U2APRS, what?

It is an APRS client application running on Google Android OS.

• It locates your position using GPS, 3G, and WiFi, and uploads it to the APRS-IS.

• It shows the APRS stations near you using the aprs.fi web (special thanks to Hessu OH7LZB).

• It sends and receives APRS messages. It reads arrived APRS messages if the Text-To-Speech function is installed in the device. Speech recognition can be used to compose a message.

It has no interface to a radio transceiver.

Please bear in mind that U2APRS is in the developing phase and provided as beta software. Use it at your own risk. Thanks.

System requirements

Smart phone with Android OS 1.6 or later

I am using the Android emulator and Sony Ericsson SO-01B for the development and test of U2APRS. I am not sure if it works on other devices, but Kobashi-san JL1LCW reported me that he successfully got it to work on Samsung Galaxy S. Kowata-san JF7ELG reported me that U2APRS is working on his Toshiba REGZA phone. Cris G4HYG reported me that U2APRS is working on his HTC Hero. Howard VK4BS reported me that it is working on his LG Optima. Charlie AI4RI reported me that it is running on his HTC droid ERIS on Verizon. Ken G0PPM is using U2APRS on his Sony X10 mini. Krzysztof sp3fyk and Rick KD4KBO got it to work. Arnaldo PY4BL runs U2APRS on his Galaxy S and GT-I9000B. Curt WE7U reported got it to work on his Viewsonic G-table with Vegan-5.1.1 ROM.

Thanks to all who sent me reports. 73!

Versions

Installation

Please note that U2APRS is available only on this page. It is not on the Android market.

Hit the button at the bottom left of your phone. Tap Settings.

You will see Settings window.

Tap Applications.

Check the Unknown sources checkbox in the Application settings.

Note: George K3RQ told me that his AT&T Galaxy S does not have the Unknown sources option. To install the applications that are not on the Android Market, you might want to try this procedure. Thank you, George!

Be sure to have "Use wireless networks" and "Use GPS satellites" in the Location & security settings checked.

Open this page with a browser of your android device. Click on the link to U2APRS.apk and download it. You will see the download history as shown below.

Tap and install it.

When you start U2APRS for the first time, it will ask you to input your callsign. Input your call there. You might want to add SSID following your call, such as JA7UDE-5.

Scroll down the view and locate APRS server, Port, and Passcode entries. Change them to proper values.

Make sure you have set your APRS validation number to Passcode. The APRS validation number consists of five digits.

Push the return key of the android device to go to the main window. You will soon see an Android robot with Mark R in the center of the window.

Mark R means U2APRS is locating your position using Radio (3G or WiFi). So your position is not exactly where you are. You can use GPS instead of Radio, which is explained later, for precisely locating your position.

If you have the following dialog "Connecting to APRS server," and get no response for a while, hit the return key of the device. Make sure your phone is connected to the Internet. Check the APRS server address and port in the Setting menu of U2APRS.

If you have successfully logged in an APRS server, the color of the Send beacon and Manual buttons become solid. If they are transparent, you failed to log in the APRS server. Check the APRS server address, port, and passcode settings.

Basic operations

U2APRS consists of three tabs: Main, aprs.fi, and Message.

The Main tab shows your position and trace.

Pushing the Send beacon button at the top left corner; then click on the aprs.fi tab to see if your beacon is stored in the APRS-IS database.

The default icon is PHONE, which can be changed in the menu.

By the way, many thanks to OH7LZB Hessu for your great contribution to the APRS world. We just cannot live without it.

If the text-to-speech tool is installed in your device, U2APRS reads the incoming messages for you.

You can compose a reply by tapping the message.

The microphone button triggers the speech recognition.

Setup menu

Press the menu button and tap Setup to open the setup menu.

Tapping the U2APRS entry of the setup menu brings you to the U2APRS web page (this page)

Fix mode

Long tapping on the map brings you to that position. The character on the android robot is changed to F.

You could send a beacon as if you were there (pretending mode?).

To return to the normal mode, push the Unfix button at the bottom right corner of the window.

GPS on demand mode

The GPS receiver consumes a lot of battery energy. An idea to mitigate it is to activate the GPS receiver only when you want to get the position. That is to say, GPS on demand. However, an APRS mobile station is supposed to send a beacon when it has traveled more than the specified distance, for example, 500 meters. If the GPS is not operating, we cannot obtain the position, and therefore cannot know how long we have traveled. Without the information of the traveling distance, the APRS mobile station would have to power the GPS receiver on, get the position data, and send a beacon at the predefined regular intervals.

In addition, we have to take account of the GPS start-up time. It takes some time for the GPS receiver to capture the GPS satellites and calculate the current position. The time for GPS capturing depends on many factors, such as the satellites' position, radio wave strength, and GPS receiver sensitivity.

