uAVD: Analog Video Decoder Windows Software for SDRs

Thank yoy to Viol Tailer for submitting news about the release of his new software called "uAVD - Analog Video Decoder". uAVD is capable of demodulating the following:

  • AM (broadcast analog television - NTSC, PAL, SECAM)
  • FM (FPV drone video links)
  • RAW (composite output from VHS, camcorders, game consoles)

The software uses the uSDR software as a host, and it passes the IQ passband stream to the uAVD via a uSDR-TCP link. uSDR is a lightweight general purpose multimode software defined radio receiver Windows application that we have posted about on the blog in the past. Currently, it supports RTL-SDR, AirSpy, BladeRF, HackRF, FobosSDR, and LimeSDR devices.

The software supports full color and grayscale modes. With a wideband receiver, it will be possible to receive full-color video. With the reduced bandwidth available with an RTL-SDR, only grayscale will be available.

The code is not open-source, but the software is freely available from SourceForge.

The image below shows it being used to receive video from a camcorder composite video output. A FobosSDR used in direct sampling mode is used to receive the signal.

uAVD Receiving Camcorder Composite Video via the Direct Sampling Input in FobosSDR
uAVD Receiving Camcorder Composite Video via the Direct Sampling Input in FobosSDR

Below is a video from a user of the software demonstrating it in action.

uSDR and uAVD analog video decoder

Waveband Hack Club YSWS For Teens Interested in RTL-SDR

Thank you to Craig Giles for writing in and sharing with us news about a club for teens that he's organizing called "Waveband Hack Club YSWS" for RTL-SDR dongles. Craig writes in his email:

Hack Club is a 501(c)(3) nonprofit that aims to teach teenagers how to code by building projects. Hack Club runs a variety of programs called YSWSs, or “You Ship, We Ships”, which are programs in which a teen works on a themed project and gets rewarded with a prize following the theme.

Waveband is a YSWS about RTL-SDR dongles, where teens make a computer program that uses an RTL-SDR dongle, and they get a V4 dongle and antenna kit in return. We are aiming to get more teens involved in SDR and give them the hardware to do so through this program. 

The club has a clever interactive website that interested teens can go to to learn more. Currently, it appears that the club is running the program for a limited time from June 11 to July 11. During this time, teens can log on to the website and get a free RTL-SDR dongle if they submit a program they've written that uses an RTL-SDR in a unique way. 

Further information is available on their GitHub page.

Waveband Hack Club YSWS Interactive Website
Waveband Hack Club YSWS Interactive Website

RTL-SDR Blog Review of the HydraSDR

HydraSDR is a soon to be released software-defined radio based on the same design as the popular Airspy R2 SDR. However, compared to Airspy, HydraSDR claims to have "Enhanced PCB layout and RF front end with superior power/noise filtering, improved temperature dissipation and peak temperature management," as well as various other improvements. HydraSDR also has the distinction of being made in the USA, whereas Airspy is made in China.

Recently, Benjamin Vernoux, creator of HydraSDR and former collaborator on the Airspy R2 project, sent us a review unit of the HydraSDR. This post is a review of the HydraSDR. However, because the HydraSDR is based on the Airspy R2 and competes directly with it, the two units will be heavily compared.

HydraSDR is launching on Digikey.com for US$189 and the Airspy R2 is available from iTead and other distributors for US$169.

Design Review

The design of the HydraSDR is very similar to the Airspy R2, which is already known to be a high-performing SDR. Both are based on the LPC4370 microcontroller and its built-in ADC, and they both use similar firmware. The circuit layout, from the top and bottom views, is also almost identical. Benjamin notes that the internal layout has been improved and that several components, such as LDOs, have been upgraded to better ones with reduced noise.

One larger change is that HydraSDR uses a Rafael R828D tuner, instead of the Rafael R860T tuner that the Airspy uses. Both tuners are very similar in terms of operation and performance as they are based on the same design and technology. The R828D has two additional RF input pins; however, on the HydraSDR, they are unused but are routed to two uFL connectors on the bottom of the PCB for advanced users.

Airspy (Top) and HydraSDR (Bottom) PCB Top Side
Airspy (Top) and HydraSDR (Bottom) PCB Top Side
Airspy (Top) and HydraSDR (Bottom) PCB Bottom Side
Airspy (Top) and HydraSDR (Bottom) PCB Bottom Side

Both the HydraSDR and Airspy come in a black anodized aluminum extruded enclosure. The Airspy's enclosure is more compact, but the HydraSDR enclosure is purposely oversized to accommodate up to three HydraSDR PCBs.

