Over on YouTube TechMinds has uploaded a new video explaining NavTex and showing how to decode it with an HF capable SDR like the SDRplay RSPDx. NavTex is a marine digital data radio service designed for transmitting information like navigational and meteorological warnings, weather forecasts and maritime safety information. It is broadcast in either the MW frequency band at 490 kHz and 518 kHz or in the HF band at 4209.5 kHz.
In the video TechMinds uses a guide put out by Mike Ladd from SDRplay (pdf warning). The guide explains how to connect SDRuno to a NavTex decoder called YanD via a virtual audio cable. The rest of the video shows a NavTex message being decoded, some sample messages, and a closer look at YanD.
Even if you don't use an SDRplay, the guide could be adapted for other SDRs too.
Decoding NavTex with Software Defined Radio - SDRuno RSPdx
SDRplay have recently released an update regarding third party software support and availability of their latest RSPdx receiver. They write:
Happy new Year from all of us at SDRplay.
Here’s an update on additional software for the RSPdx. SDRplay’s SDRuno fully supports the RSPdx but it takes several weeks for other software to catch up to the capabilities offered on the other RSP models.
Simon Brown has released his latest version of SDR Console V3 which supports the RSPdx (Version 3.0.18 dated January 1st) over on https://www.sdr-radio.com/ (make sure you download the latest API 3.x from our downloads page first)
We have released an EXTIO plugin for the RSPdx which will enable the RSPdx to work with any EXTIO-based software (e.g. HDSDR) although it doesn’t support HDR mode. HDR mode will not be added and the source code for the plugin can be found on our GitHub repository (https://github.com/SDRplay/ExtIO_SDRplay) we will not be supporting the plugin source code or extending the plugins capabilities. They are all free to be modified.
It is important to note that the RSPdx ExtIO plugin does NOT, AND WILL NOT, support HDR mode. If you need HDR mode, then SDRuno is the best option. HDR mode requires the end application to work in a certain way and this is not something that can be controlled via the ExtIO protocol.
Work has also begun on supporting RSPdx for SoapySDR based applications such as Cubic SDR (again this won’t include HDR mode). A Gnu Radio source block for the RSPdx will follow.
We are working with Steve Andrew, author of the Software Analyser software programme (see https://www.sdrplay.com/spectrum-analyser/ ) to help get compatibility for the RSPdx – this is a slightly longer process so this will take several more weeks.
Regarding stocks of the RSPs, SDRplay and most of our resellers on www.sdrplay.com/distributors/ have plenty of stock of RSP1A and the RSPduo. However there continues to be a shortage of the RSPdx whereby many of the resellers have sold out of their first deliveries. SDRplay is queuing up their replacement orders on a first come, first served basis. We also have our own quantity planned in there to allow us to sell direct from our website. We still hope that by the end of January we will have supplied this second wave of RSPdx demand.
Each test consists of a video where he runs a comparison between the RSPdx and another receiver. All SDRs are run in SDRuno, the official application for SDRplay receivers. It is left for the listener to determine which SDR sounds better. From a listeners perspective, it appears that the RSPdx performs at least identically to the other SDRs.
One of the selling points of the recently released SDRplay RSPdx is it's special High Dynamic Range (HDR) mode which can be used to improve signal performance for frequencies below 2 MHz. This mode should be especially useful in RF environments where there are strong signals that can overload the SDR and desensitize reception on weaker stations.
Over on YouTube Ivan (aka icholakov) has uploaded a video showing comparisons of signals being received with HDR mode turned on and off. He tests it on weak NDB DX signals, and on medium wave broadcast AM. The results do appear to show that using HDR mode results in an improvement in signal strength.
