Proper DX from VK

Bigly congratulations to our upside-down Australian radio dudes at Canberra DSN who have upgraded their antenna and re-established comms with Voyager2.

Mentioned in the comments and always worth a look is DSN Now


That’s a mind boggling piece of engineering (to me, anyway)…a three tonne “cone” at the focal point of a seventy metre diameter dish, working at X Band, where millimetres are critical…and all steerable. Distortion by gravity and temperature change all accounted for.
Not to mention pointing it accurately at a tiny probe 17 light hours away.

Now back to trimming a wire dipole for topband…


Just an idea, unfortunately no FT8 available in those large distance communications? Would that help to maintain the radiocommunication over even longer distances?

Well you would have to decide if FT8 is better that the current modulation scheme. Then the problem is how to add such capabilities to a 47 year old hardware design that is 17+ light hours away.

The biggest issue is power. By 2025 there is unlikely to be enough power to run any science instruments. At the point only vehicle status information would be available, no science data. The current NASA DSN prediction is that the vehicles reach the limit of the DSN in 2036 assuming sufficient power to run the transmitters.

By 2036 the vehicles will have been operating continuously for 59years. That’s longer than the working life of most people.


My question was theoretically: If they had ft8 at the time of launch, would that have improved signal strength? What scientific data can be gathered at that distance? I guess Voyager is beyond the distance of solar wind or any other influence of our sun? Can be only to measure things of “empty” interstellar space? By the way 17 light hours is measured in astronomical distances microscopical, less than 1/1000 of the distance to the nearest star Proxima Centauri. What I cannot remember is if Voyager is aimed in a certain direction?

FT8 wouldn’t improve the signal strength.

Building it with 2020 tech would allow higher data rates for effectively the same radio link performance. But you build the mission around the data rates you know you can achieve now and assume that the data rate drops with distance and at the distance you are interested in, you can gather the data that makes the mission worthwhile. In Voyager they did this but they knew the RX performance would improve as the signal got weaker effectively extending the mission as the RX improved. You could now make the TX more configurable but that wasn’t possible in an early 1970s design.

Whether building it with 2020 tech would give the same awesome reliability is an intriguing question.

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Just an idea, unfortunately no FT8 available in those large distance communications?

I think that WSJT-X et al (including FT8) were developed by Joe Taylor K1JT knowing about the possibilities of long-distance comms in space and adapting / developing them for earthly (or EME) HF transmissions.
He is after all not only radio amateur, but also astrophysicist.

See also
Joseph Hooton Taylor Jr. - Wikipedia.

73 de Martin / HB9GVW

Hi Martin,
Correct. Joe won a Nobel prize in Physics for his work, so does know a thing or two about weak signals.

FT8 is crap compared to the digital signal system used by these spacecraft. They don’t have a bunch of atomic frequency standards at the station for nothing. Amateur rigs are far too drifty for space communications. They need to know exactly what frequency they are listening to. Apart from the piddlingly weak signals there is Doppler shift to contend with. Digitising the signal and using big processing power is the only way this can work. I’m pretty sure they have improved the algorithms for decoding since launch.

JT65 was a very simplified weak signal program that Joe wrote that could be used with existing amateur equipment. It’s capability was startling to most of us.

FT8 was written for those with a short attention span but wanting to work DX during sun spot minima.

It still was too slow for some so FT4 was developed.

Everytime you reduce the time to send info you trade off signal. Faster =bless sensitive.

Whatever your mode I wish you many contacts.


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A smaller dish (only about 26m) from the now closed Honeysuckle creek station about 10 km south of Tidbinbilla was moved to Tidbinbilla and re-erected. After being used for 10 years on projects that needed to track the faster moving satellites, it was shut down and the gears welded to a fixed position. Sacrilege…

I am not sure whether this 26m dish was the one that fed the early signals from Apollo 11’s moon landing. If it wasn’t that one, it was another at Honeysuckle Creek.

The Orroral Valley and points south of there were the location of a large bushfire earlier in 2020. as if there wasn’t already enough going on… Large areas of the Namadgi National Park were burned out and those valleys are still closed to the public due to the danger of falling trees.

Andrew VK1DA

The Voyagers have certainly been remarkable. Our eldest daughter (who just happens to live conveniently at the base of VK1/CT-040, I must pay her a visit) did a project on the Voyagers when in school and that was 25 years ago. Already at that time they had achieved their primary goals and still they travel on. Whether such remarkable reliability could be reproduced today is an interesting question.


CT is not a region in the ACT. Mt Ainslie is VK1/AC-040 and Mt Stromlo is VK1/AC-043.

The closest recognised SOTA peak to Tidbinbilla Deep Space Tracking Station is Bullen Range VK1/AC-033.


Andrew VK1AD

In case you were not aware, Caltech/JPL held a 40 year Voyager celebration in July 2019.
The film The Farthest was presented during the program.
Here are links to a writeup about the program and to the film.

I had the pleasure of visiting Goldstone and the DSN in May, 2017. In a word, WoW!

David N6AN