(20 Nov. 1998) #

In reviewing the EEx2 it was hard not to compare it with the 12XL, a similarly priced GPS with similar features.  The  text seems more informative with such a point of reference, just as we have compared one Garmin against another.  The EEx2 ($248 US, shipping and cigarette lighter adapter included, from Absolute GPS) is the same shape and appearance as the Eagle Explorer and weighs in at 11.6oz (332g) vs the 12XL ($248 US, shipping included, from LW James) which weighs 8.9oz (253g).  The EEx2 is also longer and thicker than the 12XL.


The EEx2 3.00 is an improved and enhanced version of the Eagle Explorer. Click for a review of EE Ver. 1.4 features not repeated here.

The most notable new Expedition feature is more memory for waypoints (750), Positions Points (1,750), Event Markers (1,000), and three tracklogs of 3,000 trackpoints each.   The three tracklogs can be displayed individually or all at once.  The Garmin G-12 has 1024 trackpoints in only one tracklog.  However, the EEx2 has no Automatic track-logging feature, like the Garmin, which results in having to use approximately two to three times the number of trackpoints to get an equivalent track resolution.  Garmin's automatic track logging adjusts the trackpoint intervals for the various radius of curves encountered.

# The EEx2 now has 28 icons to choose from instead of 15.  You'll  notice that the battery gauge is now on the Satellite page where it can easily be monitored.  This unit has an improved battery life.  It draws less power than the 12XL 3.02 and G-III 2.04, but more than the G-II+ and later model 12XLs.  There is a Power-Save mode, but tests with this mode revealed random gross errors under tree cover.  (More on this later).

The EEx2 searches for the nearest 12 satellites to obtain lock-on, not just those in view, which should aid in locking on after moving a great distance.  The unit locked on in three-minutes-flat out of the box.  On the satellite page, the satellites are listed with the closest first (which is rather interesting) rather than by the satellite number as with the Garmins.

The unit now has audible alarms and position averaging is available along with a feature called Back Trail.  Both units have Sunrise/set calculations, but the EEx2 also has Moonrise/set and moon-phase percent.  An Estimated Position Error readout has replaced the EE's arbitrary FIX number.  The EEx2 NMEA output sentences are selectable.  GPS Monitor wouldn't run with GSA/GSV turned ON, so it was handy to be able to turn them OFF.  A new feature is Project a Waypoint with a bearing and distance from an existing waypoint.  The 12XL also has this ability.

# NOTE: As of this writing, no instructions in the manual have been found as to what Position Points, Event Markers, and Back Trail are, or how to use them.  Andrew Kalinowski explains that "Event Markers" are actually Icons (p. 15 of the manual) which can be placed on the map without names and numbers at the present position or cursor.  Thus, 1000 Event Markers and 750 Waypoints add up to the stated 1,750 "Position Points".  No one,  however, has found the "Back Trail" feature listed on the box.

Eagle Explorer Features Retained:

Pinning is used to prevent SA from causing the position to wander when still or moving slowly.  Fifteen different icons can be assigned to waypoints.  UTM, MGRS, British, Irish, Swedish, Finnish, Swiss, and New Zealand Grid reference systems are available.  As with the EE, the EEx2 has dedicated zoom keys which the Garmin 12XL does not.

A Few Problems:

A Simulator mode is provided, but few moving-map programs can take advantage of it, because the NMEA output sentences are flagged as Invalid.  Precision Mapping 3.1 and OziExplorer are designed to ignore the flags, but Street Atlas 5 and Fugawi cannot.  The EEx2 draws the same current in the Simulator mode as in the tracking mode while the Garmins draw 40ma to 90ma less in that mode.  The backlight draws 80ma while the Garmins draw only 17ma.

When tracking, the EEx2 will draw unnecessary lines between unrelated tracks made at different times, but the Garmins do not.  Unlike the Garmins, there is no dead reckoning feature in the EEx2, which results in the unit constantly losing and regaining lock under tree cover.  This also causes the backlight to come on briefly.  However, Garmin's 30-second dead reckoning and corresponding 30 second delay before indicating unlock seems excessive to me.  Joe likes it fine however.

Better Sensitivity?:

The reason for purchasing the EEx2 was that independent evaluators had indicated that the Eagle GPS had superior firmware and a more sensitive receiver.  A summary of their comments is below.

Compilation of Features by Independent Evaluators
  (28 Feb. 1998)

                            Garmin                   Eagle Series
                            --------                 ---------------
RF front end-               IBM Silicon CMOS         Gallium Arsenide
Statistical Filter-         Proprietary#             8-state Kalman
Correlation quantization-   Single-bit               2-bit
Processor-                  Intel 186 or 386         Rockwell Zodiac
Data output datum-          WGS-84*                  WGS-84
#Least squares
*Garmin outputs NMEA in the datum selected in SETUP in the GPS.  This is non-standard.  To permit external map programs to know what datum is being output by a Garmin GPS,  Garmin outputs a proprietary sentence stating the datum,  but very few map programs check  this sentence.  This can result in a plotting error unless the user manually sets the receiving map program to the same datum as is used in the Garmin GPS setup.  According to our information,  most other GPS  receivers (except Garmin units) output NMEA data in WGS-84 regardless of the SETUP datum selection in the GPS.

