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Archive for October, 2010 Page 2 of 2

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Accurate Altitude Data In Android With Get Altitude

Published in elevation, Google Maps and GPS. 1 Comment

Application Name: Get Altitude

Description: Queries webserver for accurate altitude data for a location.

Publisher’s website: room.404

Cost: Free (adware)

Version/date reviewed: v.1.2.3  /  9-28-10

Phone/OS: Droid X / Android 2.2

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Android Market link (mobile app only)
Android Market link (browser)

GPS is capable of determining your location reliably with about 3 meters of inaccuracy, roughly 10 feet. But GPS elevation measurements are nowhere near as accurate; they can easily be tens of meters off, and I’ve seen them off as much as 100 meters (~325 feet) from the true value. The Get Altitude app queries a web service with a location you select in a Google Maps interface, and returns the altitude for that spot. I’m not sure which web service it’s using, but I believe it uses the Google Maps elevation API. If that’s the case, elevation data has a horizontal resolution of about 10 meters for most of the US, but probably worse than that for the rest of the world.

ga_1

Figure 1: Starting up the app also starts up the unit’s GPS, and plots you current location in a Google Maps interface; you have the option of either the map view (seen here), or the satellite view. Oddly enough, there’s no option to directly query the altitude at your current location.

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Figure 2: Tapping on the map brings up standard zoom buttons, but you can also pinch to zoom as well; tap and drag to scroll. A long press on the screen at your desired location brings up a pop-up window with your current location, and the altitude from the web query. Using the “Share” function, you can export this data to associated apps (e.g. Email, Facebook, etc.).

How accurate is the data? The 6800-ft. contour line on the USGS topo map is right on my property, at the edge of a steep drop-off, so that seemed like a good reference point to use for comparison. At this contour line, I measured the elevation with three different GPS units (Garmin 60Cx, Holux M-1000 Bluetooth, and the Droid X’s built-in GPS), then queried the altitude using Get Altitude (position determined by Bluetooth GPS paired to the Droid X for maximum accuracy).


Elevation source Elevation (ft.)
USGS Topo Map (true value) 6800
Garmin 60Cx GPS (WAAS) 6838
Holux M-1000 Bluetooth GPS (WAAS) 6778
Droid X built-in GPS (no WAAS) 6893
Get Altitude data (from webserver) 6795


Clear winner in accuracy was the Get Altitude app, only 5 ft. off from the topo map value, and that’s likely within the error range of both the map’s precision and the GPS position accuracy. The two GPS units with WAAS weren’t half-bad, but still well 20-40 ft. off the true value. The Droid X’s built-in GPS did the worst, almost 100 ft. off. Keep in mind that the elevation returned by Get Altitude is ground level; it won’t be accurate if you’re in a building and want your height there.

Additional program options include setting the elevation units (feet/meters), coordinate format (DD/DM/DMS), and a search function to locate geographic features.

Other Issues: Had absolutely no problems with the app.

Final thoughts: If you’ve got a good data connection, and an accurate GPS position, Get Altitude can potentially give you more accurate elevation data than your built-in GPS can. Just remember that the accuracy of the returned data will be determined by both your GPS position accuracy and the resolution of the elevation database used by Get Altitude.




Measure Distances Between Points On A Map, And Distances From Points To Your Current Location, With AndMeasure

Published in distance and GPS. 0 Comments

Application Name: AndMeasure

Description: Measure distances along a string of points; also distances from points to current location.

Publisher’s website: None.

Cost: Free

Version/date reviewed: v.1.6  /  9-29-10

Phone/OS: Droid X / Android 2.2

am_qr
Android Market link (mobile app only)
Android Market link (browser)

AndMeasure doesn’t do a lot, but what it does it does very well – measure distances in a map view, either along a set of user-designated points, or between those points individually and your current location.

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Figure 1: Tap the “Add point” button, then tap on the map to place the point. Add more than one point, and get both distance between every point marked, and the total distance.

