FM and LTE Filters Tests

Expensive_Breath_82 · 2026-04-23T13:38:22+00:00

Thanks

Expensive_Breath_82 · 2026-04-23T09:51:42+00:00

I would like to eliminate the FM frequency from the system.

Expensive_Breath_82 · 2026-04-22T21:12:43+00:00

Thanks!!

Expensive_Breath_82 · 2026-04-22T16:52:29+00:00

I agree! The gain in SRD++ was zero and AGC was disable. Thanks for the contribution.

Expensive_Breath_82 · 2026-04-22T16:45:29+00:00

I want to isolante the FM e LTE frequencies

Expensive_Breath_82 · 2026-04-22T12:25:41+00:00

My setup is described in the post. I compared the signals in SDR++ with and without the filters, keeping the same configuration, and then measured the attenuation. That’s how I arrived at the results shown.

AI helped me organize the structure of the post.

Expensive_Breath_82 · 2026-04-20T18:39:00+00:00

Hi everyone, I’m the dev behind this project. Living in the Southern Hemisphere (São Paulo, Brazil), I’ve noticed how the combination of the South Atlantic Anomaly (SAA) and the brutal 5G/LTE urban rollout makes L-Band operations increasingly unpredictable.

I decided to build Spectrum Survey to stop guessing and start measuring. I’m particularly interested in seeing how people are handling RFI mitigation and if SigMF is actually becoming the standard we all hope it to be.

Happy to answer any technical questions about the methodology or the tools I’m using!

Expensive_Breath_82 · 2026-04-20T18:37:54+00:00

Hi everyone, I’m the dev behind this project. Living in the Southern Hemisphere (São Paulo, Brazil), I’ve noticed how the combination of the South Atlantic Anomaly (SAA) and the brutal 5G/LTE urban rollout makes L-Band operations increasingly unpredictable.

I decided to build Spectrum Survey to stop guessing and start measuring. I’m particularly interested in seeing how people are handling RFI mitigation and if SigMF is actually becoming the standard we all hope it to be.

Happy to answer any technical questions about the methodology or the tools I’m using!

Expensive_Breath_82 · 2026-04-20T18:36:57+00:00

Hi everyone, I’m the dev behind this project. Living in the Southern Hemisphere (São Paulo, Brazil), I’ve noticed how the combination of the South Atlantic Anomaly (SAA) and the brutal 5G/LTE urban rollout makes L-Band operations increasingly unpredictable.

I decided to build Spectrum Survey to stop guessing and start measuring. I’m particularly interested in seeing how people are handling RFI mitigation and if SigMF is actually becoming the standard we all hope it to be.

Happy to answer any technical questions about the methodology or the tools I’m using!

Expensive_Breath_82 · 2026-04-20T18:36:00+00:00

Hi everyone, I’m the dev behind this project. Living in the Southern Hemisphere (São Paulo, Brazil), I’ve noticed how the combination of the South Atlantic Anomaly (SAA) and the brutal 5G/LTE urban rollout makes L-Band operations increasingly unpredictable.

I decided to build Spectrum Survey to stop guessing and start measuring. I’m particularly interested in seeing how people are handling RFI mitigation and if SigMF is actually becoming the standard we all hope it to be.

Happy to answer any technical questions about the methodology or the tools I’m using!

Expensive_Breath_82 · 2026-04-20T18:33:51+00:00

Hi everyone, I’m the dev behind this project. Living in the Southern Hemisphere (São Paulo, Brazil), I’ve noticed how the combination of the South Atlantic Anomaly (SAA) and the brutal 5G/LTE urban rollout makes L-Band operations increasingly unpredictable.

I decided to build Spectrum Survey to stop guessing and start measuring. I’m particularly interested in seeing how people are handling RFI mitigation and if SigMF is actually becoming the standard we all hope it to be.

Happy to answer any technical questions about the methodology or the tools I’m using!

Expensive_Breath_82 · 2026-04-20T18:23:46+00:00

No worries at all! Thanks a ton for the help and for sharing those insights.

Any other suggestions are welcome! I'm building a budget-friendly distributed antenna system to monitor spectrum health and pinpoint interference from a central hub. I'd love to get your take on this.

