Category Archives: Guest Posts

Guest Post: “Radio. Now is your time to shine.”

Many thanks to SWLing Post contributor, Fred Waterer, who shares this message from his friend, Jarrad Brooke:


Radio. Now is your time to shine.

As more and more mass gatherings are cancelled and outdoor entertainment is cancelled – more and more people will turn to other forms of media for entertainment. Netflix and streaming are the obvious choices – but I believe even Free to Air TV and yes -radio will get a free kick as well.

I’m not talking about those in isolation or quarantine – as that is obviously an extremely small portion (or hopefully!) a small portion of our potential audience. I’m talking just the general population who feel they need somewhere to go, tune out, escape and be entertained… seeing as they have no where in groups outdoors to do it anymore.

Radio – now more than ever, needs to make sure they use this free kick of audience to their advantage to make sure they become loyal and stay. Everything that goes to air right now needs to be to the highest quality – every song, announcer break, commercial and element needs to fit now more than ever.

Radio did such a great job in the bush fire emergency. Now build on that and maximise it even more. You never know, you could be a listeners emergency today in needing them needing an escape from reality for a while.

Spread the radio love

Guest Post: Radiofreunde NRW’s DXpedition-grade signal distribution system


Many thanks to SWLing Post contributor, Joachim von Geisau (DH4JG), for the following guest post:


Signal distribution at SWL camps: The new JK-1000 HF distributor

by Joachim von Geisau (DH4JG)

The Friends of Radio NRW – an independent group of shortwave listeners and radio amateurs in Germany – have been organizing 2-3 SWL camps per year for a number of years, where they meet as far away as possible from electrical noise in order to listen to shortwave together.

To distribute antenna signals, we have previously used an RFT AVV01 antenna distributor.

At an SWL camp there are high demands on signal distribution. Both very weak and strong signals should be distributed well, un-distorted, without noise and other interference. The signal levels are approximately between 0.2 ?V (S1) to over 5 mV (S9 + 40 dB), with a frequency range of at least from 150 kHz to 30 MHz, thus broadcast bands from LW to SW are covered, also all amateur radio bands from 160 m to 10 m.

Popular among listeners are RFT AVV01 RF distributors from the former GDR, at least 30 years old. However, the use of an AVV01 has several disadvantages: high power consumption, difficulties in getting spare parts, high upkeep with corroded contacts and the like. In addition, the transmission of the LW/MW range drops, which is a disadvantage especially for MW listeners. The NV-14 system from Rohde & Schwarz from the late 1960s has the same weaknesses.

Two years ago, the desire arose to develop a concept for the replacement of the RFT system.
The following aspects were important:

  • Frequency range at least 100 kHz – 30 MHz, as linear as possible
  • frequencies below or above desirable
  • Running on 12 V DC or integrated noise-free power supply
  • Remote power supply for active antennas
  • Robust structure
  • Versatility
  • Hobby friendly budget

The amateur radio market offers several products for RF signal distribution (e.g., ELAD, Bonito et al.), but no solution to distribute 6-8 antennas to 10-12 receivers. It was clear from the beginning that DIY development was inevitable.

The starting point of the considerations was to integrate remote power supply for active antennas, an amplifier stage and a distribution network.

Such a distributor is able to distribute an antenna signal to several receivers; several antennas require several such distributors, which led to the decision to implement the project in plug-in technology.

With OM Frank Wornast DD3ZE (www.dd3ze.de), known e.g. for his converters, filters and the like, a well-known RF developer could be won, who took over the implementation of the concept based on the detailed specifications. OM Wornast first produced a prototype without remote power supply, which already did an excellent job of RF signal distribution.

A “hardness test” at an SWL camp showed that this distribution module easily fulfilled our requirements: Frequency range 10 kHz – 50 MHz (also usable with a few dB loss above 50 MHz). Supplemented by a switchable remote power supply and a 90V gas discharger at the antenna socket, the final PCB layout was created, representing the core of the new HF distribution system of Radio Freunde NRW

The distribution block consists of the following components:

  • Input with 90V arrester & 100 kOhm MOX resistor to dissipate static interference
  • Remote power supply, switchable, 10-14 V, max. 350 mA
  • Amplifier stage with 14-14.5 dB
  • Resistor network for distribution

The device is characterized by a very smooth frequency response and has a very low inherent noise. It offers the possibility of using levels of -120dBm with very good SNR
to process up to strong levels of up to + 14dBm. In addition, the reception on VLF is now possible, which did not work with the previous system.

 

The PCB is designed in a very practical way: series resistors for LEDs are integrated as well as fixing points for coaxial cables. The remote power supply can be switched separately, but can also be used permanently by means of a jumper.

With this concept, the distribution block can be used universally: use on an active or passive antenna with distribution to several receivers, by means of a step switch in front of it also for several antennas; if you leave the remote feed path unconnected, the block can also be used as a simple distributor, so it is almost universal for hobby purposes.

