Tag Archives: SDR Sharp

The Airspy HF+ SDR: First impressions

Yesterday, I received a package in the mail containing the new Airspy HF+ software defined radio receiver.

It came as a bit of a surprise.

I’ve been busy lately with humanitarian work, the radio spectrum archive,  product evaluations and travels–not to mention an active family life. I had completely forgotten that about a month ago, I received a message from Airspy telling me that they had dispatched their latest SDR to me for evaluation.

This morning, I unpacked the box to find that the HF+ is a very compact, relatively dense little SDR in a metal alloy case/enclosure. I’m simply floored by the size. The case feels incredibly durable and of excellent quality.

The Airspy HF+ under my business card

In terms of footprint, dimensions are nearly identical to a business card. It’s about as thick as the typical USB memory stick.

The HF+ is so thin and compact compared with the Elad FDM-S2 (which is quite a compact SDR!)

Other than my RTL-SDR dongle, it’s by far the smallest SDR I’ve ever tested.

Though compact, it sports two SMA antenna inputs: one for HF, one for VHF.

The HF port is labeled as “H” and the VHF port as “V”

The Airspy HF+ uses a common micro USB for both data and power

The HF+ is the first AirSpy product I’ve ever put on the air.

I read the HF+ product description this morning while downloading SDR Sharp–it claims the HF+ is “plug and play”.

Turns out, that is no exaggeration.

The HF+ on top of the Elad FDM-S2 and WinRadio Excalibur

In fact, the entire SDR Sharp package downloaded in seconds, installed in seconds and the only thing I had to do after opening the SDR Sharp application was select “AirSpy HF+” from the product drop down menu.

I started the application and *boom* signals all over the place!

SDR applications, in general, have become so much easier to install over the years but I believe SDR Sharp may be the  quickest install I’ve ever experienced. About as easy and lightweight as the WinRadio Excalibur application. True plug and play!

I’ve had no time to properly evaluate performance–I just put this little SDR on the air.

Fortunately, propagation is cooperating this morning–I’m hearing both WWV Fort Collins and WWV Hawaii on 10 MHz. I’m really enjoying playing with the Airspy HF+ and re-familiarizing myself with SDR#. I had forgotten how responsive and intuitive the interface is–great user design.

My first impression?  I’m impressed. More to come…

Click here to read about the HF+ on the Airspy website

Spread the radio love

Airspy’s latest: The Airspy HF+ SDR

SDR manufacturer, Airspy, has a new product shipping “really really really soon” (per their website). The Airspy HF+ promises improved frequency agility through the use of high-performance passive mixers with a polyphase harmonic rejection structure. Airspy states that no external band filters are required as they are with many budget SDRs.

There are many other improvements over their previous iterations. Here’s the product information copied from the Airspy HF+ page on Airspy’s website:

(Source: Airspy)

The Software Defined Radio revolution brought great flexibility in VHF and UHF reception. Today we offer the best wide band receivers which address these needs. We also provide a high performance extension for weak-signal wide band reception on HF – something other competing solutions fail to address efficiently.

Airspy HF+ is a paradigm shift in high performance HF radio design. It is a joint effort between Airspy, Itead Studio and a top-tier semiconductor company 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 polyphase harmonic rejection structure. No external band aid filters are required like the lower end HF receivers, which makes it the ideal companion for light portable high performance operation.

Both the architecture and level of integration achieved in this design allow us to bring top performance reception at a very affordable price.

All the major SDR software is supported. Check the download page.

State of the Art SDR streaming technology!

We concentrated state of the art DSP and networking techniques into our SpyServer software to allow multiple users to stream high quality IQ data from the same receiver at the same time. No compromises in the quality were made like it is usually done in Web SDR interfaces. You get actual IQ data you can process with your plugins and extract the last bit of information out of it.
The server software is highly scalable and can run on computers as small as the $7 Orange Pi Zero to top end 64bit servers with multiple cores/cpus, including the popular Raspberry Pi series.

