aprs.fi iOS User Guide

The app requires a working Internet connection either through Wi-Fi or cellular data. Your cell provider may charge you for transferred data. The amount of data transferred by the aprs.fi app may be monitored from iOS Settings → Mobile Data. All data is compressed by aprs.fi before it is downloaded by the app.

Some of the new features of this app are available through an in-app subscription. All basic features that are currently available in the app, and some functions which are added later on, will naturally stay available without additional payment.

In-app subscriptions provide a sustainable business model. They ensure continuous interest in developing and maintaining the application and its backend service even after all APRS-using iPhone and iPad owners have already purchased the app.

Features currently included in the Extra Features subscription are:

Many features require a free aprs.fi user account. You can sign up for the account from the More tab → My account, if you don’t have one yet. The account is used for synchronizing your settings, and for messaging and beaconing your position.

If the confirmation email does not arrive, please check your spam/junk folder. If you still do not receive the email, do contact me: Feedback and support

To track a specific station, search for it on the Search tab, and select a station to enter the station details view. Tap the Track button to start tracking. To track multiple stations at a time, search for additional stations and tap Track again.

To stop tracking a station, drag the station’s callsign button and drop somewhere on the left, as shown in the following video. Alternatively, tap Stop tracking in the station details view.

When tracking multiple stations, the Fit button will fit all tracked stations into the map view.

To center on your current location, tap the Centering button in the lower right corner of the map. Tap again to zoom in.

To center on a currently tracked station, tap the respective callsign button in the lower right corner. Tap again to zoom in. While tracking multiple stations, an additional button is shown for quickly fitting all tracked stations in the view.

If you zoom out far enough, the amount of data presented may be a little bit too much for the device, and updates will be paused. Zoom in to refresh again.

To change the time range of the map, tap the Time range button in the bottom of the map view. The time range selects how far back in time the stations are shown on the map.

The default time range is 1 hour, but you can select from a number of predefined ranges.

To filter the stations shown on the map, tap the Filter (funnel) button in the bottom of the map view. A few default filters are set up as an example.

Each of the filters in the chain can be enabled and disabled independently with the toggle switch on the left. A disabled filter has no effect. The following filter shows only iGate and Digipeater stations:

Filters are not applied when tracking specific stations.

The filter chain has two sections: Display these and But not these. If one of the enabled filters in the Display these section matches a station, it will be shown on the map. If nothing matches the filters, no stations will be shown – enable the "All stations" filter to show all stations again.

The But not these section contains filters that will hide stations which would otherwise be shown by the previous filters. It can be used to create exceptions, such as "Show all stations except weather stations". Press the red and blue up/down buttons on the right to move filters between the two sections.

The following filter will show all stations, except maritime traffic reported with AIS and weather stations:

Press the + button to add a custom filter. You can set up filters for any combination of the following criteria:

A single filter can compare for multiple criteria. For example, you may wish to show all stations with a specific symbol, but only those which are moving faster than 10 km/h. Press the + button to add comparison, and press OK when the filter is ready.

To change the station symbol size and the text size on the map, repeatedly press the scale button on the bottom of the map. This cycles through the three available sizes.

To change between navigation and satellite map styles, tap the Map style button in the bottom of the map view.

The Navigation style is a standard map with streets and place names, while the Satellite style shows satellite imagery. The third option is Hybrid, which combines the two styles, showing streets and place names on top of the satellite imagery.

The app currently uses Apple Maps for the map view.

The application stores the last view and map settings, so the next time you open the app, it will show the same view as you left it. It remembers filter settings, the tracked stations, and the map position and zoom level. It will even remember them if you power off the iPhone and turn it back on later.

However, if you choose to manually terminate the app by swiping it away in the app switcher, iOS will delete the state restoration file. The app will then open up with the default view. This may be useful if the app is misbehaving and you want to reset it.

