Thank you to Mitsunobu for writing in and sharing news about the release of his new product which is a Hi-Z (high impedance) to 50 Ohm matching transformer. This transformer allows you to use small antennas such as short telescopic whips for HF/SW reception on software defined radios.
Generally for HF reception you would want to use a full sized antenna, which can be many meters long and certainly not portable. However, by using an high impedance transformer it becomes possible to use smaller portable antennas. Reception with a small antenna and transformer will still be suboptimal compared to a full sized HF antenna, however, if the signals are strong enough the transformer will allow you to receive them decently.
In the tests shown on his blog (in Japanese, use Google Translate) he shows how the transformer adapter can be connected to a small telescopic whip and Malachite DSP SDR for portable use. Later he also shows how the adapter can make our Dipole Kit antenna work well for HF on a RTL-SDR Blog V3 with direct sampling.
Rob from Frugal Radio has recently uploaded the next episode in his excellent YouTube series on Aviation monitoring. In this episode Rob covers HF aviation communications. Rob writes:
Whether you are using a Software Defined Radio (SDR), an old school HF receiver, or utilizing a WebSDR, there is plenty to monitor when you know where to look.
This video will give you the basics of where to find the Aviation Communications that take place from 3-30 MHz (HF / Shortwave).
This episode covers VOLMET broadcasts, the Major World Air Route Areas (MWARA), and Military Nets like the US Global Communications System (HFGCS).
Remember, these signals travel thousands of miles. It can be quite exciting to receive them over such great distances. When editing this video I was listening to a VOLMET station in Auckland, New Zealand - a distance of over 7500 miles (12,200km) away!
Monitoring HF Aviation Voice Communications with your SDR Radio or a WebSDR
As a follow on to the previous post on fake SDRplay units, we also wanted to provide some guidance on fake RTL-SDR Blog V3 clones which are on the market. We are starting to receive an increase in support requests for fake RTL-SDR Blog V3 units. Please be aware that we cannot support these devices, and most of them are missing key features like the bias tee and the TCXO despite advertising these features on the listing and writing on the dongle body. Also as mentioned below a good majority of them appear to have a defect and poor performance.
Please check our store at www.rtl-sdr.com/store for our official stores on Amazon, eBay, Aliexpress and this site. We also have links on our store to our official local resellers.
We note that we tested a few of the "RTL.SDR" clones, and all had a defect causing very strange distorted spectrums where the signals where wider than they should be, and some units introduced a mysterious high pitched whine into every signal.
Spectrum from cloneSpectrum of an original RTL-SDR Blog V3
To be clear, different brands of RTL-SDR are perfectly fine - no one owns the RTL-SDR hardware concept and we are not any more "official" than any other brand (although we believe we were the first to start designing and producing significantly improved units and the first to design in a factory fitted TCXO, SMA connector, bias tee, thermal pad, and a redesigned PCB for lower noise and less spurs).
However, these clones shown in the image above can be considered a sort of scam as they attempt to trick buyers into believing that they are purchasing our RTL-SDR Blog V3 units with false advertising and by copying the enclosure design, when in fact the PCB inside is something inferior.
2021 Supply Chain Updates
As many of you may know the world is currently dealing with a major shortage of many electronics parts so we wanted to provide an update on the supply chain for the RTL-SDR Blog V3.
In particular, the world is very short on temperature compensated oscillators (TCXO's), a critical component used in our units to ensure frequency stability. The TCXO shortage is actually much worse than other components as AKM, the Japanese semiconductor factory that produces a critical component for making TCXOs burned down late last year. There are alternative suppliers, however their pricing is many multiples higher, and they are also inundated with orders increasing lead times.
We believe that we have enough TCXO stock in storage to last us several more months, however we may run into a shortage in the later months of this year. After we expend our current TCXO stock, we expect to have TCXO again around December, with more RTL-SDRs being ready by January 2022. We want people to be aware, as during these months of no stock more clones may appear on the market. Most clones do not use TCXOs, and hence have poor frequency stability.
Also on a related note our Amazon stock levels may be a little spotty throughout this year as there are currently often delays with shipping and the ports.
We also note that other products that we resell on our store such as the FlightAware Prostick Plus and NanoVNA V2+ are also experiencing supply issues, and may not have stock for a while. Production of some of our other products like the L-band Patch are also delayed due to shortages.