HF Tuner

Airspy HF+ achieves excellent HF performance by means of a low-loss band filterhigh linearity LNAhigh linearity tunable RF filter, a polyphase harmonic rejection (HR) mixer that rejects up to the 21st harmonic and multi-stage analog and digital IF filtering.
The 6 dB-stepped AGC gain is fully controlled by the software running in the DSP which optimizes the gain distribution in real time for optimal sensitivity and linearity. Harmonic rejection is a key issue in wide band HF receivers because of the large input signal bandwidth of the input signal. The output of the IF-filter is then digitalized by a high dynamic range sigma delta IF ADC for further signal processing in the digital domain.

VHF Tuners

Excellent VHF performance is also achieved by using optimized signal paths composed of band filtershigh linearity LNAs with a stepped AGC, a polyphase harmonic rejection mixer and IF filters optimized for their respective bands.
The amplifier gain is switchable in 3 dB-steps and fully controlled by the AGC running in the DSP. The RF signal is converted to baseband by a high linearity passive mixer with a polyphase harmonic rejection structure. The low-IF signal is then converted into the digital domain by the same IF ADC used in the HF chain.

IF Sampling

The IF analog to digital converter (ADC) is a 4th order multi-bit noise shaping topology; it features very high dynamic range and linearity. The IF-ADC sampling rate is determined by a control algorithm running in the embedded DSP. This advanced technique adjusts the sampling rate depending on the tuning frequency with the goal of avoiding the disturbances and spurs 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 the resolution increased. The final signal at the output has 18bit resolution and an alias rejection performance of 108 dBc. The data is then scaled to 16bit and sent to the Micro-Controller for streaming over USB.

Architectural Advantages

The main advantages over techniques from the legacy super-heterodynes up to the now mainstream direct sampling is that the whole receiver chain is well protected against out of band blockers while still relaxing the RF filtering constraints, making it simple and cost effective.
The natural filtering of the sigma-delta ADC combined with the excellent linearity and sensitivity of the analog chain reaches an unprecedented level of performance and integration.

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
  • -140.0 dBm (0.02 µV / 50 ohms at 15MHz) MDS Typ. at 500Hz bandwidth in HF
  • -141.5 dBm MDS Typ. at 500 Hz bandwidth in FM Broadcast Band (60 – 108 MHz)
  • -142.5 dBm MDS Typ. at 500 Hz bandwidth in VHF Aviation Band (118 – 136 MHz)
  • -140.5 dBm MDS Typ. at 500 Hz bandwidth in VHF Commercial Band (136 – 174 MHz)
  • -139.0 dBm MDS Typ. at 500 Hz bandwidth in the upper VHF Band (> 174 MHz)
  • +15 dBm IIP3 on HF at maximum gain
  • +13 dBm IIP3 on VHF at maximum gain
  • 110 dB blocking dynamic range (BDR) in HF
  • 95 dB blocking dynamic range (BDR) in VHF
  • 150+ dB combined selectivity (hardware + software)
  • 120 dB Image Rejection (software)
  • Up to 660 kHz alias and image free output for 768 ksps IQ
  • 18 bit Embedded Digital Down Converter (DDC)
  • 22 bit! Resolution at 3 kHz channel using State of the Art DDC (SDR# and SDR-Console)
  • +10 dBm Maximum RF input
  • 0.5 ppm high precision, low phase noise clock
  • 1 PPB! frequency adjustment capability
  • Very low phase noise PLL (-110 dBc/Hz @ 1kHz separation @ 100 MHz)
  • 2 x High Dynamic Range Sigma Delta ADCs @ up to 36 MSPS
  • 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 with 0.1 dB ripple
  • Smart AGC with real time optimization of the gain distribution
  • All RF inputs are matched to 50 ohms
  • 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/VHF Radio
  • Ham Radio (HF + 2m)
  • Short Wave Listening (SWL)
  • AM DX
  • FM DX
  • Remote Telemetry Radio Receiver
  • Low Bands IoT

Supported Operating Systems

  • Windows Vista, 7, 8, 8.1 and 10
  • Linux
  • *BSD
  • OSX

Supported Hardware

  • Intel compatible PC
  • Raspberry Pi 2 and 3
  • Odroid C1, C2 and XU4
  • Many other Single Board Computers (SBC)

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

Supported Software

Developer API

  • Open source, multi-platform user mode driver libairspyhf on github

No price point has yet been made public–at least, none that I have discovered. Of course, we’ll post shipping and pricing details when they become available. Follow the tag AirSpy for more. Check out the Airspy website for full details and documentation.