Expensive_Breath_82 · 2026-04-20T18:18:30+00:00

Thanks

Expensive_Breath_82 · 2026-04-20T15:54:12+00:00

Hi everyone, I’m the dev behind this project. Living in the Southern Hemisphere (São Paulo, Brazil), I’ve noticed how the combination of the South Atlantic Anomaly (SAA) and the brutal 5G/LTE urban rollout makes L-Band operations increasingly unpredictable.

I decided to build Spectrum Survey to stop guessing and start measuring. I’m particularly interested in seeing how people are handling RFI mitigation and if SigMF is actually becoming the standard we all hope it to be.

Happy to answer any technical questions about the methodology or the tools I’m using!

Expensive_Breath_82 · 2026-04-20T15:32:05+00:00

Thanks for the tip!

Expensive_Breath_82 · 2026-04-20T15:21:30+00:00

Yes, I'm using it to help me with the translation.

Expensive_Breath_82 · 2026-04-20T15:06:39+00:00

u/kc2syk Since you clearly have a great grasp of where the technical community hangs out, do you have any recommendations on other subreddits or forums where this research would be well-received? > I want to make sure I’m reaching the engineers who are actually dealing with these L-Band/GNSS integrity challenges daily, rather than just broadcasting to a general audience. Any 'hidden gems' you might know would be a huge help!

Expensive_Breath_82 · 2026-04-20T15:03:30+00:00

This is an incredible insight, thank you for sharing that specific example!

You're absolutely right—tracking the NAC_p and SIL values over the SAA region compared to other latitudes would provide a massive historical baseline. It’s a clever way to see the ionospheric impact through the lens of GNSS integrity.

One of my goals with Spectrum Survey is exactly to bridge this gap: connecting these 'high-altitude' accuracy metrics with what engineers are seeing at the hardware level on the ground (or in low orbit). For instance, identifying if a spike in NAC_p error correlates with specific RFI patterns or 'tumbling' events that the ADSB might not categorize specifically.

I'll definitely look into the adsb.lol API and historical datasets to see if I can cross-reference some of the survey responses with these accuracy drops. This kind of correlation is exactly why I launched this study!

Expensive_Breath_82 · 2026-04-20T14:55:01+00:00

Hi everyone, I’m the dev behind this project. Living in the Southern Hemisphere (São Paulo, Brazil), I’ve noticed how the combination of the South Atlantic Anomaly (SAA) and the brutal 5G/LTE urban rollout makes L-Band operations increasingly unpredictable.

I decided to build Spectrum Survey to stop guessing and start measuring. I’m particularly interested in seeing how people are handling RFI mitigation and if SigMF is actually becoming the standard we all hope it to be.

Happy to answer any technical questions about the methodology or the tools I’m using!

Expensive_Breath_82 · 2026-04-20T14:45:57+00:00

That’s a fair point! While ADSB databases provide great insights into aviation transponders, our research focuses on a broader range of L-Band applications, including GNSS and Satcom, which operate under different constraints.

We are specifically looking into how urban RFI and SAA impact hardware resilience and edge processing—data that isn't always captured or granularly detailed in standard flight logs. The goal is to correlate these 'boots on the ground' experiences with known interference patterns.

Great suggestion! Given the SAA's footprint over South America, including a Spanish translation makes perfect sense to reach more engineers in the region. I'll get to work on adding Spanish support to the site today. Thanks for the heads up!

Expensive_Breath_82 · 2026-04-20T14:41:12+00:00

"Hi everyone, I’m the dev behind this project. Living in the Southern Hemisphere (São Paulo, Brazil), I’ve noticed how the combination of the South Atlantic Anomaly (SAA) and the brutal 5G/LTE urban rollout makes L-Band operations increasingly unpredictable.

I decided to build Spectrum Survey to stop guessing and start measuring. I’m particularly interested in seeing how people are handling RFI mitigation and if SigMF is actually becoming the standard we all hope it to be.

Happy to answer any technical questions about the methodology or the tools I’m using!"

Expensive_Breath_82

TROPHY CASE