Tagged: HF

Testing Public Airspy HF+ SpyServers over the Internet

SpyServer is a streaming server for SDR# which allows you to use Airspy and RTL-SDR radios remotely over a network connection. There is now a list of publicly available SpyServers that you can connect to over on the airspy.com website.

The servers that are currently online include some streaming from Airspy HF+ devices, which is the hotly anticipated but as of yet unreleased HF receiver from Airspy. Over the last few months and weeks a number of prototype devices went out to testers and programmers and some have now put them online with a SpyServer. There are also some Airspy One/Mini and RTL-SDR devices available for streaming too.

To connect to one of the servers simply download the latest version of SDR# from airspy.com, and then in SDR# select SpyServer from the Source menu. Enter the URL from the list into the box and press the play button up the top. Note that you must ensure that there are no spaces after entering the URL in SDR#.

Most servers are locked to a particular frequency band, but some allow for free tuning. But if more than one person is connected to the server free tuning will be locked until there is only one person connected again. Currently streaming from most servers seems smooth, but it's possible that some may struggle if many users are connected at once.

If you want to set up your own SpyServer then we recently put up a tutorial which is available here.

The current list of SpyServers
The current list of SpyServers

Alternative streaming SDR lists for other non-Airspy SDR hardware include sdr.hu and websdr.org, but those stream compressed audio instead of IQ data.

Adam Tests his UP-64 Upconverter with an RTL-SDR

Over on YouTube Adam 9A4QV has uploaded a video of him testing out his 'UP-64' upconverter together with an RTL-SDR. An upconverter moves low frequencies 'up' into a higher frequency. This is useful for HF reception, as normal reception on an RTL-SDR starts at about 24 MHz (without using direct sampling mode).

Adam previously manufactured and sold his UP-100 upconverter, which was an upconverter of his own design that utilized a 100 MHz oscillator. These days it has been accepted that using an upconversion frequency that avoids the broadcast FM band is generally better as it avoids the interference that can come from very strong FM signals. The 64 MHz oscillator on the UP-64 avoids the broadcast FM band for the most part unlike the older UP-100.

Gospell GR-227: New SDR Based Digital Broadcast Radio Adapter for Cars

Over on the SWLing Post blog we’ve seen news of this new SDR based car radio called the Gospell GR-227. Gospell is a Chinese manufacturer of various broadcast consumer radio products including DRM receivers. It is intended to be an adapter for your car that lets you listen to digital broadcast stations such as DAB/DAB+ on VHF and DRM on UHF, but it can also be used for standard AM and FM reception. From the product sheet it looks like it will simply plug into you car USB port, and output audio through that port into your cars head unit. Control of the unit is through an Android app.

There doesn’t seem to be anything stopping someone from using this outside of a car though, so perhaps depending on the price and software hackability available it might make a good PC or Raspberry Pi based HF receiver for all modulation types too.

Over on the Gospell Facebook page are images showing the Gospell running at IBC 2017 and next to other upcoming SDR based digital broadcast receivers like the Titus II.

Gospell SDR Connected to a Car Radio Head Unit
Gospell SDR Connected to a Car Radio Head Unit

No word yet on a release date or pricing. The press release reads:

Chengdu, China, September 04, 2017 – A new adaptor specifically designed for in-car use that simplifies digital radio on the road will be introduced at IBC by Gospell.

GR-227 is a small, low-cost adaptor that acts as an aftermarket add-on to car stereos receiving high-quality digital broadcast programs and data application, and serving it to the car audio system over a USB cable. Based on software defined radio technology, GR-227 is compatible with DAB, DAB+, DRM and is DRM+ ready. It is also powerful enough to support digital audio decoding such as extended HE-AAC (xHE-AAC).

GR-227 literally works with any kind of car stereos with a USB port. Our patent pending technology allows the adaptor to behave like a thumb drive when plug into a USB port and makes it compatible with most of the music players not only in car but also for home use.

To make the most of GR-227, the Gospell Smart Tune App for Android has been included to add more features. When partnered with an Android powered car stereo, the App not only allows for playback of the broadcast audio program but data application which brings much fun to car entertainment.

By connecting the supplied triple band active antenna which can be attached to the windscreen through the SMA antenna connector, the reception in DRM, FM and DAB bands can be significantly improved, offering maximum flexibility between different broadcasting standards.

Installing the plug-and-play GR-227 adaptor to your car is easy and doesn’t require changing your car stereo. It is one of the easiest ways to upgrade your car radio to digital without replacing anything.

The Gospell’s aftermarket car adaptor range starts with USB model but more will follow to support more car stereo types.

Haochun Liu, DRM director, Gospell, said: “By leveraging SDR, we can now combine multiple broadcasting standards together to offer flexibility and cost advantages, coupled with easy installation without the necessity of buying a new car stereo as in traditional solutions.”