For use on SWL camps, we decided to install them in 19 “rack-mount technology. A standard rack can thus accommodate 4 distributors and a power supply, allowing  distribution of 4 antennas to 12 outputs each. An example of the installation is shown in the following picture: Parallel to the input is another BNC socket, which is connected via a C 100 nF where the input signal can be used DC-free for measurement purposes or the like. The distribution unit is installed in a transport case. The components themselves are mounted in slide-in housings which are provided with a corresponding front panel: Such front panels might be obtained from CNC manufacturers.

On the back + 12V DC must be supplied as operating voltage. For the power supply units, we opted for linear power supplies because we have made the best experience with these without interference. For a distribution unit with 4 slots, a power supply with 12V 1A is sufficient – each distribution block takes about 55 mA, an active antenna up to 150 mA, so even with “full load” a power supply with 1 A is sufficient. The distributor was tested with various well-known active and passive antennas, including a PA0RDT MiniWhip, active loops, long wires and T2FD.

Due to the wide input voltage range, the module can handle nearly any antenna. The cost for a distributor for 4 antennas amounts  (depending on the version: housing, sockets, switches, power supply, etc.) to about 700-1000 €. That may seem a lot at first glance. However, taking into account that a simple 5-gang distributor from mass production costs already around 250 ¬, the cost of the distribution of 4 antennas to each up to 12 outputs are not that much. The Friends of Radio NRW use two of these distribution units for SWL camps.

If you are interested in building one, please contact the author (dh4jg@darc.de) for further information. The development history of the distribution unit is also available at www.dx-unlimited.eu.


Wow!  What a beautifully engineered antenna distribution solution, Joachim!  I love how you worked together to sort out all of the requirements for your system then build it for ultimate performance and flexibility.  No doubt, you and your colleagues at  Radiofreunde NRW posses a lot of design and engineering skills!  Simply amazing and thank you for sharing your design with the radio community!

Contact Joachim for more details and check out notes and discussion at www.dx-unlimited.eu (may require registration).

Spread the radio love

Videos from DXcamp Marajó Island, November 2019

Photo: Ivan Dias & Martin Butera, during the first Dx-Camp 15.61 Crew Radio Listeners’ Marajó Island – Amazon Rainforest, North of Brazil – November 2019

Many thanks to SWLing Post contributor Martin Butera, founding member of the 15.61 Crew, for the following guest post:


The 15.61 Crew Radio Listeners, Martin Butera and Ivan Dias, give us a small video preview made in the first Dx-Camp on Marajó Island in the Amazon Rainforest, North of Brazil on November 2019.

There are more than 11 hours of SDR recordings and videos of the Ultralight radios, which will take much additional time to process, of course.

Crew is working on the report with a complete story that includes videos and photos of everything experienced during the DX-Camp–this will be published in several languages and the first LOG, which we estimate will be the first months of the South American summer 2020.

We recommend not forgetting to periodically visit the official site of the DX-Camp, to find updated information: https://dxcamp-marajo2019.blogspot.com/

Above, you’ll see a short stretch of the medium wave band with plenty of interesting content: 585 kHz, alternating between National Radio of Spain (Madrid), BSKSA (Saudi Arabia), 590 kHz, alternating with Poty Radio (Crateús / CE), Radio Diffuser (Boa Vista / RR) and Radio Continental (Buenos Aires), 594 kHz BSKSA (Saudi Arabia), 595.9 kHz SNRT (Morocco – operating off-frequency for years), 600 kHz Mirante Radio (São Luís / MA), Vale Radio (Barreiras) / BA) and Radio Gaucha (Porto Alegre / RS) and 603 kHz National Radio of Spain (Sevilla).

Videos

All of the following videos were captured during the November 2019 Dx-Camp:


Brazil is a country with vast continental distances. The following three videos showcase Brazilian radio from across the country.

Radio Diffuser Boa Vista (1408 km distance)

Radio Itatiaia 2191 (km distance)

Radio Band B (2747 km distance)


Photo: Ivan Dias & Martin Butera, during the first Dx-Camp 15.61 Crew Radio Listeners’ Marajó Island – Amazon Rainforest, North of Brazil – November 2019

More photos of the DX-Camp from the official site:

https://dxcamp-marajo2019.blogspot.com/p/photos.html

Spread the radio love

Guest Post: Radio Seribatu’s Three FM Stations Launch on January 1st, 2020

Radio Seribatu FM Tower

Many thanks for the following guest post about SWLing Post supporter, Mark Fahey, who will soon be launching three local Balinese radio stations:


Radio Seribatu New Year 2020

A 2018 personal DX-pedition by SWLing Post supporter Mark Fahey to a remote village community in Indonesia’s Bali Province was intended to capture and record local and regional MW and SW Tropical Band spectrum on a WinRadio Excalibur for the Radio Spectrum Archive.

