The shortwave
spectrum offers worldwide reception possibilities like broadcast, amateur radio
or also professional applications without great effort.
The digital revolution is also coming
to shortwave and the first digital transmissions in the new digital standard DRM
(Digital Radio Mondiale) have already started.
DRM offers will offer high quality sound in both language and music transmissions,
optional stereo reception and additional multimedia services ( text & pictures).
The DiRaBox Concept

The DiRaBox concept refers to the
principles of Software Defined Radio. SDR is also state-of-the-art used in professional
communication receivers:
First conversion to a high IF-frequency and second conversion to a very low IF-frequency
followed by DSP (Digital Signal Processing). In the DiRaBox concept DSP is replaced
by the combination PC and SDR software.
Software Defined Radio (SDR) is a radio system which replaces as much as possible
functional blocks by software technologies that enable reconfigurable system architectures.
Benefits of SDR
-
Easy implemantation of future
transmission & modulation standards
-
Any filter configuration possible
-
Integration of useful auxiliary
functions like e.g. noise reduction
-
High reproductibility by omission
of analogue components with relating tolerances
This makes is quite clear that a
flexible system like SDR is superior to a rigid system, right now when transmission
technolgy is changing from analogue to digital.
|
This simple formula describes the complete
system:
DiRaBox
+ PC + SDR Software = Universal Communications Receiver
Let us now regard the individual components:
1. DiRaBox
The DiRaBox DRB 30 is a so-called black
box receiver under computer control which converts the RF signal to a low
frequency IF signal suitable for the PC soundcard.
Computer control is provided by the rear-panel parallel interface port
(LPT). Corresponding control software is included.
2. PC
A standard PC or notebook with standard
soundcard is sufficient. The processor clock rate should exceed 500 MHz
and is related to the used SDR software.
The low frequency IF output is connected to the line input of the soundcard
(3.5mm stereo jack socket).
Sound is also provided by the soundcard via connected earphones or loudspeaker.
3. Software Defined Radio
Software
The web offers currently a handfull
SDR programs, most of them are experimental freeware.
These programs enable the demodulation of the IF signal delivered by the
DiRaBox. They can handle all analgoue mode (AM / SSB / FM) and even the
new DRM standard.
|
Technical Data
Tuning Frequency: 30KHz - 30MHz (continous)
Tuning Steps: 1/5/10/50/100/500Hz & 1/5KHz selectable
Antenna Jacket / Impedance: BNC-socket / 50Ohms & additional remote supply
voltage 9V via 470 Ohms serial resistor for an optional active antenna (switchable)
Max. Allowed Antenna Level : +10dBm typ. / saturation at -15dBm typ.
Sensitivity (0.15-30MHz): -124dBm (0.15µV) typ. noise floor / MDS
Intermodulation-free Dynamic Range: > 95dB typ.
Third-Order Intercept Point IP3: +14dBm typ. (10.10 & 10.20MHz)
DDS-related Spurious Reception Attenuation: > 70dB
Mirror Frequency Supression: > 60dB / 1.IF
IF Suppression: > 80dB
10KHz-IF Output: Bandwidth 15KHz (-6dB) via 3.5mm stereo phone jack socket
PC Control Port / LPT: D-SUB (25-pin SUB-D male connector )
Power Supply / Connector: 12 - 15V DC max. 200mA / 2.1mm DC power socket (positive
inner)
Operating Temperature: 0 - 40°C
Dimensions / Weight: 112 x 71 x 31mm / 0.15kg

What`s included ?
DiRaBox DRB 30
Please note: Plug-Power Supply, application
software (Control Panel) and connecting cables are not included !
Application software is available
directly from this page. Also available as CD-ROM on request.
Premium Edition
Selected DRB 30 PREMIUM with DRM-SNR >40dB guaranteed
(tested with 9KHz-DRM signal at 10MHz & -45dBm)
Please ask
for availability !
USB Interface
DRB USB ADP USB Interface
Adapter (plugable to the DiRaBox parallel port connector)
With the new DRB 32
we introduce a modified concept especially for semiprofessional applications with
enhanced performance:
Increased sensitivity of about 6dB
Switchable high intercept range (HighIP) for large signals
Further improved selectivity
Expanded interface with additional reset
12KHz standard IF output