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ARRL Letter

The ARRL Letter
March 4, 2021
John E. Ross, KD8IDJ, Editor
ARRL Home PageARRL Letter ArchiveAudio News


Approaches to Tackle Noise Problems Vary, Remedies Elusive

RF noise is a frequent discussion topic among radio amateurs. A proliferation of electronics has cluttered and complicated the noise environment; it's not just power lines anymore. Unless isolated from civilization, most hams experience RF interference (RFI) and spectrum scopes on modern transceivers can make it much more apparent. Various approaches to address the apparently worsening noise floor have been taken around the world, some addressing lax regulation.

"We all want to enhance our ability to copy the weak ones by increasing our signal-to-noise ratio," Alan Higbie, K0AV, said in his March/April NCJ article, "Tracking RFI with an SDR One Source at a Time." He suggests practical methods for individual radio amateurs to improve their own noise environment. "We can do that by reducing the noise on each band that we operate. Lowering the noise floor increases the relative strength of weak signals. Those who live in typical residential environments find that locating and eliminating RFI sources is a never-ending process. It is much like weeding a garden."

The International Amateur Radio Union (IARU) warns against complacency. "Radio amateurs cannot sit back, because even if the desired noise limits are agreed, there are many rogue manufacturers

Small household "wall warts" are typically noisy switching power supplies.

and dealers who will happily sell noise-generating devices, leaving out filter circuits to cut costs," IARU said. The IARU has urged member-societies to get involved.

The FCC Technological Advisory Council (TAC) -- a Commission advisory group -- initiated an inquiry in 2016 looking into changes and trends to the radio spectrum noise floor to determine whether noise is increasing and, if so, by how much. The TAC had encouraged the FCC to undertake a comprehensive noise study in 1998, and cautioned the FCC against implementing new spectrum management techniques or initiatives without first concluding one. In 2017, the FCC Office of Engineering and Technology (OET) invited comments on a series of (TAC) spectrum-management questions. ARRL, in its comments, took the opportunity to strongly urge the FCC to reinstate the 2016 TAC noise floor study, which, ARRL asserted, was terminated before it even got started. ARRL urged the FCC to "depart from the traditional regulatory model" that placed limits only on transmitters and called for "a 'holistic' approach to transmitter and receiver performance."

  • ARRL offers a wide range of information on RFI on its website.

  • Paul Giancolo, W1VLF, will offer "Finding and Fixing RFI" as part of the ARRL Learning Network webinar series, on Tuesday, April 20, at 1700 UTC.

  • ARRL Northwestern Division Director Mike Ritz, W7VO, will offer "HF Noise Mitigation" as part of the ARRL Learning Network webinar series, on Thursday, April 22, at 1930 UTC.

Greg Lapin, N9GL, represents ARRL on the TAC and chairs the ARRL RF Safety Committee. "Perhaps the best result that we obtained was an indication that illegal devices, mainly LED lights, were in circulation, and the Enforcement Bureau agreed to look into it," he told ARRL. "We never heard what they found out, but recently, I was buying some LED bulbs over the internet from a site in Texas, and they were selling non-FCC approved lights -- and didn't seem to care." Lapin said his complaint went nowhere, and the TAC's focus has been nudged in the direction of addressing 5G issues.

The Deutscher Amateur Radio Club (DARC) has been working on developing a noise-measurement system that approximates methods used by the International Telecommunications Union Radiocommunication Sector (ITU-R). DARC reported that 35 of these electrical noise area monitoring systems (ENAMS) have been delivered, and it's seeking another 20 locations as part of the effort to monitor noise interference on the HF bands. DARC said the ENAMS can help to make scientifically reliable statements about interference levels.

IARU sees wireless power transmission (WPT) as an impending major noise threat, especially from WPT electric vehicle (WPT-EV) charging systems. "For the amateur service, given the planned density of WPT-EV systems, it is calculated that there will be a widespread and serious impact in the vicinity of WPT systems" from spurious emissions, said a 2019 EE Publishers article, written by "Amateur radio societies concerned about the HF noise floor." The article also said, "To ensure a low probability of harmful interference to radiocommunication services, further study is required." Read an expanded version.

ARISS, NASA, and ESA Continue to Probe Amateur Radio Problems on ISS

Amateur Radio on the International Space Station (ARISS) International Chair Frank Bauer, KA3HDO, reports that the ARISS team worked closely with NASA and the European Space Agency (ESA) this week to identify what may have caused what ARISS is calling a "radio anomaly" on January 27. The net result has been an inability to use the NA1SS ham station gear in the ISS Columbus module. For the time being, ARISS school and group contacts with crew members have been conducted using the ham station in the ISS Service Module. The radio issues came in the wake of a January 27 spacewalk, during which astronauts installed new cabling to support the commissioning of the Bartolomeo attached-payload capability mounted on the Columbus module. The job involved re-routing the antenna cabling to the ARISS radio system onboard Columbus.