The field trip took a most unexpected turn; It was a total failure. Mark didn’t suffer any equipment problems, the loop antennas performed well; the problem was that MW, SW radio was irrelevant to the local population and there were just no longer any local stations broadcasting to archive.

Mark hanging backstage for Radio Volcano

To salvage the experience, Mark shifted his focus to recording video and audio of local gamelan and soundscapes. Seen as a strange novelty by the local jungle community, Mark was soon allocated land, the village built him a house and he has become the first foreigner to ever become a resident of the district and village.

Radio Seribatu Studio Building Studios are on Lower Levels of the house

In return, he has undertaken a project to introduce, and up-skill the village in sustainable eco-industries and educate the village millennials on how to manage these ventures using digital technologies. A component of the project has seen the establishment of three radio stations broadcasting 100% Balinese content. They are the first 24-hour radio stations in the province.

For the last six months, the three stations, Radio Seribatu – Village; Radio Seribatu – Volcano and Radio Seribatu – Mesin have been building the studio complex, solving power and bandwidth issues and training the staff. The network licensing is now permanently allocated and at midnight on January 1st, the test transmissions finish and the three stations officially open.

Each station brings many firsts to the region. They are the first to broadcasts 24 hours per day in the province, the first to broadcast 100% Balinese content and the first to deploy a fully digital workflow and studio complex.

Radio Seribatu Studio A sports state-of-the-art digital workflow

Late February, Mark is presenting a deep dive of the stations in a presentation at the upcoming NASWA Winter SWL Fest in Philadelphia, and at that time the SWLing Post will present a detailed tour of the network, discuss the journey, how unexpected twists and turns were overcome, and explain how Radio Seribatu’s test broadcasts in less than twelve months have reached the third most listened to radio network in all of Indonesia.

Most (if not all!) SWLing Post readers are beyond Radio Seribatu’s FM footprint; however, the majority of the station’s listeners tune in via their IP web streams and so can you! You will find the stations in most online radio directories, iOS and Android Apps and new generation factory fitted car radios (including Buick, Hyundai, Subaru, Mazda, Chevrolet, VW, BMW, GMC, Ford, Chrysler, Kia, Honda, Audi, Toyota, RAM, etc.).

Radio Seribatu Worldwide on Car Radio

A sure-fire way to listen is via the stream links on their website www.radioseribatu.com

 

On the Radio Seribatu VILLAGE station, you will hear everything that is happening around Seribatu village and wider across the island. This is the place to hear live gamelan, festival broadcasts and discussions about issues affecting the community.

On VOLCANO, the playlist is 100% Balinese Indi Rock, Alternative and Punk. 24 hours per day this is the place to hear Balinese bands.

On MESIN Radio Seribatu is playing 100% Balinese Electronic, Trance, House, Techno and Dance.

Each station’s test transmissions are on air right now and continue up until 6 PM Bali Time on New Year’s Eve, December 31st (1000 UTC December 31st). Then all three stations will be in simulcast, presenting a 6-hour special soundscape/actualities program that allows the listener to experience the tropical sounds of Seribatu. With the stroke of midnight; at the beginning of the new decade, all three stations launch into their regular programming.

Putu and Radio Seribatu_s Scoppy

Radio Seribatu is QSLing anyone who listens in, be it via stream or FM. Simply send a hello note and brief report of reception to info@radioseribatu.com and in return, you will receive a limited edition QSL, complete with an exotic postage stamp, posted directly from the Balinese jungle. No return postage required!


Here’s a rundown of what you can hear on the 31st December 2019 launch broadcast:

1000 UTC – (6:00 PM Bali Time)

Puja Tri Sandya Prayers

The Trisandya (from Sanskrit ??????????? ??? , Trisandhy? Puja, “three-evening prayer”) is a commonly-used prayer in Balinese Hinduism. It is uttered three times each day: 6 am, noon, and 6 pm, somewhat reflecting the Muslim azan prayers heard in other parts of Indonesia.

1005 UTC – (6:05 PM Bali Time)

Seribatu Village Awakens

Most Balinese families live within a family compound in villages that may have a population of around 700 – 800 people. In Seribatu the family compounds typically contain several homes for different members of the extended family. A typical home compound may comprise up to three families and grow to approximately 30 people. The village stirs to life just before the crack of dawn; roosters crow and chickens are fed. Early morning is a busy time in Seribatu, listen for village drums, Motor Bikes and Scooters heading off to the Dawn Market, Women sweeping their homes with a wicker brush, crickets chirp, and villagers trade at the dawn market. School starts early, and before the heat the day the Indonesian National Anthem is recited.

1017 UTC – (6:17 PM Bali Time)

Balinese Wisdom – The Song of Morality

Please don’t ever think you are very Clever; Let people either say you are good or great.

1019 UTC – (6:19 PM Bali Time)

Morning Market

Simple Seribatu village compounds do not have a refrigerator. Meat, fish and other food are purchased the local central market at dawn and the following few hours before the heat of the day descends. Farmers trade their vegetables and other produce. Merchants sell hardware and household supplies. Minivans packed to the roof with purchased fresh produce maneuver around the narrow lanes of the market.