However, over a period of about a month testing under a roof showed no difference in lock-on ability or sensitivity between the 12XL 3.02 and the EEx2.  (The two brands do, however, appear to be using different technology.)  The EEx2 was then compared to a borrowed 12XL 4.00 which contains a new hardware platform.  This 12XL was able to lock-on before the EEx2 in 12 out of 18 tries.

Performance Under Difficult Conditions:

Since the whole discussion was about the sensitivity of the units under difficult conditions, a series of tests were run under tree cover.  This is where a problem was noticed with the EEx2's Power-Save mode.  In this mode, some very large errors were recorded in the range of a kilometer.

Below is a summary of errors recorded in runs of about eight hours each over several nights.  Some maximum errors were measured by scaling Waypoint+ plots with its UTM cursor and others recorded by GPS Monitor statistics.

The "95% excursion circle" noted below is the diameter of a circle containing 95% of all trackpoints measured from the center of the scatter plot as recorded by Bryan Lord's GPS Monitor program.  Since Selective Availability is specified to contain all errors within 100m 95% of the time, anything averaged outside that limit are errors caused by conditions and/or the GPS.  Conditions, in this case, were held as constant as possible.

(Under tree Cover)
EEx2 3.00 Power-Save Mode ON (PS):

WP+ File designation:                   EE-PS-1    EE-PS-2    EE-PS-3     EE-PS-6
95% excursion circle:                   NA         NA         NA          198m
Maximum excursion recorded: 700M        1,368m     1,274m     1,365m*
*One point was over 2,000m

With the above results, The Power-Save mode was considered not usable under tree cover, and the testing was completed in the Normal-Power mode at the same location (the Garmins don't have a power-save mode.) While driving around with the Power-Save mode ON, intermittent tree cover also caused some unusual excursions in the tracklog.

Normal Power (NP): EEx2 3.00 and 12XL 3.02

WP+ File designation:       12XL-2    12XL-3  12XL-4  EE-NP-4  EE-NP-5
95% excursion circle:       NA        78m     110m    107m     117m
Maximum excursion recorded: 370m      153m    270m    269m     578m

So, the 12XL 3.02 had somewhat lower average excursions recorded than the EEx2 with normal power under difficult conditions, but probably not enough to be noticed in actual practice.  Those wishing to view the Waypoint+ scatter-plot files, can contact me privately.

Normal Conditions:

Accuracy and scatter tests of the two units averaged under clear-sky conditions over 24-hr periods showed no measurable differences.  Accuracy tests of both units were repeatable to within 5m.

There were discussions that the Eagle receivers should lock-on quicker than the Garmins while moving.  In warm-start tests in a car, the EEx2 did lock-on a few seconds before the 12XL 3.02.  However, the 12XL 4.00 locked on a few seconds before the EEx2.  Lock-on times while moving were judged satisfactory (less than one minute) for both the Eagle and Garmin units.

The EEx2 has a greenish screen while the Garmins are white.  The EEx2 buttons are noticeably harder to push.  Waypoints can be described by eight characters as compared to Garmin's only six; however, to key in a short name for a saved waypoint, at least six fields have to be edited as compared to only the number of the letters in the name with the Garmins.

No external antenna jack is included with the EEx2, but the similar Global Nav 212 has an SMB antenna jack; however, it's not powered as with the 12XLs.  Most Garmin and Magellan units provide a jack for an active antenna.

The Nav 1 (graphic) screen in the EEx2 can be programmed with 9 different fields and the Nav 2 (tabular) screen programmed with 16 different fields.  The 12XL has three programmable fields.

The EEx2 has 33 zoom levels between 0.1 and 2000 miles while the 12XL 3.02 has eleven levels between 0.2 and 320 miles and the 4.00 has 18 levels between 0.2 and 500 miles.  A new feature of the 12XL 4.00 not found in the EEx2 is that it contains a data base of all named cities and villages in North America.  (Six other areas of the world are also available in different models).

In order to develop a Route with the EEx2, waypoints must first be created by MARKing and then routepoints selected from a list of waypoints.  In the 12XLs, waypoints created by MARKing can be automatically assigned to a Route, thus selecting particular waypoints for use as routepoints isn't required.

When following a route, the EEx2 has a combination course, track,  compass, and bearing display, but the approaching Routepoint name is not indicated.  The 12XLs show a course and bearing display, along with the approaching Routepoint name.  When downloading waypoints the EEx2 downloads all 750, although only a few are used; the Garmins only download the number of waypoints used.

For moving-map and data-transfer compatibility, Precision Mapping 3.02 vector maps, Fugawi 2.16, and Ozi Explorer 360a scanned and DRG maps work well.  The EEx2 is a rugged and reliable unit that should give many years of good service.
Please send comments and corrections to:

Jack Yeazel