A Medical Information, EMS, GPS Application
Robert Robinson
medical information system with GPS mapping and routing to provide emergency
medical staff with accurate patient locations and immediate access to
essential medical data. SQL Server is used to manage that data files and one
would think that it would be a simple matter to link the patient demographic
data with map locations. It has, however, proven to be a complex project.
This information is being presented in the expectation that it may be
helpful to others who are interested in similar projects.
Hardware
Testing has been with portable equipment and we decided on a USB connected
GPS receiver because of the need of having the receiver (or an active GPS
antenna) remotely located from the computer and the convenience of the
powering the unit from the USB connection. We use a DeLorme Earthmate. It
has proven to be a reliable and accurate unit. Excellent 3D DGPS reception
is available throughout our area of interest. Vehicular use would, however,
probably be improved by permanent installation of an industrial grade GPS
receiver and an external antenna. One interesting consideration is whether
or not to continuously power the GPS receiver in order to avoid "cold start"
delays. It is practical to do this in an engine off vehicle due to the low
current requirements, but there is still the problem of loss of GPS signals
if the vehicle is located in a garage.
The computer requirements have been for a portable, fairly rugged unit with
an 8 plus inch indoor-outdoor readable display, and a reasonably compatible
operating system and programming environment. We started with a NEC 900
which is a sub-notebook with a palm top operating system. The size is very
convenient, the computer has an excellent keyboard and is generally well
constructed. Unfortunately, the display is not readable in bright ambient
light, and, at least when we were using the computer, the operating system
was an obsolete version that was not compatible with some of the required
application programs. We tried a Fujitsu Tablet PC, but it was too fragile
for field usage and Microsoft's Tablet PC operating system had multiple
major problems. We finally decided on a Panasonic CF-73 ToughBook. I would
rate it as only "semi-tough", but it does have an excellent touch sensitive,
indoor-outdoor readable display and overall good construction. The installed
XP operating system was replaced with Windows 2003 Server.
Software
We tried a number of mapping programs before deciding on DeLorme's XMap.
This decision was based on the professional mapping features and the ability
to input datasets for both display and routing operations. The intent was to
have an XMap datafile that would provide demographic information and Lat/Lon
coordinates to accurately locate home street addresses. The medical data
file contains names and addresses, but there are typically multiple people
in a home including family, staff, and visitors. There are thus multiple
links to each address. A geo-coded map with actual home locations will be
available in the Summer 2004. Unfortunately, our only current choice for
obtaining accurate home locations has been to drive to each address and
record the GPS coordinates. Given the required name/address linkages, this
process would be tedious, time-consuming and prone to error if done
manually. What we needed was a program whose display could be superimposed
on the digital map and which had access to the GPS receiver data and the SQL
Server databases. There are currently no known "virtual drivers" that
provide multiple program access to USB connected GPS data. Theoretically,
USB sniffer software could be used for this purpose. We tried two software
packages. They were able to display USB device data, but both had program
hangs and caused operating system instability. An alternative is to use a
serially connected GPS and Eltima's Virtual Serial Port driver,Ship Modul
Marine's Virtual Plex-1 driver or to simply connect the GPS serial output to
two RS-232 compatible hardware port inputs ( some care is required as to how
the hardware are connected). DeLorme does provide a USB to serial driver,
but this doesn't provide concurrent serial and USB GPS data access, nor will
the Eltima software echo a virtual as opposed to a hardware serial port. The
Eltima solution with a serially connected GPS did work, but we decided that
the most straightforward approach was to purchase DeLorme's GPSToolKit. This
software provides concurrent access to a USB connected GPS.
The final step was to write a VisualBasic program that accesses the SQL
Server name and address information and displays numerically ordered street
addresses for user selected streets in a data table control. The Lat/Long
coordinates are stored by clicking the street address when the GPS receiver
is at that location. The information is then automatically added to the
demographic information for each of the persons who reside at that address.
It is also added to a master address file that contains platt identifiers
and other county record information. Finally, the appropriate entries are
transferred to an XData file for use by the mapping program.
Robert Robinson
Doug Adomatis
Thanks for sharing this as I've had thoughts of a similar project. I'm
curious though... When and how is the destination entered in to the
navigation system? Certainly the driver would be too busy. I assume a
passenger/crew member works the nav system. Have you investigated ways for
the dispatcher to wirelessly beam the destination/coordinates to the
computer system prior to, or while, the vehicle is departing the garage?
- Doug
"Robert Robinson" <rob...@bellsouth.net> wrote in message
news:xlYnb.63991$h47....@bignews4.bellsouth.net...
Robert Robinson
The setting for the project is unusual in that the require medical database
already exists and there are some unique navigation problems especially
after dark in a setting in which there are no streetlights. GPS directions
based on street addresses are not sufficiently accurate. The mapping
programs compute these based on an estimate from some fixed point as the
beginning of a block. The map accuracy will improve as the country completes
their conversion of the platt maps from foil to digital, but this process is
not estimated to be finished before the Summer 2004.
In the interim, acquiring the coordinates simply involves driving to an
address, stopping the vehicle, and entering the data with one touch of the
touchscreen display.
We are very interested in a high speed, bi-directional digital link to a
portable and/or vehicle located computer, but the technology to do this at a
"reasonable" cost isn't here yet. We do use WiFi "in-house". It is great and
we certainly wish that there was an equivalent system for the outside world.
Robbie
Oldbie
>current requirements, but there is still the problem of loss of GPS signals
>if the vehicle is located in a garage.
If the garage is your base location, why not use a cheap re-radiating antenna to keep things alive
till you exit the garage. Alternatively, as long as you have the power on, most receivers will
retain ephemeris data and keep accurate time for the periods they are unable to receive signals, so
reacquiring sats and getting a good fix quickly after exiting the garage should not be a problem.
Robert Robinson
antenna to keep things alive
> till you exit the garage. Alternatively, as long as you have the power
on, most receivers will
> retain ephemeris data and keep accurate time for the periods they are
unable to receive signals, so
> reacquiring sats and getting a good fix quickly after exiting the garage
should not be a problem.
Thank you for your suggestions.
I agree that the acquisition time may be minimal if the receiver remains
turned on. I have had no experience with a re-radiating antenna. It is
interesting that some companies are now claiming to have GPS receivers that
work indoors without re-transmitting the signal.
Robbie