For additional information, please visit www.goscas.com or contact Gospell sales at [email protected]

About Gospell

Founded in 1993, Gospell Digital Technology Co Ltd (GOSPELL). is a private hi-tech enterprise with R&D, manufacturing, business consultancy and planning, trade, delivery, project implementation and after sales service, acting as a complete DTV and triple-play solution provider for Digital TV/OTT related projects. Headquartered in GOSPELL INDUSTRIAL PARK at Chenzhou, Hunan Province for CPE related production manufacturing, GOSPELL also has its office in Shenzhen for business/marketing management and administration, in Chengdu for R&D and headend/transmitter system production/debugging and Customer Service Center, and in 12 cities in China as well as international offices in India, Africa and Mexico.

[First seen on swling.com/blog]

Z33T’s Review of the ColibriNANO: $350 USD 10 kHz – 55 MHz SDR Dongle

Over on YouTube Mile Kokotov (Z33T) has uploaded his review of the ColibriNANO, which is a $350 USD 10 kHz – 55 MHz direct sampling SDR dongle built by Russian company Expert Electronics. It features a 14-bit direct sampling ADC which is then decimated into 16-bits at bandwidths of up to 3 MHz, or 24-bits at up to 768 kHz. This should give it excellent dynamic range preventing any sort of overloading.

In the video Mile gives the Colibri an excellent rating. In the video description he writes:

The Colibri-NANO USB stick is a powerful direct sampling SDR receiver with frequency range from 10 kHz to 55 MHz. ColibriNANO is not another cheap USB dongle found on e-bay. This high quality SDR receiver has been developed by Expert Electronics and has strongly and solidly build aluminum body, Electrostatic discharge (ESD) protection, USB 2.0 interface and a quality SMA antenna connector.

ColibriNANO has 14 bit Ananalog-To-Digital Converter, with a clock frequency of 122.88 MHz. Coverage is 10 kHz to 55 MHz, with low pass RF-filter on 55 MHz to protect from strong FM transmitters. The filter can be turned off so you can use the receiver in undersampling mode up to 500 MHz. In that case external filters and preamlifier (like the 2m filtered preamplifier from the same producer) is recommended for maximum results.. 

This excellent little SDR-receiver has nine IQ sample rates, from 48 kHz to 3 MHz so the frequency span on the spectrum window can be changed from 48 kHz up to 3 MHz.

There are no bandpass filters in the device, So one can think that a 14-bit Analog-To-Digital Converter may be subject to overload if you have powerful transmitters nearby. But the software has extensive RF gain control, so you should not have to worry too much. 
As I said before the Analog-to-Digital Converter in this wonderful SDR-receiver uses 14 Bit, and with decimation process results in an excellent 110 dB Blocking Dynamic Range. 

Another nice feature of the ColibriNANO SDR is the combined attenuator/pre-amplifier stage, which can be fine-adjusted in 0.5 dB steps from -31 to +6 dB. Together with the low noise floor and an excellent sensitivity, the result is a receiver with excellent large signal handling capabilities. The ColibriNANO is a perfect HF little SDR scanner which can be compare with much more expensive 
The Colibri-NANO can be operated directly attached to the computer of the user, or can be used remotely at a distant location. This is done with the freely available ExpertRemote software. 

At the location of the SDR a small computer is required (for example a Raspberry-Pi) and for the internet connection can be used a relatively slow internet link. This, for example, allows you to use the SDR receiver at some quiet location anywhere on the world.
Expert Electronics Software for the ColibriNANO allows you to use all the potential of the receiver: remote operation, synchronization with the transceiver, IQ channel bandwidth up to 3 MHz, control of the preamplifier and LPF and so on…

All mode for demodulation are supported. Here are Some of the software features:
– IQ output via Virtual Audio Cable
– Compatibility with any sound card installed on your PC for the audio output
– Synchronization with transceivers via CAT interface
– Remote operation with the ColibriNANO receiver 
– Special interface to control the CW Skimmer
– Screen resolution Supports FullHD and 4K monitors

And the important thing is that All new versions of the software are free!

To control the ColibriNANO via Internet you need freely available ExpertRemote system, based on the client-server connection. This system allows you to place the receiver and server in the remote location with low RF-noise but has the internet connection. This might be some remote village or place with no electrical interference and 3G/4G Internet (or any other connection type). 

Using the ExpertRemote system you can enjoy in clear noiseless reception from your phone, tablet, notebook or PC. Even simple antennas, placed in a “quiet” place, allows you to listen weak signals from the DX-stations better than in urban area filled with all kind of RF-noise.

