This L Band Helix Antenna Gives Amazing Performance

[@michaelcarey]

Great video! Reminds me of fun times back in the day of Inmarsat A with a similar antenna set up and an Icom R-100 receiver. I won't confirm nor deny that I was able to hear anything or decode any RTTY :-) Ahh, the days of analog satellite communications was fun.

[@medicalstudioimt3031]

You can go on with analog satellite communications by Inmarsat L band. Also there are some wormholes from Ku and C band to L. Bandplan depends on your location.

[@Rattletrap-xs8il]

That landscape beyond your yard is awesome

[@stevehageman6785]

That's great EoNb on the decode - I have one of those cheap 4x4 inch active patch antennas and even though the EoNb is only 8dB, it decodes all the Inmarsat ACARS perfectly. For people starting out - there are web based applications that take your location and draw you a map of where to point your antenna to get the selected Satellite(s). Makes quick work of setting up - you immediately get close and only have to tweak the antenna after that.

[@rohnkd4hct260]

Good job. You can hear some funny stuff and some very serious stuff. I’ve hear some VERY sick people flying somewhere. Heard a pilot call his base to report the “bar totals” did not add up. Would love to know how that turned out! LOL

[@georgesv8arj48]

Great video as usual. At around 8:20 jaero fails to lock. Try same setup with Airpsy-R2 or RTL-SDRv3 or Funcude Pro. You will be surprized ;)

[@craigspada1676]

Super video, I have built a number of Helix antennas for vhf and uhf for ham satellites, enjoyed the video, you always have very interesting products. 73's WA2TWF

[@TechMindsOfficial]

Cool, thanks

[@laykalayoni1314]

Excellent video Mat. I have been decoding these signals with a small patch antenna for some time now. Try decoding voice using a stock rtl-sdr v3 as my much more expensive Airspy Mini was absolutely useless.

[@user-jt5vm3mi1w]

I could hear 'send me an email' in that phone call

[@Subgunman]

That decoded audio sounded like some of the early voice encryption modules that split and inverted the audio frequencies.

[@unsafe_dB_level]

Yes, the way he "disguised" the audio does sound like voice inversion.

[@medicalstudioimt3031]

This was done intentionally for the privacy reasons. Speech sounds normally.

[@Dixy3]

HI Tech Minds, Yes, I would like to hear what you achieved with a 1.8 metre dish. Also, where we can obtain these and other dishes in the UK.

[@alf-omega]

Yep, me too… some advice on a suitable dish would be great.

[@ryank5tar]

Awesome video. I plan to build antennas like that soon.

[@fatboymotorsport]

For those of us who cant guess where is the audio from?

[@Trev1916]

Slow the audio down using 0.25 speed and you can clearly make out the medium from Poltergeist movie saying "come to the light Carol-anne"

[@rcczar2885]

The Chipmunks command centre.

[@stevehageman6785]

@@rcczar2885 I knew the Chipmunks would eventually take over! 🙂

[@patrickbodine1300]

The end of a pipe.

[@repatch43]

Same, what kind of audio is it? Is it pilots transmitting? Or are they POTS phone calls?

[@M0JHN]

Yes for the bigger dish comparison

[@earlyadapter643]

Today i just finished and tested my 2.5 turn helical feeder with increased diameter (65 mm) so that it fits around a standard LNB radome. For QO-100 it performs poorly. Maybe i should test it for L-band ? However it needs more measurements to conclude, it may spill over the dish, under-illuminate, have a bunch of ugly side lobes or the PVC tube that the helix is wound around is absorbing. I could get the SWR down to 1.3 though... As i said before, i sometimes try things even though the chance of success is 5% and sometimes it works.

[@ocsrc]

It is amazing how much L band is coming down from antennas. We have a lot of the TV and radio stations using this band for their feeds to their broadcast sites via satellite 🛰️📡 I didn't understand why the land based services and radios for the L band were eliminated. Once I saw all the data coming from the satellites I realized that if we had land based Radios they would interfere with these satellite transmissions being received like the 5G signals are interfering with the C-band signals on the same frequencies.

[@bluegizmo1983]

"Should not be decoded" ... challenge accepted! 😂

[@digitalmediafan]

Fantastic. I would try using SatDump for voice but I have never had any audio out with this when using for Noaa weather sats so guess it won't work with this ? Is the frequency shown a voice channel ?

[@sgtclubba1732]

The voice uses an ambe codec. Not used satdump for inmarsat before, gotta try now.

[@nofider1]

Thanks Mat, Some more stuff to play with..... :-)

[@fixfaxerify]

I thought a dish like that focused on the center axis in front of the dish. The helix seems to be much lower than that? Maybe the dish has an odd shape so it focuses off center or how does it work?

[@TechMindsOfficial]

This is an “offset” dish. Prime focus dishes use the centre.

[@fixfaxerify]

@@TechMindsOfficial Cool, learned something new about satellite dishes today thx :)

[@ostanin_vadym]

Thank you for pleasant further video watch.

[@TechMindsOfficial]

Thank you too

[@2182DX]

Great video Matt, couple of follow up questions… - Can confirm the performance between the dish & small helix & the grid antenna….? - I’d be very interested to understand how you got Aero H+ audio to work with Satdump…? Was this real time or from recorded baseband file…? Cheers

[@TechMindsOfficial]

Dish will always win, IMO. Satdump was real time :-)

[@pjg54g]

Great video but no idea where the audio might have come from. I guess I missed all the clues? Help!

