Just when you least expect it, what’s basically a portable scalar network analyzer starts talking to you in THIS FONT and you start disbelieving your own eyes:

Wonder if that’s from that Microsoft core fonts package that they made freely available years ago then pretended they didn’t
Oh by the way the antenna is …. Uh. It’s… not?

Root cause of that scary looking reflect plot was revealed by a quick walk up the stairs to the roof to be an almost completely disintegrated piece of LMR-400. My coworker assured me it worked perfectly fine five years ago……..

visualizing data, irritatingly

Which looks sillier to an uninitiated observer, the results of this butt-dial Google search or my mess of a DMR radio codeplug?

In other news, buzzard puke alert! Changing the “Radio IP Address” field in Motorola TRBO CPS is not how you change the repeater’s Ethernet IP, it’s just how you get it to throw blank error messages with no explanation. Well that’s a solid block of fnord.

Subchannel flatulence

Quality observation by my fellow engineer (also a radio survivor):

Music that’s been previously compressed to mp3 sounds like butthole on an HD Radio channel.

Music that’s been stored and played out uncompressed sounds like mere butt cheek on HD Radio.

And here I was thinking it just sounded like a foam cloth top brush with too many pieces missing.
Picture unrelated.

May I just take a microsecond here

Hey, it’s me, I want to give you some good frequencies. (The part I’m referring to is the very end, and the bandpass filtered beat you hear in the background is the beat to Eple, which follows it on the album. Eple will sound familiar to anyone who’s ever fired up a fresh install of Mac OS 10.3…)

But all that aside, this is about metrology and frequency standards and things my cat likes to loaf herself on top of because they’re warm.

We’re preparing for the installation of a new GatesAir Maxiva DTV transmitter at work. I was gonna say it’s an ATSC transmitter, but… I’d at least like to hope… it’s ATSC3 ready, whenever that rolls out. Sitting in the space it was going to reside in was a weird old Axcera transmitter that never worked right and was yanked out in pieces to be e-waste’d. Sitting on one of the pallets of refuse left over was the reference oscillator for the exciter, which, interestingly, was just a standalone thing without GPS synchronization. The tub in the middle is an insulated chamber containing an oven controlled crystal oscillator. Basically, this is an oscillator in a thermostatically controlled heated chamber that keeps it stable. It MUST be allowed to warm up to full operating temperature before use, or, well… it just ain’t gonna be in spec!

(insert commentary here on how silly it is that I’ve seen OCXOs in battery powered equipment that has a shorter battery life than the warmup time)

Most modern stuff uses GPS sync because it’s a good inexpensive way of obtaining a stable reference frequency and timecode. The usual arrangement is to have a voltage controlled oscillator that’s PLL locked to a 10khz timing signal output from a GPS receiver head. Aside from a little bit of phase noise possible in the system, it’s always spot on. This is why you’ll see funky little cone shaped GPS receiver antennas all over the place at broadcast facilities.

Here’s the Evertz system we have that takes GPS time and frequency references and generates our facility master clocks, black burst, and trilevel video sync. I’ve never really gotten that good a look at the way it operates but I think the black burst is generated inside the automatic changeover unit which also has some distribution amplifiers in the back as well. One of the outputs is a 10.000.00000 (I’m not sure how many significant figures) reference which can be used by a wide range of equipment. After having an, uh, experience, with one of these changeover units (see link above) I wisely do not even look at it hard while we’re in anything but 4:00 AM Sunday morning backwash programming. A frame of Grass Valley distribution amplifiers near it is used to distribute its black burst, LTC timecode, and 10mhz signals to where they’re needed throughout the facility.

This will come into play later.

The toroidal power transformer has two primary windings which were series wired for operation on 240vac. That’s why it says 240 on the AC terminal block shield. I swapped them to paralleled for 120.

More pictures and calibration process — onward

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Like a spark in the dark

Something I noticed recently…

WiGLE added Bluetooth device scanning and database functionality to their Wardriving app a year or so back. Originally, I would see a few things pop up in it, usually headsets and car entertainment systems.

Now, it seems like everything comes with Bluetooth and no fecking power switch.

This is the result of just leaving scanning active overnight as people and their Bluetooth devices move past. The newer BLE stuff has…. kinda terrifyingly long range.

It makes me think… If WiGLE is scanning this for nerds like me, there’s gotta be some shady-ass analytics company using Bluetooth to track everyone without their consent and selling that data.

Personally I use maybe three Bluetooth devices regularly, and they are all switched off when not in active use. Without trying to correlate addresses to vendors or anything, I’m just going to empirically blame Apple’s crappy AirPods for a lot of these potential tracking beacons.

dave what are you doing DAVE STAHP

I installed this board a couple years ago in Redding and then I see this on Facebook

Congratulations, you win a free upgrade to this shitty old Arrakis 1200 I dragged out of the e-waste bin.

That being said, You Can Decrease The Likelihood Of Damaged Consoles With This One Weird Trick: use consoles with a vertical front surface. Here’s an SAS like that, I stole the pic off someone else’s post and forget where it is but it’s slick.

Many early consoles had this layout, using big chunky rotary faders.

SAS has also replicated this with the Dees Digital, designed to meet Rick Dees’ desire to have a modern board with digital routing but with the classic rotary pots and vertical panel. It’s a beauty.

And now, additional folderol


Note to self:

The PISS is a magical thing I came up with using a bog standard off the shelf outboard mixer along with the telephone hybrid to perform a few different functions including mix-minus, mono feed to the console, and stereo feed for recording (jock on one channel, caller on the other) to a computer for polishing up and re-airing later. I should really make a proper CAD diagram of this, but come on man it’s called the PISS, and it’s going riiiight in the shitpost category on this blog. The REC switch box thing is there because the USB interface in use was in the Arrakis MARC-16 console AND LET US NEVER SPEAK OF THAT SHITTY THING AGAIN

Better late than never– the arcy sparky harmonic filter

I forgot to post this over a year ago…

So we were working on the old Continental Electronics 816R that sadly later got nuked by the Carr Fire when we heard a voice come out of the power amplifier.

Uhhh, FM transmitters don’t usually do that.

In addition it kept arcing plate voltage to ground with an irritating snapping sound and restarting repeatedly so it needed some work.


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