theec

Engineer's Corner
5:08 pm
Mon February 3, 2014

TheEC: Prison Radio

Sony SRF-39FP
Credit Museum of Everyday Objects

A recent article in the New Yorker about radio in prison piqued my interest.  Besides providing a window into a world that many of us know little or nothing about, it caught my eye that these Sony SRF-39FP ("FP" for "Federal Prison") radios are actually remarkably good receivers.  

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Engineer's Corner
10:08 pm
Mon January 27, 2014

TheEC: 88.1 Studio/Transmitter Link

Screenshot of the Comrex BRIC Link web GUI
Credit Aaron Read

In light of ongoing issues with the Studio/Transmitter Link (STL) for WELH 88.1, we have implemented a new STL  schema.   If you heard a lot of odd audio dropouts on 88.1 today, that was the reason.

The good news is that we should have a pretty good temporary solution in place, and a solid path for a permanent solution is on the horizon (tentatively scheduled for mid-March).   Best of all, I was able to put in a new(er) Orban Optimod 8100A audio processor to replace the less-capable Inovonics DAVID-III.  There's a little sibilance still, so I need to tweak the settings.  But overall the sound should be much louder, fuller, and more consistent.

Read on for more details...

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Engineer's Corner
11:49 am
Tue January 21, 2014

TheEC: Browser Extensions that Spy on You

Credit howtogeek.com

Taking a break from broadcast engineering this time on TheEC, and instead we'll look at the other side of my job: computers.   In particular, here's a heads-up to a recent story that's lit-up the geekier realms of the internet, but may not have percolated to your inbox just yet.  It has to do with BROWSER EXTENSIONS and how they might or might not...probably might...be spying on you.

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Engineer's Corner
4:58 pm
Fri January 3, 2014

TheEC: Digital "Chirps" on 88.1

PCAU cards. Left is WELH's Main STL encoder. Right is an unused spare.
Credit Aaron Read / RIPR

UPDATE (Jan.10):  Verizon sent a trio of techs today to examine the Digital Lines.  They found a splice point on a pole near the Wheeler Farm end of the circuit where water had gotten past the weatherproofing.  The splice was re-done, with fresh (and better) weatherproofing sealant applied, and a weather box placed around it.

That's likely the culprit here: the problems started during the snowstorm, so probably water got in there and expanded/contracted repeatedly as the water froze and melted.  That expansion wreaks havoc with (relatively) fragile copper telco wiring.

As of 3pm we are back on our main STL.  We've noticed the volume levels seemed to have changed somewhat with this repair, too, so we're still tweaking things.

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ORIGINAL POST (Jan.3): Ever since the hefty snowstorm and extreme cold on Thursday night, our 88.1 signal in Providence has been experiencing "digital chirps" now and then.  

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Engineer's Corner
4:50 pm
Thu November 21, 2013

TheEC: 1290AM Heard in Norway

Longwire antenna used to successfully receive 1290AM in southwestern Norway.
Credit Arild Skalmeraas

We've talked in the past about skywave propagation, but it's cool when you heard about real-world examples of it.   Recently I've gotten several emails from "DX'ers" (Distant Reception enthusiasts) in Europe saying they've been able to hear Latino Public Radio on 1290AM all the way across the Atlantic!   

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Engineer's Corner
1:43 pm
Tue November 12, 2013

TheEC: 91.5 is Back On the Air

From top to bottom, Bext LEX30 transmitter, Dayton 210 FM receiver tuned to 102.7 to get programming to feed the transmitter, and Inovonics 631 FM receiver to monitor 91.5 on the speakers above.
Credit Aaron Read

As of Tuesday November 12th, WCVY is back on the air in limited fashion.   As you know, WCVY suffered catastrophic damage to its equipment and facility from a roof leak during a thunderstorm in August.   The entire space had to be gutted to the concrete walls, and new electrical wiring and drywall installed.  Much of the transmitter gear either took direct water damage (e.g. electricity shorting out) or took indirect water damage (e.g. rust and other corrosion), and eventually a lot of it failed completely.

We have put a temporary setup in place with a donated 30 watt transmitter on loan (with the antenna array's gain factor of 2.1, it's really more like 63 watts of Effective Radiated Power), and a special radio that's tuned to 102.7FM (there's a high-gain FM antenna on the rooftop tower) and puts out the composite signal directly into the new transmitter.   This effectively makes 91.5 into a "repeater" of 102.7FM.

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Engineer's Corner
12:39 pm
Thu October 17, 2013

ARRRR - Pirate Broadcast on 102.9FM

Close up of a whip Antenna, believed to be the source of the 102.9 pirate.

UPDATE 01/21: Multiple letters sent with no response, and the pirate's still broadcasting.  A letter has been mailed to the FCC's Enforcement Bureau.   If you are an RIPR listener to 102.7 and you have experienced interference due to this pirate, you can submit your own letter to the FCC as well.

UPDATE 12/19: The pirate has been found!  Well, we're pretty sure we have found the pirate.  Using a directional antenna and a signal meter, we triangulated the position to a house a few blocks from the Locust Grove Cemetery in South Providence.  

A letter of notification of interference to RIPR was mailed to this address several weeks ago, but apparently this pirate doesn't care as there's still an illegal broadcast on 102.9 from this location.

UPDATE 11/5: Thanks to a fellow engineer who informed me there is a pirate broadcasting on 102.9FM and that is likely the source of the interference people have reported (see below).  Quite possibly the atmospheric changes made it worse, but the bulk of the problem is likely the pirate.

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Engineer's Corner
3:00 am
Tue October 15, 2013

TheEC: More Fiber in RIPR's Diet

Fiberoptic cable splicing tool.
Credit Aaron Read

As all RIPR fans know, we are an NPR member station.  That means we get a lot of our programming from NPR, the BBC, and other providers, via our satellite dish.   The dish is medium-sized as dishes go, but it’s pretty big in real terms: 3.7 meters (12ft) in diameter.   There’s quite literally nowhere to fit a dish that large at our studios in 1 Union Station, so instead it was installed out at our 1290AM transmitter site in North Providence (we still own 1290, but we lease it to Latino Public R

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Engineer's Corner
9:23 am
Wed August 14, 2013

TheEC: Air Conditioning at 102.7FM

The indoor half of the new split-unit A/C.
Credit Aaron Read

Air conditioning.  Cool heaven for those who have it, blazing hell for those who don't.  It didn't used to be terribly common in broadcast engineering, but it's become moreso in the last ten years.  The reason is that, more and more, audio processors, RDS encoders, audio encoders/decoders, studio/transmitter links, remote control systems, and even the transmitters themselves, have all become increasingly "computer-like" with IC's, hard disk drives, power supplies, electrolytic capacitors and the like.   All things that fail quickly when operated in temperatures above 80 or so, and the warmer it gets, the faster they fail!

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Engineer's Corner
7:56 pm
Wed July 24, 2013

TheEC: "Normal Accidents"

Jack Lemmon in The China Syndrome

Most people have heard of the "Three Mile Island" nuclear power plant accident of 1979.  But it's famous among engineers for being a "normal accident", in that there wasn't any one thing that nearly caused a meltdown of catastrophic proportions...it was a series of little things inside a highly complex system that all happened as part of "normal" operations.   None of which, by themselves, was terribly problematic.  But they all happened at once, and that was a problem.

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