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Figure 2: Tap the icon at lower-right, and AndMeasure will fire up the GPS to give you your current position as a blue marker, and change the distances next to every point you’ve marked to display the distance from that point to your current position. It’s “continuous update”, so as you move, the distances to the points will update to reflect that.

am_3

Figure 3: The “Erase” button at top erases all the points. The directions say to use a “long press” to remove a point, but you actually have to tap a point twice in succession, holding the second tap down, to remove a point (as at left).

Additional features: Set units (English, Metric or Yards (Golf)); Search for a location.

Other Issues: GPS sometimes turns itself off when in continuous update mode; just tap on the icon at lower right twice to turn it off/on again.

Final thoughts: Not a huge feature set, but it does those well; simple, easy to use interface. Recommended.




Animated Radar Precipitation Maps With Radar Now

Published in weather. 1 Comment

Application Name: Radar Now

Description: Animated NOAA radar precipitation images, and current weather conditions.

Publisher’s website: Radar Now

Cost: Free (adware)

Version/date reviewed: v.1.0  /  10-4-10

Phone/OS: Droid X / Android 2.2

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Android market link

1/31/11:  App is currently not available on the Android Market.

weatherchannel

Figure 1: Though I generally like the Weather Channel’s Android app, I’ve never been happy with the it’s radar precipitation maps. Detail is too blobby/indistinct, and the animation is often slow to show up.

currentconditions

Figure 2: Radar Now! uses more detailed precipitation radar maps from NOAA, which show precipitation boundaries and intensity more clearly. I also prefer the background map, showing terrain and hydrographic features like washes, useful in the Southwest where flooding can occur very quickly.. Opening page also includes current weather conditions and your current location, plotted using GPS

radarzoom

Figure 3: Zoom in for a closer view. Compare that with the Weather Channel radar map at top; it’s not nearly as detailed.

Final thoughts: The Weather Channel app is good for forecasts and multiple locations, and since it’s free, you should definitely have it. But when there’s rain or snow in the forecast, and I want to know if it’s headed my way, Radar Now! is my app of choice.




Ulysse Gizmo: Android MultiSensor App

Published in compass, GPS, level, magnetic fields and waypoints. 2 Comments

Application Name: Ulysse Gizmo

Description: Multiple sensor data output, including GPS and compass.

Publisher’s website: Binary Toys

Cost: Free

Version/date reviewed: v.1.6  /  12-7-10

Phone/OS: Droid X / Android 2.2

ug_qr
Android Market link (mobile app only)
Android Market link (browser)

One thing you’ll immediately notice about Ulysse Gizmo is the “fit and finish”; in terms of visual presentation, it’s one of the more outstanding Android apps of its kind I’ve seen, at least in its default “visual style”. It displays GPS, magnetic and orientation data in four different displays; each one has excellent context-sensitive help.

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Figure 1: The magnetic field sensor shows field strength, and the theoretical/actual magnetic strength/direction, along with the local magnetic declination (deviation of magnetic north from true north). More of a science toy than anything else, though I suppose you could use it to detect abnormal magnetic fields.

The icons at the edges represent the other sensor displays, and show actual active data readings. If I tap on the one at lower-left

level1_ug

Figure 2: … a nice bubble level shows up, with pitch/roll/slope orientation data displayed; I wish it also had a readout of the total slope angle along the orientation, but that’s a minor quibble. A quick tap zeroes out the level, while a longer one resets the zero level completely. The bubble level is the default view; if you tip the unit on one of its edges, say a long edge, and do a long press on the level …

inclinometer

Figure 3: It turns into an inclinometer, displaying total angle of rotation, and % slope.

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Figure 4: GPS mode displays a sky map of satellite positions, with coordinate data in the box at upper right. Latitude/longitude in DMS is the default option, but you can switch to decimal degrees, UTM or MGRS in the setting section. If you tap on the coordinate box, it will cycle through the coordinate view, a geocoded address readout where available, and …

sat_ug

Figure 5: … a GPS satellite/signal info box. It’s on the small side but packs a lot of readable data into that small space. Here, I’ve changed the visual style from the default to the alternative “Mil-tech” as a comparison to the default style seen above. I personally much prefer the default style, but this alternate might be more readable for some people. There are also day/night color options for both visual styles available from the Menu.