Bauer said NASA, ESA, and ARISS would conduct a set of APRS (automatic packet radio system) tests to determine the operational status of the ARISS radio in Columbus through employment of three different cabling configurations. The tests would use the station's APRS capability on 145.825 MHz, with the crew periodically shutting down the radio and swapping cables. The tests were expected to wrap up by March 3. No results had been reported by March 4.

"We cannot guarantee that these troubleshooting tests will resolve the radio issue," Bauer said.

Bauer said that if the tests are unsuccessful, "a contingency task" has been green-lighted for a March 5 spacewalk (EVA). "This EVA task would return the ARISS cabling to the original configuration prior to the January 27 EVA," he explained, noting that a contingency task will only be performed if time allows.

"If you definitely hear the packet system working or are able to connect through it, let us know the date, time, and grid square of the occurrence," he added.

Quantum Receiver Can Detect Huge Swath of the RF Spectrum

US Army researchers have built a so-called "quantum sensor," which can analyze the full RF spectrum and real-world signals, a report on says. The quantum sensor -- technically a Rydberg sensor -- can sample the RF spectrum from 0 to 20 GHz and is able to detect AM and FM radio signals, as well as Bluetooth, Wi-Fi, and other RF communication protocols. The peer-reviewed Physical

A Rydberg receiver and spectrum analyzer detects a wide range of real-world radio frequency signals above a microwave circuit including AM radio, FM radio, Wi-Fi, and Bluetooth. [US Army, illustration]

Review Applied published the researchers' findings, "Waveguide-coupled Rydberg spectrum analyzer from 0 to 20 Gigaherz," coauthored by Army researchers Drs. David Meyer, Paul Kunz, and Kevin Cox.

"The Rydberg sensor uses laser beams to create highly excited Rydberg atoms directly above a microwave circuit, to boost and hone in on the portion of the spectrum being measured," the article explains. "The Rydberg atoms are sensitive to the circuit's voltage, enabling the device to be used as a sensitive probe for the wide range of signals in the RF spectrum."

Cox, a researcher at the US Army Combat Capabilities Development Command (DEVCOM) Army Research Laboratory, called the development "a really important step toward proving that quantum sensors can provide a new and dominant set of capabilities for our soldiers, who are operating in an increasingly complex electromagnetic battlespace."

Cox said earlier demonstrations of Rydberg atomic sensors were only able to sense small and specific regions of the RF spectrum, but "our sensor now operates continuously over a wide frequency range for the first time." The technology uses rubidium atoms, which are excited to high-energy Rydberg states. These interact strongly with the circuit's electric fields, allowing detection and demodulation of any signal received into the circuit.

Researchers use a Rydberg spectrum analyzer experimental apparatus at the DEVCOM Army Research Lab. [US Army, illustration]

The report says the Rydberg spectrum analyzer has the potential "to surpass fundamental limitations of traditional electronics in sensitivity, bandwidth, and frequency range."

According to Meyer, "Devices that are based on quantum constituents are one of the Army's top priorities to enable technical surprise in the competitive future battlespace. Quantum sensors in general, including the one demonstrated here, offer unparalleled sensitivity and accuracy to detect a wide range of mission-critical signals." Read an expanded version.

ARRL Podcasts Schedule

The latest episode of the On the Air podcast (Episode 14) takes a deeper dive into the subject of HF antenna tuners, including some shopping tips.

The latest edition of Eclectic Tech (Episode 28) features a discussion on grabbing NOAA weather satellite images at 137 MHz and a chat with Nigel Vander Houwen, K7NVH, about how he has combined rockets and high-altitude ballooning with amateur radio.

The On the Air and Eclectic Tech podcasts are sponsored by Icom. Both podcasts are available on iTunes (iOS) and Stitcher (Android), as well as on Blubrry -- On the Air | Eclectic Tech.

Moldova Peace Corps ARISS Contact is Successful

A March 3 Amateur Radio on the International Space Station (ARISS) contact between young people in Moldova with an International Space Station (ISS) crew member was a success. The Moldova Peace Corps (MPC) was the hosting organization, and 90 students (aged 10 - 18) from a consortium of educational institutions, rural schools, and libraries from nine Moldovan villages participated.

