Tag Archives: SpaceX

Radio Waves: ATC Communications, ABC is Highly Trusted, New SW Forum in Turkey, and Did a Ham Speak To Crew Dragon?

Photo credits: NASA/Bill Ingalls

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 Michael Bird, Seyfi Genç, and London Shortwave for the following tips:


Can you hear me now: How pilots communicate with ATC while 35,000 feet in the air (The Points Guy UK)

When you’re in a sealed, pressurised tube five miles above the ground, being able to communicate effectively is essential. In the early days of aviation, flags and light signals were used before designers were able to fit basic radio equipment into aircraft.

Modern aircraft now have an array of communication devices from the rudimentary HF radios of old to sophisticated satellite-based systems that enable us to talk almost as if we were on a mobile phone.

[…]The most common form of communication in aviation, very high frequency (VHF) radio calls are what we use for around 95% of our communications with ATC. In simplified terms, the transmitting station sends a signal that travels in a straight line and is picked up by the receiving station.

VHF comms provide clear voice communications. However, as the radio signals travel in straight lines, they are limited by the curvature of the earth and objects that they may come into contact with, such as hills and mountains.

The distance which a VHF signal can travel depends on both the height from which the signal is sent and the height of the receiving station. If both the sender and the receiver are on the ground, the distance will be relatively small. If both stations are in the air, the distance the signals can travel is much further.[]

Bushfire Research shows ABC Radio highly trusted and saves lives (Radio Info)

As the Bushfire Royal Commission continues, the ABC has released independent research that shows Australians turned to the national broadcaster in record numbers during the recent bushfire crisis.

The research shows that the ABC was the most trusted information source during the fires and that lives were saved as a result of people acting on information the ABC provided.

At the height of the bushfire crisis (31 December-14 January) ABC Sydney and ABC NSW local radio produced 296 hours of rolling/continuous fire coverage, ABC Gippsland 134 hours, and ABC Melbourne 83 hours.[]

New Shortwave Forum in Turkey

73 and hello from Shortwave Forum!

A dedicated Facebook and parallel Whatsapp group, to exchange news and info by SWL’s and DX’ers from Turkey, NOW goes wider and more permanent:

http://www.shortwaveforum.com

The Shortwave Forum will be open to all who want to join and contribute. Membership is free.

With members from all corners of the globe, the content of our beautiful hobby will reach the richness it always deserves.

Register now! And keep those tips and news coming!

Did a Ham Radio Enthusiast Actually Speak to Crew Dragon? (Popular Mechanics)

In a strange turn of events, a ham radio enthusiast in Gujarat, India falsely claimed to have made contact with NASA astronauts Bob Behnken and Doug Hurley during their historic journey to the International Space Station last weekend.

Engineer Adhir Saiyadh told the Ahmedabad Mirror he decided to try to connect with the ISS as it sped over India and “coincidentally got connected to their frequency and received a response from one of the commandants of the capsule,” he said.

But NASA says it simply isn’t true.

Behnken and Hurley blasted off from NASA’s historic Launch Complex 39A on Saturday, May 30. After 19 hours in orbit, the astronauts docked with the ISS and reunited with fellow astronaut Chris Cassidy—whose ham call sign is KF5KDR, by the way—and Russian cosmonauts Anatoly Ivanishin and Ivan Vagner.

“We did check with SpaceX to confirm that they were not aware of any communication with the astronauts via ham radio, and the crew did not report having received communication,” a NASA spokesperson told Popular Mechanics via email. “We are also under the impression that may be technically impossible for the Crew Dragon to communicate through ham radio.”[]


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Quindar Tones: Those iconic NASA PTT confirmation beeps

Photo credits: NASA/Bill Ingalls

Yesterday, my family watched the successful launch of the NASA Demo-2 SpaceX Dragon via YouTube.

As astronauts Robert Behnken and Douglas Hurley communicated with Mission Control, we heard PTT confirmation beeps after each transmission.

Those beeps, of course, reminded me of past NASA missions and those iconic confirmation tones we heard in audio from the Mercury, Gemini, and Apollo days all the way into Space Shuttle missions.

Quindar Tones

Source: honeysucklecreek.net

Last year, after spending a couple of days at the US Space and Rocket Center (and attending the Huntsville Hamfest), I heard numerous NASA audio clips and that lead me down the path of researching those PTT confirmation tones.

Turns out, they’re called “Quindar Tones.”

I couldn’t find any information about Quindar Tones at the US Space and Rocket Center–although, admittedly, the place is massive and I could have easily overlooked it–so I did a little research when I returned home.

I found this archived post on the NASA’s Apollo Lunar Surface Journal wesbite:

Re: Apollo beeps

Journal Contributor Mark Burckhard writes:

“I’ve always wondered what purpose the ‘beeps’ served that one heard intermittently during the voice communications with the Command and Lunar Modules during the Apollo missions, as well as other space missions.”

Journal Contributor Mike Dinn provides an MP3 clip ( 123k ) from a network audio check that includes numerous quindar tones.

Journal Contributor Markus Mehring replies:

“‘Other space missions’ is quite an accurate observation, since the ‘beeps’, in fact, are still in use today on Shuttle flights, at least on the UHF frequencies.”

