Software Defined Radio – DSSS CDMA

Digilogic’s Direct Sequence Spread Spectrum Radio provides highly reliable communications with high resistance to interference and interception. The radio establishes a point to point communication link leveraging the spread spectrum and CDMA techniques. Prototyped based on the NI SDR Platform, the radio offers flexibility both in terms of hardware and software.

The radio consists of Radio Frequency (RF) transceiver, Field Programmable Gate Array (FPGA) for signal processing and a processor for data handling and user interface. Data to be transmitted is read by the radio over Ethernet interface irrespective of the protocol. The data is then processed and modulated in FPGA which is then transmitted through omni antenna. 

External Power Amplifier (PA) and Low Noise Amplifier (LNA) are used at transmitter and receiver respectively in order to amplify the signal. Received signal is demodulated and decoded on FPGA. Decoded data is transferred to subsystem over Ethernet interface. The radio provides full-duplex communication over a Line of Sight (LoS) range of 20km with Jamming to Signal ratio (J/S) of 21dB.

Highlights:

• Direct-Sequence Spread Spectrum (DSSS) Technique
• CDMA Architecture to achieve additional Processing Gain
• BPSK/QPSK Modulation Scheme
• Full-duplex Communication with FDD Mode
• 2-Finger Rake Receiver for multipath mitigation
• Up to 20 km Ling of Sight (LoS) Range
• Up to 20 dB Jamming to Signal (J/S) Ratio
• Built-in application for text messages and FTP