MPC promotes economic and civic development with a particular focus on developing local resources in rural and suburban communities. Another focus of MPC is to provide youth in Moldovan villages with access to STEM opportunities and build capacity among local teachers/librarians to implement STEM activities in their curricula.

During the multipoint telebridge contact, students took turns asking questions of astronaut Mike Hopkins, KF5LJG. ARISS team member David Payne, NA7V, in Oregon served as the relay amateur radio station.

In support of this contact, the MPC partnered with the staff at the Centre of Excellence for Space Sciences and Technologies within the Technical University of Moldova (UTM), the US Peace Corps Volunteer Coordinator, and the participating schools and libraries. The contact was livestreamed via the MPC and UTM Facebook pages.

ARRL is a partner in the ARISS program, which has kept amateur radio on the air from the ISS for 20 years. A hallmark of the ARISS program is the scheduled ham radio contacts made by ISS crew members with schools and student groups around the world.

North Carolina Radio Amateurs Adapt Tailgating Hamfest to the COVID-19 Pandemic

With many in-person hamfests canceled due to the COVID-19 pandemic, some radio amateurs in Raleigh, North Carolina, have come up with a way to adapt with a tailgate hamfest in an unused shopping center parking area. The event grew out of the so-called Ham Radio Taco Thursdays, begun many years ago by ARRL Life Member Alan Pitegoff, AB4OZ.

Pitegoff had to put his event on hold when the pandemic erupted. It was suggested that hams could gather and socialize at a safe distance by having a Taco Thursday with the taco truck outside in an adjacent empty parking lot. That event was a success, with participants remaining at their vehicles and bringing their own chairs. That success inspired holding a tailgate hamfest in the same spot, and it's now turned into a monthly event, called the AB4OZ Hamfest.

Pitegoff said Taco Thursday started collecting more people -- up to 15 or so -- and when Taco Bell closed due to the pandemic, the event moved to a Thursday on-the-air net, with one requirement -- that participants could not talk about COVID-19.

The tailgate hamfest was established at the new location and held once a month on Saturday at 10 AM.

"I think this is a great, uplifting, and positive experience for all of us hams to get out and socialize," participant Charles Murray, KI4DCR, said. "We might not be able to have a big hamfest, but these micro tailgate hamfests might be the future for a good while. I've met a lot of good people. There's a lot of cool stuff out here. The weather's great, you know, and there's plenty of space for everybody to be socially distanced. I think it's fantastic." -- Thanks to Martin Brossman, KI4CFS

ARRL Learning Network Webinars

Visit the ARRL Learning Network (a members-only benefit) to register, check on upcoming webinars, and to view previously recorded sessions.

Technicians: Life Beyond Repeaters -- Anthony Luscre, K8ZT

Maybe you just received your Technician-class license, or perhaps you have had it for a while and are burned out waiting for sparse FM repeater contacts. Take a new look at the possibilities available to you beyond repeaters. Explore Tech HF and 6-meter privileges for SSB, CW, and digital modes such as FT8, RTTY, and PSK31 to expand your operating modes and your station's outreach. Explore other VHF/UHF uses, including SSB, satellites, FM simplex, digital modes, contesting, and more.

Tuesday, March 9, 2021 @ 1 PM EST (1800 UTC)

The Art and Science of Operating Ultra-Portable -- Mike Molina, KN6EZE

Ultra-portable operation, or being able to carry your radio over distances (e.g., in a backpack), is quickly growing in popularity. Whether for SOTA, POTA, backcountry survival, or just spending time in nature, learning how to operate ultra-portable is a fun and rewarding experience. In this presentation, Mike, KN6EZE, will cover the basics of ultra-portable operating for both the new and experienced ham radio operator.

Tuesday, April 6, 2021 @ 8 PM EDT (0000 UTC on Friday, April 7)

The ARRL Learning Network schedule is subject to change.

Amateur Radio in the News

ARRL Public Information Officers, Coordinators, and many other member-volunteers help keep amateur radio and ARRL in the news.

Share any amateur radio media hits you spot with us.

Army MARS Volunteers Recognized with Gold-Level President's Volunteer Service Award

A dozen US Army Military Auxiliary Radio System (MARS) volunteers have been honored with gold-level recognition for the President's Volunteer Service Award for 2020. They are:

  • Bob Mims, WA1OEZ

  • Ron Tomo, KE2UK

  • Mark Bary, N4EOC

  • Billy Pearson, KO4XT

  • Dave Bock, W8OHS

  • Bob Baker, K5LLF

  • John Monson, WB0PLW

  • Gary Geissinger, WA0SPM

  • Brian Handy, W8JBT

  • Bliss Wheeler, W7RUG

  • Jim Hamilton, K4QDF

  • Daniel Wolff, KA7AGN

Each award recipient receives a letter signed by the President of the United States, a certificate of achievement, and a presidential volunteer service lapel pin.