1044 UTC – (6:44 PM Bali Time)

Ducks in the Rice Fields

Rice is a staple food in Bali, and it has strong ties to the Balinese culture. The cycle of rice growth pretty much sets the tone for much of the traditional Balinese life. The Balinese community views rice as a gift from God and a symbol of life. For thousands of years, the Balinese people have been growing rice and cultivating the beautiful rice terraces of Bali where three kinds of rice are grown: white rice, black rice, and red rice.

1102 UTC – (7:02 PM Bali Time)

Balinese Cleansing Ceremony

This ceremony is intended to cleanse the bhuana alit (the inner world of the individual human being or the micro-cosmos) of negativity so that he/she will be able (again) to enclose and utilize this inner power in an appropriate, spiritual way. The symbolism of this ceremony is intended to remind the individual to guard himself against the selfish desires and actions of the ego in favor of the unselfish goals of the soul or higher self. One prays for a clear mind with positive thinking and for strength to keep one’s self- control in situations where negative emotions are bound to arise.

1114 UTC – (7:14 PM Bali Time)

Satria Bird Market

As a popular Indonesian saying goes, a man is considered to be a real man if he has a house, a wife, a kris (dagger), and a bird. Keeping wild birds as pets is a massively popular hobby in many parts of Indonesia. The better the bird sings, the higher the demand for it. On a visit to Bali’s Satria Bird Market, you will see many thousands of birds from hundreds of species. Many of the birds are caged in poorly maintained conditions. Among the strangest are vendors who keep birds in bags, from unfledged chicks still in nests to breeding adults.

1115 UTC – (7:15 PM Bali Time)

Bats at the Goa Lawah Temple

One of nine sacred temples on the island of Bali, the cave temple of Pura Goa Lawah is home to thousands of bats. If the local legend is to be believed, it also hides a river of healing waters and a titanic snake wearing a crown.

While the site had no name when the temple was built, it gained its name due to the thousands of bats that cling to the ceiling and walls of the natural chasm, “Goa” meaning “cave” and “Lawah” meaning “bat.” It is thought that the cave may extend through the mountain right to a nearby town. The legend goes that the dark recesses of the tunnel are home to a mythical snake king known as Vasuki, a massive naga that wears a crown on his head. He is said to live on the copious amounts of bats in the cavern. Yet another legend claims that a river of miraculous healing waters rushes through the depths of the cave.

1120 UTC – (7:20 PM Bali Time)

Balaganjur Traditional Musicians Rehearsal

Baleganjur music is an inseparable part of life and death in Bali, heard in every village across the island. Its traditional purpose is to accompany funeral processions, so this intensely rhythmic yet dignified ensemble has a permanent role in Balinese society. The musicians play their instruments as they walk, and due to this portability, Baleganjur is now a fixture of all celebratory processions. A standard Baleganjur ensemble consists of about 20 musicians, plus helpers to carry gongs, but these days in Bali bigger is better!

1155 UTC – (7:55 PM Bali Time)

A Brief Balinese Radio Interlude

Listeners phone in and sing, callers discuss the terrorist bombings in Bali, Rinso (Indonesia’s most popular detergent) Soap Powder advertisement and how to cure a stubborn cough.

1242 UTC – (8:42 PM Bali Time)

Subak – Water Irrigation

Subak is a traditional ecologically sustainable irrigation system that binds Balinese agrarian society together within the village’s Bale Banjar community center and Balinese temples. For the Balinese, irrigation is not simply providing water for the plant’s roots, but water is used to construct a complex, pulsed artificial ecosystem. The water management is under the authority of the priests in water temples, who practice Tri Hita Karana Philosophy, a self-described relationship between humans, the earth and the gods.

1255 UTC – (8:50 PM Bali Time)

Temple Ceremony

In Bali, there are over 4,500 temples where ceremonies take place almost every day of the year. Temple festivals are held on the anniversary of when the temple was consecrated and usually on a new or full moon.

An Odalan or temple ceremony usually lasts for three days, but larger ones, which occur every 5, 10, 30 or 100 years, can last for 11 days or longer. The Balinese are honoring the deities that rule over the temple by giving them a myriad of offerings, performances of vocal music, dance and gamelan music. They invite them down from their abode on Mount Agung to partake in the activities. Every ceremony in Bali is to maintain the natural balance of positive to negative, so the Balinese do not destroy the negative forces, but balance them in harmony with the positive.

1426 UTC – (10:26 PM Bali Time)

Seribatu Evening

As the end of the year and the decade approaches, the sounds of frogs, crickets and tropical rain delight the ear while a cool bottle of Bintang refreshes your thirst.

1505 UTC – (11:05 PM Bali Time)

Radio Seribatu Countdown to Launch

Sinaga Goatama’s (Mendira Village) original electronic composition “Blazing Fire” guides us to midnight and the launch of regular programming on all three Radio Seribatu stations.