Due to the shortages component prices are also significantly increasing, and you may notice an increase in RTL-SDR pricing from us and competitors too. We hope that we will be able to reduce our pricing again once the global shortage is over, most likely around early next year.
We've posted about various fake clones of various brands of SDRs a few times on this blog, and recently this week SDRplay reiterated their warning noting that the fake SDRplay clones may not work with official SDRplay software.
There are sellers of fake RSPs on the internet. They are selling counterfeit devices some of which appear cosmetically the same as the genuine SDRplay® devices. There is a high likelihood that these devices will not work – according to unsuspecting buyers* who have contacted us.
These counterfeit devices attempt to make use of:
Stolen IP
Stolen software product (SDRplay proprietary API and driver software)
In addition, the counterfeiters have no access to our rigorous production test solution and so these devices are probably untested.
* Here’s what one AliExpress customer posted:
The rest of the post goes on to highlight how you can be sure that you are not purchasing a fake clone.
The ##rtlsdr IRC Freenode chat channel will be moving to irc.libera.chat. However ##rtlsdr admins note that the Freenode channel will remain open for now. This move is in wake of the recent takeover drama surrounding Freenode, and the resignation of the majority of Freenode staff.
The ##rtlsdr IRC channel is where many RTL-SDR, software defined radio and RF enthusiasts hang out. You can join and idle with any IRC client, or a web client is available at https://kiwiirc.com/nextclient/irc.libera.chat/##rtlsdr.
A discussion about the move has also been opened on Reddit /r/rtlsdr.
Many other related project channels such as #gnuradio are also moving over to Libera.
Over on his YouTube channel saveitforparts has uploaded a video showing how he has built an automated weather satellite image collector for the NOAA APT and Meteor M2 LRPT satellites. The video shows a time lapse of him building a QFH antenna, and how he's mounted a Raspberry Pi and RTL-SDR inside a waterproof enclosure attached to the antenna mast. He goes on to show how he's automating the system with the Raspberry-NOAA V2 software.
Automated Home Weather Station (Satellite Image Collector)
Thank you to Ihar Yatsevich for writing in and sharing his open source project called "rpitx-coax-pcb" which is an expansion board for the Raspberry Pi that converts the GPIO pin used by RPiTX into a coaxial SMA connector for easily connecting the output to an antenna. He notes that there are two revisions. One includes a filter in the in the GP1212 / GP731 case and the other does not. Filters in this type of enclosure can be found from Minicircuits. Finally he notes that he has not yet fully tested the design, but believes that there will be no problems.
The GitHub contains the EasyEDA design files, schematics and gerbers which you can use to print and build the PCB yourself.
If you are unfamiliar with it, RPiTX is a program for Raspberry Pi single board computers that allows you to transmit almost any type of signal on frequencies between 5 kHz up to 1500 MHz with nothing more than a wire connected to a GPIO pin. However, it is highly recommended that appropriate filtering be used if you are transmitting with an amplifier or longer range antenna as the RPiTX contains harmonics that can cause interference with other devices.
RPiTX Coaxial PCB Expansion Board for the Raspberry Pi
A few weeks ago we posted about "LikWidChz"'s work on using GNU Radio to channelize multiple NRSC-5 HD-Radio transmissions for simultaneous decoding with GNU Radio and an RTL-SDR. He has now also submitted a way to channelize pager traffic. He writes:
Quite a while ago I wanted to decode pager traffic, specifically Flex. When I started doing some basic poking around I figured out that there were multiple pager transmissions going on at once. Thinking about GnuRadio and its ability to chop up signal.. I was curious if anyone tried to decode them all at once.. I didn't get a whole lot of answers on the subject and It didn't seem like people used GnuRadio to pass MultiMonNG data.. I had my work cut out for me.
In my area all of the flex transmissions were between 928Mhz and 932Mhz and quite strong... You don't need much of an antenna to RX these transmissions. A simple wire of appropriate length will do nicely.
My plan was to design a graph and tune into the center of the range I was interested in and somehow channelize it. The remaining steps are required to format the data to allow MultiMonNG to process that audio stream. This is done a couple times depending on how many you want to decode in parallel. Have fun!
This this zip file we have uploaded his GRC file, and his full PDF description of the flowgraph. Again we note that to get in touch with the author you can log on #gnuradio and ##rtlsdr on freenode IRC and fine him under the nickname "LikWidChz".
