HF SDR Transceiver is a high performance, low IF transceiver specifically designed for modern HF software defined radios for long range sky-wave communication. HST can be interfaced with a baseband processing card, through serial USB interface, to complete HF software radio hardware. Any commercial off-the-shelf card with DSP, FPGA or even a single board computer can be used as processing platform. One of the main advantages of HST is that it can be interfaced, through USB, with desktop computers or laptops for rapid prototyping of HF radios. Unlike conventional HF radios, it allows up to 48 KHz of input channel bandwidth that could be very useful for building high data rate HF radios by using modulation techniques like OFDM which can handle large delay spread of HF channels. HST has onboard state of art direct digital synthesis chip (DDS) by Analog Devices for carrier generation across the entire HF band from 3 to 30 MHz. It offers high frequency agility and sub hertz of tuning resolution that is beneficial for building HF radios with frequency hopping and automatic link establishment capabilities. Furthermore it can be used for HF cognitive radio applications which require the scanning of the entire band. HST uses Tayloe detector for down conversion which is ultra low noise, high performance, low IF product detector and preamplifier. Because of its direct conversion architecture, carrier image frequency related issues will be avoided. The advantage of having low IF instead of zero IF is that only one analog to digital converter (ADC) is needed at the receiver. Furthermore the IQ imbalance problem that is common in direct conversion receivers will not be an issue anymore. High adjacent channel rejection can be achieved by the digital FIR filters after ADC sampling in the digital domain. HST transmitter has output power of 3 watts across the entire HF band when operated with a properly matched antenna. An external amplifier will be required for long range skyway operation.
- Direct interface through USB with DSP, FPGA card and single board computers
- DDS based highly agile carrier generation for fast frequency hopping applications
- Tayloe detector based high performance, direct conversion transceiver
- Long range ground and sky-wave transmission with external amplifier
- Highly stable low phase noise frequency synthesis for OFDM HF radios
- Front end filter banks for increased adjacent channel rejection
- Time division duplexed (TDD) transceiver operation
- Ideal platform for the development of JTRS, NATO compliant or custom HF SDRs
- Direct interface with PC through USB for rapid prototyping of HF radios
- Spectrum sensing and scanning for HF cognitive radio applications
- HF spectrum monitoring for regulatory purpose
At the transmitter end, HF waveforms are generated from the digital processing card at a low intermediate frequency (IF) up to 24 KHz. The generated IF waveform is sent to HF SDR Transceiver (HST) through the USB interface. HST transceiver takes this analog IF signal and performs digital to analog conversion (DAC), frequency up-conversion to the desired carrier frequency in HF band. This signal is further amplified, filtered and transmitted by the HF antenna. HST is configurable through USB interface and user can control parameters like carrier frequency and output power level from processing platform.
At the receiver end HST receives the HF signal through its antenna and performs a series of receiver operations like channel filtering, low noise amplification, frequency down-conversion and analog to digital conversion. This IF signal is sent to the processing card through USB interface for baseband receiver tasks. Renzym SDR Framework (RSF) can be used to aid radio prototyping with its more than 15 built in waveforms and APIs for custom waveform development.