1600 UTC – (Midnight AM Bali Time)

It’s 2020 and Radio Seribatu has Launched!

All three of Radio Seribatu’s Radio Stations; Village, Volcano and Mesin radio are officially on-air, and commence their regular programming!


Wow, Mark! This is a most impressive endeavor and, no doubt, all three Seribatu stations will have a loyal following in Bali and across the planet! I’ve already become a fan of MESIN! 

We wish you and the Seribatu staff/volunteers massive success in your 2020 launch year!

Post readers: Again, Radio Seribatu, is QSLing anyone who listens in. Send a brief, accurate report and you will receive a limited edition Seribatu QSL. Send all reports to: info@radioseribatu.com

Spread the radio love

Guest Post: Decoding WEFAX using an RSP SDR and SDRuno

Many thanks to SWLing Post contributor, Mike Ladd with SDRplay, who shares the following guest post:


Basics to decoding WEFAX using an RSP and SDRuno

by Mike Ladd

SDR I use:
RSPduo from SDRplay using the Hi-Z input. Any model RSP’s can tune WEFAX transmissions. https://www.sdrplay.com/rspduo/

Antenna I use: Megaloop FX from Bonito. In an Inverted delta loop configuration pointed N/E-S/W. Any good antenna placed outdoors should be fine. It’s all about the SNR, not your S-meter reading. https://www.bonito.net/hamradio/en/mega-loop-fx/

Software:

SDRuno v1.32
SDRuno is an advanced Software Defined Radio application platform which is optimized for use with SDRplay’s range of Radio Spectrum Processing receivers.
https://www.sdrplay.com/downloads/

VBcable (donationware) vPack43
Transfers audio, digitally from one application (SDRuno) to another (Black Cat HF weather Fax) with zero loss.
https://www.vb-audio.com/Cable/

VAC (paid for use) v4.60
Transfers audio, digitally from one application (SDRuno) to another (Black Cat HF weather Fax) with zero loss.
https://vac.muzychenko.net/en/
https://www.sdrplay.com/docs/SDRuno_VAC.pdf

Black Cat HF Weather Fax (paid for use) beta 19
Decodes and produces images from the WEFAX transmissions from the output of SDRuno using a virtual audio cable.

Use the discount link available here
http://blackcatsystems.com/register/black_cat_hf_weather_fax_sdrplay_promo.html
https://www.blackcatsystems.com/software/hf_weather_fax.html

Black Cat Uno UDP
UnoUDP allows you control SDRuno’s VFO frequency from within Black Cat HF Weather Fax scheduler. This is done over a virtual com port pair using a virtual com port emulator. http://blackcatsystems.com/download/UnoUDP.zip

VSPE or COM0COM
VSPE is a paid for use app. COM0COM is completely free. Either one of these applications will work. A virtual com port emulator allows you to create a virtual com port. The pair will internally link Black Cat Weather Fax decoder to SDRuno’s using UnoUDP as the transport protocol.

VSPE http://www.eterlogic.com/Products.VSPE.html
https://www.sdrplay.com/docs/SDRuno_VSPE.pdf

COM0COM http://com0com.sourceforge.net/
https://youtu.be/dZg7puQ9Ajk

Introduction:

(some text taken and edited from various website)

This document is not a definitive guide to the WEFAX protocol, the process of decoding WEFAX images or reading a synoptic weather chart https://youtu.be/kzfNSvQREu8. This is only a collection of information that I have found scatter throughout the internet and re-compiled into a document, this document. Expect typographical mistakes, inaccuracies, or omissions.

WEFAX is an analog mode for transmitting monochrome images. It was the predecessor to slow-scan television (SSTV). Prior to the advent of the commercial telephone line “fax” machine, it was known, more traditionally, by the term “radio facsimile”.

Facsimile machines were used in the 1950s to transmit weather charts across the United States via land-lines first and then internationally via HF radio. Radio transmission of weather charts provides an enormous amount of flexibility to marine and aviation users for they now have the latest weather information and forecasts at their fingertips to use in the planning of voyages.

Radio fax relies on facsimile technology where printed information is scanned line by line and encoded into an electrical signal which can then be transmitted via physical line or radio waves to remote locations. Since the amount of information transmitted per unit time is directly proportional to the bandwidth available, then the speed at which a weather chart can be transmitted will vary depending on the quality of the media used for the transmission.

Radio fax data is available from the web on sites such as the ones hosted by the National Oceanic and Atmospheric Administration (NOAA). https://tgftp.nws.noaa.gov/fax/marine.shtml Radio fax transmissions are also broadcasted by NOAA from multiple sites in the country at regular daily schedules https://www.nws.noaa.gov/os/marine/rfax.pdf. Radio weather fax transmissions are particularly useful to shipping, where there are limited facilities for accessing the Internet.

Black Cat HF Weather Fax is a program that decodes WEFAX (Weatherfax, HF-FAX, Radiofax, and Weather Facsimile) transmissions sent from fixed locations around the globe.

