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PulseModem A

"PulseModem A" is an iOS APRS client, that reads and reports APRS location and messages. It works on both iPhone and iPad as an iOS universal app.

APRS is a digital communications protocol that can exchanges information among large number of stations both local and global.

Download PulseModem A at AppStore now

PulseModem A Screenshot

What is APRS

APRS stands for: Automatic Packet Reporting System.

APRS is a digital communications protocol that can exchanges information among large number of stations both local and global.

You as a licensed Amateur Radio operators can send and receive APRS location and message in 2 ways:

  • Direct to the APRS-IS Network
  • Radio Frequency with Amateur Radio at 2 meter band at 144MHz

APRS-IS network

You can connect directly with the global APRS-IS network by Internet. Messages reaching the gateways will be relayed to the APRS-IS feed.

The PulseModem A will display messages from the APRS-IS, 100km around your current location.

Radio Frequency with Amateur Radio at 2 meter band at 144MHz

APRS messages are short in length, in less than 100 bytes.

Messages are encoded in AX.25 protocol with Bell 202 AFSK modulation.

PulseModem A will play the encoded message through the audio port of your iOS device, to your radio.

Roadmap for PulseModem A

The "A" of "PulseModem A" stands for APRS. Future versions of PulseModem will decode other formats.

PulseModem A aims to be the finest RF telemetry APRS & virtual TNC on iOS. The app will be updated as much as possible.

Below are the current roadmap of PulseModem A.

1. BLE Hardware Companion & PTT triggers

Given that the 3.5mm TRRS audio port has been removed from the current line-up of iOS devices, PulseModem A is expected to have a companion hardware in BLE4 for easy interface with commonly available VHF radios.

High on the list would be a proper PTT triggers for Baofeng, Kenwood & Yaesu radios.

2. Updated icons

The original APRS specifications have a limited set of icons.

That has been changed a few years ago, which gave rises to almost 1000+. PulseModem A aims to provide a more comprehensive support.

3. Better Messaging Parsing

Given that this is the first release of PulseModem A, there could be a myriad combinations of APRS messages that could trigger errors.

Along with other kinds of malformed messages from network or software errors...

This app will be updated with better message handling.

And more...


Please install libao with Mac Ports: sudo port install libao


The PulseModem A is developed by Pulsely
(C) 2018 by Pulsely
leveraging the following hard work from these forward thinkers, developers & designers:

Bob Bruninga
APRS is a registered trademark of Bob Bruninga. He is the creator of the APRS system.

APRS Library
multimon - original program to decode radio transmissions
(C) 1996/1997 by Tom Sailer HB9JNX/AE4WA

multimon-ng - great improvment of multimon, for the RF Receive function
(C) 2012-2018 by Elias Oenal

ax25beacon - AX.25 beacon packet generator for APRS
By Philip Heron

libfap - ARPS parser
Originally written by Tapio Sokura, OH2KKU and Heikki Hannikainen, OH7LZB and ported to C by Tapio Aaltonen, OH2GVE

iOS components

EZAudio - iOS and macOS audio visualization framework built upon Core Audio
by Syed Haris Ali

TPCircularBuffer - A simple, fast circular buffer implementation
by Michael Tyson

AFNetworking - delightful networking framework for iOS, macOS, watchOS, and tvOS
AFNetworking is owned and maintained by the Alamofire Software Foundation.
AFNetworking was originally created by Scott Raymond and Mattt Thompson in the development of Gowalla for iPhone.

DZNEmptyDataSet - drop-in UITableView/UICollectionView superclass category for showing empty datasets
Copyright (c) 2016 Ignacio Romero Zurbuchen

UICKeyChainStore - simple wrapper for Keychain on iOS, watchOS, tvOS and macOS
By kishikawa katsumi,

RMessage - crisp in-app notification/message banner built in ObjC
Copyright (c) 2016 TouchSix, Inc. Adonis Peralta

Onboard - easily create a beautiful and engaging onboarding experience
Copyright (c) 2014 Michael Amaral

Chameleon - lightweight, yet powerful, color framework for iOS
by Vicc Alexander

CocoaAsyncSocket - Asynchronous socket networking library for Mac and iOS
Copyright (c) 2017, Deusty, LLC


aprs-symbols APRS symbol set, high-resolution, vector
by Heikki Hannikainen

App icon:
Icon by By Oksana Latysheva, UA

Transmit icon:
Power by & from the Noun Project

Map icon:
Map by Adrien Coquet from the Noun Project

List icon:
List by Iconstock from the Noun Project

Info icon:
about by Hector from the Noun Project

Cloud icon:
servers by Jony from the Noun Project

Sleeping cat:
Sleeping Cat by parkjisun from the Noun Project

Apple Icon:
Apple by Milinda Courey from the Noun Project

Missing Acknowledgements?

We try not to missing anyone, but if you know someone is missing, please contact PulseModem A via its github repo.


This project is licensed under the GNU General Public License v3.0 - see the LICENSE file for details


"PulseModem A" is an iOS APRS client, that reads and reports APRS location and messages.





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