Unexpected Ethernet QRM

I made a quick-and-dirty directional Yagi antenna out of PVC pipe and measuring tape for some future Radio Direction Finding (“fox hunt”) fun. (Instructions here)

2-meter tape-measure Yagi antenna

Since I spent an evening sticking it all together, I had to test it out. So I connected it to a 2-meter (144MHz) radio, tuned it to an unused frequency, opened the squelch so I could hear the noise, and waved it around my apartment, watching the signal meter go up and down.

What I found was kinda surprising. Apparently I have a hot zone of radio frequency noise in a corner of my living room, right where the cable modem, router, and Gigabit Ethernet switch sit on a shelf. It’s typically not a problem when I’m working nearby repeaters and stations on FM (which is largely immune to this sort of noise), but if I’m doing SSB weak-signal or am using a handie-talkie at my desk, then it’s definitely going to be a problem.

So I asked the Internet what frequency the 1GB Ethernet standard (802.3ab 1000base-T) operates at. Turns out the signalling frequency is 125MHz, really damn close to the 144MHz passband of my radio’s receive filter. Thankfully, the voltage and current levels that exist in the cable and termination circuitry are relatively low, and are mitigated by the hashing effects of 4 differential twisted pairs of copper wire inside the cable keeping their electromagnetic impacts contained. But if I’m pointing a highly-directional antenna at a device that has an Ethernet port, I’m gonna hear something.

At this point, I’m not sure if wrapping every cable in a clamp-on ferrite or putting the entire networking stack inside a metal box will fix anything. But it’s something to consider if I intend to do weak-signal work with an omnidirectional antenna near that corner of the room (both of my 2m/70cm and 1.25m omni groundplane antennas outside are up on a pole 10 feet away through a wall).

If you look hard enough, you really can find QRM in surprising places.

Tunnels

In high school — a much gentler time — in the sighing hour after school let out, when I was supposed to be walking home to my nervous mother, I would sometimes dawdle around campus, haunting the hallways without need of a hall pass, breathing in the open-air spaces between buildings, poking at the toys in the physics lab, before eventually shrugging my backpack homeward to my wrong side of the tracks.

Prized among my amateur urban explorations was a 7′ × 7′ drainage tunnel that ran from the opposite side of the street to partially under the school. It was fed by a neighborhood creek, so it always had a trickle of water and storm debris. But as it made its way under the street, under the lawn, and under the school’s new addition, it terminated at a concrete shelf of 3′ high and 5′ deep, with two small pipes underneath that drained downhill toward the creek behind the school. In the wall over the shelf, two culvert pipes opened to a grassy spot sunk between buildings, and above was a steel grate where you could look up to see people walking overhead. The best way into the tunnel was to step down to the grassy washout and steal into the culverts when nobody was around to ask questions.

It was there that I felt something new. I felt like I was simultaneously committing a trespass and getting away with something wrong, and yet was expanding my knowledge of the world and claiming the space as mine. And during those moments of probing around in the dim light thinking bright thoughts, it was mine. It was my secret space, my place to hide, where I could just exist without pressure.

Those places are magical, especially when you’re a kid.

I don’t know where the guilt of being in those spaces comes from. Once, I spent so long on the dawdle that the sun was fading by the time I got home, and my mother grilled me about where I was. Of course I didn’t spill the beans, but that’s not where the guilt comes from. I think it’s the guilt of doing something unexpected, something sneaky, something outside the definition of normal; going off-map to see where this leads, or what’s under there, or what’s behind that door. It’s the guilt of standing up in defiant ingress and staking a claim, even if it wasn’t mine to stake.

Sure, it was potentially dangerous. Could’ve been all manner of beasts intent to do me harm. Could’ve been neighborhood kids tagging, or smoking, or likewise staking claims of their own with a mind to defend it. Or I could’ve been spotted by school administrators and given a stern reprimand with punishments on the school and the home fronts.

But that’s the thrill, isn’t it?

So, I think, in my heart of hearts, I’m an explorer, an investigator, a wanderer. I get bored easily, and get off on finding the secret passages behind the world; get off on slipping into the engineered and ignored spaces that make our world work so I can learn, so I can take notes, so I can slip those notes into my pocket as a safety. I like learning how things work, how systems interplay. I get bored with surfaces; I like structures.

It’s outside the norm, but that’s where people like me thrive. We take the random direction and see what’s there. By going into unknown places, we find the new food, the new materials, the new techniques. And by carefully sharing our findings, we elevate the norm. That’s how a species survives.

The last time I saw that building, the culverts had been covered with locked gates. Some other explorer was unwise in sharing their findings…or got caught. Or some administrator playing a game of What-If asked the right question and got the gates installed. The norm can stake its claim too.

But, still, explorers press outward into the ghostly forest beyond the ever-brightening campfire light. That’s where the magic is.

Hopefully, that’s where you’ll find me.

Dark York

And then there was that time I got laid off and drove up from Texarkana to Fayetteville AR pumping Le1f out my buzzing car speakers, like I was up on the new-new NYC sound tip and was so woke I would peel the eyelids back on any redneck whose truck I passed with just my sound waves.

Was a good trip regardless, even if I had to turn around after one night and head back home to AUS via TXK.

When you ain’t got nothing left to chew, you savor the flavor, and smirk because of your above-it-all secrets. Like what you got is next level, and they ain’t hip.

Like they ain’t find me. Like they ain’t reach me.

“When I’m Down”

We clamor for and adore artists who pour out their heart and soul and expose their vulnerabilities for us, to show us it’s alright to be weak, broken, terrible. And how terrible it is to be the artist who commits that to record, and then has to cut open old wounds night after night on tour to support the record!

Listening to Chris Cornell’s “Euphoria Morning”, which is perhaps his first record made with few nonsense lyrics (his work with Soundgarden was laden with lyrics made of words and phrases that sounded great but meant nothing). Being a solo project, it meant he was free to plug us in and tell us how he really feels, without the burden of speaking for his former bandmates. When he pens “When I’m Down”, we know he’s down; it’s his record.

And he has to repeat those songs ad infinitum for as long as he tours. Cutting open those wounds again and again, until he finally opens his body and ends his own life.

What a terrible fate.

Grunge was a miraculous flame that burned bright and kept us warm, because we all knew, we all felt, that the artists who wrote those great songs and performed them for us across this busted world of ours really, really meant what they said, and it killed them. The flame that burned twice as bright lasted half as long.

Their error was in being truthful.

Is it better to speak truths and die for them before your time, or is it better to add a wrinkle of disconnection, say things we’ll connect to anyway, believing they are speaking as one of us, and survive to speak another day? What is integrity worth?

I wish I had that answer.