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Figure 6: Finally, compass mode. This has been vastly improved from earlier versions, which didn’t include a permanent “Heading” readout. Red needle always points towards true north, blue towards magnetic north; the numbers at top represent the counter-clockwise deviation from north, not the actual heading, which is a bit confusing. But the true heading (and orientation) are always visible in the center. Tapping once on the compass sets the current heading as a direction bearing, aiding in navigating in a constant direction; a long press resets that bearing.

The original version of this review before publication noted that there was a setting for waypoints, but it hadn’t been implemented. Just a few hours before scheduled publication, that changed …

Figure 7: From the menu on the compass page, choose the “Waypoint” option, and you’ll get a local map. A long press on the map at any location will place a waypoint there, and you’ll see info about the waypoint (bearing, distance, coordinates) at the top

Figure 8: Tap and drag on a waypoint lets you relocate it, and brings up a magnified view of the area under the waypoint – a nice touch, since your finger will block that part of the map as you’re moving the waypoint.

Figure 9: Returning to the compass page, the info box now includes data on the waypoint. There’s also now a small white circle on the edge of the compass ring, which shows the bearing direction towards that waypoint. You can remove the waypoint from an option in the waypoint menu, and also “link the bearing” to the waypoint; that will make the bearing display inside the compass correspond to the bearing to the waypoint.

Other Issues:

None – worked fine.

Final thoughts:

Ulysse Gizmo is a  visually-appealing app that shows off the Android sensors nicely. I prefer other apps for GPS status and coordinate data, and I don’t really see any need on my part for a magnetic field sensor. But the orientation app, especially the inclinometer option, is really nice, and the compass’s ability to let you set a bearing is useful. The author was very responsive to suggestions and bugs, and is working on adding additional features. Recommended.




Easy Android Waypoint Creation And Management With SavePoint

Published in Google Maps, GPS, location marking and waypoints. 0 Comments

Application Name: SavePoint

Description: GPS waypoint acquisition and management.

Publisher’s website: 3trust

Cost: Free

Version/date reviewed: v.1.1  /  11-7-10

Phone/OS: Droid X / Android 2.2

sp_qr
Android Market link (mobile app only)
Android Market link (browser)

Lots of Android map apps include the ability to save a location as a waypoint, but you often have to wade through multiple app levels to get to it, and keeping them organized by category can be difficult. SavePoint does only one thing, save waypoint positions in user-specified collection tags, but it does it pretty well.

SP_collections

Figure 1: The installed program comes with a single “Example” collection for storing points; you can add additional collections by tapping on the “Collections” button, then choosing “Add New” from the menu. I’ll add a new collection called “Near My House”

collect

Figure 2: Tapping on the Get Position control at bottom brings up the form for saving a position. Tapping the other “Get Position” button at lower left in the form starts up the GPS for constant position coordinate acquisition, and in this mode the app will take the GPS position. With GPS acquisition stopped, you can also enter coordinates manually.

Tapping on the dropdown near “Collection” lets you choose the collection in which the point will be stored. Tap “Save”, and the point will be saved after you enter a name for it. In this example, I’ve collected three data points and put them in the “Near my house” collection. Going back to the Collections section, and tapping on the “Near my house” collection listing …

nmh_1

Figure 3: … I’m given the option to “Edit” the name of the collection, view/edit/map individual points in the collection, or map all the points in the collection …

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Figure 4: … in a Google Maps view. Tapping on a waypoint flag brings up a popup with coordinate/altitude/date/time info for that point

checkbox

Figure 5: Tap on the checkbox to the left of the collection name, and you’re given the option to delete it, empty it, or export it into the “savepoint” directory on the memory card. Currently, the only two export options are CSV (comma-separated variable) and SQL; I would prefer a GPX or KML export option. Version 1.1 now has KML and GPX export, in addition to CSV and SQL. Also, the default delimiter for CSV is not a comma, but a semi-colon; you’ll probably want to change that to a comma in the app’s Settings section. Finally, you don’t have a choice in the export filename; it’s always “savepoint” with the date and time appended (plus .csv), stored in the “savepoint” directory.