However, additional holes for two extra SMA ports and two extra USB-C ports have not been pre-drilled, so we assume the 3x unit may be a separate product coming out in the future. The HydraSDR also utilizes an SMA port for the optional CLK-IN port, unlike the MCX port on the Airspy.

Airspy (Left) and HydraSDR (Right) Side Profile
Airspy (Left) and HydraSDR (Right) Side Profile

A major win for the HydraSDR is its use of a USB-C connector, whereas the Airspy R2 still uses a micro USB connector. (We note that it is a USB-C connector, but not USB3.0, it is still USB2.0).

The microUSB connector on the Airspy R2 is less robust and can easily disconnect if bumped, even with brand-new cables. The connection on the HydraSDR is rock solid, and no amount of reasonable bumping of the cable can disconnect it.

The HydraSDR spec sheet also mentions its suitability for phase-coherent applications, such as radar. However, although you can run all three from the same clock, from what we can see, specialized firmware, software, and external signal and/or noise source hardware would still be required for sample and phase alignment, as the system can not be naturally coherent. We're unsure whether the company will be directly supporting coherent use cases or if coherence is left as an exercise for the customer. 

Software

Both Airspy and HydraSDR use the same USB VID/PID identifiers, so most software should recognize them as the same device.

We decided to see if it would run in SDR#, the official software of Airspy. Upon selecting the device as an Airspy R2 in SDR#, we were able to see it work and operate just like a genuine Airspy R2. We want to note that Youssef has mentioned that, in his view, using non-Airspy products like the HydraSDR with the Airspy source would be in violation of SDR# terms, but we will use it in this review for comparison purposes.

HydraSDR Running in SDR# as an Airspy R2 Device
HydraSDR Running in SDR# as an Airspy R2 Device

This is interesting because in SDR++, the software recommended by HydraSDR, selecting Airspy R2 as the device results in the device being unable to connect. Currently, SDR++ does not support HydraSDR in its latest releases; however, support is being developed.

For now, until SDR++ officially supports HydraSDR, Benjamin has released a custom fork of SDR++ that will be available on the HydraSDR website.

HydraSDR Running in SDR++ (HydraSDR Fork)
HydraSDR Running in SDR++ (HydraSDR Fork)

We note a few differences between SDR++ and SDR#. SDR# restricts the visible bandwidth of Airspy devices to 8 MHz, as this hides the edges, which contain aliased signals. SDR++ does not hide the sides. SDR# also has an 'HDR' (high dynamic range) mode for Airspy devices, whereas SDR++ does not. More on HDR mode is discussed under the testing heading. 

When HDR mode was turned OFF, no differences in performance between SDR# and SDR++ were noticed.

We are also aware that HydraSDR is now supported by gr-osmosdr (GNU Radio source block), SatDump (satellite decoding software), and URH (Universal Radio Hacker). 

We also found that HydraSDR runs as an Airspy in SDR-Console V3. Official Airspy software, such as SpyServer and adsb_spy, also work with HydraSDR. We suspect that most software that supports the Airspy will be compatible.

Testing

No Antenna Test

In this test, we connected each SDR to a dummy load and used SDR# to look for signals. If the SDR is shielded well, no signals should be received.

We noticed that the HydraSDR has excellent shielding and is very well protected against signals entering through paths other than the antenna. The Airspy was able to receive a strong TV channel without any antenna, indicating that it has shielding issues.

HydraSDR (Left) Airspy (Right) No Antenna
HydraSDR (Left) Airspy (Right) No Antenna Connected

Across the spectrum, the HydraSDR also has a cleaner spectrum with lower power levels on most internal spurs.

Real World SNR Tests

In this test, we received real-world signals with each SDR connected to a roof-mounted Discone, which was in turn connected to a splitter. We increased the gain settings to optimize each SDR for best SNR, which is typically just before it overloads and creates images.

We noticed that the gain distribution on the HydraSDR was slightly different from that of the Airspy, as the HydraSDR would overload on a lower gain setting compared to the Airspy. When optimizing for SNR we found that a gain setting 1-3 notches higher on the Airspy was required.

Once optimized, we found that results were very similar, with a slight 0.5 - 1 dB sensitivity edge going to the HydraSDR; however, this may be within chip-to-chip variances, so we can't say for certain if one is more sensitive than the other.

