Below the Noise Floor

James
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 Below the Noise Floor is a self-education project turned podcast. One licensed amateur radio operator learning HF radio and AetherSDR from the ground up - the bands, the waterfall, the voice chain, the digital modes, the antennas - and sharing the process. These episodes are mostly AI-generated content built around real curiosity and real equipment. If you are new to HF or new to software-defined radio and want something that starts from zero and builds methodically, this might be exactly what you were looking for. 

  1. 2d ago

    Below the Noise Floor — Episode 13: "The AetherSDR Voice Chain, Part Two: EQ and Processing"

    With a clean baseline signal established in Episode 12, this episode covers the refinements: transmit equalization, speech processing and compression, VOX sensitivity and hang time tuning, and how to save everything as a profile. Part two of two.

  2. 4d ago

    Below the Noise Floor — Episode 24: "CW for People Who Do Not Intend to Become CW Operators"

    This is not an attempt to talk you into becoming a CW operator. It is the narrower argument: that a small amount of Morse knowledge makes you a better listener and a better judge of what your antenna is actually doing, even if you never send a character on the air. In this episode: Why CW is the only mode whose bandwidth comes entirely from the switching, and how a hundred hertz against two and a half kilohertz turns into roughly fourteen decibels of noise you never have to fight.Why the CW portion of a band opens first and closes last, and how to use that as a ten second propagation check without decoding a single letter.What CW looks like on a waterfall, and why you will never mistake it for voice or FT8 again.The reverse beacon network: keying a dozen characters and getting back a real, over-the-air measurement of your antenna with no contact and nobody at the other end.The worldwide beacon rotation, and how a three minute listen on one frequency gives you a path margin with an actual number attached.Where decoders are better than people, where they fail silently, and the minimum floor of code knowledge that covers the gap.No music, no sound effects, no ads. Sleep-listener pacing throughout. Next episode: contesting and portable operation, not as competition, but as the fastest way to find out what your station does under load.

  3. Aug 15

    Below the Noise Floor — Episode 12: "The AetherSDR Voice Chain, Part One: The Basics"

    The AetherSDR transmit voice chain has enough controls to be genuinely overwhelming the first time you open it. This episode cuts through that by starting from zero and walking the signal path from microphone to antenna one stage at a time. Part one of two.

  4. Aug 13

    Below the Noise Floor — Episode 23: "Bonding, and the Panel Where Everything Comes In"

    Lightning protection is not really about lightning. It is about potential difference, and once you see it that way almost every decision gets easier. Your radio is connected to two separate worlds at once: the coax that goes outside and up in the air, and the power cord that goes into the wall. Those two paths meet at a circuit board. When the earth under your tower and the earth under your service entrance briefly disagree about what voltage they are at, that circuit board is what bridges the difference. That is the failure, almost every time. This episode covers the strategy that follows from that: make everything rise and fall together. The single point entry panel and why the singleness matters more than the protection. Why the separate, isolated, dedicated station ground is both a code violation and actively more dangerous than no ground at all. Why inductance rather than resistance dominates at lightning rise times, and what that means for flat strap versus round wire, for run length, and for why a sharp ninety degree bend is somewhere energy leaves the conductor. Gas discharge tube versus quarter-wave stub protectors, including the DC-pass trap. The conductors almost nobody armors, which are the ones that become the failure path. And the control that beats all of the others and costs nothing. Also an honest account of the limits. Nothing here reliably survives a direct hit. What it is genuinely good at is the near miss, which happens dozens of times more often. Next time: Morse code for people who have no intention of ever becoming a code operator.

  5. Aug 8

    Below the Noise Floor — Episode 11: "Noise Reduction and AGC"

    Noise reduction and AGC are two of the most misunderstood controls in SDR software - not because they are complicated but because they solve different problems. This episode explains what each one actually does, when to use it, when to leave it alone, and how the noise blanker fits into the picture.

  6. Aug 6

    Below the Noise Floor — Episode 22: "Height, and What Is Underneath It"

    Last episode was the noise you make yourself. This one is the question that follows it: not what antenna to build, but how high you can get the one you already have. In this episode: Why height is measured in wavelengths and never in feet, and how the same thirty-five foot tower is a good low-angle antenna on ten meters and a near-vertical radiator on eighty. What ground reflection does to a horizontal antenna at a quarter wavelength, a half, a full wavelength, and two, and the resulting takeoff angles. Why a wire dipole at sixty feet beats a beam at twenty, and why gain aimed at the wrong angle is not gain you get to use. The Fresnel zone: why the ground that sets your low-angle performance is out in the next field, why a downhill slope is worth real decibels, and why you cannot fix low-angle takeoff by improving the soil at the base of the mast. Why horizontal antennas are forgiving of poor ground and verticals are not, and what saltwater is actually doing for coastal stations. The two separate jobs of the ground under a vertical: near-field current return, which radials fix, and the far-field mirror, which they do not touch. What Brown, Lewis and Epstein found in 1937, where the curve flattens, and why four elevated radials can match a large buried system. Next: lightning protection and station entry panels, done properly.

  7. Aug 4

    Below the Noise Floor — Episode 21: "The Noise You Make Yourself"

    Phase 5 begins with the thing the show is named after. For most operators in most houses, the noise floor is not something that arrives from outside. It is something you are generating yourself, inside your own walls, and it is very likely the largest single limit on what you can hear. Reading noise signatures on the waterfall: broadband haze, picket-fence carriers, power line arcing, drifting LED and inverter tones. The breaker test, done safely. Hunting with a cheap AM radio and its ferrite loopstick, and why you use the null and not the peak. The usual culprits, from wall warts and recessed LED cans to solar inverters, EV chargers, and powerline networking. Ferrite chokes and common-mode current. And why receiver noise reduction changes how noise sounds without lowering the floor at all. Then grounding, carefully: three separate jobs that all get called by one name. Electrical safety, lightning protection, and RF management in the station. Bonding solves noise problems, earth rods solve lightning problems, and the green wire solves safety problems. They are not substitutes for each other.

  8. Aug 1

    Below the Noise Floor — Episode 10: "Receive Filters Explained"

    Receive filters are the single most powerful tool for pulling a signal out of a noisy band - but only if you understand what they are actually doing. This episode covers the fundamentals of digital filters, passband width and shape, high and low cut controls, notch filters, and the audio peaking filter for CW.

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About

 Below the Noise Floor is a self-education project turned podcast. One licensed amateur radio operator learning HF radio and AetherSDR from the ground up - the bands, the waterfall, the voice chain, the digital modes, the antennas - and sharing the process. These episodes are mostly AI-generated content built around real curiosity and real equipment. If you are new to HF or new to software-defined radio and want something that starts from zero and builds methodically, this might be exactly what you were looking for. 

Information

  • Creator
    James
  • Years Active
    2026
  • Episodes
    18
  • Rating
    Clean
  • Copyright
    © 2026 Below the Noise Floor
  • Show Website
    Below the Noise Floor