Narrowband SETI drift search pipeline, progress and a verification question
Ayushman Tripathi
Hi all,
I have been working on a narrowband SETI pipeline for some time now. It is still not finished, and I am fixing bugs, so I am not sharing the code yet. Once I can verify that it actually works, I will put it up on GitHub and share it.
Right now I am running three setups. The main one is a 2.4 m dish at a remote rural site with an Airspy Mini at 1420. This is my main hope because that site has almost no RFI. Apart from that I have a Ku band setup with a HackRF and a PLL LNB, and another L band one with an RTL-SDR on a laptop parked on the HI line.
Taking the 2.4 m one as the example, the idea is actually simple. I slice about 3 MHz of spectrum into roughly a million channels, so each channel is only about 2.9 Hz wide. To give a feel of how narrow that is, individual hydrogen clouds are a few kHz wide, so a single cloud spreads across around a thousand of my channels. A technosignature is expected to sit in just one or two of them, because nature cannot make a signal that narrow.
Then I stack about 150 seconds of this into 30 rows, like a small waterfall. Each row is simply the spectrum, that is the power in each of the million channels, averaged over about 5 seconds. So the 30 rows are 30 time steps placed one below the other, with frequency going across and time going down. A signal that stays at one frequency shows up as a straight vertical line, and one that slides in frequency shows up as a slanted streak.
Then I divide each channel by its own median down the 30 rows, so anything which sits still in one channel for the whole 150 seconds simply gets divided away. But a real source in the sky is not sitting still. As the Earth turns, our speed towards it keeps changing, so its frequency slides. At 1420 that slide is up to about 0.15 Hz per second, so in one 150 second block it moves roughly 22 Hz, which is about 8 of my channels. Since it only passes through each channel briefly, it survives the division. The fixed junk disappears and the sliding signal stays.
After that I search for these slides at every possible rate, and for each hit I also record its width and how steadily it was present through the block, as extra sanity checks. One thing I learnt the hard way is that the SDR's own spurs are not steady, some flicker on and off, so a simple median does not fully remove them and the search then fits a false slide to them. Sorting that out is tied to the next point.
At the 2.4 m site there is really no external RFI. Whatever I was detecting turned out to be instrumental, coming from the SDR itself, and that part is now covered.
One thing which may be useful for others. For SETI the Airspy Mini's TCXO is simply not stable enough. It drifts around 0.05 to 0.1 Hz per second, which is about the same as the 0.15 Hz/s slide I am trying to measure. It is like standing on a slowly moving walkway and trying to judge whether a parked car is moving. The car is not moving at all, but it appears to be, because you yourself are sliding. So we cannot simply say that zero drift means terrestrial. For now I am correcting for it in software, but the proper fix is a GPSDO.
Stephen suggested the Leo Bodnar LBE-1420 mini GPSDO, which I am planning to get. The Mini itself has no clock input, so I will also need an Airspy which has CLK IN. My HackRF does have one but it is already in use for Ku and I haven't measured Hack's behavior/internal spurs with this kind of process yet.
Where I am stuck is verification. 1400 to 1427 is a protected band, so I cannot transmit any test signal to prove the pipeline will catch a real one. If I inject a signal into the raw data in software, it finds it properly, but that only tests the software and not the receiver chain. Also, a transmitter sitting on the ground has no sidereal Doppler, so it cannot test the drift path unless I chirp it deliberately. I am still thinking about how to do a proper test.
If anyone here has verified a drift search end to end on real hardware, kindly let me know how you managed it.
Over the last ~290 blocks at the 2.4 m site, there were 1795 detections, every one of them traced back to the instrument and rejected, and there were zero real candidates, as expected.
Soon, I'll try to save raw data also, but currently it's not possible at the 2.4 site because the Pi is running on an SD card after the SSD proved to emit high RFI.
Any suggestions are welcome.
Thanks
Adrian
Ayushman,
Just curious as you mentioned that "My HackRF does have one but it is already in use for Ku",
I was wondering how you were using it for monitoring Ku as its upper frequency is only ~6GHz.
Are you utilizing a frequency converter to get up to Ku say 10 - 12 GHz with the the HackRf?
Anyway thanks, your SETI search pipeline seems like a well though out approach, and a great valiant effort.
Also have you considered other potential "SETI Magic Frequencies" besides the hydrogen line.