HydraSDR (Left) Airspy (Right) Same SNR on BCFM in SDR#
HydraSDR (Left), Airspy (Right). Same SNR on BCFM in SDR#
HydraSDR (Left), Airspy (Right). Same SNR on BCFM in SDR++
HydraSDR (Left), Airspy (Right). Same SNR on BCFM in SDR++
HydraSDR (Left), Airspy (Right). Slightly better SNR for the HydraSDR at 457 MHz.
HydraSDR (Left), Airspy (Right). Slightly better SNR for the HydraSDR at 457 MHz.

Real World Comparison SDR++ vs SDR# 1921

HydraSDR recommends using SDR++, whereas Airspy recommends using the Airspy native software SDR#. While HydraSDR currently works on SDR#, we're not sure if this will continue, as SDR# could possibly block the use of clones and spinoffs. So, it seems fair to compare HydraSDR with SDR++ and Airspy with SDR#.

Under normal operation, with moderate strength signals, both programs appear to give nearly identical performance in terms of audio quality and signal SNR.

However, Youssef has pointed out that SDR# (and SDR-Console) has a special mode called HDR (high dynamic range) available for Airspy products. HDR mode works by optimizing the DSP chain specifically for the Airspy hardware whenever decimation is used. With HDR mode on, we can push the gain setting much higher than we would have otherwise without experiencing overload, resulting in a better SNR.

We are currently aware that only SDR# and SDR-Console V3 implement the Airspy HDR mode tweaks, and SDR++ does not.

Comparing performance between two different programs can be a bit tricky because each uses a slightly different FFT algorithm, resulting in different SNR values being calculated. SDR++ consistently calculates a somewhat higher SNR for the same signal.

To illustrate the effect of the Airspy HDR mode, we will use two SDR# instances and disable HDR mode for the HydraSDR, simulating the effect of using it in SDR++, which does not have HDR mode. 

HydraSDR with HDR Mode OFF (Left), Airspy (Right) HDR Mode ON
HydraSDR with HDR Mode OFF (Left), Airspy (Right) HDR Mode ON

This test showed a rather dramatic +7 dB improvement with HDR mode on. With HDR mode on we were able to increase the gain much further without overload. In the screenshot we increased the gain as far as possible to optimize the SNR on each receiver as much as possible.

For an audio comparison that directly compares Airspy on SDR# vs HydraSDR on SDR++, here is an audio file of the Airspy running SDR# with HDR mode ON, 16x decimation, receiving a weak signal sandwiched between strong signals.

And here is the audio file of SDR++ with 16x decimation receiving the same signal.

Both signals were optimized for the best SNR possible which was just before the SDRs overloaded and displayed intermodulation products. There is a clear difference in audio quality that can be heard, with SDR # emerging as the winner. Note that these HDR improvements may only be seen in a high dynamic range environment (when strong signals are mixed with weak signals) and when decimation is used .

Conclusion

With the Airspy R2 starting to feel a bit dated, the HydraSDR looks to be a great addition to the choice of available SDRs. However, we consider it to be essentially a spinoff of the Airspy with some minor changes made to improve performance and usability. The improved shielding and USB-C port are particularly notable enhancements that we love. Compared against the Airspy, HydraSDR is clearly the better hardware choice.

But if you already have an Airspy R2, there are not enough improvements here to consider the HydraSDR as a next-generation upgrade worth purchasing. That said, if you're looking for a new SDR made in the USA, the HydraSDR should be on your radar.

The Airspy maintains some software advantages, such as official software support and compatibility with SDR#’s and SDR-Consoles HDR mode, which excels in strong signal environments. However, the HydraSDR is directly compatible with the Airspy and currently functions as one in SDR#, allowing it to benefit from HDR mode as well. But this compatibility relies on SDR# not actively blocking it. It's also important to note that Youssef has mentioned that, in his view, using the HyraSDR in SDR# would be in violation of the SDR# licensing agreement, as would loading the HDR enhancements in SDR-Console V3 with HydraSDR (note that we have not verified the legality of this claim).

We also note that Benjamin wants to emphasize that HydraSDR is not designed for use with SDR#, and only SDR++ and other HydraSDR software should be used with it. 

Disclaimer

We have no financial interests in either Airspy or HydraSDR (apart from reselling the YouLoop). The Airspy R2 used in this review was provided to us back in 2015 as a free review unit, and HydraSDR was provided to us recently as a free review unit.

Airspy 2025 Summer Sale: 20% OFF All Airspy Products

Airspy has just announced the start of its yearly summer sale, offering 20% off all Airspy products from June 27 to June 30, 2025. The summer sale has historically only been 15% off, so this year there is an extra discount.

