Tag Archives: Paul Evans (W4/VP9KF)

The Birth of Radar Memorial

Photo by Amanda Slater

Many thanks to SWLing Post contributor, Paul Evans, who writes:

Interesting article on the new monument to radar between Daventry and Towcester in Northamptonshire, UK.

https://www.atlasobscura.com/places/birth-of-radar-memorial

Legend has it that this was conducted around 25-28 MHz, which was the very top end of higher power RF at the time.

The location sits closer to Towcester, although the event is always quoted as having taken place at Daventry (the source, not the receiver).

It’s fascinating that Plessey Research Caswell was set up almost immediately, not very far away and was heavily involved in radar and other solid-state research through to the 1990s.

[Disclosure: the author (Paul) worked at Plessey Caswell and was Two Terminal device Manager at Plessey Microwave, Towcester in the 1980s]

Many thanks, Paul, for sharing this fascinating bit of history.

Spread the radio love

Radio Waves: Sun Up-Close, Super NZ Public Broadcaster, One SDR, and ABC Emergency Broadcasting

Radio Waves:  Stories Making Waves in the World of Radio 

Because I keep my ear to the waves, as well as receive many tips from others who do the same, I find myself privy to radio-related stories that might interest SWLing Post readers.  To that end: Welcome to the SWLing Post’s Radio Waves, a collection of links to interesting stories making waves in the world of radio. Enjoy!

Many thanks to SWLing Post contributors, Paul Evans, Troy Riedel, Michael Bird, and Marty for the following tips:

Sun’s surface seen in remarkable new detail (BBC News)

Source: Daniel K Inouye Solar Telescope

Behold the Sun’s convulsing surface at a level of detail never seen before.

The Daniel K Inouye Solar Telescope on Hawaii has released pictures that show features as small as 30km across.

This is remarkable when set against the scale of our star, which has a diameter of about 1.4 million km (870,000 miles) and is 149 million km from Earth.

The cell-like structures are roughly the size of the US state of Texas. They are convecting masses of hot, excited gas, or plasma.

The bright centres are where this solar material is rising; the surrounding dark lanes are where plasma is cooling and sinking.[]

The New Zealand Cabinet plans to create a new, super-sized public broadcaster (Asia-Pacific Broadcasting Union)

It is understood the NZ cabinet has signed off on a high-level decision to proceed and to commission a business case, after the Minister for Broadcasting, Kris Faafoi, presented a revised paper on Monday.

There was pushback from some senior Labour and New Zealand First ministers about the way the preferred option was landed on, the implications for public broadcasting if RNZ ceased to be a standalone company, and the speed at which it had been progressing.

The plan was to work towards having the new media company in place by about 2023 and that appears to still be the goal.

RNZ was told the amended proposal puts a specific emphasis on the fact the new company will be primarily a public service media outlet, and to ensure that is made crystal clear in any legislation, and through a charter.[]

One SDR: A new website focusing on the basics of software defined radio

Good morning. I have been following SWLing over the years and it’s an amazing resource.

I’m writing from https://onesdr.com which is an Education website with articles that simplify Software-defined Radio. I write about practical aspects of SDR including associated components such as Low Noise Amplifiers, Filters, Bias Tees, etc. My goal is to demystify RF technology and make it more accessible to the growing community of SDR enthusiasts.

As well I have been contributing to several RF-related Wikipedia pages* to popularize RF and Wireless in general.

Interim Report of Survey of ABC Emergency Broadcasting in Bushfire Affected Communities (ABC Friends)

95% of respondents to ABC Friends’ Survey of ABC emergency broadcasting in bushfire affected communities believe there is a need for a national plan of additional essential communications infrastructure.

This devastating bushfire season attests to the ABC’s position as Australia’s pre-eminent emergency broadcaster. The number of ABC emergency broadcasts has risen from 256 in 2017-2018 to 371 in 2018-2019 to 673 to date this year (4 Jan). The ABC’s emergency broadcasts continue in the face of ongoing funding cuts and with no additional funding to cover the resources which have been poured into the effort.

On 3 January, via Facebook, ABC Friends National asked for feedback about the ABC’s emergency broadcasts from those affected by the bushfires. Whilst highly praised, there were reports that access to ABC broadcasts was sometimes a problem.

ABC Friends subsequent media release made an urgent call for the Federal Government to restore funding that guarantees infrastructure and transmission that is vital for emergency services broadcasting. It also advised of the launch of a survey (see appendix 1) to obtain more formal feedback about access to emergency broadcasts. This survey was delivered on 13 January via Facebook and via email through our membership and supporter base.

750 people responded to the survey.

91.1% of those surveyed said that the ABC local emergency broadcasts were important to them during the crisis.

96.1% of those surveyed said that ABC staff with local knowledge was important to them.