For example HI x pi or HI x e ... etc. , I know the possibilities can be endless.
Here is link to an article describing the general approach for these so called Schelling points.
https://www.supercluster.com/editorial/searching-for-setis-magic-frequency
Adrian
Ayushman Tripathi
Hi Adrian,
Thanks! I am using an Inverto PLL LNB for Ku, it does the downconversion in the feed itself so the HackRF never sees Ku directly. Low band 10.7 to 11.7 GHz downconverts to 950 to 1950 MHz, high band 11.7 to 12.75 GHz to 1100 to 2150 MHz. So the HackRF only sees L-band IF. Also this avoids running Ku over coax, losses would be huge there, and no affordable SDR tunes 12 GHz directly anyways, I think.
The good part is this is a common TV LNB so it's very cheap, but this one I'm using is PLL type instead of DRO. DRO ones free-run and drift a lot with temperature, PLL locks to a crystal reference, so it's stable, but I measured mine still drifting about 3.6 Hz/s with temperature. I power it with 12V through an external bias tee over the coax. Also, I found on Es'hail-2 forums that it's possible to jerry-rig an external GPSDO/OCXO reference to this exact same LNB, I'll look into that.
On the pipeline, current goal is making sure ground RFI and instrument artifacts do not show up as signals for manual review, once that works the review list will have much less clutter. Even if it flags a satellite that is fine for now, if it can detect a sat it means the chain is working. Ku is on a smaller dish for testing, will move to a 1.5m later. Same algorithm is also running on my 2.4m system and it has some progress, instrumental artifacts are gone and much of the ground RFI too after fixing drift rate, but still many things to test.
Thanks for sharing that magic frequencies list, I have not seen it yet, will read it. My thinking is if there are radio astronomers on other planets, they will know the hydrogen line for sure, but that is human logic. What if they do not think like us. Also, our own radio bubble is only around 110 light years out, nothing compared to 26,000 light years just to the galactic center, so anyone waiting to detect us first has almost certainly not heard us yet. And the reverse also holds, signals sent thousands of years ago could be arriving right now, the same way the hydrogen we map left its clouds tens of thousands of years back. For me the search itself is interesting either way, this space is so unexplored that even a natural finding would be really amazing, if Wow were natural, we still could not explain why it never repeated.
Thanks.
https://inverto.tv/lnb/445/single-high-gain-low-noise-40mm-pll-lnb
Adrian
Do you use a sat box to do the LO switching with its 22 Khz signal for the high band and or use the LNB just on the low band with no 22KHz tone and just the bias Tee to power it with.
I guess if you are mainly on QO-100 then the low band covering 3cm downlink is what you use with no 22 KHz tone. It's too bad that we in NA still don't have an amateur Geo transponder yet.
As far as a GPSDO hack for even better LNB frequency stability, it is almost trivial. You simply need to swap out the PLL xtal for an input from the GPSDO equivalent frequency to the PLL, Almost the same thing you have done with your HACK RF. Possibly just needing a couple of additional small isolation capacitors etc and as you said you will be getting a Bodnar GPSDO, you can thren adjust it's locked frequency to the same as the old xtal. Then a external SMA or BNC simple connector to input its signal to the xtal output lines for the PLL and your locked generator signal will make the frequency rock solid at Ku.
Take a quick read at the frequency link its pretty basic and just describes more the concept than anything else for the rationale to look in those frequencies as alternate techno markers that could substitute for directly using the 21cm line. Mainly due to the fact that the actual Hydrogen line is screaming so loud there and also in its surrounding frequencies due to its doppler shifts.
Is someone detects another WOW it should be really interesting even if as you said it is a naturally produced phenomena.
andrew....@googlemail.com
With regards to the question, will astronomers on other planets think like us – the answer is probably yes. The reason for this is convergent evolution – all creatures that swim in open water look like torpedoes – does not matter what they started as – they will end up over time looking like torpedoes because it is the most efficient way to swim in open water. Creatures that live in different environments do not look like torpedoes but rather like something optimised to those environments – e.g. octopi. So, if astronomers on other planets live in deep water environments, then they won’t have two legs etc. BUT they will need to create tools to look at the same parts of the radio universe once they look at the deep night sky = in the same way we have done so although we don’t have the natural senses to see these areas without aid.
Thinking is a tool to explore the world around us and deep night sky exploration requires similar tools.