  • Airspy R2: US$169.00 US$135.20
  • Airspy Mini: US$99.00 US$79.20
  • Airspy HF+ Discovery: US$169.00 US$135.20
  • Airspy SpyVerter R2: US$49.00 US$39.20
  • YouLoop Antenna: US$39.95 US$31.96

The sale is active at all participating resellers, which includes our own store, where we have the YouLoop on sale for US$31.96, including free shipping to most countries worldwide (excluding tariffs!). 

We also note that recently, iTead, Airspy's manufacturing partner in China has opened a US warehouse, which means that US customers ordering from their store will not experience high tariffs. iTead sells all Airspy products, except for the YouLoop.

Some good reviews of the YouLoop include the YouTube videos done by Frugal Radio where he reviews HF reception and VLF & LF reception with an Airspy HF+, and later tests it with an RTL-SDR Blog V3 using direct sampling. Techminds also has an excellent review on his YouTube channel. 

If you're on X, be sure to retweet the sale post for a chance to win a freebie.

Airspy 2025 Summer Sale: 20% OFF
Airspy 2025 Summer Sale: 20% OFF

HackRF Pro Pre-Order: Frequency Range and RF Performance Improvements, USB-C, TCXO Added

The HackRF by Great Scott Gadgets, released in 2014, remains among the most popular software-defined radios (SDRs) on the market due to its open-source nature, affordability, wideband tuning range, wide 20 MHz bandwidth, and transmit capability.

However, over the past 10 years, very little has changed with the HackRF, with most changes only being made out of necessity due to end-of-life components. It has mostly been the open-source community and clone manufacturers innovating on the circuit.

Today, Great Scott Gadgets has finally announced the HackRF Pro.

Key improvements include expanding the lower frequency limit from 1 MHz down to 100 kHz, integrating a TCXO for enhanced frequency stability, upgrading the microUSB port to USB-C, and improving RF performance with additional shielding, a flatter frequency response, and the elimination of the DC spike. They have also added more RAM and flash memory, and added a 16-bit output mode for low sample rates.

The product is available from their usual distributors (listed on the release page) and costs US$400. Note that the HackRF Pro is currently in pre-order, with production slated to begin in July 2025 and shipping in September 2025. 

The full release article from Great Scott Gadgets reads:

HackRF Pro from Great Scott Gadgets is a Software Defined Radio peripheral capable of transmission or reception of radio signals from 100 kHz to 6 GHz. Designed to enable test and development of modern and next generation radio technologies, HackRF Pro is an open source hardware platform that can be used as a USB peripheral or programmed for stand-alone operation.

  • 100 kHz to 6 GHz operating frequency
  • Tunable from 0 Hz to 7.1 GHz
  • Half-duplex transceiver
  • Up to 20 million samples per second
  • 8-bit quadrature samples (8-bit I and 8-bit Q)
  • Compatible with GNU Radio, SDR#, and more
  • Software-configurable RX and TX gain and baseband filter
  • Software-controlled RF port power (50 mA at 3.3 V)
  • SMA RF connector
  • SMA clock input and output for synchronization and triggering
  • Convenient buttons for programming
  • Internal pin headers for expansion
  • High-Speed USB 2.0 with Type-C connector
  • USB-powered
  • Open source hardware

Compared to HackRF One, HackRF Pro introduces a host of new and updated features, including:

  • Wider operating frequency range
  • Improved RF performance with flatter frequency response
  • Modern USB Type-C connector
  • Built-in TCXO crystal oscillator for superior timing stability
  • Logic upgrade from a CPLD to a power-efficient FPGA
  • Elimination of the DC spike
  • Extended precision mode with 16-bit samples for low sample rates (typical ENOB: 9-11)
  • More RAM and flash memory for custom firmware
  • Installed shielding around the radio section
  • Trigger input and output accessible through clock connectors
  • Cutout in the PCB provides space for future add-ons
  • Improved power management

Software that works with HackRF One is already compatible with HackRF Pro. We designed HackRF Pro for backward compatibility, following the same basic architecture of HackRF One but with many small enhancements. Prior to shipping HackRF Pro, we will publish a migration guide that will show software developers how to take advantage of certain new capabilities of HackRF Pro, but out-of-the-box HackRF Pro will behave like HackRF One with superior performance. In addition to host software compatibility, our migration guide will address firmware, allowing developers to port custom firmware to the new platform and take advantage of its unique capabilities

The HackRF Pro
The HackRF Pro

Decoding SSTV Transmissions from the QO-100 Satellite

Over on his YouTube channel dereksgc has uploaded a video showing how to decode Slow Scan Television (SSTV) transmissions from the QO-100 satellite. QO-100 is a commercial geostationary communications satellite available in some parts of the world that also carries a popular transponder for amateur radio. SSTV is an amateur radio communications analog protocol for transmitting images over a narrowband RF signal.

