Tagged: WSPR

Receiving WSPR with an RTL-SDR V3 and with Automatic Band Changing

RTL-SDR V3 + Raspberry Pi WSPR Receiver
RTL-SDR V3 + Raspberry Pi WSPR Receiver

WSPR (pronounced "Whisper") is short for Weak Signal Propagation Reporting, and is a HF ham mode typically run on very low power levels such as 1W. The data from WSPR reception can be used to determine how good or bad HF propagation is currently around the world as each WSPR message contains a callsign, 6-digit locator and the transmit power level used. Received messages are all reported to the internet and can be viewed on an online map at http://wsprnet.org/drupal/wsprnet/map.

With an RTL-SDR V3 running in direct sampling mode it is possible to receive and decode these messages on a Raspberry Pi 3 using the WSPRD software.

Over on his website IT9YBG has uploaded a tutorial for a method that allows the WSPRD software to automatically change bands depending on the time of day. The method simply uses the crontab in Linux to automatically run a script that stops and then restarts WSPRD on a new frequency at certain times of the day. This is useful because different WSPR bands tend to become active at different times of the day due to changing HF propagation conditions.

WSPR messages received from all over the world.
WSPR messages received by IT9YBG from all over the world.

GridTracker: A WSJT-X Mapping Program

Thanks to RTL-SDR.com reader Henry for letting us know about the release of a new piece of Windows software by Tag Loomis (N0TTL) called GridTracker. GridTracker is a live mapping program for WSJT-X which is a software decoder for low power weak signal ham communications modes such as FT8, JT4, JT9, JT65, QRA64, ISCAT, MSK144 and WSPR. Although these are low power modes, the protocols are designed such that even weak signals can potentially be received from across the world. Mapping the received signals can be interesting as it may give you an idea of current HF propagation conditions.

GridTracker is a Windows (XP or above) companion program for WSJT-X. It listens to WSJT-X or JTDX decodes and displays them on a map.

A great way to visualize communicating amateurs around the world!

Display on a large second monitor in your amateur radio club, hamfest or as a demonstration in a classroom. Everyone gets excited when they can see what you’re doing!

You can also load your ADIF log files from WSJT-X, Qrz.com, LoTW, PSKReporter and others to get a visual view of ‘stations worked’, stations that can hear you and more!

It might be an interesting project to set up a permanent GridTracker display using an RTL-SDR V3 in direct sampling mode, or RTL-SDR with upconverter. Low cost x86 single board PCs that can run Windows 10 such as the LattePanda, UP board or Udoo might be possible candidates for host hardware.

Henry warns us that the software is still new, so it may be a little buggy.

GridTracker Mapping out Weak Signal Communications.
GridTracker Mapping out Weak Signal Communications.

Securing the Bitcoin network against Censorship with WSPR

Bitcoin WSPR Test Setup
Bitcoin WSPR Test Setup

If you didn't know already Bitcoin is the top cryptocurrency which in 2017 has begun gaining traction with the general public and skyrocketing to a value of over $19,000 US per coin at one point. In addition to providing secure digital transactions, cryptocurrencies like Bitcoin are intended to help fight and avoid censorship. But despite this there is no real protection from the Bitcoin internet protocol being simply blocked and censored by governments with firewalls or by large ISP/telecoms companies.

One idea recently discussed by Nick Szabo and Elaine Ou at the "Scaling Bitcoin 2017" conference held at Stanford University is to use the something similar to WSPR (Weak Signal Propagation Reporting Network) to broadcast the Bitcoin network, thus helping to avoid internet censorship regimes. To test their ideas they set up a HackRF One as a transmitter and RTL-SDR and used GNU Radio to create a test system.

Other ideas to secure the Bitcoin network via censorship resistant radio signals include kryptoradio, which transmits the network over DVB-T, and the Blockstream satellite service which uses an RTL-SDR as the receiver.

If you're interested in the presentation the talk on WSPR starts at about 1:23 in the video below. The slides are available here.

A Tutorial on Receiving WSPR with an RTL-SDR V3

Over on YouTube user Veryokay has uploaded a video that shows how he uses the HF direct sampling mode on one of our V3 RTL-SDR’s to receive WSPR signals. WSPR (pronounced “Whisper”) is short for Weak Signal Propagation Reporting, and is a HF ham mode typically run on very low power levels such as 1W. The data from WSPR reception can be used to determine how good or bad HF propagation is currently around the world as each WSPR message contains the callsign, 6-digit locator and the transmit power level used.