Adrian can probably discuss this more sensibly than me.
Andy
--
--
You received this message because you are subscribed to the Google
Groups "Society of Amateur Radio Astronomers" group.
To post to this group, send email to sara...@googlegroups.com
To unsubscribe from this group, send email to
sara-list-...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/sara-list?hl=en
---
You received this message because you are subscribed to the Google Groups "Society of Amateur Radio Astronomers" group.
To unsubscribe from this group and stop receiving emails from it, send an email to sara-list+...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/sara-list/49447dd1-3381-45bb-810a-a97ee5c3ff24n%40googlegroups.com.
Ayushman Tripathi
Hi Adrian,
Thanks for the GPSDO attachment guide, that makes it sound very doable. I will try that once the GPSDO arrives.
Yes, I use it with just a plain bias tee, no 22 kHz tone, so low band only for now. I only got this LNB this month for Ku-band SETI attempts, never did QO-100, mainly because it was cheap to try and it lets me test my code on narrowband sats in the sky. Low band is fine for now, later I will think about injecting the 22 kHz for high band.
Also nice point about the hydrogen line being too loud there. A civilization might deliberately use a relatively silent method or frequency exactly because the natural H line screams over everything around it, that is a good argument for the alternate marker frequencies.
Also, one thing about small dishes is they have a feature the ultra-big ones do not, more beamwidth. At 1420 MHz a ~2.4m dish has a beam around 6 degrees wide, roughly 28 square degrees of sky at once, while a 100m class dish has a beam around 0.018 square degrees. That is around 1500 times more sky area per pointing for the small dish. So if the signal is strong enough, say the civilization is a million years ahead of us or the transmission is aimed at Earth or the Natural Source is strong enough, then even a small dish has a chance, and it covers far more sky in the same observing time.
Ayushman Tripathi
Hi Andrew,
I think you are right, they would need hands at minimum, or something like them, to develop tools. It is often proposed that if dolphins ancestors had kept hands instead of going fully to fins, they might have become an advanced civilization well before us, the fins basically stopped tool development. But if a civilization is a million years ahead of us, we cannot really know how they would think even if they started like us. We cannot even know what humanity will look like in a million years, every generation already shifts how we think, and by then it could be bots integrated with humans or something we cannot imagine.
The other possibility is that compared to the age of the universe, humanity might be among the first intelligent civilizations to appear. Some work suggests this is not actually the peak era for life, that comes far in the future with long lived red dwarf stars, so early arrivals would be rare exceptions.
And on Earth itself, LUCA, the last common ancestor of all life, is now dated to around 4.2 billion years ago, extremely early, almost as soon as the planet was habitable. Every living thing from humans and cats to mosquitoes shares the same genetic code and core molecular machinery, which means all present life descended from that one ancestor. My thinking is, if the origin of life were really common, why is there only one LUCA, why not many separate lineages. It is not proof, the others could have arisen and been outcompeted, but it makes me think that life is rare.
Either way there is a lot we do not know and a good chance we will not answer these in our lifetime. But I am in my 20s and I want to do this search for a long time, 60 to 70 years if I can, because that way I keep learning about space and about any chance that we are not alone.
https://en.wikipedia.org/wiki/Last_universal_common_ancestor
Thanks
andrew....@googlemail.com
I didn’t mean they would need hands – but to observe the universe they would need to develop tools that allowed them to observe the universe across its wavebands (hence develop similar technology): they would need to develop something to observe in hydrogen line for example. We are a good example of a species that does not have the natural ability to observe the hydrogen line but we created tools to do so – they would achieve the same = or at least if they have technology to communicate across interstellar distance that would need to be able to do so.
The question is not whether aliens can do as us – rather the question is whether it is even possible to communicate using any form of light = any signal we or they produce deceases with square of distance and becomes ludicrously weak after a few light years. I think it is going to be impossible unless some other form of interstellar communication is discovered. So, in that, aliens might be well ahead of us, and until we also discover it, we can’t communicate with anyone, and remain isolated!
To view this discussion visit https://groups.google.com/d/msgid/sara-list/edd7e6f9-1b3b-42e0-8c50-efb47b1d4c09n%40googlegroups.com.
Ayushman Tripathi
Hi Andrew,
Yes, agreed, they would need to build tools to observe just like we did.
