martedì 27 giugno 2017


Build a radio beacon with the material found in the house at a cost of few euros.

We start with the idea that digital radio audio signals can be recorded and then decoded. Among my videos you can see how to decode a digital signal found on youtube.

You can use countless software and protocols. Important is that you can generate the signal, transmit it with a radio transmitter, receive it with a radio and record it here. Then this audio will be retransmitted.

Below are some low cost examples:  

1. FM Radio Beacon


2. AM Radio Beacon


3. Multi Channel Radio Beacon AM & FM 

If you plan to use this system standalone you can associate an additional power generator (solar panels, wind power generator, hydro turbine, etc)

Good Fun.

lunedì 20 marzo 2017

Various app Android audio decoders to play with RTL SDR


To simplify the reception of radio messages is possible to simulate the same.
To simulate the messages you need:

- Audio FM Transmitter via Jack
- RTL SDR with the drivers and software installed in your mobile phone
- OTG cable
- Smartphone jack output adapter to split microphone and headphones
- Audio file containing the signal, previously registered or already prepared (eg found on the internet)
- Software to decode or / and encode message



Scanner Radio receive


SDR Touch supports receiving FM radio, AM, SSB and CW broadcasts including HAM radio amateurs, police, air traffic, weather reports, fire department and emergency stations, taxi traffic, audio of analogue TV broadcasts, digital broadcasts and many more! Depending on the hardware used, its radio frequency coverage could span between 50 MHz and 2.2 GHz. Turn your mobile phone or tablet into an affordable and portable software defined radio scanner. SDR Touch currently demodulates WFM, AM, NFM, USB, LSB, DSB, CWU and CLW signals.

2. RF Analyzer

Use an OTG (on-the-go) USB cable to connect your HackRF/RTL-SDR to an Android phone/tablet and this app will visualize the RF spectrum (frequency magnitude and waterfall plot)!

Various Decoder Demodulator Audio


This app has been created by Dave, W1HKJ and can be used to decode digital modes used on shortwave and other forms of radio including programmes such as VOA Radiogram and DigiDX., CW (morse) and RTTY.

2.AndFlmg FLDigi for Android

AndFlmsg is a combination of Fldigi and Flmsg for portable devices running Android.


ACARS Decoder lets you view ACARS transmissions on your android device. Just connect it to a VHF radio (or even set it next to the radio's speaker), tune in an ACARS frequency, and watch the decodes.


NAVTEX Decoder lets you view NAVTEX marine weather transmissions on your Android device. Just set it near a radio (or for better quality decoding, connect a cable from the radio's audio output jack to the microphone jack), tune in a NAVTEX frequency, and watch the transmissions.

5. HF Weather Fax

HF Weather Fax lets you receive marine weather radiofascimile transmissions on your Android device, using the audio from your HF marine radio. Just set it next to the radio's speaker or headphones, tune in a weather fax frequency, and watch the images come in.

6. DroidNavtex for marine

DroidNavtex decodes NAVTEX messages from your receiver through your phones/tablets microphone or through a connected interface. Special audio filters even decode very weak signals through the microphone and make DroidNavtex a very affordable alternative to high priced decoders.

7. Robot36 - SSTV Image Decoder

It decodes the following modes at the moment:

Robot Modes: 36 & 72
PD Modes: 50, 90, 120, 160, 180, 240 & 290
Martin Modes: 1 & 2
Scottie Modes: 1, 2 & DX
Wraase Modes: SC2 180

8. SSTV Encoder

Currently supported modes:
Martin Modes: Martin 1, Martin 2
PD Modes: PD 50, PD 90, PD 120, PD 160, PD 180, PD 240, PD 290
Scottie Modes: Scottie 1, Scottie 2, Scottie DX
Robot Modes: Robot 36 Color, Robot 72 Color
Wraase Modes: Wraase SC2 180

9. DroidSSTV - SSTV for Ham Radio

DroidSSTV lets you transmit and receive amateur radio (ham radio) slow scan TV (SSTV) on your Android Smartphone or Android tablet. This communications app is a great tool for portable amateur radio SSTV operation. Just connect your Android phone or tablet to an HF radio (or even set it next to the radio’s speaker), tune on to an SSTV frequency, and watch the pictures scroll onto the screen.DroidSSTV supports the ham radio modes Scottie 1, Scottie 2, Scottie DX, Martin 1, and Martin 2 at this time.