A fax is transmitted line by line, typically at a rate of 120 lines per minute, or half a second per line. For example, to send a weather chart, you would start in the upper left corner. You would send the value of that pixel (dot), black, white, or perhaps a shade of gray. Then you would move over one pixel to the right, and send that pixel, and so on, until you reach the edge of the chart. Then you’d move all the way back to the left edge, and move down slightly, one line, and repeat the process.

Each pixel is converted into a certain audio frequency or tone. By convention, a tone of 1500 Hz represents black, 2300 Hz represents white, and frequencies in-between represent shades of gray. So if you listen to a fax transmission, you’ll hear the different tones as each pixel is present. For example, listen to a chart with mostly white background being sent. You’ll hear mostly the high pitch 2300 Hz, and some lower (1500 Hz) blips as each black pixel is sent. When a horizontal line is sent, you’ll hear a long half second burst of 1500 Hz, since the line is all black.

The transmitting station frequency modulates the carrier. That is, when a black pixel is transmitted, the carrier shifts down 400 Hz. When a white pixel is transmitted, the carrier shifts up 400 Hz. For a medium gray pixel, it stays on the assigned frequency. This is how most fax transmissions are made. Since we’re tuning it in SSB, it sounds to us as if the station is transmitting a variable frequency audio tone. The two processes are identical. This accounts for the confusion regarding what frequency to tune the radio to in order to properly decode the fax transmission. Different stations list their frequency in different ways. It is important to remember that a black pixel produces a 1500 Hz tone, and a white pixel produces a 2300 Hz tone within the AUX SP.

The setup works as follows. SDRuno demodulates the received signal. The demodulated audio is piped from SDRuno using virtual audio cable and sends it to the HF weather fax decoder. HF weather fax decoder receives this audio from the virtual audio cable that was demodulated from SDRuno and processes it, producing a picture on the screen

HF weather fax decoder can also set the VFO (tune) frequency of the RSP in SDRuno. This is done over the virtual com port pair using the UnoUDP application as the transport.

SDRuno can internally emulate a Kenwood TS-480, UnoUDP sends the Kenwood TS-480 serial commands via UDP over the virtual com port pair in order to set the frequency selected from the HF Weather Fax Scheduler option over to SDRuno.

You will need to install and configure the following applications.

1: A virtual audio cable.

2: A virtual com port emulator (If you would like HF Weather fax to communicate with SDRuno).

3: UnoUDP (If you would like HF Weather fax to communicate with SDRuno using the virtual serial emulator).

4: HF Weather Fax.

5: A simple wire antenna placed outdoors.

Virtual Audio Cable:

A virtual audio cable allows you to pipe the audio from one application (SDRuno) into another application (a decoder like HF Weather Fax) digitally. I will assume SDRuno is already installed with your device attached and functioning properly.

You can now download a virtual audio cable package.  If you already have a virtual audio cable package installed, you can skip to the next section. If you don’t have a virtual audio cable application installed, you only need to choose one and install only one of the two that are available.

Close any running apps, install the virtual audio cable and reboot your computer. When your computer boots to your desktop, your computer will now have a virtual audio cable pair installed on the system.

You can verify it the installation by going to your Control Panel and double clicking the Sound icon. VB-Cable and Virtual Audio Cable will only install a single virtual audio cable pair, one is for the input (Recording) and one is for the output (Playback). A single pair is all that is needed (as shown below).

Virtual Serial Port:

A virtual com port emulator is only needed if you would like Black Cat HF Fax decoder the ability to tune the station in SDRuno when you double click a station name in the HF Fax Decoder scheduler.

Please use the links provided (additional PDF’s and YouTube videos) on Page 2 of this document for an installation / configuration walkthrough.

You can download my WEFAX frequency bank for use in SDRuno below should you choose not to use a virtual com port emulator. https://signalsacrossthepond.com/download/mike-kd2kog-sdrplay-complete/

Download Black Cat HF Weather Fax and UnoUDP:

Download the latest HF Weather Fax beta package and the UnoUDP application from the link provided on Page 2 of this document. I suggest making one main folder called HFfax and two subfolders within HFfax for each of the applications. One folder is for the HF Weather Fax Decoder and the other folder is for the UNO UDP transport application.

Double click the HF Weather Fax beta ZIP file you downloaded and extract the full contents of this ZIP into the folder you created on your local drive. Right click the “Black Cat Weather Fax” EXE file and send a shortcut to your Desktop.

Double click the UnoUDP zip file you downloaded and extract the full contents of this ZIP into the folder you created on your local drive. Right click the “UnoUDP” EXE file and send a shortcut to your Desktop.

You should have two shortcuts on your desktop, One for the decoder and one for the transport app.

Black Cat UnoUDP:

HF Weather Fax needs a way to communicate with SDRuno, this is done via UnoUDP and the virtual com port emulator.