98.5% of those surveyed said that it was important to them that their local ABC outlet remain open and well-staffed.[]


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

A compact homebrew Si5351-based SDR

(Image source: Circuit Salad)

Many thanks to SWLing Post contributor, Paul Evans, who writes:

I see this receiver as a remarkable break through. Using audio processor to emulate modes from IQ is very, very clever. This is perhaps the article of the year!:

(Source: Circuit Salad)

[…]This is a revised version of my FV-1 based SDR. I replaced the CS2100 clk generator with the Si5351 clk generator. The Si5351 has some advantages over the CS2100, namely you can generate quadrature clks directly. This simplifies the hardware design and improves the quadrature accuracy. The sideband rejection in LSB/USB modes is impressive..somewhere around 60 db as best I can measure. The DSP processing is accomplished by the use of a FV-1 audio processor. The device makes the base band signal processing a snap. It requires some code to be loaded on a EEprom but the circuitry is simple and allows for up to 8 selectable programs. I created three: AM/USB/LSB . The FV-1 provides for three analog POT inputs to control any parameters you choose. Gain, variable filter bandwidth and depth, AGC are some examples of adjustable parameters if you desire. I kept it simple and created fixed band pass filters to taste. I did use one of the controls for AF gain. The design has no tuned circuits or band pass filters but they could easily be added.  It works just fine without them. Occasionally, I come across a ghost signal from harmonic mixing, when tuning, but not enough to matter. The design uses an OLED display and a rotary encoder for tuning. The frequency coverage is from 2.7 Mhz to 25Mhz. The bottom limit is created by the inability of the Si5351 to support quadrature below this frequency. Although I have improved my DSP programs for the FV-1 and have developed new display drivers and the new code for the Si5351, useful detail about using the Fv-1 can be found in my original design from a few years ago: https://circuitsalad.com/2015/06/19/comming-soon-stand-alone-software-defined-radio-baseband-demodulator-no-computer-required/

The design uses a LTC6252 low noise op amp as an RF input with gain. It provides a constant and reliable resistive Rf termination for the sampling detector.  This allows for random antennas to be used without adversely affecting the input termination to the detector. All the code to operate the main processor(display/clk generator/tuning, band select and receive mode) was written in MikroC which is a C compiler for PIC and AVR processors. The generation of quadrature signals out of the Si5351 is not difficult to implement once you know how but..figuring that out took me a couple weeks of experimentation! You can connect switches, the encoder, volume pot and display directly to the main board for operation but I created a secondary board to mount the display and encoders. Instead of an analog pot and selection momentary switches, I used another microcontroller and two encoders(with one built in momentary push switch each) to create all of the switching signals, gain control, etc. This allowed me to have just two controls for all features.  The controls include: tuning, audio gain, mode, and tuning step. Tuning resolution is from 1Hz to 100KHz . For fun, I made the output of the FV-1 differential into the audio amp. This is not necessary.

Here is a link to all the files used to build this radio in a zip file(updated 1/18/20):

https://www.adrive.com/public/Fq3pNr/Si5351%20SDR%20Data.zip[…]

Demo video

Click here to read the full article, download all design notes/files and watch videos at Circuit Salad.

Wow–that is fascinating! Thanks for sharing, Paul. I’m curious if any SWLing Post readers have experimented with the Si5351.

Interestingly, SWLing Post friend Dave Richards (AA7EE), also recently shared this video of an amazing Si5351-based VFO built by JF3HZB:

This must be one of the best analog emulations I’ve seen on a display. Marry the SDR receiver above to this VFO and you could have a top-shelf homebrewed receiver!

Spread the radio love

Ham CAP and VOA Prop: Fixing SSN look-up files

VOA Prop

Many thanks to SWLing Post contributor, Paul Evans, who notes:

Users of these two propagation prediction programs will find that they don’t work beyond Dec 2019 because the SSN look-up files didn’t go any further.

I noticed this 2-3 years ago and added to the end of the files required. I entered guesses for solar activity values, but with auto mode turned on they will fetch current values. At least this will get you started again. Or my guesses might be right!! 🙂

For Ham CAP use: http://w4.vp9kf.com/SSN.dat

For VOAProp use: http://w4.vp9kf.com/ssndata.txt

Download them and swap them into the directory where the application is located.

Thanks or the help, Paul!

Spread the radio love

VOA Museum featured in Atlas Obscura

VOA Bethany

(Source Atlas Obscura via Paul Evans W4/VP9KF)

The former Voice of America broadcast site at Bethany Station is now a museum. It covers the history and role of Voice of America, as well as the history of broadcast and radio itself.

Tucked into the former equipment bays are row upon row of early radio examples. You’ll spot everything from early broadcast equipment to novelty radios from the ’70s.

From 1944 to 1994, the site was used to broadcast news and information to Europe and North Africa. It was originally run by the Office of War Information. Adolf Hitler complained after a Cincinnati broadcaster impersonated him.

In 1963, the Voice of America took direct control of the broadcast facility. Using the expertise of the local Crosley Broadcasting Corporation’s engineers, enormous 250-kilowatt transmitters were built.

Although the towers were torn down in 1998, the Art Deco broadcast building remains, and houses the Amateur Radio Association, Media Heritage, and the Gray History of Wireless collections call the facility home.[…]

Click here to read the full article in Atlas Obscura.

Spread the radio love

Final step for proposed rule to allow AM broadcasters to use all-digital transmissions

Many thanks to SWLing Post contributor, Paul Evans, who notes:

The Federal Register has today published the proposed rule for AM stations to go digital. This is close to the final step.

https://www.federalregister.gov/documents/2020/01/07/2019-27609/all-digital-am-broadcasting-revitalization-of-the-am-radio-service

Comments before 2020-03-09, replies by 2020-04-06.

Thanks for the tip, Paul!

Spread the radio love