Cross Country Wireless SDR-4++ Dual diversity general coverage SDR receiver
The SDR-4++ is an HF general coverage dual diversity SDR receiver covering from 0.85 to 70.5 MHz.
It has a Si570 low noise synthesised VFO, relay switched band pass filtering, high linearity silicon germanium RF amplifiers and built-in USB soundcards.
It uses two of our SDR-4+ receivers using a common oscillator so that both receivers are phase coherent for receiver diversity or radio propagation analysis using two separate antenna systems.
Key design features include:
Antenna isolation transformer with a 50 ohm impedance input for use with coax fed antennas
RF overload protection up to 150W for 10 seconds
Extra antenna isolation when the receiver is powered down
Relay switched RF band pass filters
RF amplifier using a high linearity silicon germanium amplifier in the receiver front end
Crosstalk isolation between the receivers typically better than 50 dB
Built-in 16 bit USB stereo soundcard gives 89 dB dynamic range. Typically 8 bit SDR dongles have 45 db and 12 bit SDR receivers have 70 dB dynamic range. The total dynamic range is limited by the sound card so the receiver has a socket to connect to a external 24 bit sound card if required
3.5mm IQ audio output from each receiver for connection to external high sampling rate sound cards
3.5mm soundcard audio output from each receiver for headphone monitoring or connection to datamodes program
3.5mm soundcard audio output with outputs from both receivers for headphone monitoring or connection to datamodes program
Built in a compact aluminium case 175 x 106 x 45 mm for full RF shielding
Frequency range: 850 kHz to 70.5 MHz
Input impedance: 50 ohms
Clipping RF level: -13 dBm
Maximum frequency display: 48 kHz internal sound card, up to 192 kHz external sound card
Minimum discernable signal: -140 dBm
Input IP3: +10 dBm (measured with two -20 dBm carriers with 20 kHz spacing at 14 MHz, attenuator off)
Receiver modes: Depends upon the SDR software used with the receiver
Supply voltage: 5 Volts (from USB ports)
Supply current: 420 mA (from USB ports)
Connectors: Two BNC female (RF in 50 ohms), three USB B ports, five 3.5mm stereo jacks
Overall dimensions: 185 mm (L) x 110 mm (W) x 50 mm (H)
The images on the right show a SDR-4++ receiver using two HDSDR sessions to display each receiver channel simultaneously. For the demonstration the receiver on the top waterfall uses a vertically polarised Fractal Vertical antenna. The receiver for the bottom waterfall uses a horizontally polarised terminated inverted V dipole. The images show typical displays on medium wave broadcast, short wave and the last image shows an Over The Horizon Radar (OTHR) transmitting in the 20m amateur band. It is interesting to note the difference in interference pick-up between the two antennas and also that some signals appear on one antenna and not the other.
Monitoring the dual receiver output with headphones is interesting. Background white noise appears as a wide stereo field while wanted signals appear in the centre of the stereo image. It was easier to read a weak signal low down in the noise especially during fading as often fading is due to polarisation changes over ionospheric paths. When antennas of different polarisation are used with this receiver the effects of fading are minimised.
The SDR-4++ dual receiver guide can be downloaded as a PDF file here .
A typical SDR-4++ receiver test sheet can be downloaded as a PDF file here .
The SDR-4+ USB driver installer can be downloaded as a zip file here . The USB installer program loads a driver certificate then the driver file so that it works on the latest versions of Windows.
The SDR-4+ and SDR-4++ setup program can be downloaded as a zip file here . This installer program stores the USB drivers in a folder C:/SDR-4+ and places the ExtIO files in the HDSDR and Winrad folders in Program Files and Program Files (x86).
This is a link to our CloudMe folder allowing the files included on the CD shipped with each receiver to be downloaded here .
The SDR program we recommend for first time users of SDR receivers is HDSDR which can be downloaded here .
Authors of SDR software programs or other radio programs can add support for the SDR-4++ to their software using the SDR-4+ interface specification.
Here are some short recordings of a SDR-4++ receiver used with our dual polarisation antenna. The test location is just outside our workshop so there is some noise on the vertical antenna. It best to listen to these files with headphones.
Sample diversity recording using a SDR-4++ receiver and CCW Dual polarisation antenna RAF VOLMET 5.450 MHz strong signal single hop
Sample diversity recording using a SDR-4++ receiver and CCW Dual polarisation antenna US station on 20m SSB
Sample diversity recording using a SDR-4++ receiver and CCW Dual polarisation antenna 9H5DZ Malta on 20m SSB with interesting multi-path echo
Sample diversity recording using a SDR-4++ receiver and CCW Dual polarisation antenna HZ1BL Saudi Arabia on 20m SSB
Contact Cross Country Wireless via Email address hidden from spambots for more details.