Manual termination of apps is normally not necessary, as iOS will automatically stop apps in the background, and release them from memory when memory is needed for other apps. This is transparent to the user, as the apps will be restarted automatically when you open them again. Apps are not allowed to execute in the background for long periods of time, so they will not consume battery power when you are not using them.

Pull the information table down to refresh the information. It will be refreshed periodically, too.

Graphs of speed, altitude, weather and telemetry can be drawn for many stations. On an iPhone, the graphs can be accessed using the graphs button in the top right corner, or by swiping the details view to the left.

You can add stations to your favourites by tapping the Star button in the station details view. Favourites are shown in the Favourites tab in Search, and can be tracked from there. On the iPad, starting from iOS 18, the search text entry field needs to be activated to view the search scope tabs (Stations, Favourites, Addresses).

Favourite stations are synchronised with the aprs.fi service, so they are available on all your devices. You can also access your favourites on the web site using the Star button on the right side of the map view.

You may set up multiple APRS station profiles in the app, each with different symbol and other settings, allowing quick switching between the stations.

To set up a new profile in the Beacon tab, tap the current station callsign to view the list of profiles. Tap the New station button, and enter the callsign, SSID (Secondary System Identifier), and other settings for the new profile.

The SSID is a number between 1 and 15, appended to the callsign with a hyphen, e.g. N0CALL-1. The SSID is optional, but it is needed to distinguish between different stations and devices of a single user. The SSID if 0 is, by convention, reserved for the main station, and not shown.

Non-numeric SSIDs of one or two characters are allowed, but they cannot be used when beaconing to APRS-IS, or when using a TNC.

To rename a profile, tap the Rename button at the bottom of the Beacon tab, and enter a new name. To delete a profile, tap the Delete station and all data button at the bottom of the Beacon tab, and confirm the deletion.

When transmitting beacons to RF using a TNC and a radio, a suitable packet path should be selected. The packet path selects the amount and type of digipeaters which are requested to retransmit the packet.

The default of WIDE1-1,WIDE2-1, which requests two digipeater hops, is suitable for most cases, but you may wish to change it to meet local network requirements.

A TRACE2-2 path requests two digipeater hops, where the digipeaters should insert their own callsigns into the packet. This is useful for tracing the route of the packet through the network.

The ARISS path is used when transmitting via the ISS (International Space Station) digipeater and other APRS satellites.

An empty path will not request any digipeaters, and the packet will only be transmitted by your own station. This is useful for testing, or when you wish to transmit a position without any digipeater retransmissions.

The aprs.fi blog has a detailed article on APRS paths and digipeaters.

The aprs.fi app implements a smart beacon timing algorithm which adjusts the transmit interval based on your speed and movement. It will transmit more often when you are moving faster, and less often when you are not moving. It will also detect tight turns and send a new position as soon as possible. This helps to save battery power and reduces the amount of data sent over the network.

Increasing minimum transmit interval will reduce the frequency of transmitted beacons. If you wish to transmit a less exact position for for privacy reasons, you can increase the minimum interval and enable position ambiguity to further reduce position accuracy.

Decreasing maximum transmit interval will increase the frequency of transmitted beacons while you are not moving.

If the minimum and maximum interval are set to the same value, the smart beacon algorithm will not be used.

APRS-IS beaconing is available with the Extra Features subscription. To enable APRS-IS beaconing, go to the Beacon tab, enable Beacon via APRS-IS.

Note that the APRS-IS is a public network, and your position will be visible to anyone. There is no privacy. Data sent to the APRS-IS is archived by a number of services, and will be available for download or viewing even after you stop transmitting.

To transmit your position via a radio, you need to set up a TNC connection. Please see Connecting to a radio.

After a TNC is set up, enable Beacon via TNC in the Beacon tab.

Data transmitted on amateur radio frequencies is not private, and will typically be received by iGate stations which forward the data to the APRS-IS.

The app will continue to transmit your position in the background, if it is allowed by iOS privacy settings. For the app to be able to transmit in the background, you need to enable background location updates (aprs.fi More → Settings → Privacy → Location).

