HAMNET Report 19th December 2021

By Monday of this week, Philippine nationals were being warned of the arrival of Tropical Cyclone RAI-21, moving from East to West, and due to strike the Philippines amidships on about Thursday.

The Global Disaster Alert Coordination System was predicting winds of up to 260 km/h, an alert level of RED, and 13 million people to be in the line of the strike zone. Thousands of people were being evacuated from their homes in central and southern Philippines.

The central and western Visayas region was the most threatened, with Mindanao and Luzon areas also expected to bear part of the brunt of the storm. Very heavy rain, strong winds and storm surges were to strike southern, central and western Philippines on Thursday.

By Saturday the death toll stood at 18 as the disaster agency warned of “severe damage” in the hardest-hit areas. More than 300,000 people fled their homes and beachfront resorts as Typhoon Rai ravaged the southern and central regions of the country, knocking out communications in many areas and toppling concrete power poles.

This is clearly still a developing story.

Rick, Palm, K1CE, who manages the Emcomm pages in QST magazine, has a problem that I definitely identify with. Writing in the weekly ARES letter from America, he says:

“[I have] a case for not programming repeaters into the memories of your radios.

“If you are like me and most other operators, you have programmed your area repeater frequencies into the memory channels of your radios. Recently, when I needed to switch to a new repeater frequency, I could not remember how to enter the [CTCSS] tone and offset – an aggravating factor may be that I’m almost 70 years old with a slowly eroding memory! I resorted to reading the radio’s operating manual. Now, I forego using the memory channels and instead enter the repeater frequency, offset, and [CTCSS] tone manually each and every time so that I’ll have the muscle memory needed to select repeater parameters on the fly in the field. Think about it – it only takes a second to enter the parameters.” Close quote.

He is not wrong. If I have two radios, I can’t remember how to do it on either of them!

On December 24th, SAQ in Grimeton, Sweden, is scheduled to transmit a Christmas message to the world, using the 97-year-old 200 kW Alexanderson Alternator on 17.2 kHz CW. At 0730 UTC, a livestream will begin on YouTube.

Start-up and tuning of the Alexanderson alternator will begin at 0800 UTC and transmissions soon after.

Some test transmissions will take place on December 23 between 1200 UTC and 1600 UTC and SAQ will be on the air for shorter periods during this interval, when technicians will be carrying out some tests and measurements.

Comments and reports are welcome. Amateur radio station SK6SAQ will be active on 3.535 MHz, 7.035 MHz, and 14.035 MHz CW, and on 3.755 MHz and 7.140 MHz SSB. Two stations will be on the air most of the time.

Thanks to the weekly ARRL newsletter for this summary. The 24th December is this Friday, folks, and the sunspot number and solar flux index has suddenly shot up. Let’s hope conditions remain good for this coming Friday.

Now, combining my two interests, I can tell you of the use of amateur radio repeaters in association with Magnetic Resonance Imagery (MRI) technology to improve diagnostic capability in medical investigations.

In Imaging Technology News on 16th December, I learnt that Scientists at the University of Tsukuba demonstrated how conventional magnetic resonance imaging (MRI) machines can be retrofitted to detect sodium ions using a cross band radio-frequency repeater. This work may allow for new medical diagnostics to be performed without expensive new equipment.

Magnetic resonance imaging has become a crucial part of the medical toolkit for non-invasive visualization of internal organs. MRI machines operate by placing the patient in a very strong magnetic field, which will cause the nuclear spins of atoms in the body to align in the same direction, essentially acting like tiny magnets. Then, a radio-frequency (RF) signal of a very specific frequency is applied, which has the ability to flip the direction of the spins. When the nuclei relax back to their original aligned state, the precession of these spins about the magnet field direction can be measured by RF detector coils to determine the concentration of that particular atom. The majority of MRI machines in use today are optimized to look for the presence of hydrogen-1 (1H) nuclei, which are naturally abundant in the body as a component of water molecules. Retrofitting such a machine for detecting other isotopes, like sodium-23 (23Na), would require a great deal of expensive hardware upgrades.

Now, a team of researchers at the University of Tsukuba have demonstrated a proof-of-concept method for equipping a conventional MRI machine with the capability to image 23Na by installing a cross band RF repeater system. This is a device that receives signals at a certain frequency and rebroadcasts at a different one. “The RF repeater, which is a commonly used device in amateur radio, can be placed directly inside the magnet bore of an existing MRI machine as a cost-effective upgrade,” explains author Professor Yasuhiko Terada. This allows the frequency produced by 23Na, which is around 17 MHz, to be detected by the coils tuned at the 64 MHz frequency of MRI.

The research team tested the system with a saline “phantom” and an anesthetized mouse. Even though the resulting signal was much lower compared with custom-built 23Na machines, it could be amplified to produce comparable images. “Watching the motion of sodium ions inside the body provides detailed metabolic information not available from conventional MRI images,” Professor Terada says. 23Na imaging has already been shown to be useful for applications involving the kidney, owing to its large sodium concentration, as well as the brain and heart. This approach may substantially reduce health care costs by providing completely new abilities to existing machines without requiring a complete refurbishment.

The work is published in Magnetic Resonance in Medical Sciences. Thank you to ITN for this report.

It remains then only for me to wish those of you who celebrate at this time of year, a very Happy Christmas, where appropriate, and a safe and healthy 2022. Here’s hoping that the Omicron version of the Coronavirus will so overwhelm previous mutations, as to make the pandemic fizzle out into an endemic state, with very little morbidity and even less mortality!

This is Dave Reece ZS1DFR reporting for HAMNET in South Africa.