Last month we saw news of the Airspy HF+, which is a yet to be released software defined radio with a focus on high performance reception in the HF bands. Some preliminary specs were unofficially released back then on the Airspy Yahoo forums.

Now over on the Airspy website, the official specifications have been released and they are pasted below. The specs suggest that the Airspy HF+ will have extremely high performance when it comes to strong signal handling. This means that there should be little to no chance of overloading, and thus no intermodulation or spurs.

The goal pricing is to be below $200 USD. If this is true, then it will compete heavily with the $249.95 USD ColibriNANO which is another new HF specialty radio with similar specs.

The Airspy team write:

Airspy HF+ is a paradigm shift in high performance HF radio design. It is a joint effort between Airspy, Itead Studio and some famous chip maker to build a state of the art SDR for HF and VHF bands.

Like most high-end HF receivers, the HF+ uses very high dynamic range ADC’s and front-ends. But unlike the current offerings in the market, it also brings more frequency agility by using high performance passive mixers with an excellent overtone rejection structure.
Both the architecture and level of integration achieved in this design allow us to bring top performance reception at a very affordable price.

HF Tuner

Airspy HF+ achieves excellent HF performance by mean of a low-loss band filter, a high linearity LNA, a high linearity tunable RF filter, an over-tone-rejection (OTR) mixer that rejects up to the 21st harmonic and an IF filter.
The 6 dB-stepped AGC gain is fully controlled by the software running onto the DSP which optimizes the gain distribution in real time for optimal sensitivity and linearity. OTR is a key issue in wide band HF receivers because of the large input signal bandwidth. The output of the IF-filter is then digitalized by the IF ADC for further signal processing.

VHF Tuners

Excellent VHF performance is also achieved by using optimized signal paths composed by band filters, high linearity LNAs with a stepped AGC and an over-tone-rejection mixer and IF filters optimized for their respective bands.
The amplifier gain is switchable in 3 dB-steps and is fully controlled by the AGC processing running onto the DSP. The RF signal is converted to baseband by a high linearity passive mixer with overtone-rejection structure. The low-IF signal is then converted into the digital domain by the IF ADC for further digital signal processing.

IF Digitalization

The IF digital to analog converter has a 4th order multi-bit topology; it features very high dynamic range and linearity. The IF-ADC sampling frequency is determined by a control algorithm running on the DSP. This advanced technique changes the sampling frequency depending on the tuning frequency with the goal of avoiding the disturbances generated by the switching discrete-time sections of the IF-ADC.

Digital Down Converter

Once the IF signal is digitalized, the high sample rate I/Q stream is then frequency translated and processed with cascaded CIC and FIR decimation stages. After every stage, the sample rate is reduced and more the resolution is increased. The final signal at the output has 18bit resolution and the alias rejection performance is 108 dBc. The data is then scaled to 16bit and sent to the Micro-Controller for streaming over USB.

Use it over the network!

Connect as many SDR applications as needed to the HF+, over the Internet or in your own local network with near zero latency thanks to the new SPY Server software.
This setup basically brings all the flexibility of Web based SDRs while still benefiting from the full power of desktop applications. The IQ data is processed in the server with state of the art DSP and only the required chunk of spectrum is sent over the network. What is sent is the actual IQ signal, not compressed audio. This means you can use all your favorite plugins to process the IF, eliminate noise and perform heavy lifting of the signals as you are used to do with locally connected SDR’s.
We have a tradition of building multi-tools, so we made sure the SPY Server runs on 32/64bit Windows and Linux on Intel and ARM processors without any compromises. Low cost Raspberry Pi 3 and Odroid boards are in the party.

Technical specifications

• HF coverage between DC .. 31 MHz
• VHF coverage between 60 .. 260 MHz
• -138 dBm MDS at 500Hz bandwidth in HF
• -142 dBm MDS at 500Hz bandwidth in VHF
• +26 dBm IIP3 on HF at maximum gain
• +13 dBm IIP3 on VHF at maximum gain
• 110 dB dynamic range in HF
• 95 dB dynamic range in VHF
• 120 dB Image Rejection
• Very low phase noise PLL (-110 dBc/Hz @ 1kHz separation @ 100 MHz)
• +10 dBm Maximum RF input
• No Silicon RF switch to introduce IMD in the HF path
• Routable RF inputs
• Wide Band RF filter bank
• Tracking RF filters
• Sharp IF filters
• Smart AGC with real time optimization of the gain distribution
• All RF inputs are matched to 50 ohms
• 2 x High Dynamic Range Sigma Delta ADCs @ up to 36 MSPS
• 600 kHz alias and image free output
• 18 bit Digital Down Converter (DDC)
• 0.5 ppm high precision, low phase noise clock
• 4 x Programmable GPIO’s
• No drivers required! 100% Plug-and-play on Windows Vista, Seven, 8, 8.1 and 10
• Industrial Operating Temperature: -45°C to 85°C

Typical Applications

• High Performance Networked HF Radio
• Ham Radio (HF + 2m)
• Short Wave Listening (SWL)
• AM DX
• FM DX
• VHF-L TV DX
• Remote Telemetry Radio Receiver
• Low Bands IoT

Supported platforms

• Windows Vista, 7, 8, 8.1 and 10 (For Windows XP, please contact us)
• Linux
• *BSD
• OSX

Minimum hardware requirements

• 1GHz Pentium or ARM
• 1GB of RAM (to run your own OS, HF+ barely needs 1MB of memory)
• High speed USB 2.0 controller