the transmitters to build new
search scenarios cost valuable training time.
By designing a control console (Figure 3) for
as many as 16 remote transmitters activated
via radio link, we enabled trainers to quickly
and easily simulate new accident situations.
In order to handle 16 remote transmitters
we required more I/O lines than what is
available on a microprocessor. We chose to
use two Xilinx CoolRunner-II devices,
which provide a compact solution with low
console battery consumption.
PCM Codec to RAM Interface
We also found CoolRunner-II CPLDs
effective in reducing transmission loss. To
initiate transmission over a private mobile
radio, you must press a PTT (push to
talk) button and wait before the transmitter
is ready for you to start speaking. If
you’re under stress, there’s a strong tendency
to start talking before the transmitter
is ready, and the beginning of your
transmission will be lost. You may have to
repeat the whole transmission in order for
the receiver to make sense of it. This is
inconvenient and, especially in emergency
situations, can cause additional
stress and frustration.
Figure 2 – Internal view of training transmitter
Figure 3 – Transmitter control console
Fall 2003 Xcell Journal 51