I ran a rough calculation for fun. Take a civilization with even 2x our best transmitter power, beamed and narrowband like Arecibo was. Arecibo's 1974 beam was around 2x10^13 W effective, and at a narrow bandwidth a matching 305m dish could detect it out to roughly 25,000 light years on the optimistic end (Drake's estimate, enough to reach M13). Double the power and that grows by about 1.4x, since range only goes as the square root of power. And 2x is a very conservative guess, a far more advanced civilization could easily be 100x or more, which is 10x the range, so on the order of 250,000 light years.
So, the real limit is whether they exist and are beaming toward us or us towards them, whether we are on the right frequency, and whether we are listening at the right time.
Thanks
Adrian
“Not only is the Universe stranger than we think, it is stranger than we can think.”
With that insight in mind, I would disagree with the convergent‑evolution argument — not because it is wrong, but because its application is limited to very specific environmental constraints. Convergence only happens when the boundary conditions are identical. Change the chemistry, the sensory modalities, the ecological pressures, or the technological scaffolding, and the “torpedo principle” evaporates.
Andrew, you mentioned that creatures swimming in open water all look like torpedoes. Well, swimming perhaps — but not motility in general. The Nautilus moves by jet propulsion inside a spiral shell. Jellyfish use rhythmic tentacle pulsation. Ctenophores use ciliary paddles. Octopi use distributed tentacular gait. Even on one planet, under one biosphere, locomotion is solved in wildly different ways. Hydrodynamics has a narrow optimization basin; cognition and technology do not.
So I’d argue that convergent evolution only predicts convergence within identical constraints, and alien constraints will not be identical. There is no reason to assume our hypothetical “radio astronomers” would think like us, build tools like us, or even notice the same parts of the electromagnetic spectrum we obsess over.
LUCA is not meant to be the first life form, only the one best suited to survive those early conditions. Other proto‑life forms almost certainly arose but were outcompeted or failed to meet the environmental challenges. That’s how selection works.
Suppose their planet is rich in nearly perfect ruby crystals. Their version of Marconi discovers that polishing the ends and blasting intense light through them produces a coherent beam of astonishing brightness. Their early technology becomes laser‑centric by cultural accident and environmental convenience. Meanwhile, whatever that low‑frequency radio hiss is — the stuff we treat as sacred hydrogen‑line real estate — they might dismiss as background noise from the sky.
And from their perspective, the sky is full of colors and coherent light sources. So of course they conclude:
“Everyone knows you communicate across the stars with lasers.”
Right? Why would anyone use that muddy, slow, low‑frequency stuff?
In other words, their entire technological trajectory could diverge from ours simply because their environment nudged them toward a different early discovery. And once a civilization commits to a technological paradigm, it tends to double down on it for centuries.
This is why SETI must avoid anthropocentric assumptions. The universe may be stranger than our engineering imagination, not just our biology.
Adrian
Ayushman Tripathi
Hi Adrian,
Really well put, and I agree with most of this. The convergence point is fair, and life appearing so fast does hint it may be easy to start, and thanks for the LaserSETI idea.
One thing I keep wondering about though. If it was that easy, on a big planet it probably started many times, yet every living thing we have ever found, deep rock microbes, vent extremophiles, us, uses the exact same biochemistry, same genetic code, same left handed amino acids, same ATP. Not one exception. And Earth is huge. If one chemistry began somewhere like the Pacific and another somewhere like the Arabian Sea, oceans apart, I am not sure why they could not both grow and multiply for a long time without ever meeting.
And if over millions of years life formed independently even a thousand times, not a million, just a thousand, what are the odds that only one of them survived, on the same Earth where we see coexistence even in the most unexpected environments? On a world where mice live alongside cats, we might expect at least two chemistries to have made it, but we see only one.
Do you think that points to life starting just once, or to many starts where only one chemistry made it ?
Thanks
Earth around the time the first life was forming, generated by AI: 
Don Latham
From: Ayushman Tripathi <ayushmantr...@gmail.com>
To: Society of Amateur Radio Astronomers <sara...@googlegroups.com>
Date: Tuesday, 21 July 2026 11:20 AM MDT
To view this discussion visit https://groups.google.com/d/msgid/sara-list/ceeb83ec-16fa-4ecc-ae55-fa94a696b589n%40googlegroups.com.
