SUMTER COUNTY
Amateur Radio Emergency Services Association (ARES)

 Sumter County, Florida

APRS - Android

 
Android App: APRSdroid-APRS Client  $4.95

APRSdroid is an Android smartphone application for Amateur Radio operators and requires a FCC license to use.  It allows periodic reporting of your position to the APRS network which displays nearby amateur radio stations and facilitates the exchange of APRSmessages.  APRSdroid is Open Source Software written in Scala and licensed under the GPLv2.

You can use APRSdroid to connect to the APRS network via different means:

  • APRS-IS via Internet (WiFi or mobile data connection)
  • AFSK (audio connection between your radio and the smartphone
  • Bluetooth-serial connection to a TNC

APRSdroid can be used in different ways, according to your requirements.  By default, it connects to APRS via the Internet (APRS-IS) and deploys SmartBeaconingTM for position reports.  If you what to change its configuration, there are three main areas you should consider:

  • APRS Settings (your call sign and SSID, plus eventual pass code for APRS-IS)
  • Position Reports (how and how often your position is reported)
  • APRS Connection (how you connect to a radio or the APRS-IS network)

For your own position reports, you can choose among the following configuration ("Location Source")

  • SmartBeaconingTM (position is posted automatically depending on your movement speed)
  • Periodic position reports (you can use the GPS or the network location feature here, reducing the position precision)
  • Manual position entry (e.g. for tablets which stay at home; use this to completely disable position reporting).

There are also several ways to connect to the APRS network ("Connection Protocols"):

  • APRS-IS  APRS over the Internet, using a WiFi or mobile data connection
  • Connection with a TNC (currently supported only by using a Bluetooth serial adapter attached to a radio
  • Direct audio connection to a radio (AFSK)
  • Kenwood APRS-capable NT/Mobile integration (APRSdroid simulates a NMEA-GPS to feed the Kenwood and parses its waypoint output)

Setting Up APRSDroid Software Application on You Phone

Go to the Google Play Store and buy APRSDroid. At the time of this writing, it’s only a few bucks and well worth everything that its creator is asking. Once you have it installed, we’ll do some configuration.

1. Go to preferences.

2. Enter in your call sign. In APRS you’ll often see stations with an additional identifier after their call. This is to delineate between different stations that they may own. When APRSDroid says “without SSID,” they mean without the additional identifier. Just enter in your FCC call sign.

3. Assuming that you don’t already have an APRS-IS passcode, request one through the link in the preference menu now. APRS has an internet backbone. It’s what lets you see radio traffic through websites like APRS.fi. It’s also what lets APRS text messages reach beyond the local area. Note: APRS-IS will require proof of your license, as they should. You will be passing traffic across their network that will eventually cross the RF line. They have a duty to verify that you are licensed. If you’ve registered for a service like Echolink, then you know what I’m talking about.

4. Once you get your APRS-IS pass code, write it down somewhere safe (you will forget it) and type it into APRSDroid.

5. SSID. Choose what type of station you are. In my case, I use -9 because I run this setup in my car. As you can see from the drop down menu, there are several options available.

6. APRS Symbol. This is one place I think the program should include additional information. In short, there are a bunch of different symbols that can represent stations on an APRS map. The only way to know what is available is to look at a chart such as the one here. http://www.aprs.org/symbols.html

The Cliff’s Notes version is this: /- if you’re a house, /> if you’re a car, /k if you’re a truck, /v if you’re a van. There are many more options, but this will get you started. I recommend ditching the default /$ (a phone handset) unless you’re using APRSDroid exclusively through the cell network.

7. Comment field. This is how you let people know how to reach you. If you had a slick Kenwood or other APRS integrated radio, this field would auto populate with the frequency that you are monitoring. While it can be a 

hassle to keep up with, I recommend that you try to do the same as it will be particularly helpful for people passing through the area. Maybe one of repeater frequencies and tones? I’ve also seen people put email addresses here, but beware of spambots that crawl the internet (your radio packets will end up on the internet if an IGate hears them). Remember, the goal is communications, not vehicle tracking. If you don’t tell people how to communicate with you, then you just have a ham based LoJack.

8. Unless you’re a base station, I’d turn SmartBeaconing on. Some software decides to update your position after a set amount of time regardless of whether you’re moving or not. SmartBeaconing knows to transmit more frequently when you’re moving quickly or when you’re changing direction.

9. Location Settings. This is where you fine tune SmartBeaconing. For a fixed station, any reporting more often than once every 30 minutes is a bit overkill unless you’re a weather station. 15 is the recommendation there. Remember, unlike your computer, if there is a packet collision, the packet isn’t resent in this system. Overloading the frequency means preventing messages from getting through. Northwest APRS, one of the best organized regional APRS booster organizations in the US, recommends no more frequent updates than the following for mobile stations:

If using no relay or WIDE1-1, 1 min.

If using WIDE1-1,WIDE2-1, 2 mins.

If using WIDE1-1,WIDE2-2, 3-5 mins.

WIDE2-2 is the recommended path setting for fixed stations, WIDE1-1,WIDE2-1 for mobile, and WIDE1-1,WIDE2-2 is ok if you’re in a very rural or mountainous area. More on paths in a little bit.