[@paaao]

5 db stronger signal with dish, but also a 5 db stronger noise floor = a wash correct?

[@snaily1972]

Not sure if you have done a video, cant search at the moment. Have you tried Aero on C-Band?

[@TechMindsOfficial]

Not yet! But I plan to, just need to get the LNB for it as I have a 1.8m dish I can utilise .

[@snaily1972]

@@TechMindsOfficial great look forward to it. I'm wondering what the minimum sized dish one could get away with on C-Band. Would love to have a go but space is at a premium.

[@DAVIDGREGORYKERR]

What about trying QAM,QPSK or OFDM.

[@sparcnz]

Great video as normal. Just to clarify, is this antenna suitable for all Inmarsat systems? I would be looking at the Pacific based Satellite coverage. Regards.

[@TechMindsOfficial]

L-Band yes, i.e around 1.5 GHz.

[@Monitoring_Everything]

Is it right hand or left hand polarized? Are Immarsat L or R?

[@RubenSmitGooglePlus]

Inmarsat transmits a right hand polarized signal. When you recieve that signal via dish the polarization flips, it is mirrored. So this antenna is left hand polarized.

[@antunes7831]

88 PY9BG

[@XRinger]

At the beginning of the vid, I was thinking that small LHCP antenna was a dish feed, rigged for RHCP satellites. Long ago, when I had a 10 foot dish, I made a 1420 MHz RHCP feed, so my dish would reject RHCP GPS etc signals. I could listen in on the hydrogen line at 1420 without all the GPS RFI. Radio Astronomy was fun, and I could hear EME SSB from South American hams. 🌙 Bounce.

[@Allan_aka_RocKITEman]

Great video...👍

[@maeswdy]

Tell us about the pirates on inmarsat

[@вечная_мерзлота]

LNA - low noise amplifier . who in their right mind would wanna amplify the noise ? I want to lower the noise to be able to amplify the signal .

[@TechMindsOfficial]

Not sure if you’re being serious or not, but I guess that’s a literal way of reading it. An LNA is an amplifier that has low noise…

[@вечная_мерзлота]

​​​@@TechMindsOfficial then it needs to be called properly because that's how I understood it . looks like Google translation from Chinese . we amplify signal not noise .

[@Zarathustran]

It was a very cruel joke parents who would have just thrown us in asylums in the 50s and 60s played on autistic kids concealing our diagnoses in the 70s 80s and 90s. Once the world had again forgotten that the pathogenic etiology is postpartum psychosis (wish for the child to become "unborn") diagnosing autism became a virtue signal for activating parental savior complexes. If you're from the older group you're completely unaware of your 'tism and if you're from the diagnosed younger group you can see what I mean about your diagnosis having done you no good but being of benefit to whoever left your symptoms so untreated. Either way the autistic experience of exclusion and isolation leads to a perspective that could declare an established nomenclature incorrect because of its own misunderstanding. Gifted autodidacts need to know we're autistic so that our literal thinking doesn't blind us to the need for intellectual humility. Exceptional fluid reasoning can't kick ass in a crystallized intelligence world without realizing an IQ over 130 makes it easy to see all the stupidity in the world EXCEPT OUR OWN AS SEEN FROM THE PERSPECTIVE OF THE OTHER 98%. Headcount dominance is achieved by consensus, not correctness. Like it or not the world is run by people of average intelligence--and they have their egos invested because ego function IS WORKING CORRECTLY when it offsets competence gaps. If we didn't mistake our feelings for facts shit like hunger and fear wouldn't work at all. But because extraversion is only positively correlated with IQ below the mean it's easy for someone far above the mean to get by with no need of extraversion (adaptive solicitation of unknown information and unfamiliar skill from others). Abandoning extraversion prevents you from learning that duplicity is humanity's most adaptive trait... which is indeed the goal of grooming a kid to autism in the first place. So to fit in and better-understand new material there are lots of times it's more important to agree than to be right. Otherwise people mistake our lack of self-awareness for narcissism and enjoy leaving us to the process of making fools of ourselves. Which we' promptly double down on Google and do for having no understanding of why. Like I said -- very cruel.

[@petewright2283]

I have a spare LNA & SDR I can let you borrow

[@KA4UPW]

Wish it had more than three turns

[@stargazer7644]

Then it wouldn't be terribly useful for illuminating a dish.

[@KA4UPW]

@@stargazer7644 Is this true? Thought that was a function on how far from the dish its mounded?

[@stargazer7644]

@@KA4UPW It will always be mounted at the focal point of the dish - a fixed distance from the dish. The number of turns on the helix depends on the angle needed to illuminate the dish correctly without overspilling or underilluminating the edges.

[@KA4UPW]

@@stargazer7644 Then it sounds like the number of turns need to be optimized for the size of the dish. I definitely need to research this more before making any purchases

[@heyitsburt]

please show us as I am getting into the hobby and thankful for you showing the applications and how you have things running

[@rogerhargreaves2272]

I work at Inmarsat.

[@maeswdy]

Tell us about the pirates on inmarsat

[@rogerhargreaves2272]

@@maeswdy Oh, that’s for commercial shipping transmissions; I work in the aviation sector of Inmarsat.

[@kurtbrauer855]

? For What?

[@sky173]

"...yes ...see if there's anything else....Totally unavailable. what else you [we] got? Any... um... naw, yea, naw... what ummm ... ok, so... Sorry? yes, this is an email address." This is all can can figure out. The accent is very hard to understand.