Other Issues:

None – program never had a glitch or force close.

Final thoughts:

Now that SavePoint offers a GPX/KML export option in addition to CSV/SQL, its strong waypoint organization features make it very handy to have on hand. Recommended.




Two General Android GPS Apps: GPS Test and GPS Status

Published in compass and GPS. 1 Comment

Sometimes, you just need a quick display of GPS satellite status and current position. GPS Test and GPS Status are two handy Android apps for just that, with additional functionality as a bonus.

Application Name: GPS Status

Description: GPS satellite status and coordinate display.

Publisher’s website: Eclipsim

Cost: Free (ad-supported); €1.49 euro donation removes ad.

Version/date reviewed: v.1.01  /  10-2-10

Phone/OS: Droid X / Android 2.2

gpsstat_qr
Android Market link (mobile app only)
Android Market link (browser)

Of the two apps reviewed here, GPS Status has more settings and is more technical, which has both good and bad aspects. Starting with the main screen …

stat_1

Figure 1: Loaded with info, not all of which is GPS/orientation related. Top listings in the data display are for pitch/roll, magnetic field, and acceleration. That might be interesting but not as useful as the GPS/orientation data, and there’s no way to turn those off. You can’t turn off the battery voltage/temperature readout either.

The green bars represent GPS satellite signals with a full data lock; they’re gray if a signal is picked up, but full position data isn’t yet acquired. The position of the bar left to right represents the GPS satellite ID number, which runs from 1 to roughly 30 depending on how many satellites are currently active in the GPS constellation. I wish this display was larger, and more detailed; the bar display is a bit too foreshortened to display signal strength accurately, and figuring out which bar goes with which satellite number is problematical.

The green and brown circles in the satellite display are related to the device orientation, with the brown circle being a “level indicator” and the green circle an “orientation indicator”. If you tilt the device so that the green circle overlaps a green satellite dot, your Android unit is pointed directly at that GPS satellite; fun once or twice, but not particularly useful. And there are better “level” apps than this one. Fortunately, you can turn these two orientation indicators off in Settings.

On the plus side, this is one of only a few Android GPS apps that displays “DOP”, Dilution of Precision, a measure of the best GPS coordinate accuracy you can expect based on the geometry of satellites as scattered across the sky; lower is better (H = horizontal, V = Vertical).

The displayed coordinate can be changed in Settings; supported coordinate systems include latitude/longitude, UTM (as here), MGRS, and the Swiss CH1903 coordinate system; datum isn’t specified for the first three, but I assume it’s WGS84.

gs_radar

Figure 2: GPS Status also has a “Radar” mode, essentially a tool for navigating from or two a point. “Mark” a point in the Menu, and as you move away from it, the position of that marked point will show up on the “radar screen” as a green dot, with each circle on the radar screen representing a distance away from your current location. Data readouts show coordinate data for your current location and marked point, heading (where you’re currently pointed) and distance/bearing (the distance/direction to go to get to the marked point.  As you get closer to the marked point, the brown circle expands; further away, it shrinks.

You can also use the radar screen as a compass, as it always rotates so that your heading is up (slightly SSW in the image at left). Direction is true north; the “needle” embedded in the center is aligned to magnetic north, usually slightly off from true north. As a compass app, it’s not all that great, but the radar screen is a nice touch.  And you can display the marked position, and your current position, in a map app like Google Maps.

Lots of options in the Settings section for display and control. Of particular note are controls for managing assisted GPS (aka A-GPS). If you have A-GPS enabled on your Android unit, it will download GPS satellite data based on your position as determined by the nearest cellular base station antenna, which can increased the speed with which you get a position fix. GPS Status has options in Settings => GPS & Sensors that let you delete/refresh this data, useful if it’s gotten corrupted somehow; you can also configure the app to refresh this data every time it starts up.

Other Issue:

No problems; worked fine every time I tried it.

