The RS-HFIQ is a high performance Software Defined Radio (SDR) 5W Transceiver for CW, SSB, AM, FM and digital modes.

Product Summary

Not just another SDR – The RS-HFIQ offers real RF performance for serious communications. Covering the 80-10M Amatuer Radio bands with excellent RX performance and 5 watts of TX power, using open-source SDR software for CW, SSB, AM, FM and digital modes, the RS-HFIQ sets a new standard for shortwave SDR communications.

Specifications

Frequency Range – 3-30 MHz (performance guaranteed on 80/60/40/30/20/17/15/12/10M ham bands)
Sensitivity – MDS <-128 dBm on 80M dropping to <-135 on 10M (depending on processing bandwidth and sound card performance)
Noise Figure – <15 dB on 80M decreasing to <10 dB on 10M
TX Power 5W typical, 4W minimum
LO Feed-thru < -50 dBc @ 5W output
Spurious and Harmonics <-50 dBc typical <43 guaranteed
DC Power 13.8VDC, 2A max, plus USB power for the Arduino Nano

Who should buy one?

Amateur Radio Operators – Both newly licensed Hams looking for their first shortwave radio and experienced operators looking to explore the world of software defined radios
Experimenters – Hams and non-Hams who like to work with hardware and software will find the open-source aspects of the RS-HFIQ invite innovative shortwave experimentation
Radio Clubs – what better way to insure that newly licensed hams become active than including a transceiver with a licensing class?
Shortwave Listeners – From BBC to Radio Tanzania to oceanic air traffic control, there’s plenty to hear on shortwave. The RS-HFIQ is a great place to start and ready to TX if you decide to get an amateur radio license.

Shortwave Communications

The RS-HFIQ radio board turns your PC and sound card in to a high performance shortwave transceiver for operation on Ham Radio and MARS frequencies. Unlike most radio channels in use today that are limited to line-of-sight ranges, shortwave signals have the unique ability to reflect from the ionosphere high above the earth and be heard thousands of kilometers away. With some perseverance and operating skill it is possible to work all 50 states and more the 300 different countries with the RS-HFIQ radio.

High Performance RF Design

As you might imagine, operating requirements for a radio that send signals nearly to space and back are more stringent than requirements for radios that only have to communicate with the nearest cell tower. The technology and techniques are not new; on December 12, 1901, Guglielmo Marconi succeeded in sending the first radio transmission across the Atlantic Ocean. During the intervening 115 years, many innovators have left their mark on the shortwave communications art. Today, with properly designed equipment, like the RS-HFIQ, it is possible to achieve long range communications as a matter of routine.

As with every technology today, the incredible computing power that is available at minuscule cost has completely changed the way signals are processed. Software is available that processes shortwave signals in a way that Sr. Marconi could not even have imagined. Filters that would be impossible to construct using analog techniques and decoders for everything from Morse code to weather data are implemented in programs running on a computer.

But as powerful as computers are at processing signal data, they rely on high performance circuitry, as found in the RS-HFIQ, to convert the signals coming from the antenna system to a clean baseband signal ready for digitizing. Techniques developed by Marconi, Armstrong, Rhode, Tayloe and other radio pioneers to maximize RF performance and minimize interference and distortion are as applicable today as when they were first developed. A combination of solid RF design and state-of-the-art processing software creates a world-class shortwave operating experience.

Keep Your Software where it Belongs: In The Computer

Computers were made to run software. A desktop computer can store many different programs, provides massive amounts of data storage, allows connectivity to the internet and provides brilliant displays. Many software defined radios use embedded computers which have limited storage, can be difficult to upgrade and rely on desktop computers for user interface and display.

The RS-HFIQ is a radio that acts as a high-performance analog front-end for an external processing asset; either a desktop/laptop/tablet computer or an application specific platform. All internal functions are controlled via USB or TTL serial communication using open-source software running on the ubiquitous Arduino Nano that is provided with the RS-HFIQ.

There are many different SDR software packages that can be used with the RS-HFIQ here is an example of HDSDR running under Windows 10 displaying all of the signals in 96 kHz of the 80M Ham band:

SDR software is not limited to Windows PCs; LINRAD, QUISK and GNU Radio run under Linux and DSP Radio runs on the Mac OSX. The RS-HFIQ converts the radio frequency signals to the I and Q signals that all of the software packages read via a high-performance sound card to display, record, decode and generate shortwave radio signals.

Filters, Filters, Filters

One of the key aspects of any radio communications system is eliminating signals and noise that you don’t want to hear while enhancing the signals that you do; the closer to the antenna the better. If we rely solely on the software to reject unwanted signals then our digitizer must be capable of digitizing all of the signals captured by the antenna; quite a feat when the static crash from a lightning strike 50 miles away can be 10,000,000,000 times louder than the station we are trying to hear coming from half-way round the world.

The RS-HFIQ uses a bank of carefully designed bandpass filters which divide the shortwave spectrum in to narrower bands prior to the active circuitry. The down-converter and baseband provide additional filtering so the signals passed to the digitizer contain only the information needed for processing.