The ALLOW LOCATION ACCESS setting should be set to Always. If you select While Using the App, the app will only transmit your position when it is in the foreground and the screen is not locked.

If you wish to delete the position history uploaded to aprs.fi, go to the Beacon tab, scroll down to the bottom, and tap the Delete station and all data button. This will delete all positions uploaded by the app from the aprs.fi service.

If you have transmitted data via the APRS-IS or using a TNC, it will be likely archived by other services, and may still be available for download or viewing.

There is no privacy in APRS messaging. Messages sent via the APRS-IS network are public, and anyone can read and archive them. Messages sent via a TNC are transmitted on the radio frequencies, and can be received by anyone with a radio receiver.

The aprs.fi backend service will send push notifications for new messages to the app. To receive push notifications, you need to have them enabled in the iOS Settings app. When first using messaging, the app will ask you to allow notifications. If you accidentally denied notifications, you can enable them again in iOS Settings → aprs.fi → Privacy → Notifications.

The app will transmit each message up to 6 times, with an increasing delay between each transmission. This is to ensure that the message is delivered even if the first transmission fails due to poor radio conditions or other issues.

When the recipient’s APRS software receives the message, it will send an acknowledgement (ACK) back to the sender. The message will be marked as delivered, and further retransmissions will be stopped.

If you wish to resend a message, keep your finger for a moment on the message in the message thread, and select Retransmit from the menu. This will initiate a new sequence of retransmissions.

It is also possible to abort the retransmissions of a message by keeping your finger on the message in the message thread, and selecting Abort.

The APRS messaging system is not always very reliable. For a message to be delivered to a recipient on the RF network, the recipient must be within range of a transmit-capable (TX) iGate gateway station, or a digipeater near such a gateway. The network currently does not have means to indicate whether such coverage is available.

Unfortunately many APRS iGates are receive-only (RX) and do not transmit packets, due to licensing issues or hardware limitations. Receivers are cheap, transceivers are more expensive, and in many countries an automatic transmitting station requires a special license. In such cases messaging may only work to one direction - from RF to APRS-IS, but not back to RF.

When you’re transmitting packets from RF to the APRS-IS via a receive-only iGate, the acknowledgement packet will not be transmitted back to RF. The app will not know that the message was received, and will keep retransmitting it until the maximum number of retransmissions is reached.

In the message threads view, you can search for conversations by entering a search term in the search field at the top of the view. The search will match against the recipient callsign and the full text of the latest message.

Individual messages can be deleted by keeping your finger on the message in the message thread, and selecting Delete from the menu.

A message thread can be deleted by swiping left on the thread in the message list, and tapping the Delete button. Alternatively, swipe the thread all the way to the left and it will be deleted with a single movement. Be careful, there is no confirmation dialog or undo for this action!

This will delete all messages in the thread and the thread itself. The messages will only be deleted from the app on this device.

BLE (Bluetooth Low Energy) is a wireless technology for connecting devices with low power consumption. It is a part of Bluetooth 4.0 and later, and is supported by all iPhones and iPads. iPhone apps may connect to BLE devices, but they cannot communicate with classic Bluetooth devices. Many older Bluetooth-capable devices only support the classic Bluetooth Serial Port Profile (SPP) and are not accessible from iOS apps.

The aprs.fi iOS app automatically detects and supports all TNCs which support the BLE KISS specification. There is no need to add support for new radios or TNCs to the app, as long as they follow the BLE KISS specification. They just work, and they also work with a number of other apps following the common protocol.

BLE devices are automatically discovered and listed in the Select a TNC view. If you have multiple BLE TNCs, you can select the one to use for the connection. BLE TNCs do not need to be paired with in iOS Settings. Just turn the BLE device on, enable BLE in the device if necessary, and pick it from the list. It feels like magic!