In the meantime, Rob KD0FTJ gave me an interesting idea (TNX Rob). Most Android phones have a direction sensor built in. Supposing the power dissipation of the direction sensor is less than that of the GPS receiver, the direction sensor could be used to trigger the beacon.

Here is the strategy. If the interval timer expires or if the device direction changes more than the preset value, U2APRS turns the GPS receiver on. It then waits for the GPS receiver to get the position. If the GPS receiver provides the position data to U2APRS in the predefined time, send an APRS beacon. If the GPS receiver does not, U2APRS gives up sending an APRS beacon and wait for the next trigger.

Go to the setup window.

• Position source must be Gps
• Check the GPS on demand
• Put an appropriate value to the GPS search time (sec). U2APRS powers the GPS receiver on and wait for the time specified here. If U2APRS receives the position from the GPS receiver, it composes and sends the APRS beacon packet. If U2APRS does not receive the position in, for example, 12 seconds, it does nothing. U2APRS powers the GPS receiver off and wait for the next trigger.
• Put an appropriate value to the Direction change (deg). If U2APRS detects that the device changes its direction more than this value, for example, 60 degrees, it powers the GPS receiver on and attempts to get the position data. Note that the minimum beacon interval is 25 seconds. Even if you constantly rotates the device, U2APRS will not send a beacon at the interval of less than 25 seconds.

Setting 0 to the direction change value disables the direction change trigger, and thus the beacons are always driven by the interval timer.

On May 1, 2011, I have added a new option for the GPS on-demand mode. It disables the GPS search when the mode has started. The default is ON. If it is OFF, U2APRS powers GPS on only when it generates a beacon.

Customization of the button and text sizes

Likewise, you could change the size of other buttons and texts on the main page

GPS satellite viewer

To give Android OpenGL a try, I have implemented a simple GPS satellite viewer.

In the GPS mode (not Radio mode), tap the text at the bottom right corner of the main window.

Green circles represent GPS satellites. The brighter the green color, the stronger the radio strength.

APRS symbol mode

I have added an option that displays your position by an APRS symbol instead of an Android robot.

Check Use APRS symbol checkbox in the setup menu.

Small R on the left shoulder of the ICON indicates that your position is located by using Radio. When you are using GPS to locate your position, small G is shown.

Bud sensor

Bud sensor notifies you of activities of your buds in the APRS-IS net.

Open the setup menu. Scroll down to the Bud sensor category.

Tap Bud list to open the bud list editor. Input callsigns you want to "watch over" their activities. As you can see the figure below, you can use * as the wild card. The maximum number of callsigns is 20 (Enough? I do not have many friends, hi).

Check or uncheck each box left to the call sign field. Only checked call signs are watched over.

When you have finished the input, tap the device's return button.

Check Sensor operation. Check Voice notice if you want the device to speak the notice. Check Vibrate if you want the device to vibrate with the notice.

Tap the device's return button. It should be noted that U2APRS automatically attempts to reconnect to the APRS-IS server. So, hold on a second.

When U2APRS detects the activities of your buds, it displays an orange toast in the center of the device window. The screen shot below shows that JA7UDE-5 has just sent a beacon.

You want to send him an APRS message? Go to the message tab and tap his packet.

The message composer window pops up. Enter your message and hit the Send button.

You want to see where he is moving? Long tap his packet.

You will be directed to the aprs.fi tab.

OK, JA7UDE-5 is in the center of Sendai city.

Enjoy!

Known problems and future plan

• According to Kobashi-san's (JL1LCW) report, the GPS is not turned off when U2APRS is terminated. This seems to happen Android OS 2.2. I cannot reproduce the problem with my Xperia OS 2.1. Kobashi-san reported me that this problem disappeared after he upgraded the OS from 2.2 to 2.3.
• If the connection to the APRS server is disconnected, U2APRS tries reconnecting to the APRS server. However, it sometimes does not succeed.
• Tapping login at the top left corner of the aprs.fi tab results in a white screen.
• Power hog. In particular GPS consumes battery energy a lot. U2APRS uses a TCP/IP constant link to an APRS server for real-time messaging. It could use HTTP or UDP to report the position, but messages cannot be handled in real time. Hmmm.
• SmartBeaconing? I am not sure we need it on the phone.

U2APRS running on an Android Tablet, HoneyComb　3.0

A few screen shots here.

U2APRS is freeware. The author of this software accepts no responsibility for damages resulting from the use of this product and makes no warranty or representation, either express or implied, including but not limited to, any implied warranty of merchantability or fitness for a particular purpose. This software is provided "AS IS", and you, its user, assume all risks when using it.

APRS is a registered trademark of APRS Software and Bob Bruninga, WB4APR.