IGate2 のアプリ分析 12月2日

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 in: https://play.google.com/store/apps/details?id=marto.rtl_tcp_andro . 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 http://aprs.fi/ (or aprsdirect.com). 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. 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), do not 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 in the app site. App permissions: • This app uses Location permission (if you grant it) to get the IGate’s position for the beacon message. • Audio input permission (if you grant it) for processing the audio of an external receiver (not SDR). Other related Apps: • Tracer2 : an APRS Tracker for Android using an external transmitter (or internet). Notice: • This app is free trial of the IGate2 Pro app. It has a limit of 100 forwarded packets per session. If you like this app, buy the full-feature version (IGate2 Pro) in the Google Play Store. It is cheap! • This app has been tested in devices running Android 5 and up. If you find any error on your special device, please, do not give a negative feedback but feel free to mail the problem to the author and he will fix it.