Another feature of this system is that the receiver’s software can be synchronized with transceivers and be used as the panorama adapter with high resolution. In that way you can use the transceiver to transmit signals, and receive on your remotely located receiver via the ExpertRemote system. 

The ColibriNANO can be used with third party software like HDSDR etc.
You can find more information about this great 14 bit SDR-receiver on Expert electronics official website.
If you are interested in Radio technic and electronics fell free to visit my web-pages: www.qsl.net/z33t

This device appears that it will soon compete with the Airspy HF+ which is an upcoming SDR that claims similar performance for HF. We will work on comparing the two in a later review post.

A Homebrew One Transistor Upconverter for the RTL-SDR

Recently Qrp Gaijin wrote in to us and wanted to share his experiences on building a one transistor diode-ring mixer upconverter for his RTL-SDR. An upconverter for the RTL-SDR translates low HF frequencies ‘up’ into ones that are receivable by the RTL-SDR. This is a different method to the direct sampling mode used in the V3 dongles to achieve HF reception.

Qrp Gaijin’s post goes into some detail about his circuit and shows the schematic as well. He also shows the results with an active loop antenna, RTL-SDR and the upconverter in some videos. In the email to us he also notes that his upconverter is still a work in progress as the LO is quite noisy and he suspects that it may be too weak to drive the 1N4148 based diode ring mixer. There is also no filtering on the circuit yet, so there is some broadcast FM breakthrough.

Another project he worked on was attempting the direct sampling mod on a standard RTL-SDR. However, Qrp Gaijin’s method is slightly different to most attempts as instead of soldering the wires into the Q-branch holes he simply uses hot glue to hold them mechanically in place. This may be an idea to consider for those who want to attempt the mod on a standard RTL-SDR, but don’t have any soldering tools or experience.

New Cross Country Wireless HF Preselector

A new reasonably priced 5-band HF preselector has been released by the company Cross Country Wireless, and it looks perfect for use with SDRs. The price is $56.95 GBP, which right now is about $72 USD. They write:

This can be used to provide additional front end selectivity for HF and medium wave receivers protecting the receiver from strong out of band transmissions, wideband noise and other transmitters on multi-station field days.

As the sunspot cycle declines and more listening is done on the lower HF bands with long wire antennas and strong NVIS signals then the HF Preselector is an ideal accessory to aid receiver performance.

It is invaluable when using simple conventional superhet or SDR receivers such as RTL-SDR dongles with upconverters or SDRPlay with large HF antennas.

It is an ideal tool to reduce ADC overload on the Icom IC-7300 with the new second receiver socket modification kit.

It can also be used with other transceivers that have sockets for a separate receiver input and receive antenna output.

It also covers the medium wave broadcast band for MW DXers.

The Preselector is a passive high Q design that does not use an additional amplifier or require external power.

  • Frequency tuning range: 0.5 to 52 MHz in five bands
  • Input impedance: 50 ohms
  • Output impedance: 50 ohms
  • Bypass option on switch
  • Galvanic isolation between input and output
  • Insertion loss: 2 dB
  • Selectivity: See HP network analyser plots below
  • Connectors: BNC female (RF in 50 ohms), BNC female (RF out)
  • Tough polycarbonate case
  • CCW Z Match
    Overall dimensions: 125 mm (L) x 85 mm (W) x 55 mm (H)
  • Weight: 192 g
The Cross Country Wireless HF Preselecter
The Cross Country Wireless HF Preselector

DK8OK Review of the Airspy and SpyVerter

Recently DK8OK wrote in to us and wanted to share his latest review of the Airspy and SpyVerter combo (pdf). His review focuses on HF usage and he shows various examples of HF signals that he has received with the Airspy+SV such as the CHU time station, STANAG, DRM, ALE, HFFAX, VOLMET and HFDL. He also shows some tricks for optimizing HF reception, a tutorial on performing multi-channel audio recording and decoding in SDR-Console, a tutorial on playing and analyzing recorded files as well as some examples of weak signal reception.

Overall DK8OK praises the Airspy+SV combo citing it’s excellent dynamic range as one of the reasons it performs so well.

We should note that for prospective buyers, the Airspy team is currently working on a new complimentary solution for HF monitoring called the Airspy HF+. This will have extremely high dynamic range (even higher than the Airspy+SV combo), but it will have a smaller bandwidth. So the Airspy+SV combo will still be the best for monitoring a wide 9 MHz chunk of the HF band, whilst the HF+ will be the best for getting into those very hard to receive signals.

Update: The paper is now also available in French.

Multi-channel decoding in SDR-Console with the Airspy+SypVerter
Multi-channel decoding in SDR-Console with the Airspy+SpyVerter

Airspy HF+ Official Specifications Released

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
  • 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
The Airspy HF+ Architecture
The Airspy HF+ Architecture