Final thoughts:

I liked some of the extra technical data displayed (e.g. DOP), the radar screen is a novel navigation aid, and the A-GPS tools are useful. But the app is a bit too busy with extraneous data displays for my taste. It’s a permanent app on my Android phone, but it’s not my first choice for checking on GPS satellite/signal status.
Application Name: GPS Test

Description: GPS waypoint acquisition and management.

Publisher’s website: Chartcross Limited

Cost: Free; £1.50 Plus version adds compass/altimeter/speedometer page.

Version/date reviewed: v.1.19  /  10-2-10

Phone/OS: Droid X / Android 2.2

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Android Market link (mobile app only)
Android Market link (browser)

GPS Test has a very distinct and clear graphic style …

test_1

Figure 3: Here’s the main GPS satellite signal page; the color scheme is the default Android, but you can choose between 7 different color schemes in the Settings section. GPS satellite signal strength is clearly plotted by height, color and numbers at the top of the bar; the satellite ID is shown clearly at the bottom of each bar. The buttons at the very bottom of the display switch you to different displays.

test_2

Figure 4: The satellite sky map shows the position of every satellite in the sky. It’s linked to the compass bearing, so it rotates as you change direction. So, you could use it as a compass, but it’s not really a very good one. The local magnetic declination (difference between true and magnetic north) is shown at lower left.

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Figure 5: Coordinate choice is one of GPS Test’s biggest pluses. You can choose between seven different coordinate systems, and independently choose between 5 different datums (WGS84, NAD83 CONUS, NAD27 CONUS, ED50 – Mean, ED50 – Spain). Daylight/night map isn’t necessarily that useful, but kinda cool.

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Figure 6: HUD (Heads-Up Display) view might be useful for auto use; you can change the units for virtually every app data readout in Settings.

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Figure 7: Time display …

gpstestplus

Figure 8: The paid “Plus” version adds an additional display, with a better compass and dial displays of altitude and speed.

Other Issues:

None on my unit – always worked fine.

Final thoughts:

While I appreciate some of the functions of GPS Status, GPS Test is my go-to app for checking my Android unit’s basic GPS status. The display is clearer and easier to read, and the larger choice of coordinate systems and datums is a huge plus. Both apps are available in free versions so you can have both, but if you only need/want one app of this type, GPS Test is highly recommended.




Android External Bluetooth GPS Apps: Bluetooth GPS Provider

Published in Bluetooth and GPS. 3 Comments

Application Name: Bluetooth GPS Provider

Description: Replaces internal GPS coordinate signal with one from an external Bluetooth GPS receiver.

Publisher’s website: mobile-j.de

Cost: Free

Version/date reviewed: v. 1.2.5c  /  10-20-10

Phone/OS: Droid X / Android 2.2

bgp_qr

Android Market link (mobile app only)
Android Market link (browser)

Note: Before using this app, you will need to pair your external Bluetooth GPS with your Android phone, and enable “mock locations”; see the Appendix at the bottom of this post for more info.

This used to be a paid app, but now it’s completely free.

bgp_1

Figure 1: The first time you start up the program, you need to choose the Bluetooth GPS receiver you want to connect to. Unlike Bluetooth GPS Mouse, which require you to choose the GPS receiver every time, Bluetooth GPS Provider remembers your choice the next time. If you want to switch to a different Bluetooth GPS, you’ll have that option in the Preferences section.

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Figure 2: Here, I’d choose my Holux Bluetooth GPS…

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Figure 3: … and then press “Start” to connect to the Bluetooth GPS unit. Unlike other apps, which could require multiple “Start” attempts, this app worked after only one press – very nice!

bgp_sats

Figure 4: After a successful connection, a satellite status screen shows up, as well as a program icon in the status bar. I wasn’t happy with this satellite status indicator; it didn’t seem to show every satellite available, and the satellite number at the bottom of the signal bar sometimes corresponded to non-existent GPS satellites (e.g.  I saw satellites #38 and #41 listed, neither of which are real). Finally, there didn’t appear to be any indicator for the WAAS satellite, which is a significant drawback. WAAS is a major justification for the use of an external Bluetooth GPS, since most Android phones have no WAAS capability with their internal GPS.

