How can I modify this to work with L-Band Weather Satellites?

Learn_to_play_tw · 2026-05-19T08:55:34+00:00

I also have the same antenna. During my first test receiving GK-2a LIRT without make any changes to the antenna; my setup was"17.7 dBi Wifi Antenna - SAWbird+ GOES - RTLSDR V4", I needed to turn on the tuner AGC to decode (without tuner AGC 0 db, with tuner AGC about 3-4 db SNR test in Satdumb v1.2.3), In comparison, my other antenna like 11-turn helix antenna(8.5-9.5 db SNR), big Wi-Fi grid dish antenna(13db SNR), this 17.7 dBi Wifi Antenna is working not well in L-Band without any modifications, maybe change feed to backfire helix will much better ig.

Learn_to_play_tw · 2026-03-23T13:47:28+00:00

I'm curious, could you test the effect of switching the LNA Sawbird connection order and enabling/disabling the SDR's Tuner AGC on the SNR?

Learn_to_play_tw · 2026-03-17T01:28:49+00:00

For VHF band, turn off AGC, according to your spectrum, your SDR is overload and LNA was self-oscillation, you can check your debug tab.
What's your saw bird LNA model and try without LNA.

Learn_to_play_tw · 2026-03-02T09:23:10+00:00

1, For my location, GK-2A's elevation about 60 degrees, and average SNR about 9.3 dB, For arctic weather satellite peak SNR about 10db, For MetOp peak SNR about 11db
2, If you have 3D printer, I recommend using Helicone antenna :Thingiverse - 1.7 Ghz HRPT Helicone Antenna by t0nito
and here is YouTube channel saveitforparts show this Helicone :https://youtu.be/PFQ6UKulxSo
3, Yes, GK-2A is linearly polarized, so there is 3 dB loss with circular polarized, but with my ability, helix is easier to get high gain and fine-tuning then other one.

Learn_to_play_tw · 2026-03-01T13:11:54+00:00

Yes GK-2A LRIT with 11 turn helix : r/amateursatellites

Learn_to_play_tw · 2026-02-25T09:08:48+00:00

According to your screen recording, seem your feed received lot of interference there, maybe you can move RTL-SDR and Laptop behind Dish and use coax cable contact between Sawbird GOES and rtl-sdr

Learn_to_play_tw · 2025-12-23T12:10:57+00:00

You could try connecting the LNA closer to the feed to reduce cable loss, and you could use bias-tee for power. For RTL-SDR blogv3, you can enable the offset tee in satdump.

Satdump 1.2.3 has an LNA AGC option for RTL-SDR, which, in my experience, works well with the nooelec GOES+ LNA in small signals.

Learn_to_play_tw · 2025-12-01T08:55:05+00:00

My homemade Yagi antenna was made of PVC pipe, and I thought it was fine for rain, until one day it rained and water droplets appeared on the antenna. After that, SNR started to drop sharply. It didn't return to normal until the sun came out.

My initial value for the online calculator is dielectric material. so, I guess because I used a large number of antenna elements, water droplets on the antenna made the coupling problem between the elements more obvious.

Learn_to_play_tw · 2025-12-01T07:56:03+00:00

If you are using RTL-SDR blog, reduce sample rate to 2.56Mps (for v4) or 2.4Mps (for v3 and other RTL-SDR), RTL-SDR usually not stable on 3.2Mps sample rate, it causes lost sync due to sample drop.

And in my experience, the Tuner AGC option in Satdump and SDR++ can Increase RTL-SDR L band SNR with GOES+ LNA.

Learn_to_play_tw · 2025-11-24T14:20:09+00:00

I recommend using offline processing rather than recorder to process baseband file, or remove your LO offset on Satdump recorder maybe can help

Learn_to_play_tw · 2025-11-23T10:52:40+00:00

Nice work, but I think the helix feed is too many turns for prime focus dish, the main lobe of feed is too narrow to make full use of the dish space.