Most current BLE TNCs only support a single connection at a time. If you are also using a separate configuration app for the device, you may need to disconnect the TNC from that app before you can connect to it with the aprs.fi app. Likewise, you may need to disconnect the TNC from within the aprs.fi app before you can use it with another app.

Here are some of the supported BLE devices:

Notably, none of the current Kenwood APRS radios support BLE KISS. The B.B. Link Adapter can act as a bridge between the classic Bluetooth TH-D74/D75 radios and BLE, allowing the app to connect to the radio.

The app contains a high-performance software modem which allows you to connect a transceiver directly to the headphone/microphone connector of an iPhone or iPad. The DSP modem is available when an Extra Features subscription is active.

The aprs.fi app can connect to KISS TNCs and software modems with a TCP KISS port over the network. If a TNC on the local Wi-Fi network supports mDNS service discovery (Bonjour), it will be automatically discovered and listed in the Select a TNC view. If not, you can add a TNC manually by entering its DNS hostname or IP address, and the TCP port. Using the manual method you can also connect to a remote TNC through a VPN connection.

A popular option is to install the Dire Wolf software DSP modem on a Raspberry Pi, or on a PC running Linux, Windows or macOS. The software can be configured to listen for TCP KISS connections on a specific port (8001 by default), and it will work with the aprs.fi app. Dire Wolf supports mDNS service discovery on Linux and macOS.

The WX3in1 device also has KISS over TCP, but it only supports receiving packets, and does not have mDNS.

Application settings can be accessed from the More tab → Settings. Settings are divided the following sections:

A basic receive-only iGate is available in the app. It will receive packets from a TNC, and upload them to the APRS-IS via the aprs.fi backend. The iGate currently does not transmit any packets, and it does not support digipeating.

The iGate is enabled from the More tab → iGate. The iGate will use the callsign-SSID selected in the Beacon tab.

A table of recently heard stations can be accessed from the iGate tab. It shows the callsign, symbol, distance, and the time of the last heard packet for each station. When packets from a station are received via different paths, all the paths are displayed. The table is also maintained when the iGate is disabled.

This is where you can log in to your aprs.fi user account, or create a new one. Logging in is necessary for messaging, beaconing your position, and sychronizing your favourites and settings with the aprs.fi service.

You may also change the main callsign attached to the account here, using the Change button.

If you have multiple callsigns, you can set up multiple station profiles in the Beacon tab, each with a different callsign, SSID and settings. The callsign-SSID selected in the Beacon tab is used for beaconing and messaging. The callsign-SSID of each profile can be changed with the Rename button in the Beacon tab.

A subscription is required to use the Extra Features of the app. The subscription can be purchased from the Subscription tab in the More tab. The subscription model is used to ensure funding for the continued development and maintenance of the app and the aprs.fi service.

The subscription is available as a monthly or yearly plan. The yearly plan is cheaper than the monthly plan, and it is recommended for long-term users.

Subscriptions are managed by Apple, and can be cancelled at any time. If you cancel your subscription, you will still have access to the Extra Features until the end of the current billing period. Cancellation must be done at least 24 hours before the renewal date to avoid being charged for the next period.

The yearly subscription, as well as the application itself, can be shared with family members using Family Sharing.

If you have purchased the app or subscription accidentally, or you are not satisfied with it, you can request a refund from Apple.

Please note that refunds are handled by Apple, and the aprs.fi developer cannot issue refunds directly. All sales and payments happen via Apple, and the aprs.fi team does not have access to your payment information.

If you have any questions, feedback, or issues with the app, please contact the developer via More tab → Feedback → Send feedback over email. The application is developed by a single developer, myself, and I will do my best to answer your questions, but sometimes it may take some time to respond. Please be patient!

You can also send a message to the aprs.fi discussion group where many users and APRS developers are active.

The group is a good place to ask questions and report issues, but please note that it is specific to the aprs.fi web site and the iOS app, and not a general APRS group. Messages about other APRS applications or services may be rejected. Messages from new users are moderated, so they will not appear immediately.