IGate2

IGate2 is a mobile app that performs a receive-only APRS IGATE.

It is a software for HAM radio amateurs that uses a radio receiver or an SDR (software defined radio) dongle and an internet connection.

The radio receiver or the RTL-SDR dongle tuner (cost starting from 10 €) and its antenna, receives the information contained in APRS packets transmitted from HAM radio stations, and then a phone device, with IGate2, forwards them to the world wide web using its internet connection (WiFi or 3G).

IGate2 acts as a Software Defined Radio Demodulator, a TNC Modem and an Internet Gate.

It needs the installation of a driver (Martin Marinov’s driver) for the SDR dongle that you can find here.

If you already own an unused cellular phone (or tablet or TV Box), IGate2 represents a very cheap, compact and easy-to-use solution for suppling an IGATE service to radio amateur community.

Raw data contained in radio packets are visible on the phone screen and may be routed (if you check this option) to the APRS-IS network. All data convoyed and shared in APRS-IS network can be seen in maps and bulletins on particular websites, for example aprs.fi or aprsdirect.de.

To be authorized to send data to APRS-IS you must have a HAM CallSign and a PassCode. See aprs-is.net. If you are not a radio amateur, you may only use your equipment in receive only mode.

The app has an audio monitor useful for tuning the parameters of the Sdr receiver (it may not work well in old devices with low memory). In the main page there is a frequency switch, a hub with the text of received packets, two indicator lights: one for the Sdr connection (or for Mic level) and one for the Aprs-Is connection, three counters reporting the number of: received, forwardable and forwarded packets. When you leave the main page while the IGate is running, the app service will continue working in the background, you can recall the main page by tapping the service icon in the android status bar. The app has an option for AutoStart function that is useful for unattended TV Box devices (with Android 6.0 or up). The preset of the UHF Aprs frequency is 432.500 Mhz.

Since the device and the Sdr dongle drains much power from the phone battery, it is recommended to use the phone charger or a power bank. You will need an OTG power cable or a powered usb hub. It is not easy to find a working cable, maybe you can do it yourself. The reception quality of the IGate depends, above all, on the antenna connected to the Sdr dongle. With very strong FM broadcasts in your area, it may be helpful to manually adjust the gain of the receiver or use a band-stop filter. If you use an analog receiver you will need an audio cable (useful also for the tracker app). It is not recommended to use an acoustic coupling by bringing the microphone of the phone close to the speaker of the receiver and also be sure that the power saving function is not active on the receiver, otherwise some truncated packets will be discarded. An example of the audio cable is shown below.

Get this app from Google Play Store

Using a TV Box

A possible and convenient choice, to run IGate2 from a fixed station, is to use an Android TV Box instead of a mobile phone. An SDR dongle or an analog receiver can be connected to the TV Box. TV boxes start at around $ 20.
If necessary, an FM Band Stop filter (purchased or self-built) can be used to improve the reception of signals from an external antenna.

App Privacy Policy

IGate2 is an app aimed exclusively at radio amateurs, it shares the set position and status with other amateur radio operators.

Amateur radio activity is not covered by any of the secrecy notions in Radio Regulations. In most legislations, encryption is forbidden on amateur radio frequencies, and this is extended to the APRS-IS network on the Internet.

The app does not collect any personal data for itself, but the information in radio packets will be sent to APRS-IS network and stored by public and private Aprs listeners for an indeterminate time.

The following app permissions are needed to manage specific features. Any permission is requested, and may be granted, only if you use the corresponding feature.

Location permission, to automatically get the IGate’s position for the beacon message.
Audio input permission, for processing the audio of an external receiver (not SDR). Data is only decoded locally on your phone.

Default Settings Values

· IS Beacons interval: 30 minutes

· Squelch threshold: 0 (recommended)

· IF AGC: NO

· RF No AGC: NO

· PPM Correction: 0 (center position)

UHF Aprs frequency preset: 432.500 Mhz.

Audio Cable

(for analogic receiver)

OTG Y Cable

(for SDR dongle and mobile phone)

The insertion of a 100 KΩ resistor *, between pins 4 and 5 of the phone's micro usb plug, allows the device to be charged.

* This value depends on the phone brand. Another value is 64.9 K which can be obtained through series and/or parallel resistors. Not not all phones have this feature.