bgp_prefs1

Figure 5: The Preferences screen offers basic control of the selected GPS receiver, whether it overrides the built-in unit, and other options. Unique to this app, though, is the ability to access special features in some GPS chipsets. If you select GPS Type …

bgp_gpstype

Figure 6: You can select between units that use the SiRF chipset or MTK chipset to access special features for those; if your Bluetooth GPS has a different chipset, you’d choose Other. I didn’t have a SiRF unit to test; my Holux M-1000 has an MTK chipset, so I could select that and enable several additional settings in Preferences….

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Figure 7: … like the ones here at the bottom.

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Figure 8: The default position update rate for most GPS units, including MTK models, is 1 Hz (once per second); however, the MTK unit lets you set a slower update rate (not available here), or a faster speed, up to 5 times per second (5 Hz). Not clear that this will be that useful, as most of the GPS apps I tried only updated the position once a second. Perhaps future apps will be able to take advantage of this faster update rate, potentially useful if you’re traveling at a high speed.

bgp_dgps

Figure 9: DGPS Mode lets you set the differential GPS correction mode. WAAS (EGNOS in Europe) is standard with MTK chipsets, and I was surprised to see that it wasn’t selected as the default here (nothing was chosen the first time I opened this); you can poll the receiver’s status to find out what mode it’s in. RTCM is a ground-station-based correction system which isn’t in common use, and is slated to be shut down soon in the US (if it isn’t already).

I can’t think of any good reason to turn DGPS off, as using it improves average accuracy. When I tried turning it off, the position shifted about 5 meters away from the actual position; that’s just one snapshot, but it’s suggestive. WAAS will become more critical in improving accuracy as the sun becomes more active over the next few years.

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Figure 10: SBAS (Satellite-Based Augmentation Service) is synonymous with WAAS/EGNOS; this lets you turn that option on/off in your MTK unit

As with the previous two similar apps reviewed, Bluetooth GPS Provider seemed to work fine with every GPS app I tried it with. No conflicts with the built-in GPS receiver, even when it was enabled. The app author does indicate that some apps like Wikitude don’t currently work with it, but is working on making it compatible with every app that uses GPS position information.

Other Issues:

One case where Google Maps couldn’t pick up the location data, followed by force-close and several error messages. Restarting the app seemed to fix the problem.

Final thoughts:

This was the app that did the best job of establishing a Bluetooth connection, and had the most advanced options. Apart from one minor glitch that resolved itself fairly quickly, it worked perfectly. The only downside is a quirky satellite display, and no WAAS satellite indicator. If  those were fixed, this would easily be my first choice among all the available apps of this type.

Appendix: Setting up an external Bluetooth GPS for use with your Android unit.

A link to my original post on the advantages of using an external Bluetooth GPS receiver instead of your Android’s built-in GPS.

Here are some inexpensive external Bluetooth GPS units; a search on Amazon.com or eBay will bring up many more:


After you’ve bought the unit, charged it up and turned it on:

1. Go to Settings => Wireless & networks, and make sure Bluetooth is turned on.

2. Go to the “Bluetooth settings” section, and have your Android unit scan for new Bluetooth devices.

3. After it finds your Bluetooth GPS, it may ask you to enter a four-digit security code; for GPS units, if no code is included with your unit,  “0000” usually works.

4. Your Android unit will now be “paired” with this Bluetooth GPS device; any apps that support Bluetooth GPS will have this device listed as an option. Unless you remove this pairing, you only need to do this once.

5. To use a Bluetooth GPS with apps that don’t support it natively, you’ll need either the app reviewed here, or one that performs a similar function. You will also need to enable “mock locations”: Settings => Applications => Development => check the “Allow mock locations” box.

6. DON’T DISABLE THE BUILT-IN GPS ON YOUR ANDROID. Some apps (e.g. Google Maps, Bing Maps) won’t work with external Bluetooth unless you have the built-in GPS enabled, even if they don’t actually use the built-in GPS for positions.




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