Launch UnoUDP with the above configuration. Set your UDP Receive port to 58084 and your UDP send port to 58083. UnoUDP must be left running in the background, this will control SDRuno. You can minimize the application or right click the shortcut and have UnoUDP auto minizine on launch.

You should see a Firewall popup prompt asking permission to allow UnoUDP to pass data within the system. You must allow this traffic to pass or external control of SDRuno will not be possible from the HF Weather Fax decoder scheduler.

Assign 1 of the 2 com ports from the virtual com port emulator to UnoUDP (the 2nd com port will be assigned to SDRuno).  My com port pair is Com 1 and Com 2, SDRuno uses Com1 and UnoUDP uses Com 2.

Black Cat HF Weather Fax:

HF Weather Fax needs to be configured in order to communicate with UnoUDP, this is done via the UDP settings. Click “Edit” and “Preferences” Set the UDP Send port to 58084 and the UDP Receive port to 58083.

You should see a Firewall popup prompt asking permission for HF Weather Fax to pass data within your system. You must allow UDP traffic to pass or external control of SDRuno will not be possible from the HF Weather Fax decoder scheduler.

SDRuno:

SDRuno needs its Output assigned to the Virtual Audio Cable. The output can be changed via the RX CONTROL panel, clicking the SETT. button on the top left and clicking the OUT tab.

SDRuno needs a com port assigned so it can be externally controlled. The serial port is assigned via the RX CONTROL panel, clicking the SETT. button on the top left and clicking the CAT tab.

I recommend running the RSP in LOW-IF mode, this is selected via the MAIN panel. This reduces the need to track separation between the Tuned frequency and LO (local oscillator) https://youtu.be/Fsns4P3JxrM

LOW-IF mode also minizines the LO being placed outside of the desired preselect filter of the device in use, Remember the preselect filter is automatically enabled based on the LO frequency https://youtu.be/w-vkiVp7Q4E

I also recommend leaving the IF AGC enabled and placing the RF GAIN as high as possible without causing an ADC OVERLOAD warning within the MAIN panel. If an ADC OVERLOAD warning appears, back the RF GAIN down.

https://www.sdrplay.com/wp-content/uploads/2018/06/Gain_and_AGC_in_SDRuno.pdf

Your first WEFAX decode (Using UnoUDP)

Launch UnoUDP and minimize it.

Launch Black Cat HF Weather FAX.

Launch SDRuno. Set the mode to USB and the filter width to 2.8k
HF weather fax will not set the mode or filter width at this time.

Click the Sked button in Black Systems HF Weather Fax. A current WEFAX transmission schedule will appear. Stations listed in White are either scheduled to transmit or about to transmit based on your computers clock. Stations show in Grey at the bottom of the list are currently off the air or not transmitting.

In the Freq Offset: box enter -1.9 and hit enter (Reason for this is on Page 5).

Click any of the stations listed in the Fax Transmission Schedule and it will automatically tune SDRuno to the correct frequency.

Black Cat HF Weather Fax folder will have a file named “Black Cat HF Weather Fax Docs” Please view this file to understand some of the advanced features available.

Your first decode (Without UnoUDP)

Launch Black Cat HF Weather FAX.

Launch SDRuno.

Navigate to the Memory Panel (MAIN panel and click the MEM PAN button)

Right click the Memory panel and select “Open bank”. Navigate you C drive telling SDRuno the location of WEFAX.s1b

Double click any of the frequencies shown within the WEFAX bank and SDRuno will set the correct mode and tune that station.  My WEFAX.s1b file defaults to the Hi-Z port. If your device lacks a HI-Z input, navigate to the port section within the memory panel, double click the stations port you want to edit and change it to the correct port that’s available or in use for your device. Right click the memory panel and “Save bank” to save the changes.

To use my SDRuno WEFAX frequency bank properly. The MCTR button must be enabled within the RX CONTROL panel, enabling this option allows you to double click and tune a station that is stored within the WEFAX bank. Make sure the LO is not locked in the MAIN panel (LO LOCK).

If a decoded WEFAX image looks blocky or skewed or possibly pixeled, I recommend that the lock output fractional resampler option is enabled in SDRuno. You can enable this from the RX CONTROL panel, clicking the SETT. button on the top left and clicking the OUT tab.

