Eart-Venus-Earth experiment

[fasleitung3]

On March 22nd, 2025, an experiment to send a signal to Venus and
receive the reflected signal back on earth was conducted by the
Dwingeloo telescope in the Netherlands in cooperation with the
Astropeieler Stockert telescope in Germany. Both are 25-m dishes.
Dwingeloo sent a carrier signal at 1299.5 MHz for 278 seconds. The
round trip time of the signal is about 280 seconds, so the reflected
signal could be received after the transmission ended. The Stockert
telescope was in receive mode all the time.
The experiment was successful, both telescopes could receive the
reflected signal exactly at the predicted doppler shifted frequency.
Since the transmission is a carrier signal, the signal shows as a
narrow line in the spectrum.
The attached graph shows the received signal at Dwingeloo, Stockert and
the combined signal integrated over 4 transmission cycles.
Unfortunately, after this 4 cycles the transmitter failed, so further
experiments could not be done.

On the same day, the same kind of experiment was planned by the DSES
group in the US. The Stockert telescope was set to receive their
transmission frequency of 1296.5 MHz in parallel to the Dwingeloo
signal. Unfortunately, the DSES transmitter failed after the first
transmission cycle of 3 minutes. While the signal was recorded at the
Stockert telescope, the tranmission time was too short to identify a
signal.

This experiment took advantage of the lower conjuction of Venus, where
the distance is comparatively short. The next lower conjunction is
expected in October 2026 and planning has already started to do this
again.

Further information is available at Dwingeloo's website
https://www.camras.nl/en/blog/2025/first-venus-bounce-with-the-dwingeloo-telescope/

I would like to thank all the teams involved in this experiment for
their dedication to make this happen.
Best regards,
Wolfgang

[Alex P]

VERY Impressive :)

If you sent slow Morse Code, might you hear them reconstructed as audio ?

[Dimitry UA3AVR]

Many congrats, Wolfgang ...

понедельник, 24 марта 2025 г. в 14:45:31 UTC+3, fasleitung3:

[fasleitung3]

It takes a minimum integration time of ~ 5 minutes to get the signal sufficiently out of the noise. So if you repeat a slow morse code multiple times and integrate over the code sequence sufficiently long you should be able to detect it.

This would have been another experiment if the transmitter would not have died.

Wolfgang

Am Montag, den 24.03.2025, 05:03 -0700 schrieb 'Alex P' via Society of Amateur Radio Astronomers:

VERY Impressive :)

If you sent slow Morse Code, might you hear them reconstructed as audio ?

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[Stan Koren]

Congratulations!!!! What an awe inspiring project...Stanley Koren VE3PSE

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Stanley A. Koren

Electronics Engineering Technologist

Computer Scientist, Mathematician

Canadian Amateur Radio Advanced License VE3PSE

LinkedIn  www.linkedin.com/in/stanleykoren

Web: www.oldsudburybookstore.ca

[Jon Wallace]

Fascinating! Thanks for sharing! Hope you can do it again in 10/26!

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[Marko Cebokli]

What was the TX power used?

Marko Cebokli

2025-03-24 12:45, je 'fasleitung3' via Society of Amateur Radio Astronomers napisal

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[fasleitung3]

The TX power was 1000 W.

Wolfgang

[Marcus D. Leech]

On 24/03/2025 14:05, 'fasleitung3' via Society of Amateur Radio Astronomers wrote:

The TX power was 1000 W.

Wolfgang

I would love to see the full paper on this when it comes out!

Am Montag, den 24.03.2025, 16:41 +0100 schrieb Marko Cebokli:

What was the TX power used?

Marko Cebokli

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[Thomas D Jacobs]

Wolfgang:

I am assuming that the 1,000 watts was the output of the final power amplifier of the transmitter. Here in the USA this is colloquially referred to as the "full legal limit".

I am also going to assume that there was a "significant" increase in the ERP from the gain of the antenna system.

Clear skies and gentle breezes,
tdj

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Take care,
Tom Jacobs

Wilmington, North Carolina
mailto:cretaceou...@gmail.com
mailto:td...@bellsouth.net
KD4BFQ
+--------------------------------------------------+
|                                                  |
|         In war, resolution; in defeat,           |
|         defiance; in victory magnanimity;        |
|         in peace, goodwill.                      |
|                                                  |
|               -- Winston S. Churchill            |
|                  1874-1965                       |
|                                                  |
+--------------------------------------------------+

[fasleitung3]

Yes, this was the power at the output of the PA. The EIRP is substantial higher due to the antenna gain. I would need to ask the Dwingeloo team for an exact number but assuming a typical gain of a 25-m dish at that frequency of 45 dB gives you ~ 31 MW EIRP.

It is worth noting that using 1000 W output required a special permission by the Dutch regulator which was only granted shortly before the day of the experiment.

Wolfgang

[fasleitung3]

Definitely there will be a paper on this but it may take a little while.

Wolfgang

[Marcus D. Leech]

On 24/03/2025 16:43, 'fasleitung3' via Society of Amateur Radio Astronomers wrote:

Definitely there will be a paper on this but it may take a little while.

Wolfgang

Is it too early to ask if baseband data can be shared?

Dan Marlow (emeritus, Princeton) is interested in looking at the data.  Princeton had hoped to use their
  TLM-18 for this, but it just wasn't ready in time--it has been "down" due to mechanical problems for
  several years, and I think they're just getting back to a place where they can consider some experiments.

I do know that for now, they're using our dish for their undergrad astrophysics lab courses (mostly involving
  pulsars).

Am Montag, den 24.03.2025, 14:13 -0400 schrieb Marcus D. Leech:

On 24/03/2025 14:05, 'fasleitung3' via Society of Amateur Radio Astronomers wrote:

The TX power was 1000 W.

Wolfgang

I would love to see the full paper on this when it comes out!

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[Adrian]

What an amazing accomplishment for the amateur radio astronomy community. Congratulations to all those who participated in this incredible endeavor. 

Looking forward to the 2026 conjunction and another successful experiment.

Adrian Clausell

KJ6GYC

[Preston Ozmar]

Great  news!!! Congratulations!!!

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[fasleitung3]

Hi Marcus,

The data will be publicly available. We are coordinating with Dwingeloo how to best do this.

Wolfgang

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[Marcus D. Leech]

On 26/03/2025 15:42, 'fasleitung3' via Society of Amateur Radio Astronomers wrote:

Hi Marcus,

The data will be publicly available. We are coordinating with Dwingeloo how to best do this.

Wolfgang

Thanks!

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