For the antenna Veryokay uses a simple random wire antenna directly connected to the SMA port of the V3 up on top of the roof of his apartment building. This gets him reception good enough to receive many WSPR signals. Then together with SDR#, VB Cable and the WSPR-X decoder software, signals can be received and decoded.

He has also uploaded a document detailing the instructions in text and image form at bit.ly/wspr-rtlsdr.

Receiving WSPR with a Direct Sampling Modified RTL-SDR

Over on YouTube user Veryokay has uploaded a video showing how he was able to receive WSPR (Weak Signal Propagation Report) signals at 14 MHz with his direct sampling modified RTL-SDR. WSPR is a HF mode designed to be received even if the signal is very weak. It is used to help determine radio propagation conditions. Direct sampling mode allows you to receive HF signals on an RTL-SDR without the need for an upconverter, but it is more difficult to implement and get good results with. To get the best results Veryokay built an add on PCB that fits onto the RTL-SDR which contains and LNA and single ended to differential operational amplifier to amplify and get correct impedance matching on the input.

His video mainly shows how to calibrate the receiver correctly to receive WSPR as incorrect calibration is the most common error when trying to receive WSPR for the first time. In the video he also explains that he is transmitting WSPR himself using his Raspberry Pi and a QRPi WSPR filter shield for use with Rpitx.

Receiving WSPR with the RTL-SDR in direct sampling mode and WSPR-X.
Receiving WSPR with the RTL-SDR in direct sampling mode and WSPR-X.

PiTX QRP TX Shield for WSPR on 20M Now For Sale

Back in October 2015 we posted about a piece of software for the Raspberry Pi called PiTX. PiTX allows you to turn your Raspberry Pi into a fully functional RF transmitter. When combined with an RTL-SDR a full transceiver radio can be built using the QTCSDR software.

PiTX works by modulating the GPIO pins on the Pi in such a way that it is able to produce FM modulation. The major problem with using this method of producing radio is that it creates large amounts of harmonics and interference outside of the intended transmit frequency. Interference like this is illegal and could potentially disrupt life critical radio systems such as emergency services, cellphones and air traffic control.

In order to cleanly transmit with PiTX an output RF filter should be used. Recently, the team over at TAPR.org have released a 20M WSPR TX filter shield. WSPR is pronounced “Whisper” and is short for “Weak Signal Propagation Reporter Network“. It is a type of amateur radio signal that can be broadcast and received around the world by using very low transmit power. Radio amateurs use it to see how far their signal can travel when using very low power (QRP) and to investigate signal propagation conditions. 

The 20M WSPR shield sells for $20 at www.tapr.org/kits_20M-wspr-pi.html.

The WSPR shield sitting on top of a Raspberry Pi.
The WSPR shield sitting on top of a Raspberry Pi.

Receiving WSPR with the RTL-SDR

Recently RTL-SDR.com reader DE8MSH wrote in to let us know about his experiments with receiving WSPR with his RTL-SDR. WSPR is an acronym for “weak signal propagation reporter” and is a software program and RF protocol designed for very weak signal radio communications between ham radio users. With less than 5W of transmitting power, a WSPR signal could potentially be copied all over the world.

To receive WSPR, DE8MSH used a direct sampling modified RTL-SDR dongle together with a 9:1 unun, 10m RG58 coax cable from RTL-SDR to unun and a 12m wire antenna outside his house. Then by using SDR# together with the WSPR software he is able to copy signals from all over Europe and Canada/USA from his home in Germany.

Some Received WSPR Locations
Some Received WSPR Locations
WSPR Report Information Including Distance
WSPR Report Information
The WSPR Software
The WSPR Software

Tutorial: HF Decoding Tour with the FUNcube Dongle Pro+

On the FUNcube Dongle blog/store amateur radio enthusiast DK80K (a.k.a Nils) has sent in a link to a 16 page pdf file showing a comprehensive tour on the FUNcube Dongle Pro+’s capabilities on the HF spectrum.

He gives an overview of many digital ham and HF utility modes including DRM, WSPR, RTTY, Olivia, MFSK16, PSK31, Pactor, Packet, Hellschreiben, ROS, SSTV, HF ACARS, SSB, CW, DSC/GMDSS, SITOR-A/B, Globe Wireless, Time Signals, ALE, Baudot, FAX and Stanag 4285.

The FUNcube is a software defined radio similar to the RTL-SDR, but with better sensitivity and noise performance, but at a higher price (around $200 USD). These modes can also be received with the RTL-SDR and an upconverter such as the Nooelec Ham-It-Up upconverter.

Download his pdf here (Mirror)