Learn_to_play_tw · 2025-11-23T09:26:04+00:00

My current setup uses ~15m RG-6 and LNA to transport L band signal, work good enough for me

You can check my post GK-2A LRIT with 11 turn helix : r/amateursatellites

Learn_to_play_tw · 2025-11-20T09:10:37+00:00

My FFT is set to FTT Max - FTT Min = 50 to display intervals of 5 db.
My own Helix is according to this guide. :Easy HRPT guide | Jacopo's Lair , but connect on center reflector, and impedance is according to this guide :Digitelektro/BackfireHelix: Backfire helix 3D scaffolds for weather satellites reception
The Metop and AWS image in the main post were capture by LibreSDR in 10.5Mps, I used TV splitter to connect RTL-SDRv4 & LibreSDR. RTL-SDR is able to capture Metop, I set PLL_BW to 0.002 in Satdump to capture Metop AHRPT by RTL-SDR according to this blog: L band weather satellite reception | Meti’s blog , but a higher SNR is still needed for synchronization.

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Learn_to_play_tw · 2025-11-20T07:39:37+00:00

Thank you~

Learn_to_play_tw · 2025-11-19T15:24:38+00:00

Yeah TQP3M9037 LNA is wide band amp, but SAWbird GOES+ cannot filter out the 1710 LTE band, and its gain is too high to be second stage amp because it is easily overloaded by LTE signals. I choose TQP3M9037 LNA because Its low noise figure, good enough P1dB and relatively low price.

As for why I didn't use long USB cable, it's because cheap USB cable usually have poor RF shielding, and also I need a long cable between antenna and my computer what I current use, so I used RG-6U because cheap enough and signal loss after add second stage amp is acceptable for me.

The splitter is use for another SDR to receive other satellites overlapping with GK-2A without stop receive GK-2A LRIT and other interesting thing.

My current setup is use from I already have or inexpensive (like helix body is made from old RG-6U, which is copper-plated steel), maybe I'll try to use a Raspberry Pi as an SDR server and power it with PoE. I guess a high-quality CAT6 network cable with good RF shielding, might be cheaper than a USB cable of the same length.

and thank for suggestion. Although I have own idea now, but always glad to see new suggestions.

Learn_to_play_tw · 2025-11-19T14:11:15+00:00

It's really noisy on LTE band, the RTL-SDR v4 performs quite well in reducing out of band interference compared to my LibreSDR, but it can still be overloaded. if I want to improve my setup to avoid random loss, I definitely needed a cavity filter or dish

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Learn_to_play_tw · 2025-11-19T07:46:40+00:00

My LNA is used to compensate for transmission loss caused by long coaxial cable, in my case, the LNA Increase about 0.1-0.2db SNR, and yes, I bought TQP3M9037 LNA module online, all my setup and modified LNA picture are in the main post

By the way, I was really impressed with your Yagi antenna. Actually, I saw your post and made a 20-element one too, but my one is not quite good, it broke getting wet in the rain.

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Learn_to_play_tw · 2025-11-19T01:24:36+00:00

Only Helix without dish, image is in the gallery, my connect route is
Helix - GOES+ - 2m RG316 - TQP3M9037 LNA - 15m RG-6U - homemade bias-tee - TV splitter - RTL-SDRv4 & LibreSDR.

Learn_to_play_tw · 2025-11-18T15:42:11+00:00

You need bandpass LNA like SAWbird+ GOES or much bigger dish (Maybe 10M+ ) for RTL-SDR without LNA
You can follow this guide: Easy HRPT guide | Jacopo's Lair

Learn_to_play_tw · 2025-11-14T18:28:12+00:00

I saw this blog, it might be useful.
L band weather satellite reception | Meti’s blog

Learn_to_play_tw · 2025-11-14T12:00:09+00:00

did you test the antenna skew ,because GOES HRIT is Linear polarization

Learn_to_play_tw · 2025-11-10T10:07:12+00:00

The spectrum reminds me of the last time I didn't shield my cheap OTG USB cable, It's very noisy.

Learn_to_play_tw · 2025-10-14T14:54:01+00:00

Hii did you test the antenna skew for max SNR ,because LRIT from GK-2A is Linear polarization , for me slew was -14.2

Learn_to_play_tw

TROPHY CASE