A. C.
Of course, any real evidence about how many proto‑ or pseudo‑life forms may have arisen more than 4 billion years ago is almost certainly gone, erased by Earth’s active tectonics and constant recycling of its surface. As for whether isolated ecosystems existed where alternative forms of life could have developed — yes, that’s possible. However, Earth underwent extensive surface restructuring, and at the time it first formed solid land, it likely had only one ocean and essentially one continent, unlike the later breakup that produced the many isolated landmasses we see today. Isolation requires stable geography, and early Earth didn’t have it. That makes any long‑term isolated ecosystem very unlikely to have remained protected from contact with others, and thus it would have been exposed to strong competitive Darwinian pressures.
As you note, all life today — from viruses to humans — operates using the same restricted set of left‑handed amino acids, right‑handed DNA sugars, and a largely universal genetic code. Could other combinations of these features have supported alternative life forms? For at least some of them, we can say with reasonable confidence that the answer is yes.
Even today, there is an active and sometimes contentious debate about laboratory‑generated “mirror life” forms. These organisms — and we are really talking about bacteria here — would be engineered microbes built from essentially the same kinds of proteins that normal bacteria use, except all the amino acids would be the right‑handed versions. Some of these mirror‑proteins have already been synthesized from the alternate amino acids, and they function much like their normal counterparts, though they strongly prefer right‑handed molecules and mainly generate right‑handed products, so the entire chemistry tends to run in the opposite chirality.
So in essence you’re raising a question that sits right at the center of why all modern life appears so homogeneous, tracing back to what we call FUCA — the First Universal Common Ancestor. We can only speculate that some subtle asymmetric advantage allowed this particular set of molecular choices to win out in the long run. It’s a puzzle in the same spirit as the cosmological question of why the Universe contains matter but almost no antimatter, even though our best theories say the Big Bang should have produced equal amounts of both. These really are some of the deepest and most fascinating questions, the kind that keep not only you but also me up late at night.
You received this message because you are subscribed to a topic in the Google Groups "Society of Amateur Radio Astronomers" group.
To unsubscribe from this topic, visit https://groups.google.com/d/topic/sara-list/eTqSh1_wg0M/unsubscribe.
To unsubscribe from this group and all its topics, send an email to sara-list+...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/sara-list/1304578343.1896991.1784654639930.JavaMail.zimbra%40blackfoot.net.
Adrian
"My God, it's full of stars!"
Dave Bowman
Andrew Thornett
Sent: Tuesday, 21 July 2026 23:30:38
To: sara...@googlegroups.com <sara...@googlegroups.com>
Alfred Aburto
Yes, so long as there is NO reason to suspect that there is
anything special about the third planet around our star.
But what if they had an optical telescope that was 10 times
bigger than our James Webb? What if they discovered that our
planet had oxygen (O2), methane (CH4), ozone (O3), and nitrous
oxide (N2O) in our atmosphere? Maybe then they would attempt to
send a very narrrow band pulsed signal to Earth?
My question would be regarding the parameters of the transmitting
antenna, "R" light years away, so that it could be received by a
small (minimal) dish antenna on Earth?
Al
To view this discussion visit https://groups.google.com/d/msgid/sara-list/1304578343.1896991.1784654639930.JavaMail.zimbra%40blackfoot.net.
Adrian
[URE3] — caused by misfolding of Ure2, a nitrogen‑regulation protein
[PIN⁺] — caused by misfolding of Rnq1, a Q/N‑rich protein
[SWI⁺] — caused by misfolding of Swi1, a chromatin‑remodeling factor
[OCT⁺], [MOT3⁺], [ISP⁺], etc. — several others identified later
And as far as restricting conversatonal topics to radio astronomy in the forum, that is a fair proposition and perhaps maybe that should be a rule established and enforced as an absolute by the new adminsitratio in order to maintain a nice tidy and clean exclusive radio astronomy conversation devoid of any ancilliary distraction and divergence from any change. Spectra in aeternum regat..