APRS.net recommends the following speed settings for normal driving:

Fast Speed – 60 mph or 97 kph

Fast Rate – 180 sec

Slow Speed – 5 mph or 8 kph

Slow Rate – 1800 sec

Min Turn Time – 15 sec

Min Turn Angle – 30 deg

Turn Slope – 255

10. Position Privacy. If you want someone to know that you’re in radio range, but you don’t want them to know what specific house or store you’re parked at, change your position ambiguity. I personally use setting 2 and for my purposes, I turn off speed, bearing, and altitude. If I was tracking a balloon launch, I’d want all of that. For a mobile station, I just want people to know I’m in radio range. You could make the case for enabling the speed setting, though, so people can deduce that you may not actually be in your car at the moment (it’s parked?).

11. Connection Protocol. Select Bluetooth TNC.

12. Connection Preferences.

Client mode should be checked.

Your Mobilinkd TNC should be selected under TNC Bluetooth Device.

I made no changes to Channel (blank), TNC init string (blank), and TNC init delay (300).

Bluetooth settings… this should take you to Android’s Bluetooth settings. No changes needed here.

APRS digi path. This is the main thing that you will want to change in this menu. See step 9 for the discussion on digi paths. NWAPRS.info is a good source for descriptions on how the path process works. The quick answer is, you probably want “WIDE1-1,WIDE2-1” if you’re mobile.

13. Keep Screen Awake. I ride with my cell phone mounted on my dash like a GPS allowing me to see who is nearby. If that’s you, you’ll want to enable “keep screen awake.”

APRS Settings

Call sign and pass code  These values are used to identify one as a HAM radio operator.  The pass code is required by the APRS-IS network and not specific to APRSdroid.  You can use your existing APRS-IS pass code or request a passcode if you are new to APRS-IS.  No pass code is required if you wnat to directly connect APRSdroid to a radio or TNC.

SSID   The SSID represent the basic type of device you want to represent.  Typical values are 5 for cell phone, 7 for NT, 9 for a mobile radio, and 10 for Internet (APRS-IS).

Position Reports

Symbol and Comment  In the APRS symbol field you can enter the text representation of your symbol. /$ represents a phone booth icon, /[ is a running person, and there are many more.  You can use overlay symbols as well!  The comment can contain information about yourself and it is recommended to add your ORG in it.  Just write the frequency as xxx.xxxMHz or use other optional fields. 

Location Source and Settings  Choose how APRSdroid will obtain your geographic location and how often it will report it.

SmartBeaconing  Your position is posted according to your movement speed and direction.  Currently, no settings are possible, the update interval is between 15 second (corner-pegging) and 20 minutes.

Periodic GPS/Network Position  You can set the minimum update time interval in minutes and update distance in km.  The values for distance and interval are always check together, before an update is sent.  This is meant to reduce the traffic on the APRS radio band.  If you want to send updates every minute, regardless of your movement, you have to set the following:

  • Update interval: 1 [min]
  • Update distance: - [km]

Unfortunately, there is no easy way in the Android to receive location updates when either condition is met, without using too much battery reserve. 

The GPS precision setting allows to tune position quality vs. battery use.  Low will use the firstGPS result available; Medium will keep GPS on for 30 seconds and use the latest result; and High will keep the GPS on all the time.  It is recommended to sue SmartBeaconing instead of the High setting.

The network location option allows to sue GSM/3G and WiFi networks to obtain your position.  This data is not very precise (100m..10km) an can cause a duplicate position reports.  However, it has a significantly lower battery use than GPS.

Manual Position  You can enter your coordinates as decimal values.  Enter negative values for south and west.  As an example, the center of Los Angeles would be Latitude: 34.052222 and Longitude: -118.243611.  If you want to keep your position private, disable Automatic Posting.  Your position will only be announced if you use the Single Shot button.  However, you may not receive messages to your call sign without posting your position.

Position privacy  You can "hide your tracks" by setting the positon ambiguity of your reports or disable the posting of speed and/or direction.  It is not recommended to sue this in combination with Smart Beaconing.

APRS Connection  Use this setting to choose how APRSdroid should connect into the APRS network.  You can configure the chosen protocol using Connection Preferences.

TCP Connection  This connects you to the APRS-IS network.  It is the default, suggested connection type, and allows to utilize APRSdroid over the Internet.  This setting maintains a bidirectional connection to an APRS-IS server, as long as the tracking service is running.  You can use the Neighbor radius to set the areas of interest, and the Message filter to receive selected packets.  You should choose a rotate address for you region from the Tier 2 APRS-IS servers or a server from the APRS-IS server list.  It is also possible to connect to an iGate near your location. 

UDP (not recommended)  The packet is sent via UDP to port 8080.  This is unreliable and packets may be lost without a message.  Nevertheless, because there is no feedback, APRSdroid show them as "UDP OK".  You need to check an external reference like aprs.fi to see if your packets actually arrived.

HTTP Post (not recommended)   Packets are sent via HTTP.  This is more reliable than UDP, however causes higher traffic levels.

Bluetooth TNC  This allows to connect APRSdroid to a TNC using a Bluetooth serial (SPP) adapter.  You need to pair the Bluetooth serial adapter in the Android Bluetooth preferences, than you can use it to connect to a TNC in KISS mode.  It is possible to set the Bluetooth channel to connect to the TNC (leave empty for auto-discovery of SPP).  To initialize the TNC, you can set a TNC init string.  Multiple lines can be entered, APRSdroid will wait the init delay time after each new line.  In some cases, you might have a Bluetooth device operating in client mode (initiating a connection to your smartphone).  For these seldom situations (or to directly connect two Androids), you can disable Client Mode.

 

 Last Update:  09/12/2016    © Copyright Sumter County ARES. All Rights Reserved.