In the video dereksgc shows how to use SDR Console V3 together with a program like MMSSTV for decoding the image. He goes on to discuss the specific SSTV frequencies on QO-100, the different SSTV modes, and some demonstrations of images being received.

Decoding SSTV transmissions from the QO-100 satellite (QO-100 pt.2)

SDR ProTrack: Android Radio Direction Finding with RTL-SDR and Directional Antennas

Thank you to Alexandre Gellibert for writing in and sharing his new Android App, "SDR ProTrack." SDR ProTrack is a radio direction-finding app that uses an RTL-SDR and directional antenna to determine a bearing towards a transmitter.

Interestingly, Alexandre notes that this app was initially developed to track Asian hornets, a bee-killing pest. With hornet tracking, a miniature RF transmitter is attached to a caught hornet, and the hornet brings it back to the nest. RF tracking techniques can then be used to find the nest.

It's possible to determine the bearing toward a transmitter by using a receiver such as an RTL-SDR paired with a directional antenna like a Yagi. Directional antennas have high sensitivity in one primary direction and significantly lower sensitivity in all others. By rotating the antenna until the strongest signal is identified, you can establish the precise bearing angle. Typically, following this bearing will guide you directly toward the signal's origin.

Alexandre wrote in an email to us the following:

Just to let you know we just launched a new Android app compatible with RTL-SDR dongles (though mostly tested on RTL-SDR v4).

App is free to use. Advanced features (like Compass to point the signal potential source) are for premium users.

It's plug and play, easy to use, much more user friendly than SDR++.

Any feedback is really appreciated :)

If you want to know more about the project or the 2 developers behind it (we develop it in France to be able to track asian hornets that kill all the bees), please feel free to contact us.

And the Android page describes SDR ProTrack in the following way:

Unlock the power of radio tracking with SDR ProTrack!
Transform your Android smartphone into a signal-tracking powerhouse using an RTL-SDR dongle and a directional antenna. Affordable, versatile, and perfect for enthusiasts, researchers, pros or anyone tracking signals—like Asian hornets or wildlife.

★ Key Features ★

• Automatic RTL-SDR dongle recognition and connection (free)
• Spectrum Visualization (Free): View signal shapes in the frequency domain effortlessly.
• Compass (Premium): Pinpoint the strongest signal direction with precision.
• Signal Strength Display (Premium): Monitor signal power with an intuitive interface.
• Custom Settings (Premium): Adjust bitrate, sample rate, and frequency sensitivity to your liking.

★ Requirements ★

• Requires an external RTL-SDR device.
• Check compatibility: https://osmocom.org/projects/rtl-sdr/wiki

Need an RTL-SDR dongle, emitters, receptors, or antennas?
Visit our website: https://www.intuite.fr/en_GB/pricing

★ About Us ★

Intuite is a company specialized in locating Asian hornet nests. We developed SDR ProTrack to provide a robust, cost-effective solution for radio signal tracking, combining innovative technology with our expertise in signal detection.

★ Open Source Community ★

Join our mission to advance radio tracking! Our open-source library, RTL-SDR Bridge Android Lib, powers SDR Pro Track.
Contribute to development, report issues, or explore the code at https://github.com/alexandreGellibert/RTL-SDR-Bridge-Android-Lib.
Support our work and help shape the future of signal tracking!

Download SDR ProTrack today and start tracking signals like a pro!

SDR ProTrack Screenshot
SDR ProTrack Screenshot

A Video Tutorial on Setting up RTL-SDR ADS-B Reception with Dump1090 and Virtual Radar Server

Thank you to Paul Maine for writing in and letting us know about his YouTube video showing how to set up ADS-B reception with an RTL-SDR, dump1090, and Virtual Radar Server on a Windows machine. ADS-B reception is a common project for RTL-SDR users; however, as Paul notes, most of the video tutorials available on YouTube are outdated.

Paul has also been uploading other videos to his YouTube channel recently, including tutorials on GNU Radio and setting up rtl_433, so check it out if you are interested.

E11 Tracking Airplanes using RTLSDR with Virtual Radar and ADS-B