Adrian
Ayushman Tripathi
Ayushman Tripathi
Hi Alfred
Using the Arecibo reference (2x10^13 W EIRP seen by a 305 m dish at 25,000 ly), the minimum receive dish scales as R / sqrt(EIRP). Assuming they beam a narrowband signal at us:
At 1000 ly:
10x our best transmitter (2x10^14 W): Receive dish is about 3.9 m
100x (2x10^15 W): about 1.2 m
1000x (2x10^16 W): about 0.39 m, a satellite TV dish
Full stellar power: a few microns, i.e. any antenna at all
At 10,000 ly:
10x (2x10^14 W): about 39 m
100x (2x10^15 W): about 12 m
1000x (2x10^16 W): about 3.9 m
Full stellar power: still microns
By "full stellar power" I mean a civilization that has somehow found a way to capture and use their star's output that otherwise just radiates away into space wasted, on the order of 4x10^26 W for a Sun-like star, about 20 trillion times our strongest transmitter.
On the transmit side: the received signal is just EIRP times our collecting area divided by range squared, and EIRP is transmit power times transmit-dish gain. Both are products, so power and aperture trade freely and there is no fixed minimum dish. To be heard by a 3 m dish here at 1000 ly they need about 3x10^14 W EIRP, roughly 16x Arecibo, which a 300 m dish makes with only about 25 MW, a single power plant. And 25 MW is not a ceiling. Give them 100x that, 2.5 GW behind the same dish, and our receive dish shrinks tenfold to about 0.3 m. Another 100x and it is 3 cm. They can always trade brute power for a smaller antenna on either end.
The one real constraint is the beam. A 300 m transmit dish at the 21 cm line is a 0.05 degree pencil, so more transmit aperture buys cheap detectability but forces them to aim precisely at our Sun, and if they sweep it like radar we only catch a brief flash.
Formula: D_rx = 305 m x (R / 25,000 ly) / sqrt(EIRP / 2x10^13 W)
For reference, the SETI Institute makes the same point about the 1974 Arecibo message: the 305 m dish concentrated a megawatt transmitter into a narrow beam, equivalent to a 20 trillion watt omnidirectional broadcast, detectable just about anywhere in the galaxy with a receiver the size of Arecibo.
Ref: https://www.seti.org/research/seti-101/project-phoenix/arecibo/
Thanks
Ayushman
Alfred Aburto
Great!
Thank you!
Since Earth, from a far away alien planet, is already "known" to have an interesting atmosphere, then their minimum beamwidth would be the diameter of the Earth's orbit around the Sun! A potential very narrow beamwidth packing lots of power.
The minimum bandwidth, if memory serves, would be about 0.1 Hz because of dispersion of the interstellar medium?
My main point is that it is really worth it to do a wide beam
(from multiple sensors) search near the "water hole"... Probably
it would take a long time for something to alert the monitors, but
it would be monumental!
Al
To view this discussion visit https://groups.google.com/d/msgid/sara-list/edfeb744-9d29-4cac-a727-7b195703c420n%40googlegroups.com.
ja...@ganssle.com
>· And as far as restricting conversatonal topics to radio astronomy in the forum, that is a fair proposition and perhaps maybe that should be a rule established and enforced as an absolute by the new adminsitratio in order to maintain a nice tidy and clean exclusive radio astronomy conversation devoid of any ancilliary distraction and divergence from any change. Spectra in aeternum regat..
Well, my worthless $0.02 on this is that one of the astonishing results of professional radio astronomy is the discovery of the building blocks of life throughout the universe. A search for, not the building blocks of life, but life itself is a noble goal. Speculations on what that life might be like are essential to creating the instrumentation needed to find it. For instance, some here have talked about alternate chiralaties. I don’t know if that would manifest as spectra different those from from proteins et al with Earthlike chiralaties, but if it did, well, there’s an area to investigate.
I’m finding this discussion fascinating.
Jack
From: sara...@googlegroups.com <sara...@googlegroups.com> On Behalf Of Adrian
Sent: Tuesday, July 21, 2026 7:19 PM
To: Society of Amateur Radio Astronomers <sara...@googlegroups.com>
Subject: Re: [SARA] Re: Narrowband SETI drift search pipeline, progress and a verification question
Andy,
To view this discussion visit https://groups.google.com/d/msgid/sara-list/d5fe2be3-514d-45d3-a3a7-cbbe1781a676n%40googlegroups.com.
Adrian
"
Francesco Di Giovanni
Andrew Thornett
Sent: Thursday, 23 July 2026 18:25:00
Alfred Aburto
hear hear!!
To view this discussion visit https://groups.google.com/d/msgid/sara-list/AS8PR06MB8117743269731DDBEE2869FDFFC02%40AS8PR06MB8117.eurprd06.prod.outlook.com.