“These beeps are called ‘Quindar-Tones’. Their purpose is to trigger the ground station transmitters when there is an outgoing transmission from Earth. The CapCom in the Mission Control Center, who is taking care of communications with the crew, uses his communication gear in a PTT mode exclusively. ‘PTT’ is short for Push-To-Talk, which means that the CapCom presses a button every time and as long as he wants to talk. (The crews back during Apollo – and also today – usually communicate via PTT as well, but they also have the so-called ‘VOX mode’ at their disposal, in which their microphones are voice-triggered by a certain adjustable threshold volume levels. VOX is used when they don’t necessarily have their hands free.)

When the CapCom presses his PTT button to start a transmission, an intro tone (2.525KHz sine wave with a length of 250ms) is generated and triggers the ground station transmitters to send. And when he is finished talking and releases the button again, a slightly lower outro tone (2.475KHz, sine, 250ms) is generated to trigger the ground station transmitters to turn off. So in short, these are remote control trigger tones.

CU! Markus”

I then discovered this article via the Internet Archive Wayback Machine, which gave more detail about the Quindar Tones’ name and some of the idiosyncrasies of the system:

The story behind the “Beep”

Steve Schindler, an engineer with voice systems engineering at NASA’s Kennedy Space Center, offers the following history of [Quindar Tones] origins.

“Quindar tones, named after the manufacturer of the tone generation and detection equipment, are actually used to turn on and off, or “key,” the remote transmitters at the various tracking stations (Merritt Island Launch Area–now Kennedy Space Center, Bermuda, Australia, etc.) that were used to communicate with the Mercury through Apollo spacecraft and, in some cases, are still used with the Space Shuttle.”

[…]”Although it usually worked well, there were a couple of peculiarities with this system. If the transmitter was keyed and the telephone line connection broken, the transmitter would never get the tone to turn off. To prevent this there was a “transmitter on” light at each remote site that would come on when the transmitter was keyed. Someone was supposed to monitor the circuit and if the audio dropped, but the “transmitter on” light was still on, they would have to manually unkey the transmitter. Also, just before communications was handed over to a new tracking station, the key-unkey tone pair was sent 10 times to ensure that everything was functioning correctly. This was done before the audio was patched to the tracking station’s line so it wasn’t heard in the control room or on NASA Select audio.

The Quindar system was actually built from a piece of equipment that was used to put multiple teletype circuits on a single phone line by means of frequency domain multiplexing. Because replacement parts are no longer available, an “out-of-band signaling” system was installed in 1998 for the transmitters located in the U.S. This system uses a continuous tone that is below the normal audio frequency range. When the tone is present, the transmitters are keyed. When the tone is not present, the transmitters are unkeyed. It worked fine, but the Astronaut Office complained about the lack of tones which everyone had become accustomed to as an alert that a transmission was about to start. So, the Quindar tone generator, which was still installed in case it was necessary to key the transmitters at an overseas site, was re-enabled.

Even though you won’t hear the same Quindar tones in present-day space missions, you can listen until your heart is content at the website Apollo In Real Time.

The Internet Archive also has a massive collection of Apollo audio free to stream and download.

Quindar Music

If you’re fascinated with the NASA audio soundscape in general, you might check out the electronic music duo Quindar featuring longtime Wilco member Mikael Jorgensen, and art historian-curator James Merle Thomas.

Quindar: Mikael Jorgensen & James Merle Thomas. Photo by Chad Ress, Spacesuits by Cassandra C. Jones

Science Friday featured an extended interview with the group in 2017. If you love electronic music–especially if you’re a fan of Wilco, it’s well worth a listen:

Check out their latest video, Choco Hilton:

Speaking of Mikael Jorgensen and Wilco, I should note here that their album yankee hotel foxtrot has a deep shortwave motif.

Anyone else fascinated with Quindar Tones and NASA audio? Feel free to comment and share any other resources or projects you’ve found.


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SpaceX’s Falcon 9 payload includes the HawkEye 360 radio-wave emission seeker

Many thanks to SWLing Post contributor, Balázs Kovács, who shares the following:

Hi Thomas,

Just found: the launch of the SpaceX’s Falcon 9 rocket was delayed today, part of the load is a new radio-wave emission seeker satellite system the Pathfinder from HawkEye 360:
https://www.businessinsider.com/spacex-to-launch-70-satellites-radio-tracking-2018-11

Some parts from the article:

“An unprecedented rocket mission for SpaceX, called SSO-A, will launch 71 small satellites at once on Monday. Three of the satellites belong to HawkEye 360, a startup that aims to “see” radio-wave emissions all over Earth. HawkEye 360’s software will identify each unique radio signal and use it to track “dark ships” that may be trying to hide illegal activities.”

[..] The antennas of Pathfinder can detect a wide range of radio signals above about 1 watt in power. [..] This means the cluster can triangulate normally hard-to-pinpoint signals from satellite phones, push-to-talk radios, and marine radar. [..] In the future, they aim to launch five more three-satellite clusters, which will create a constellation that can map Earth’s radio signals once every 30 to 40 minutes. [..] Another planned use of Pathfinder is more down-to-earth: The technology could detect improper use of the radio-frequency spectrum, including interference between cell-phone towers.”

Thank you for the tip, Balázs!

I also discovered the following short video which introduces and describes the system:

Click here to view on YouTube.

Sounds like an amazing system although it certainly does feel a little “big brother”–!

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