He shows instructions on how to perform the required modification to get the IF output of the ICOM, and also shows how to interface the PC with the ICOM so that it may be controlled directly via HDSDR.
D-STAR or (Digital Smart Technologies for Amateur Radio) is a Frequency Division Multiple Access (FDMA) Gaussian Minimum Shift Keying (GMSK) digital voice and data protocol used in amateur radio.
Up until recently it was possible to decode D-STAR headers using either DSD 1.6 or dstar.exe and an RTL-SDR, but it was not possible to decode voice. Now amateur radio hobbyist PU2VLW has brought to our attention that the latest DSD development version 1.7 is capable of decoding D-STAR audio (his post is in Portuguese so we suggest using Google translate). He shows a video of some example D-STAR decoding which we show at the end of this post.
DSD 1.7 can currently be downloaded as source from it’s GitHub respository. Instructions for installing DSD 1.7 on Linux can be found on the post by PU2VLW and the GitHub readme. PU2VLW built DSD 1.7 in Ubuntu 10.04, noting that newer versions of Ubuntu have removed OSS (Open Sound System) support which DSD requires. He then runs SDR# on a Windows PC, tuned to a D-STAR signal, and uses an audio out cable to connect the Windows PC’s audio out to the Ubuntu PC running DSD 1.7.
Update: See this post for installing DSD 1.7 on Windows.
Decodificando Dados e Voz da tecnologia D-STAR sem utilizar DV Dongle
YouTube user Łukasz Kosson has uploaded a video showing how he was able to decode RTTY signals on 10m (28 MHz). RTTY is an acronym for Radio Teletype, and is a method used to transmit text. To decode RTTY he used HDSDR and piped the audio output to fldigi.
YouTube user Troy McQuinn has uploaded a video showing how he is able to decode amateur radio APRS signals. APRS is an acronym for Automatic Packet Reporting System and is used by ham radio users to send data like messages, announcements and also GPS coordinates. To decode APRS he uses SDR# and pipes the audio to QTMM AFSK 1200 Decoder.
His results show that the RTL-SDR and portable receiver are comparable in terms of performance, with a slight edge to the RTL-SDR. He adds that software tweaks available in SDR# can improve the voice quality for the RTL-SDR. However his final recommendation for general shortwave listening is that the portable is still the better option due to it’s ease of use.
RTL-SDR + Upconverter vs. Portable Shortwave Radio
The High Performance Software Defined Radio (HPSDR) project is an open source SDR project that aims to create a modular SDR for ham radio use. The idea is that users only need to include the specific HPSDR hardware that they need for their particular application.
Using his tool Richard was able to get seven R820T RTL-SDR dongles running simultaneously on an EKB311 Quad core ARM Cortex A9 based mini-pc using a USB 2.0 hub with a modified power supply to provide 5V@2A.
Seven RTL-SDR USB SetupFive RTL-SDR Dongles used with RTL_HPSDR and csSDR64Two RTL-SDR dongles running on PowerSDR
Revision 5 promises to be lower priced as it will run using the direct sampling mod instead of using an upconverter which would require more components. It will also use a Mini-Circuits MAR 8 wideband amplifier to improve weak signal performance.
There is an amateur radio group in Germany known as DL0SHF which transmits a 10 GHz (QRG = 10.368.025 MHz) beacon at the moon whenever it is visible at their site. The goal of this transmission is to detect the very weak beacon reflection.
Amateur radio hobbyist Rein (W6SZ) has written in to let us know about his, DK7IJ’s and the DL0SHF groups success with receiving the beacon using the RTL-SDR. He writes
DL0SHF transmit a signal to the moon when the moon is visible at the site. The run 2 modes 50 and 500 W output, 20 seconds on, 40 seconds off.
Last night, I managed to detect the beacon with a very simple receiving package. Amazing enough, using WSJT moon tracking data, the signal appeared right away when the moon appeared here above the trees.
The signal lasts only 20 seconds but then 40 seconds later, it returned! By the books.
I use a simple 10 GHz receiver here that I use for scouting signals on 10 GHz terrestrial as member of the San Bernardino Microwave Society.
It consists of a RTL Dongle IF block tuned to 618 MHz as IF.
Front-end is a PLL LNB, not modified, running with 9.750 GHz LO
The LNB is powered with 12 Volts by means of a Bias Tee.
Both items can be acquired for about USD 25.- on eBay and other places.
The antenna is a standard 18 inch satellite off-set dish.
The antenna has some elevation control and the feed ( LNB ) can be rotated for polarity control.
Every variable is manually operated.
At times I measured the beacon as high as 15 dB above the noise using HDSDR as DSP processor software.
The beacon was running in the 500 W output mode during these observations.
Moon bounce visible on the waterfallMoonbounce Equipment Setup