Spread the radio love

London Shortwave’s portable “spectrum capture lab”

SWLing Post contributor, London Shortwave, just posted a photo of his portable SDR setup on Twitter and noted:


“Portable spectrum capture lab back in operation. Grabbing the grey line hour on the 49 mb. Listening to Radio Fana!”

Wow!  I love this go kit!

Looks like London Shortwave is running an AirSpy with Spyverter via SDR# on his Windows tablet.

Having played a lot of radio in the field, I think what’s great about this setup is the fact it’s all contained and properly laid-out inside the padded case. Simply open the case, deploy an antenna, and you’re in business! With all components inside the case, there’s much less chance a connector, battery, cable or SDR will be left in the field accidently. Quick deployment and quick pack-up time; that’s what it’s all about!

Great job, London Shortwave! I’m happy to see you’re back in the park capturing spectrum and logging DX!

Spread the radio love

London Shortwave refines his tablet-based portable SDR

IMG_0248 (1)

One of the great things about the SWLing Post is that readers share their varied–and highly creative–methods of playing radio.  A few weeks ago, SWLing Post reader, London Shortwave, shared his portable SDR set-up with us; he uses this outdoors to mitigate London’s heavy radio interference. Dennis Walter, president of Germany-based Bonito, commented, and later posted an alternative portable SDR solution using the Bonito RadioJet IF receiver.

Below, London Shortwave shares a guest post (also viewable on his blog) which describes in detail his design for his portable SDR around the FunCube Dongle Pro+ and an 8″ Windows tablet, and explains how effectively it works for him. This post includes recordings and a video; it’s an excellent tutorial:


This article is a follow up to the submission I made to the SWLing Post a little while ago. In short, the idea was to combine the FunCube Dongle Pro+ USB-based software defined radio (SDR) with an 8″ Windows tablet running SDR# to have a portable, on-the-go SDR solution.

The original inspiration

The original inspiration

Tablet radio interference

At the outset, I thought that all that was necessary was a tablet (I chose Toshiba Encore 8″), the FunCube dongle itself and just some antenna wire. This turned out to be a naive assumption because the tablet’s USB interface injected enormous amounts of radio frequency interference (RFI) into the SDR, making listening on some shortwave frequencies essentially impossible. Just to be sure that I wasn’t being plagued by a defect of my chosen tablet model, I tried out the same set-up on a Dell Venue 8, with identical results.

To deal with the issue of tablet-generated RFI, I bought a galvanic USB isolator, which, in essence, is a box that breaks the electrical connection between the USB dongle and the tablet’s USB interface while allowing USB data to pass through in both directions.

Heros Technology galvanic USB isolator

Heros Technology galvanic USB isolator

Additional power for the SDR


The isolator resolved the RFI issue completely, but created another problem altogether: the device specifications state that the isolator’s power output is restricted to 100mA at 5V. This is sufficient for USB devices that are self-powered but not for the FunCube dongle that draws all of its power from the USB port to which it is connected.

USB Y cable

USB Y cable

One way to supply extra power to a USB device is to use a “Y-cable”. Such cables have one extra USB plug that can be attached to a source of additional power (for example, a USB power bank). This solution is commonly used to connect power-hungry items, such as large hard disks, to low-power, portable computing devices (laptops and tablets). Having bought this cable, my next step was to find/improvise a battery that meets the USB power specifications (5V, 500mA).

Yet more interference

My first thought was to use the mobile USB power bank that I use to charge my iPhone while on the go. After all, it already has a USB port and supplies power with the right voltage. Once again, my expectations were confounded and RFI reared its ugly head! The power bank radiates significant interference into the circuit because it uses a switching regulator to maintain steady voltage. Luckily, I came across Gomadic’s portable AA battery pack with regulated 5V output that emits way less interference than any of the other USB batteries I tried (my intermediate solution used 4 rechargeable AA batteries and a makeshift USB connector, and although this resulted in zero additional interference I decided that it’s not safe to supply the SDR with unregulated voltage that doesn’t match the rest of the circuit). I used the handy passthrough USB voltmeter I bought in Maplin to check that Gomadic’s nice-looking gadget does indeed give out 5V as advertised.