Volunteer awards are based on the certifying organization's recommendation and the number of documented volunteer hours for the year. Gold-level volunteers must accrue a minimum of 500 hours volunteer time supporting the organization. Silver awardees must achieve 300 hours and bronze must achieve a minimum of 100 hours volunteer time.

Army MARS Chief Paul English, WD8DBY, was to conduct a virtual awards presentation on Thursday, March 4. -- Thanks to Paul English, WD8DBY

  • The Amateur Radio Contest DX Club (ARCDXC) will activate the C7A call sign during March, with activity SSB, CW, and digital modes on all HF bands, 1.8 - 28 MHz. C7A counts for Austria for DXCC purposes.
  • The ARRL International DX Phone Contest is March 6 - 7 (UTC), and the DX will abound. It's a chance even for modest stations to snag a few new contacts. In this major event on the radiosport calendar, the DX will be looking for you! Operators in the US and Canada work stations everywhere else in the world. It's not only an opportunity to pit your station and operating skills against those of your peers but to expand your knowledge of propagation on the HF and MF bands and tweak your contesting skills.
  • R125PR is a special event call sign to mark 125 years since the reputed "world's first radiogram." Sponsors say that historic event took place in 1896 when Alexander Popov at the Russian Physical and Chemical Society of Saint-Petersburg Imperial University sent the two words "Heinrich Hertz" a distance of 250 meters.
  • The Radio Society of Kenya (RSK) and the South African Radio League (SARL) have signed a formal memorandum of understanding. The SARL will assist RSK with the amateur radio examinations and administer the technical aspects of the examination on RSK's behalf and assist with training materials.
  • Members of the Northern Corridor Radio Group in Australia plan to activate Cocos (Keeling) Island -- VK9C (not to be confused with Cocos Island -- TI9). Cocos (Keeling) is #70 on the Club Log Most Wanted DXCC List. The vacation-style operation will take place March 16 - 23, using the call sign VK9CE. -- Thanks to The Daily DX
AMSAT-DL Operators Track Mars Probes

Members of Germany's AMSAT organization, AMSAT-DL, in cooperation with the Sternwarte Bochum Institute in Bochum, Nordrhein-Westfalen, Germany, have been using the institute's 20-meter (65.6-foot) diameter dish antenna to listen directly to signals from probes in Mars orbit. Signals have been copied from the Chinese Tianwen-1 and the Hope Emirates Mars Mission (EMM) spacecraft now orbiting Mars and transmitting in the 8.4 GHz band.

Recordings of the signals can be heard on YouTube with regular updates by following @amsatdl on Twitter.

In 2003, radio amateurs added phase-locked receivers in the 2.3, 5.8, and 10.4 GHz amateur bands, as well as an 8.4 GHz receiver. There is also an S-band 2.4 GHz amateur transmitter running 250 W PEP (peak envelope power).

In 2006, the dish was used to copy signals from Voyager 1 at a distance of nearly 15 billion kilometers (9.3 billion miles). -- Thanks to AMSAT News Service

January 2021 Volunteer Monitor Program Report

The Volunteer Monitor (VM) Program is a joint initiative between ARRL and the FCC to enhance compliance in the Amateur Radio Service.

In January 2021, Volunteer Monitors reported 2,277 hours monitoring the HF frequencies and 2,162 hours monitoring VHF frequencies and above.

The Volunteer Monitor Coordinator issued 11 Advisory Notices. An Advisory Notice is an attempt to resolve rule violation issues informally before FCC intervention:

  • Operators in Milwaukee, Wisconsin; Centralia, Washington; Edmond, Oklahoma; Fontana, California, and Orleans, Massachusetts, received advisories concerning operation outside their license class.

  • An operator in Thorn Hill, Tennessee, received an advisory concerning interference.

  • An operator in Ridgely, Tennessee, received an advisory regarding excessive bandwidth.

  • Operators in Miami, Florida; Friendly, West Virginia; Collinsville, Illinois, and Keansburg, New Jersey, received advisories concerning station ID issues.

  • An operator in Philadelphia, Pennsylvania, received an advisory regarding improper use of a linear amplifier.