SDRPlay RSPdx HDR mode on and off - testing Non Directional Beacons and Medium Wave
Over on YouTube the TechMinds channel has uploaded a new video about decoding Differential GPS (DGPS) using an SDRplay RSPdx SDR. DGPS is a terrestrially transmitted long wave signal that is used to help correct and improve GPS position data calculations which may have timing errors due to atmospheric propagation delays. It works by broadcasting correction data calculated by the difference in received GPS location and the known location of the DGPS transmission site. DGPS is typically transmitted on longwave between 285 kHz and 315 kHz, but in Argentina there are two stations at 2570 and 2950 kHz.
In the video TechMinds explains how DGPS works, and some location around the world from where it is transmitted from. Later in the video he shows a DGPS signal being received by a SDRplay RSPdx SDR, and then show a demo of how it can be decoded with MultiPSK.
We note that there also various other DGPS decoders available including decoders for Android and iOS. A list of decoders can be found on the DGPS sigidwiki page.
DGPS Differential GPS Decoding With RSPdx And MultiPSK
In the review Thomas notes that while having the advantage of being a wideband receiver, the predecessor to the SDRplay RSPdx (the SDRplay RSP2) was never able to compete with the similarly priced Airspy HF+ and Airspy HF+ Discovery units when it came to HF, MW and LW receiving performance.
But now with it's 0 to 2 MHz enhanced HDR mode activated, Thomas notes that the new RSPdx is majorly improved over the RSP2 in terms of sensitivity and selectivity on the medium wave bands. Thomas' tests also show substantial improvements in the shortwave bands.
Over on YouTube the Scanner and Sdr Radio channel has uploaded a video comparing four different brands of HF wideband loop antennas using an SDRplay RSPduo. The loops he tested include the cheap Chinese MLA-30 (~$40), the Cross Country Wireless (CCW) loop ($70), Bonito ML200 (~$442) and the Wellbrook 1530LN (~$305).
The MLA-30 was slightly modified with the cheap coax removed and a BNC connector added. Each of the antennas used a wire loop with diameter of approximately 1.6m, except for the Wellbrook which has a fixed size solid loop of 1m.
The tests compare each loop against the Wellbrook which is used as the reference antenna. In each test he checks each HF band with real signals on the RSPduo and compares SNR between the two antennas.
The results show that the two expensive antennas, the Bonito and Wellbrook, do generally perform the best with the lowest noise floors, but surprisingly the MLA-30 actually performs very well for it's price point, even outperforming the Wellbrook reference on SNR in some bands. We note that some of the improvement may be due to the larger 1.6m loop size used on the MLA-30, compared to the 1m loop on the Wellbrook.
Also we note that it can be hard to compare antennas in single tests, because the differences in antenna radiation patterns could be favorable for some signals, and less so for others, depending on the location.
SDRplay recently released news about their upcoming RSPdx software defined radio, which replaces the RSP2 as the top of the line unit in the SDRplay lineup. The RSPdx is not yet on sale, but a few YouTube reviewers have already received their units. The first review comes from Mile Kokotov who is known to have reviewed several SDRs in the past. Mile's impressions are that the receiver works very well. He writes on his video blurb:
Today i have received the new SDR receiver from SDRplay, the RSPdx and was eager to turn it on and do some tests receiving on HF and VLF. Although at the moment my mini-whip antenna is not operational, I have connected some 20 meters wire as an antenna and start listening on VLF, LW, MW and HF...
I have to say that SDRplay team did a good job with this SDR-receiver, putting better filters and redesigning front-end to improve dynamic range and enhance overall performance in relation to its predecessors RSP2 and RSP2pro. The new RSPdx is very good indeed. Especially on HF and below.
The RSPdx has new features like HDR (High Dynamic range) mode for reception within selected bands below 2 MHz. HDR mode delivers improved intermodulation performance and less spurious responses for those challenging bands.
The New SDRplay RSPdx receiver - First Impression: Excellent!
The second review is by SevenFortyOne who runs through the various features of the SDRplay and also tests it on various HF signals.
SDRplay RSPdx Overview and SDRuno V1.33 Demo
The third video isn't exactly a review, but here TechMinds shows us how to run the RSPdx as a panadapter on his FTDX-3000.