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DRB 32-4

4 Channel Coherent HF Receiver Configuration

Final DRM performance check for DRM-SNR >40dB (PREMIUM criteria)


Working Principle

The DRB 32-4 coherent receiver configuration consists of a master unit and four slave receivers.

The master unit generates the coherent 1.& 2. LO signals.

Due to the common LO signals the slave receivers are tuned to the exact same frequency.

Master Unit

The first LO signal (45-75MHz) is generated by a direct digital synthesizer (DDS). The DDS principle combines small tuning steps with very low pase noise and excellent short-time stability. The last-mentioned criteria is absolutely important for distortion-free DRM reception

Second LO signal (45.012MHz) is provided by a very stable crystal oscillator. The second LO signal is also used as reference signal for the DDS.

The unit is controlled by the parallel interface (LPT) or via optional USB interface (DRB USB ADP). Application software (Control Panel) is available.

Slave Units

The four slave units are DRB 32 PREMIUM units which use dual conversion.

A high-IP actice first mixer with an additional switchable high level (HighIP) range converts the RF signal to a high IF frequeny of 45 MHz. Two cascaded monolithic crystal 4-pole filters guarantee in combination with a selective input low pass filter for extraordinary performance concerning selectivity and mirror frequency supression.

An integrated automatic gain control ( AGC ) always delivers the optimum level for the soundcard. The AGC is internally switchable (fast/slow/off).

Second conversion is done to the very low second IF of 12KHz, which can be handeld by a standard PC soundcard. Each channel has three indepedant buffered outputs.

Front view (cover removed)

Back view (cover removed)

Technical Data

The combination includes four coherent DRB 32 PREMIUM receiver units with 1x antenna input & 3x 12KHz IFoutputs per channel.

Tuning Frequency: 30KHz - 30MHz (continous)
Tuning Steps: 1/5/10/50/100/500Hz & 1/5KHz selectable
Antenna Jacket / Impedance: BNC-socket / 50Ohms
Max. Allowed Antenna Level : +10dBm typ. / saturation at -15dBm typ.

Noise Floor (0.15-30MHz BW 2.3KHz):
Standard: < -131dBm (0.06µV) typ.
HighIP: < -119dBm (0.25µV) typ.

Intermodulation-free Dynamic Range (200KHz offset):
Standard: > 97dB typ.
HighIP: > 95dB typ.
In-Band-Blocking: > 88dB typ.
(20KHz offset / interence signal -33dBm & desired signal -121dBm=S1)

Third-order Intercept Point IP3 (@7.00 & 7.20MHz):
Standard: +14dBm typ.
HighIP: +24dBm typ.

Frequency Stability (15min. warm-up period): +/- 1ppm typ.
DRM-Performance (9/10KHz): Max. SNR >35dB, PREMIUM >40dB *
DDS-related Spurious Supression: > 70dB typ.

Image Frequency Rejection:
>65dB / 1.IF (LO + 45MHz)
Standard: >57dB / 2.IF (In-Band -24KHz)
Premium: >70dB / 2.IF (In-Band -24KHz)

IF Suppression: > 85dB

AGC (internally switchable): Slow (default) / Fast / Off

3x 12KHz IF Outputs per Channel: 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. 800mA / 2.1mm DC power socket (positive inner)
Operating Temperature: 0 - 40°C
Dimensions / Weight: 435 x 55 x 165mm / 1kg