Ayushman Tripathi
Hi Francesco,
Thanks, yes, I am getting the R2 for exactly that reason. I have the Airspy Mini currently for 2.4m dish system, which does not have the clock input. Its TCXO drifts around 0.05 to 0.1 Hz/s, so that is exactly the problem I am facing though I am able to fix it in software for now because the drift is common-mode, subtracting it per block leaves the real relative drift intact.
My HackRF does have CLKIN, but it is already in use with my Ku band setup with an OCXO.
Adrian
Andy,
Please don’t be concerned — having made a response to your comment, I interpreted your remark simply as a topical observation within the broader discussion. My own reply was intended as a lightly tongue‑in‑cheek counterpoint, though I recognize that the phrasing may have introduced ambiguity. In retrospect, greater clarity would have better conveyed my position. I would also like to emphasize that your opinions, ideas, and comments are valued, and I encourage you to continue expressing them. Your contributions both within and adjacent to the forum’s core topic enrich the dialogue and undoubtedly enhance its overall significance.
From my perspective, the statement remained entirely within the bounds of a collegial, debate‑style dialogue — a routine exchange of ideas within the discussion, without any personal dimension and simply expressing a divergent position. As such, I feel no apology is necessary, as no intended hurt or distress was perceived, and in addition, I also appreciate the opportunity to clarify the intent behind my earlier comments. I speak only for myself in this regard and do not presume to represent the views of any other participants in this discussion
Adrian
Andrew Thornett
Sent: Friday, 24 July 2026 04:26:31
fdseller
Ayushman Tripathi
On 24 Jul 2026, at 07:18, fdseller <fdse...@gmail.com> wrote:
To view this discussion visit https://groups.google.com/d/msgid/sara-list/6a6349f6.e9cff95d.186a9.d34c%40mx.google.com.
Ayushman Tripathi
I am thinking of getting this HydraSDR instead of the Airspy R2, as the RTL-SDR Blog review shows it has better shielding and lower internal spurs than the R2, and it has an SMA connector for clock in instead of MCX on the R2.
https://www.rtl-sdr.com/rtl-sdr-blog-review-of-the-hydrasdr/
Has anyone here used it at 1420?
Thanks,
Ayushman
Andrew Thornett
Sent: Saturday, 25 July 2026 22:03:15
Stephen Arbogast
Ayushman Tripathi
It is being sold now, I just bought one from DigiKey. DigiKey seems to be the only channel for it.
https://www.digikey.com/en/products/detail/benjamin-vernoux/HYDRASDR-RFONE/26256067
I did find it on eBay as well, but who knows if that one is a Banggood clone :)
Don Latham
From: Ayushman Tripathi <ayushmantr...@gmail.com>
To: Society of Amateur Radio Astronomers <sara...@googlegroups.com>
Date: Saturday, 25 July 2026 3:03 PM MDT
To view this discussion visit https://groups.google.com/d/msgid/sara-list/a8f4949e-9340-4dac-b9b7-ef5ef662cf27n%40googlegroups.com.
Ayushman Tripathi
Hi Don, Yes, it is fine for me. I am running my current observations at 3 MHz anyway, so 10 is fine for now. Long integrations at higher rates also get heavy on storage quite fast which is limited.
For me the deciding factor between the Hydra and the R2 was the better shielding, so RFI does not leak in through the enclosure, as the RTL-SDR Blog review found, plus lower internal spur levels.
RTL-SDR mentions: "We noticed that the HydraSDR has excellent shielding and is very well protected against signals entering through paths other than the antenna. The Airspy was able to receive a strong TV channel without any antenna, indicating that it has shielding issues."
Thanks
Don Latham
From: Ayushman Tripathi <ayushmantr...@gmail.com>
To: Society of Amateur Radio Astronomers <sara...@googlegroups.com>
Date: Saturday, 25 July 2026 5:26 PM MDT
To view this discussion visit https://groups.google.com/d/msgid/sara-list/43dec977-5488-4174-b8ee-8758f7be29d8n%40googlegroups.com.
Stephen Arbogast
Ayushman Tripathi
https://hydrasdr.com/downloads/HydraSDR_RFOne_Datasheet.pdf
https://www.rtl-sdr.com/rtl-sdr-blog-review-of-the-hydrasdr/