DVB-T Dongles in Amateur Radio

Transcription

DVB-T Dongles in Amateur
Radio
Or, Extra Cheap Software Defined Radio
Al Floyd, W8ADF
What is a Dongle?
A USB Stick originally designed for
European Television
Contains a I/Q decoder chip, that can be
used to decode I/Q radio signals
Covers the spectrum from approximately 60
MHZ to 1700 MHZ. Some devices have
slightly different coverages.
QST, January 2013
The article that introduced
me to DVB-T Dongles.
This article is great
background information,
and lists sources for the
various pieces of
computer software
required to use the device.
The DVB-T dongle was designed for European television.
Antti Palosaari first noticed that the device contains a
Realtek RTL2832 quadrature decoder chip, and that this
might have possibilities as a general radio receiver.
With a team of other developers. Antti wrote a driver that
accesses these capabilities, and made this driver open
source software. Since then, numerous developers have
generated applications using this driver and these cheap,
but very sophisticated devices.
How cheap? Under $15.00 from China, including shipping.
Two Dongles,
with various
antenna cords.
The plug for the
dongle is the
tough one to
find!
The DVB-T dongle is a VHF/UHF device. To make it useful for
the HF amateur bands, an upconverter is required. The
original W9RAN article in QST described such a converter, and
suggested that a circuit board was available from FAR Circuits.
While assembling parts to put together one of these
upconverters, I found a “W9RAN Kit” at the Dayton Fleamarket
in 2013. The kit was also available this year.
Commercial Upconverter, NooElectric
Commercial Upconverter, NooElectric
Performance of the commercial Upconverter
The DVB-T is not the most sensitive receiver! As with
any receiver, the better the antenna, the better the signal
(so what's new about that?). This is a lesson we all
learned from our earliest days in radio.
One solution is to add a low noise wideband amplifier.
There are numerous designs for these, and the simplest
is to use a device such as a MAR-6 with input and output
filters.
Simple LNA with
suggested PC
board.
There is a
commercial version
of this type of device
available in Europe,
either as a finished
device, or as a
circuit board only.
Software to use the DVB-T

SDR#, simple, flexible, and free
HDSDR, the old Winmor. Also Free
SDR-Radio, steep learning curve, but free
Linrad, Advanced features, difficult to learn, but also free
GQRX, Mac and Linux, but free
ShinySDR, based on GNU radio, free
SDRTouch, for Android devices. Not free
CuSDR, used also with HPSDR hardware, free
And many others, both free and paid
SDR# screen
showing both
frequency
display and
waterfall.
Some DVB-T Applications

Receiving unencrypted Police/Ambulance/Fire/ EMS
Aircraft control communications
Tracking Aircraft positions with ADSB decoder
Decoding aircraft ACARS messages
Trunking radio conversations
Unencrypted digital voice transmissions
Maritime boat positions with AIS decoding
Decoding POCSAGFLEX pager traffic
Cordless phones and baby monitors
Meteorological weather balloon data
Wireless temperature sensors and wireless power meters
VHF amateur radio
Uses, continued

Decoding Amateur radio APRS packets
Sniffing GSM signals
Using RTL-SDR on Android as portable scanner
Receiving GPS signals and decoding them
Using RTL-SDR as spectrum analyzer
Receiving NOAS weather images
Listening to satellites and the International Space Station
Radio Astronomy
Monitoring meteor scatter
Listening to FM broadcast and decoding RDS information
Use as a panadapter for traditional radio hardware
Decoding taxi mobile data terminal signals
Use RTL-SDR as a true random number generator
QST, January 2014
W9RAN article on
tracking aircraft using the
DVB-T.
QST. April 2014
Using a DVB-T dongle as a
panadapter with a
commercial SDR, and a
small color display. The
software for this application
was developed using the
Python libraries that have
been developed for the
DVB-T devices.
Software Plugins for SDR#

Unitrunker Trunking Plugin
Orbitron - Satellite tracking with Doppler shift correction
Frequency Manager + Scanner and frequency entry package
Easy Scanner - similar to standalone radio scanning
Auto Tuner - sort of a level control
ADSB# - Aircraft tracking
DDE - DDE interface so programs like WXTrack and use
Audio FFT
ScopeView
Audio EQ Balance
Other Applications
One individual has demonstrated using a DVB-T dongle with a
Raspberry Pi computer, attached to a network. This makes all of
the functions of the dongle available to any computer on the
network
Another individual has demonstrated use of up to seven DVB-T
dongles on a single computer, and being able to monitor seven
different frequencies or bands at a time. To use this idea for the
HF bands would also require duplicate upconverters.
Future dream - I would like to use the Python libraries that
are available to write a software application using a single
DVB-T with upconverter as a HF/VHF band activity monitor.
As the bandwidth of the device is sufficient to cover an
entire HF band, and the relevant portions of the VHF bands
It should be possible to create a small window on the
computer desktop that displays a single band spectrum.
The window would scroll through each of the bands of
interest, dwelling only long enough for the display to be
seen. A refinement would be to set a signal level detect,
and sound an alarm when activity was detected. This
feature would be useful for sparsely populated bands, but
would need to be disabled for more active bands.
The advantage of such an application would be that it would
indicate when signals were being received at the location of
interest, not just those sites that post to the Internet.
Other sources of information
One of the best sites on the Internet is RTL-SDR.com. This
site has links to many of the plugins available, and also links to
other sites with information.
A good place to start in RTL-SDR is with the original W9RAN
article in January, 2013 QST. The information in that article
alone will get you receiving signals with your DVB-T dongle.
A Google search using the terms DVB-T and RTL-SDR will
generate hundreds of leads.
New applications appear almost daily using the DVB-T, so
frequent returns to sites, and frequent searches will help to
keep you up to date.
Have fun, and hope you all are inspired to acquire a Dongle!