I hope this document helped guide you in getting started with decoding WEFAX transmissions from around the world. I am sure I missed some key features, remember this is only a primer/basics to decoding WEFAX. I do have an accompanying video located here

https://youtu.be/vAYGVimzNX8

Warmest of 73,
Mike-KD2KOG

Disclaimers

SDRPlay modules use a Mirics chipset and software. The information supplied hereunder is provided to you by SDRPlay under license from Mirics. Mirics hereby grants you a perpetual, worldwide, royalty free license to use the information herein for the purpose of designing software that utilizes SDRPlay modules, under the following conditions:

There are no express or implied copyright licenses granted hereunder to design or fabricate any integrated circuits or integrated circuits based on the information in this document. Mirics reserves the right to make changes without further notice to any of its products. Mirics makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does Mirics assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation consequential or incidental damages. Typical parameters that may be provided in Mirics data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters must be validated for each customer application by the buyer’s technical experts. SDRPlay and Mirics products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the Mirics product could create a situation where personal injury or death may occur. Should Buyer purchase or use SDRPlay or Mirics products for any such unintended or unauthorized application, Buyer shall indemnify and hold both SDRPlay and Mirics and their officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that either SDRPlay or Mirics were negligent regarding the design or manufacture of the part. Mirics FlexiRFTM, Mirics FlexiTVTM and MiricsTM are trademarks of Mirics .

SDRPlay is the trading name of SDRPlay Limited a company registered in England # 09035244.

Mirics is the trading name of Mirics Limited a company registered in England # 05046393


Do you enjoy the SWLing Post?

Please consider supporting us via Patreon or our Coffee Fund!

Your support makes articles like this one possible. Thank you!

Spread the radio love

Mike’s tips for decoding SW Radiogram broadcasts

Many thanks to SWLing Post contributor, Mike (KA3JJZ), who writes:

Have you ever heard of the SW Radiogram digital broadcasts? These are produced by Dr. Kim Andrew Elliott and started way back when as the VoA Radiogram. They are now carried on 2 other stations (WRMI and WINB) on a schedule (check every week for a summary of images) that you can find on the SW Radiogram website;

https://swradiogram.net/

These tests consist of both text and images. Currently MFSK32 and 64 have been used, and an occasional ‘secret’ mode has been slipped in at the end of the transmission. The last time this was done, the mode was PSK125R.

You might ask how you can receive these broadcasts, and what you need to decode them. We have 2 wiki articles that go into great detail – one for PCs, and one for Android devices – here;

https://wiki.radioreference.com/index.php/Decoding_the_SW_Radiogram_Broadcasts

https://wiki.radioreference.com/index.php/Decoding_the_SW_Radiogram_Broadcasts_with_TIVAR

Yes, you can copy these broadcasts using an Android powered phone or tablet using an application called TIVAR. John VK2ETA has written a quick start guide which is available on the SourceForge website as well as the RadioReference wiki (the links are provided in the article)

These articles are written for folks who are just getting their feet wet, so the above articles touch on radios (no, you don’t need to use an expensive radio, though many do), antennas, propagation and more. The most popular software is FLDigi, but if you happen to have MultiPSK or DM780 (part of Ham Radio Deluxe), they can be used as well. Links are given for the software and any available support.

Along with Tumblr, SW Radiogram has both a Facebook and Twitter page (where members often post decoded images) here…

https://www.facebook.com/groups/567099476753304/

https://twitter.com/swradiogram

Thank you, Mike! Yes, I’m a big fan of the SW Radiogram–the community that has formed around this particular shortwave program is quite amazing. Thanks for all of the tips!

Click here to view the SW Radiogram website.

Spread the radio love

Paul’s report from the UK’s National Hamfest

Many thanks to SWLing Post contributor, Paul W4/VP9KF, who shares the following report from the UK’s National Hamfest:


Your travelling foreign correspondent took in a visit to the UK’s National Hamfest held in Newark, Notts.

We arrived right on opening time (10am) and were the first in the door.

There was a ‘rush’ to the SDRPlay stand because they were giving away some nice FLASH drives to the first 25 people to get there. The author managed to get one and later found it was a) fast b) pre-loaded with software for all things SDRPlay. They were busy showing the new diversity software amongst other things.

bhi had some new hardware and I took the chance to thank them for a prize won in the W5KUB Xenia draws.

The hall was pretty empty (this was the second day and a Saturday). Noticeable was that some products were already sold out and on back order [such as the amazing nanoVNA].

It’s a shadow of the former Leicester Show which was the precursor to this event with a lot less parts on sale.

I had a long chat with Eric of Elecraft while twiddling with the K4 and suggested some improvements to the button usage, which he said would be tested in use. A date of the ‘beginning of the year’ for first shipments was mentioned and that the first batch would be ‘large’ [much more than 100] followed by smaller batches. Components are on order, some of which are on long lead times (and have to arrive in good shape for surface mount assembly down the line).

The K4 was ‘playing’ the 7 Area QSO Party on several bands and most controls were operable. This was streaming from an IQ recording and an RF modulator straight into the rig. Just exactly how close this was ‘to the original sound’ and TRUE performance of the rig and/or software is
to be seen.

The weather was fine for the show (although patchy – XYLs reported that it poured with rain back in Nottingham itself!). Turnout was very disappointing and a lot of grey hair was to be seen in the one (yes one) Hall Building.

73,

Paul W4/VP9KF [and G4BKI]


Thank you so much for the report, Paul. I do want to make a pilgrimage to the UK’s National Hamfest one year–any excuse to visit my home-away-from-home country! 

Spread the radio love