Introduction

SatFinderAndroid is a program that locates geostationary satellites and aids accurate satellite receiver dish pointing. It's used by professionals who install satellite dishes in homes and businesses, and it's also used by people like RV and yacht owners who, while traveling, must realign their satellite dishes on a daily basis.

Quick Instructions

• Short-press most program pages (satellite views in particular) to toggle full-screen mode.
• Long-press the live-view SKYVIEW page to toggle a light/dark overlay color scheme, for use in changing light conditions.
• Your device must have a way to locate itself. Android devices provide two ways to get this information — the network, and GPS. Your device should have at least one of these methods enabled. SatFinderAndroid will ask to enable location sensing on its first run.
• Next, touch the LOCATION tab and confirm that you have position data for your Android device. If you do, the "Position Source" will display either "Network" or "GPS", and your present position will be shown.
• Next, touch the TARGET tab and select any number of receiver dishes or satellites by touching the desired lines. Your choices will be highlighted in red. If you have difficulty choosing specific lines, first use the two-finger zoom gesture to increase the text size.
• On the same tab, you may also choose between "U.S. Sats" and "All Sats" lists. The "U.S. Sats" list is easiest to use — it has pointing angles for popular receiver dish models as well as individual satellites. The "All Sats" list is a comprehensive list of worldwide geostationary satellites with pointing data based on your present location.
• Next, touch the SATCOMPASS tab and note that a big red arrow is pointing in the direction of your first choice of satellite dish or satellite (multiple satellite choices take effect in the next tab — SKYVIEW).
• The red arrow's pointing direction is called "azimuth", meaning a horizontal angle. The same angle can be gotten from a hand compass using magnetic coordinates and the pointing information provided at the bottom of the SATCOMPASS tab.
• If your android device hasn't acquired a location yet, or if you haven't selected a dish or satellite, the arrow will point north and there will be no satellite information on display. If this happens, repeat the instructions above.
• Next, turn your device so the red arrow is pointed away from you, then tilt your device upward toward the sky. A blue ball will come into view that shows the elevation angle for your chosen dish or satellite (when the blue ball is centered in the green circle, the angle is right). Now, by looking across your device toward the sky, you can use it as a pointing tool to show the location of the desired satellite.
• At this point you have both angles needed for dish alignment — horizontal (azimuth) and vertical (elevation) angles. And by using your Android device as a sighting tool, you can establish whether you have a clear line of sight to your chosen satellite.
• The SATCOMPASS feature described above is primarily for Android devices that don't have a camera. If your Android device does have a camera, touch the SKYVIEW tab and rotate your device to see your satellite choices superimposed on the sky in their correct positions.
• The SKYVIEW feature uses your Android device's position (pitch and roll) sensors, the magnetic compass, the location-finding features, and the camera — pretty much everything. And by displaying any number of targets selected at the TARGET tab, this feature tells you at a glance whether you're in a suitable location for a multiple-satellite receiving dish. You can walk around with your Android device until you find a location with a clear view of all your chosen targets.
• When you need to scout for a dish location, take your Android device with you and use the SatFinderAndroid sighting features to assure that you have a clear line of sight to the desired satellite. It's never been easier to find a good dish location!
• SatFinderAndroid remembers all your choices between uses, so if you always need to know the position of a given satellite, then on each new run you can go directly to the SATCOMPASS tab and orient your dish.

More Use Details

• Level Indicator
  • On the SATCOMPASS tab display, along with the azimuth arrow, there are two alignment balls:
    • As explained above, the blue ball shows the elevation of the chosen satellite.
    • The other ball, brown in color, can be used to turn your Android device inoto a handy level.
  • A typical Android device's level accuracy is pretty good, but to calibrate the level ball for greatest accuracy, do this:
    • Place a mechanical bubble level on your Android device.
    • Use the level to assure that your device is perfectly level.
    • Now touch the "Calibrate Level" button.
    • You can touch the "Calibrate Level" button repeatedly. Each calibration is independent — there's no need to press "Reset Level" between calibrations.
    • After you have touched the "Calibrate Level" button, check for agreement between the bubble level and the brown "Level" circle.
    • To reset the level calibration to the device's default, press "Reset Level".
  • By calibrating the level ball, you will have increased the accuracy of the blue satellite elevation ball and the SKYVIEW display.
• Compass Bearing Issues
  • In my experience, the quality of magnetic sensors isn't consistent between Android devices.
  • There are various magnetic sensor calibration procedures described on the Web, but this is probably the most useful:
    • Rotate your device slowly, display up, through several turns.
    • Now slowly flip your device over, top to bottom, repeatedly.
    • Now slowly flip your device over, left to right, repeatedly.
  • This may seem like an informal way to recalibrate a magnetic sensor, but Android doesn't include a formal way, and typical magnetic sensors are to some extent self-calibrating when exposed to a "three-axis" rotation procedure as above.
  • After the above calibration procedure, if your device still shows poor magnetic direction indications, try moving away from metal objects and magnetic fields.
  • As a last resort, if you can't get your Android magnetic sensor to behave, use a hand bearing compass and the magnetic bearings provided by SatFinderAndroid (listed in the data table under "Az M") to set your dish azimuth. In such a case, the elevation sensor should still produce accurate results (it's a different sensor).
  • For critical installations, or in cases where the target satellite is not being detected, use a hand bearing compass to double-check the Android device's magnetic sensor.
• Android Enclosure Issue
  • An important issue has come up in testing. Many Android tablets are placed in protective enclosures that, when closed, cause the device to automatically shut off its display. Unfortunately, this feature requires use of permanent magnets as signaling devices, and those magnets prevent your device from reliably orienting itself in Earth's magnetic field. This sort of enclosure disables accurate satellite positioning. The remedy is to temporarily remove your Android device from such an enclosure for use with this program, or any other program that requires accurate magnetic field detection.
• Skew
  • The rightmost values in the satellite data table are "Sk:0" and "Sk:90".
  • These two values are used to adjust the tilt of a satellite receiving dish, with both commonly used ways to express the skew angle.
  • Whenever a dish is located at a terrestrial longitude different than the orbital longitude of the satellite it's pointed toward, there is a difference in rotation angle between the satellite's sense of the horizontal and that of the dish site, and this difference may need to be accounted for.
  • Skew is only important for dishes that are equipped to receive more than one satellite (or non-U.S. dishes that don't use circular polarization). If your dish only has one microwave sensor and uses circular polarization (i.e. all U.S. dishes), don't bother adjusting skew.
  • By contrast, many newer dishes are equipped to receive two or three satellites simultaneously. These dishes need the skew adjustment.
  • Multi-satellite dishes typically have a separate scale and adjustment for skew, clearly marked.
  • Negative "Sk:0" skew values, or "Sk:90" values less than 90 degrees, mean the dish is to be rotated counterclockwise when viewed from behind, by the specified angle. Positive values, or values greater than 90 degrees, indicate a clockwise rotation.
  • For skew adjustments to be effective, the mounting mast for a multi-satellite dish must be vertical.
  • The symptom of a bad skew adjustment is the inability to receive all the satellites equally well.

