Generating shortwave DRM and analog broadcast
signals very easy
With the DiRaGen
30 USB we introduce a further variety of our shortwave
In close coorporation with Michael
Feilen, the developer of the leading DRM modulator software SPARK, we created
a symbiosis with unique features:
- Direct frequency setting
- Full compatiblity to the
- Compatible to all analog
broadcast signals with 20KHz maximum bandwidth
DRM or analog modulation -
Why not use both ?
In combination with the SPARK
modulator software it is possible to generate either DRM or any analog broadcast
This guarantees a maximum of
flexibility. It is possible to change the modulation mode and time automatically
-For instance DRM trial transmissions over a certain period of time in change
with standard AM modulation.
The following broadcast signals
could be generated in combination with the SPARK transmitting software:
according DRM 30 with 4.5KHz to 20KHz bandwidth
modulation modes with 20KHz maximum bandwidht:
or without supressed carrier
with added informations timestamp, languagel,transmtting label, service Identifier,
modulation LSB & USB with or without supressed carrier
It is also
possible to implement other or new modulation modes which offers a flexible
solution for upcoming developments.
What is needed ?
1. Transmitter Software SPARK
Michael Feilen had developed
the early version of the SPARK modulator software already for his master thesis
at the university of applied sciences in Kaiserslautern. The software was continuously
optimized and includes now all actual used and scheduled broadcast modulation
Besides pure audio transmission
basing e.g. on a WAVE file source, MP3 playlist or soundcard input additional
transmission of text & image files is also possible.
A PC or notebook equipped with
a standard (AC 97) sound card allows the generation of a DRM or analog AM radio
The low-frequency baseband signal
is available at the line output of the sound card as OFDM (Orthogonal Frequency
Division Multiplex ) signal.
As an alternative to the PC soundcard
it is also possible to use our new developed USB DAC 48.
3. DiRaGen 30 USB
The sound card OFDM signal is
connected to the audio/IF input and converted in the shortwave range.
Any output frequency can be seleted
within 130KHz to 30MHz directly via SPARK.
Standard DRM radio signal
with 9KHz bandwidth:
Well prepared for the future
- Extended DRM signal with 20KHz bandwidth:
AM modulated radio signal
with 10KHz bandwidth:
Highest linearity and easy
In order to achieve the highest
possible signal-to-noise ratio (SNR) the conversion must be absolutely linear.
Overloading or compression degrades the SNR severly.
The DiRaGen 30 USB has an easy-to-read
integrated overload control (red LED) at the rear panel. Adjust the PC volume
(audio level) control settings until the LED starts just to flicker. This is
the optimum level to reach the highest possible SNR.
Due to a high performance design
with triple frequency conversion in combination with efficient filtering very
good unwanted sideband rejection and carrier suppression values are achieved.
All internal frequencies are
derived from a stable crystal clock generator (master clock) to prevent odd
frequency drifting effects.
A Direct Digital Synthesizer
(DDS) acts as VCO combining good phase-noise and short time stability. We use
this reliable principle already for our PC-controlled shortwave receivers.
Please note. In case of further
amplification of the RF output signal additional selective filters must be
Furthermore the legal regulations
shall be observed.
of DRM receivers, laboratories & testing facilities
a standard DRM signal for demonstration purposes
test transmission & DRM transmitter
Tuning Range: 130KHz - 30MHz
Smallest Tuning Step: 1KHz via SPARK (1Hz. eff.)
RF Output Connector / Impedance: BNC socket / 50Ohms
Output Level: -10dBm eff. +/- 3dB typ. (thermal measurement)
Audio / IF Input Level: 0.1Vss @ 1KOhm via 3.5mm stereo phone jack socket
DRM Output SNR: MER>40dB,
typ. 45dB (mean value / measured via SoDiRa 072 & DREAM Transmitter)
Suppression of unwanted carriers referred to maximum output level (PEP):
Unwanted Sideband Suppression
( -112KHz): > 60dB
Carrier Suppression (-56KHz): >55dB
Harmonics Suppressions: 0-30MHz >40dB; over 30MHz >60dB
Spurious Signals Suppression (0-30MHz): >35dB
Frequency Stability (15min. warm-up
period): +/- 1ppm typ. (20°C)
Max. Baseband Bandwidth (Audio/IF): 15KHz @12KHz IF center frequency
Power Supply / Connector: 12 - 15V DC max. 250mA / 2.1mm DC power socket (positive
USB connector: USB-B (socket)
USB 2.0 (backward-compatible)
Operating Temperature: 0 - 40°C
Dimensions / Weight: 125 x 71 x 31mm / 0.20kg
What`s included ?
DiRaGen 30 USB
Please note: Plug-Power Supply,
application software and connecting cables are not included !
As a DRM-Brasil founder member
and as a DRM researcher I can say that NTi
plays a very important role in pushing DRM forward providing affordable
equipment for demonstration and trials.
The DiRaGen 30 together with the PostAmp provides an incredible
equipment for DRM demos.
Not to forget the great DRM software
modulator - SPARK, that works
perfectly with the NTi chain.
I do recommend to anyone who is interested in trying DRM here
in Brazil and worldwide,
talk to Rudolf of NTi.
Rafael Diniz / Brazil