Tagged: HF

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

Airspy HF+: An upcoming low cost yet high performance HF SDR

Over on the Airspy Yahoo forums and Twitter we’ve seen news of an upcoming new product from the developers of the Airspy SDR. The new product is called the Airspy HF+ and will be a low cost, yet extremely high performance HF specialty radio.

Preliminary specs:

  • HF coverage between DC .. 31 MHz
  • VHF coverage between 60 .. 260 MHz
  • -138 dBm MDS
  • -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
  • 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 @ 36 MSPS
  • 600 kHz alias and image free output
  • 18 bit 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

Basically, this addresses the lack of affordable and good performing receivers for HF and VHF.
Target price < $200

As with all Airspy products the SDR focuses on achieving extremely high dynamic range. From the specs is seems that the dynamic range and image rejection will be high enough so that even extremely strong broadcast AM or FM stations will not require any filtering or attenuation. They are also confident enough to say that no gain sliders will need to ever be adjusted to avoid overload.

For SWLers and MW DXers this seems like the ideal SDR as it should perform as well as high end SDRs like the Perseus, RFSpace and Elad SDRs, but at a fraction of the price.

The product is still in development and no release date has been offered yet, but judging from the Twitter feed the prototype is already working.

Listening to February 2017 HAARP Experiments with an HF Capable SDR

This year at the end of February HAARP (High Frequency Active Auroral Research Program) scientists are planning to run several experiments that involve transmission. HAARP is a high power ionospheric research radio transmitter in Alaska, which typically transmits in the 2.7 – 10 MHz frequency region. The transmissions are powerful enough to create artificial auroras in the sky. Due to a lack of funding HAARP research was shut down in May 2013, and then later given to the University of Alaska Fairbanks (UAF) in 2015.

UAF plans to activate HAARP again at the end of Feburary, so it seems that it would be interesting to receive the waveforms with an HF capable SDR such as the RTL-SDR v3, or with an upconverter like the SpyVerter. Under some conditions the signal could propagate all over the world. It seems that the researchers are also interested in reception reports from listeners and they plan to post updates closer to the dates of transmission. The full press release reads:

The University of Alaska Fairbanks Geophysical Institute is planning its first research campaign at the High Frequency Active Auroral Research Program facility in Gakona.

The High Frequency Active Auroral Research Program facility near Gakona includes a 40-acre grid of towers to conduct research on the ionosphere. The facility was built and operated by the U.S. Air Force until August 2015, when ownership was transferred to UAF’s Geophysical Institute.

At the end of February, scientists will use the HAARP research instrument to conduct multiple experiments, including a study of atmospheric effects on satellite-to-ground communications, optical measurements of artificial airglow and over-the-horizon radar experiments.

Members of the public can follow one of the experiments in real time. Chris Fallen, assistant research professor in space physics, will be conducting National Science Foundation-funded research to create an “artificial aurora” that can be photographed with a sensitive camera. Observers throughout Alaska will have an opportunity to photograph the phenomenon, which is sometimes created over HAARP during certain types of transmissions.

Under the right conditions, people can also listen to HAARP radio transmissions from virtually anywhere in the world using an inexpensive shortwave radio. Exact frequencies of the transmission will not be known until shortly before the experiment begins, so follow @UAFGI on Twitter for an announcement.

For more details on the dates and times of Fallen’s experiments, as well as information on how to observe, visit https://sites.google.com/alaska.edu/gakonahaarpoon/. Information is also available at the HAARP website, the UAF http://gi.alaska.edu/haarp-0 and the official UAF HAARP Facebook page, https://www.facebook.com/UAFHAARP/.

Operation of the HAARP research facility, including the world’s most capable high-power, high-frequency transmitter for study of the ionosphere, was transferred from the U.S. Air Force to UAF in August 2015.

On their Google sites page they write how to participate:

Anybody who wants to participate and follow HAARP experiments should follow the official and unofficial announcements linked at the top of this page. There are two main ways to participate in the campaign: by listening to the radio transmissions from HAARP itself or by photographing artificial auroras created by HAARP. Amateur (Ham) radio operators can also use temporary ionosphere irregularities created by HAARP to open new propagation modes for their own transmissions.

A shortwave radio and knowledge of the time and frequency of the HAARP transmissions provides opportunities to “listen in” since the radio wave energy often (but not always) propagates very large distances, sometimes worldwide! Shortwave radios capable of receiving frequencies in the same range that HAARP can transmit, between approximately 2.7 and 10 MHz (2700 and 10,000 kHz) allow anyone to hear HAARP transmissions provided long-distance radio propagation conditions are sufficient and the radio is tuned to one of the frequencies where HAARP is transmitting. Ham radio operators also have an opportunity to reflect (or “bounce”) their own transmissions, typically in the HF, VHF or UHF bands, off ionosphere irregularities created above HAARP during high-power experiments. This creates propagation modes that would normally only be possible during certain space weather events such as aurora.

The video below shows one of the last scheduled HAARP transmissions from when it was still under the control of the US Air Force.

[First seen on swling.com]


A Visualization of Yearly Shortwave Activity with WebSDR

The WebSDR from the University of Twente, Netherlands is a wideband HF SDR that is accessible from all over the world via the internet. It was first activated in 2008 making it the very first WebSDR ever. The creator of the service Pieter-Tjerk de Boer PA3FWM has recently made available spectrum image archives which show the HF band conditions over the last two years.

Intrigued by this data, London Shortwave decided to make a timelapse animation of this image data. The results are shown in the videos below, and London Shortwave adds:

The X axis represents the frequency and the Y axis is the time of day, starting at the top. Conventional wisdom about band behaviour can be easily confirmed by watching this video: the 60m, 49m and 41m bands are mostly active after dark, with the 60m and the 49m bands being generally busier during the winter months. The 31m band is most active around sunset, but carries on all night until a few hours after sunrise. The 25m band is active during sunrise and for a few hours afterwards, and around sunset during the winter months, but carries on all night during the summer. Peak activity on the 22m and 19m bands is also clustered bi-modally around the morning and the evening hours, though somewhat closer to the middle of the day than on the 31m and the 25m bands. The 16m band is mostly active during the daylight hours and the 13m band is quiet throughout the year except for the occasional ham contest.