Limitations and Use Strategies

Since this program was first released, a great number of new Android devices have been designed and marketed, many with poor position sensing abilities and compass reliability. As a result, for some Android devices, even though the computed satellite positions are very accurate, the SKYVIEW feature of SatFinderAndroid won't work very well, for reasons beyond the author's control.

To maximize the usefulness of the SKYVIEW feature, try rotating the entire Android device in three independent axes to calibrate its compass. Then, specifically for the SKYVIEW feature, try different display orientations. Some Android devices function better in a "landscape" orientation (wider than tall), others in a "portrait" orientation (taller than wide), and in some cases a 180 degree rotation of the device produces a better SKYVIEW display. The key to having the best device orientation is that the blue horizon line, and the compass bearing indications, will stay synchronized with the camera image reasonably well.

Some devices won't be able to use the SKYVIEW feature very well at all, and for this the author apologizes. This application is much more dependent on the hardware details of a specific Android device than most applications, and this special view mode may not work at all with some devices.

As explained above, if your Android device is enclosed in a protective cover, check to make sure the cover doesn't contain magnets. Such magnets, common in Android cases, will prevent your device's compass from functioning as it should.

Except for the issue described above, for Android devices that have acquired an accurate geographic position, this application's computed satellite positions are very accurate.

Technical Description

SatFinderAndroid is the most recent incarnation in a series of satellite-related applications I've written over about a decade, starting with Satellite Finder (a.k.a SatFinder), and an online version of SatFinder, uncleverly named Satellite Finder Online. But when I first got an Android device and realized it had the ability to locate itself as well as sense magnetic bearings and local elevations, I realized this would be a perfect platform for SatFinder.

SatFinderAndroid produces satellite pointing angles in this way:

1. The program acquires a location for the Android device. This is acquired either from a network positioning method, or GPS. The results can be seen on the LOCATION tab.
2. The program lists all geostationary satellites and popular receiver dish models on the TARGET tab, and allows the user to select any number. This gives the program target locations to point to.
3. With the results acquired in (1) and (2) above, the program computes azimuth (both true and magnetic) and elevation angles for the selected targets, at the device's location.
4. Using the result acquired in step (3), the program uses magnetic and level sensors to create sighting displays on the SATCOMPASS and SKYVIEW tabs that allow the user to locate target satellite positions in the sky (or establish a pointing angle for a satellite receiver dish).

Geostationary satellite geometry and pointing is not mathematically difficult, because the satellites are stationary with respect to Earth, they're all lined up over the equator, and they're all at the same altitude. Other, seemingly less important things are are actually more difficult, like computing a magnetic declination for any location where a satellite position might be needed (for comparison with a hand bearing compass or an Android device's magnetic sensor), or creating a convenient display of azimuth and elevation angles for a given target.

Until this program was written, dish installers needed to compute sighting angles for each desired satellite in advance of a field outing to a particular location, then carry a hand bearing compass for azimuth and and an inclinometer for elevation, to have any chance to optimally position a receiver dish. But with SatFinderAndroid and an Android device, installers have the entire process in their hand — a complete list of satellites, a way to locate themselves, and sensors to help point the dish.

Privacy Policy

Last updated: 02.03.2017

I (Paul Lutus) operate a Website with the URL http://arachnoid.com as well as write and distribute a number of Android applications hosted by the Google Play online store. This page describes my policies regarding the collection, use and disclosure of Personal and/or Sensitive Information collected by the aforementioned Android applications.

My privacy policy is defined by these points:

1. Any personal or sensitive information collected by my Android applications is coincidental to the immediate operation of the application and is neither stored nor transmitted elsewhere.
2. Any personal or sensitive information collected by my Android applications is made use of solely as described in point (1) above and is then promptly and completely discarded.
3. No personal or sensitive information collected by my Android applications is archived, recorded, logged, transmitted, exploited, or otherwise made use of in any way whatsoever beyond the immediate purpose described in point (1) above.