ARRL had two meetings in January with FCC Enforcement Bureau personnel. -- Thanks to Riley Hollingsworth, K4ZDH, VM Program Administrator

Video Documents Removal, Preservation of 250 kW Voice of America Transmitter

With the former Voice of America Delano relay site in Central California scheduled for eventual demolition for resale, the Collins Collectors Association (CCA), in association with the Antique Wireless Association (AWA), came up with a plan in 2014 (working, among others, with past ARRL Midwestern Division Director Rod Blocksome, K0DAS, a former Collins engineer) to retrieve one of the Collins 821A-1 250 kW HF transmitters from the site and put it on display at the AWA museum in Bloomfield, New York.

The Delano site went on the air in 1944 with a 170-foot rhombic antenna. The Collins 821 A-1 transmitter was autotuned and could shift frequencies between 3.95 and 26.5 MHz in 20 seconds. The transmitter and its associated components represent an era when equipment was large and heavy.

The Delano site, now owned by the General Services Administration (GSA), remains with antennas still standing and buildings in place and demolition on hold, because it was discovered to be the habitat for an endangered species of shrew.

A video presentation featuring Dennis Kidder, W6DQ, describes and illustrates the entire removal and relocation effort, and offers some background on the VOA. On the continental US, the only remaining VOA site is the Edward R. Murrow Greenville Transmitting Site in North Carolina.

The K7RA Solar Update

Tad Cook, K7RA, Seattle, reports: Monday was the only day with no sunspots over the reporting week, so average daily sunspot numbers declined slightly from 19.6 to 18.9. Two new sunspot groups appeared on the following day. Average daily solar flux edged up from 75.7 to 76.7.

Average daily planetary A index softened from 16 to 14.7, and the middle latitude average went from 12.4 to 10.4. Geomagnetic indicators remained somewhat active due to persistent solar wind. On Monday, Alaska's high-latitude College A index reached 34. reported a G2 class geomagnetic storm on March 1.

Predicted solar flux for the next 30 days appears anemic: 74 on March 4; 75 on March 5 -- 10; 73, 71, 72, and 70 on March 11 -- 14; 71, 72, 71, and 73 on March 15 -- 18; 76, 75, 76, and 78 on March 19 -- 22; 81, 80, 80, and 79 on March 23 -- 26; 78 and 73 on March 27 -- 28; 74 on March 29 -- 30; 73 on March 31 - April 1, and 74 on April 2 -- 3.

Predicted planetary A index is 12, 8, 10, 20 and 15 on March 4 -- 8; 10 on March 9 -- 10; 8, 15, 10, and 5 on March 11 -- 14; 15, 8, 5, and 18 on March 15 -- 18; 20 on March 19 -- 20; 18, 12, and, 8 on March 21 -- 23; 5 on March 24 -- 27; 20, 15, and 10 on March 28 -- 30; 5 on March 31 - April 1; 12 on April 2, and 5 on the following 5 days.

Sunspot numbers for February 25 - March 3 were 31, 16, 14, 13, 0, 28, and 30, with a mean of 18.9. The 10.7-centimeter flux was 80.1, 80.1, 79.2, 77.7, 71, 74.7, and 74.2, with a mean of 76.7. Estimated planetary A indices were 13, 11, 4, 6, 26, 20, and 23, with a mean of 14.7. Middle latitude A index was 13, 8, 3, 4, 16, 14, and 15, with a mean of 10.4.

A comprehensive K7RA Solar Update is posted Fridays on the ARRL website. For more information concerning radio propagation, visit the ARRL Technical Information Service, read "What the Numbers Mean...," and check out K9LA's Propagation Page.

A propagation bulletin archive is available. For customizable propagation charts, visit the VOACAP Online for Ham Radio website.

Share your reports and observations.

Just Ahead in Radiosport
  • March 5 -- NCCC RTTY Sprint

  • March 5 -- NCCC CW Sprint

  • March 6 -- Wake-Up! QRP Sprint (CW)

  • March 6 - 7 -- ARRL International DX Contest (Phone)

  • March 6 - 7 -- Open Ukraine RTTY Championship

  • March 7 -- UBA Spring Contest (CW)

  • March 7 -- NSARA Contest (CW, phone, digital)

  • March 7 -- WAB 3.5 MHz Phone

  • March 10 -- VHF-UHF FT8 Activity Contest

  • March 10 -- RSGB 80-Meter Club Championship (CW)

  • March 10 - 14 -- AWA John Rollins Memorial DX Contest (CW)

Upcoming ARRL Section, State, and Division Conventions

Many conventions and hamfests have been canceled or postponed due to the coronavirus pandemic. Check the calendar of canceled events on the ARRL website.

Find conventions and hamfests in your area.

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The ARRL Letter offers a weekly summary of essential news of interest to active amateurs that is available in advance of publication in QST, our official journal. The ARRL Letter strives to be timely, accurate, concise and readable.

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