So, what can one do with the remaining RFI from the additional power supply? It turns out that it can be mitigated quite effectively by inserting a balun (item 10 on Figure 2) between the SDR and the antenna wire (item 12). The balun is connected to the SDR with a coaxial cable (the “feed line”, item 11). Additionally, ferrite choke rings (item 9) attached to the feed line help reduce this RFI further: winding the feed line through the choke rings several times is sufficient. However, neither the balun nor the chokes are effective enough to replace the USB isolator! It appears they only help with the noise generated by the power supply, which is relatively minor anyway.

 Cost vs Portability

When SWLing Post published the details of my intermediate solution, Dennis Walter – one of the engineers behind Bonito RadioJet – popped up in the comments section and suggested that my setup is too tedious, as it involves lots of cables, and that his SDR is superior in terms of portability and the supplied software. While I haven’t had the chance to evaluate RadioJet, I pointed out that the cost of his radio is significantly higher than that of all of my components put together. I also mentioned that the free SDR# software I use is superb: it sounds excellent and offers a number of features that many software packages and conventional radios don’t have. So, having finalised my design, I thought that it might be time to tally up the cost and listen to the results.

Below is the full component list:

1) Toshiba Encore 8″ tablet $194

2) On The Go USB host cable for Toshiba’s micro USB connector: $7

3) Heros Technology USB Isolator: $125

4) USB Y cable with two males + 1 female plugs: $8

5) Gomadic Portable AA Battery Pack with regulated 5V output: $20

6) Gomadic female USB connector tip: $6

7) FunCube Dongle Pro+: $208

8) USB volt-meter (optional): $33

9) 2 ferrite choke rings: $10

10) Wellbrook HF Balun: $50

11) Feedline cables $7

12) 6 metres of thick copper antenna wire: $8

Adding up the prices of items 2 – 12 (and excluding the optional voltmeter) brings the total cost to  $449 vs. Bonito RadioJet’s $689. For the price difference you can throw in the Toshiba tablet at $194 and still have some change, enough to buy a carrier bag and perhaps even a nice pair of headphones!

Figure 1. Radio components

Figure 1. Radio components

Figure 2. Antenna components

Figure 2. Antenna components

In terms of portability, the entire setup fits nicely into an 11″ laptop carrier bag.

Figure 3. Packing the components into an 11" carrier bag

Figure 3. Packing the components into an 11″ carrier bag

Figure 4. Ready to go

Figure 4. Ready to go

Setting things up in the field is not particularly cumbersome, either:

Figure 5. Portable SDR setup in action in a local park

Figure 5. Portable SDR setup in action in a local park

As for the results, listen to the below snippets and be the judge. The only thing I will say is that none of my other portable radios have ever given me this kind of performance, not even with the long wire antenna attached:

And while we’re at it, here’s a demo video:

Portable SDR on Toshiba Encore 8″ Tablet from London Shortwave on Vimeo.

At one point I wanted to build an enclosure to house the FunCube dongle, the power supply and the USB isolator in a single tidy unit, but I no longer see the need. It’s easy to pack all of those items into the carrier bag and also they are all useful individually: the USB isolator can be paired with other SDRs, and I recently discovered a neat additional use for the Gomadic battery pack.

Well, that brings me to the end of this post. I hope my design will inspire you to come up with your own portable SDR system, and that you will share your results with me in the comments section. Happy listening!


Spread the radio love

Designing a truly portable SDR

SWLing Post reader, London Shortwave, is working on a portable SDR (software defined radio) system based on his Toshiba Encore 8″ Windows tablet, FunCube Dongle Pro+, and supported by the excellent SDR# application. Today, he shared this photo of his entire kit, including his comments. If you’re interested in a similar portable SDR, take note of the USB isolator and extra (AA battery) power supply.

LondonShortwave-PortableLondon Shortwave plans to make an enclosure for the SDR, AA power supply, and USB isolator.

And although it may be easier said than done, it would be super if this enclosure has the same footprint as the Toshiba tablet, and the whip antenna can be mounted on the enclosure…He would then essentially have a case that he could attach to the tablet for instant portable shortwave radio fun.  (Oops–did I just raise the bar for you? Ha!)

Thanks for sharing, London Shortwave!

Spread the radio love