10. APSK

this app receives BPSK31 through the microphone and displays the received text on the screen. it probably won't work at all without a pretty fast processor. also, the waterfall doesn't line up right yet.

11. DGPS

This app can decode DGPS (Differential Global Positioning System) beacon transmissions. DGPS stations transmit the difference between positions indicated by GPS satellite systems and the known fixed position of the station. This allows higher accuracy.

12. DroidPSK - PSK for Ham Radio

DroidPSK is an application to decode and encode Ham Radio BPSK31 and BPSK63. A great tool for portable Amateur Radio PSK operation.
DroidPSK is able to decode a BPSK31 or BPSK63 signal though the build in microphone. Just hold your Android phone or tablet close to the speaker of you Amateur Radio transceiver, adjust the waterfall slider to the PSK carrier frequencies and DroidPSK will start decoding.
In transmitting mode characters can be entered trough the keyboard. 20 Macros are also available to store standard texts like "name and qth" and "station info"
Starting V2.0 DroidPSK now also includes a logbook. Callsign, Name RST etc can be easily transferred into the lookbook from the receiving screen. The logbook also includes ADIF export and import to transfer your logbook data to a PC based logging software.

13. DroidRTTY for Ham Radio

DroidRTTY is an application to decode and encode Ham Radio RTTY with the build in microphone/speaker or wired to your radio.
A waterfall shows the frequency spectrum of 100Hz to 2500Hz. Just slide the waterfall slide on a RTTY carrier frequency and DroidRTTY will decode the signal.

14. Morse Code Reader

Listens to Morse code through your phone's mic and translates it to text.

15. EPIRB Distress Radiobeacon 406Mhz

Décoder les trames audio des balises de détresse 406MHz à l'aide d'un PC, d'un téléphone ou d'une tablette ANDROID

16. HAB Modem and Tracker

Ground tracking app for high altitude balloons, complete with RTTY modem, offline mapping, online distributed listener integration, chase car location reporting and more.

17. Radio ID

Identify two-way radio transmissions made using Motorola MDC-1200, GE STAR, or Kenwood FleetSync radio identifier formats. Also decodes QuickCall II tone paging. (All formats trademarks of their respective owners).

18. DTMF Decoder

DTMF decodes and encodes DTMF (Dual-tone multi-frequency) tones trough the phones speaker and microphone.

19. Alert Field Decoder

Field technicians who work on 'Alert' transmission equipment can now use their Android phone to decode the transmitted alert data.
This application decodes 300 Baud FSK data transmitted in the common Alert 1 protocols, BDF and IFLOWS.
Just connect your RF scanner audio output to your microphone input, or hold your built in microphone next to the scanners speaker.
This app decodes data from Handar, Campbell Scientific, High Sierra, and other alert transmitters.
This app does NOT decode the Alert 2 protocol

20. Pisces Decoder

Pisces Decoder listens for the sound of a telemetry tag via the microphone. If a valid tag is heard, it will display the code along with the time, coordinates of the device, signal strength, and be recorded to a file which can then be exported. The app can be used with any audio receiver or scanner without decoding capability that can be tuned to VHF frequencies of telemetry tags creating a relatively inexpensive means for manual tracking.

DIY Transfer Data

1. Modem_FSK

It communicates in the style of an acoustic coupler. 
Only an alphanumeric character corresponds. 
It can communicate with Modem_FSK_Receiver.


This application enables the user to transmit data between air-gapped devices using audio. 
It uses a simple MODEM algorithm to enable the user to send and receive short data messages (up to 250 bytes, within up to 3 seconds) between nearby phones or computers, utilizing the sender's speaker and the receiver's microphone.