Engineer's Corner

Credit Credit: Ryan T Conaty

The Engineer's Corner is an occasional series penned by RIPR's IT & Engineering Director, Aaron Read.  

Any time he thinks there's something useful, important, amusing, or otherwise interesting enough to write about?  This is where you'll find it.  The highest compliment he gets, and frequently, is from readers who assure him that even though they have no idea what he's writing about, they love that he's writing it.

TheEC: Phantom Power

Jul 12, 2013

BOO!  This time on the Engineer’s Corner, we’ll talk about PHANTOM POWER.   Usually not as ghoulish as one might expect, phantom power has to do with microphones.   Specifically, some microphones have active circuitry inside them.   That means they need power to operate, but it’s unwieldy to run a separate power cord and audio microphone cable.   So a phantom circuit is used to provide DC power on the same three wires (positive/hot, negative/cold, and ground) out to the microphone that the audio from the mic also uses.

A phantom circuit is one of those nifty things in electronics that looks, to the layman, like it can’t possibly work...but it does anyway.  

TheEC: Time Delay

Jun 11, 2013
102.7FM transmits in HD Radio
Aaron Read

This time on the ENGINEER’S CORNER we go back in time – none of Doc Brown’s famous DeLoreans needed!  Actually, it’s about TIME DELAY, specifically, the time delay on 102.7FM in Narragansett.

TheEC: Zombies and EAS

Feb 12, 2013

“This is not a test, the dead are rising from the grave.”

Not quite what was spoken, nor quite a real alert, this weekend nonetheless saw KRTV-TV in Great Falls issue a LAE (Local Area Emergency) alert for several counties in Montana, and spread as far as WLW in Chicago.   The LAE was, yes, a zombie alert, with an audio component that said: “the bodies of the dead are rising from their graves and attacking the living. Do not attempt to apprehend or approach these bodies as they are considered extremely dangerous.”

RIPR Satellite Dish Heater
Aaron Read

  Oh the weather outside is frightful…

Actually, this winter we haven’t seen too much snow.  Nevertheless, snow is something of a chore for us at RIPR, because it builds up on our SATELLITE DISH, which blocks the satellite signal.  Specifically, our NPR and BBC signal, and that means when it snows = dead air on RIPR!

TheEC: Lightbulbs!

Jan 1, 2013
Track lights
Aaron Read

It’s a Star in the East!   It’s shiny Christmas lights!  It’s a slightly-silly, holiday-themed ENGINEERS CORNER on LIGHTBULBS!

Here at RIPR, our offices and studios in 1 Union Station were designed in 1999, and designed to look like our original owner’s studios, WBUR.   Their studios were designed and built in the salad days of the dot-com era: 1995.   So to say that incandescent track lighting is a big part of our lighting scheme, is an understatement.

Providence, RI – This week on the Engineer's Corner we talk about power. Not so much "fight the" as "emergency backup"! In fact, this week we're installing a new power generator for our 88.1FM (WELH) transmitter facility. You might've noticed we had issues with a lack of reliable power for almost three days during Hurricane Sandy; we had a generator but it just didn't have the features and capacity we needed.

So in advance of winter storms, falling trees, rime ice and downed power lines, we're putting in a Kohler RES14a propane generator with three 100lb tanks. Yes, the same company that makes excellent faucets for your kitchen, also makes excellent generators, believe it or not.

An Omnia 6 FM processor, also used on WRNI 102.7FM

Providence, RI – Audio purists refer to it as the scourge of music, but AUDIO PROCESSING is a critical part of any radio station's transmitter. An audio processor typically accomplishes several goals:

TheEC: Height is King for FM

Oct 24, 2012
Broadcast Peak in Santa Barbara CA
Aaron Read

By way of analogy, think of an FM transmitter as a big lightbulb on top of a pole. The taller that lightbulb is, the easier it is to see that lightbulb from wherever you are. The lower it is, the more likely it is that a hill or a house or a tree might block your view.

TheEC: Solar Outages

Oct 11, 2012

It has to do with our satellite downlink from NPR. We have a hefty 13-foot-diameter satellite dish, located in North Providence; there's no room for it at One Union Station! It points to "Galaxy 16," a telecommunications satellite in "geostationary" orbit that all NPR stations use.

"Geostationary," also popularly referred to as "geosynchronous," means that the satellite orbits the Earth in sync with the Earth's rotation...about 6800 MPH. That's pretty fast, but the key is that it's the SAME speed for both. So from our perspective here on Earth, the satellite just floats there, not moving, over 22,000 miles up in the sky!  To put that in perspective, it's like driving from northeastern Maine to southwestern California, SEVEN TIMES.

In Galaxy 16's case, the satellite is at 99.0 degrees west longitude, meaning it's fixed above a point on the equator over the Pacific Ocean, about 500 miles west of the Galapagos Islands (near Ecuador).

In general, geostationary orbits work great for communications satellites like for NPR, but there's a catch: twice a year there's times when the Sun, the satellite, and our dish all line up perfectly.  It's only for four or five days, and only for four or five minutes per day...but the Sun puts out so much energy on ALL frequencies that it completely swamps the satellite's own signal, so we lose all NPR, BBC and other satellite programming.

A common tech support request I get is for help with our stream/webcast from our listeners. The "digital illuminati" often like to claim that the web will mean the death of radio any day now, but streaming is still decidedly more complex and more tricky than radio's "push button, turn knob, get programming" simplicity.

EAS Emergency Alert System
FCC

Those iconic words, coupled with the tell-tale "brraaaaap... brraaaaap...brraaaaap" data tones, are widely known as the EMERGENCY ALERT SYSTEM, or EAS. Like its predecessors the Emergency Broadcast System and CONELRAD (CONtrol of ELectromagnetic RADiation), EAS is - at its core - a means by which the US Government can disseminate emergency information to the public at large in a short amount of time.

Wikipedia

Providence, RI – Not long ago we talked about "tropospheric ducting" for FM and some TV signals. This time on the Engineer's Corner, we'll talk about its cousin for AM signals: skywave!

www.comrex.com

Providence, RI – This time on the Engineer's Corner let's talk about CODECS. Short for "encoder / decoder," codecs are a fact of modern life; used in cellphones, digital cable TV, digital television, the internet, you name it! Anywhere there's data, there's probably a codec involved.

TheEC: Atomic Clocks

Aug 1, 2012

A somewhat radio-related topic this time on the Engineer's Corner: Atomic Clocks! At NPR stations, like Rhode Island Public Radio, we rely on precision timekeeping because we coordinate our local programming with NPR's national programming via each end paying attention to a very specific clock. Everything is timed down to the second and, in some cases, to half-seconds! We use a special clock system from ESE to synchronize all our clocks in the studios. Such systems are expensive, costing thousands of dollars, because of their very high precision. But at home you can get pretty close by using an "atomic clock", available at most Radio Shacks, Walmarts and other, similar stores.

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