As of Sept 20th, The Public's Radio is now broadcasting on 102.9FM in the greater Providence area. It's technically a small signal, just 50 watts, but it's from way up on top of the WPRO-FM tower on Neutaconkanut Hill (on the Johnston/Providence line, just west of where Routes 6 & 10 split). That's 728ft above sea level, and since FM is a "line of sight" technology, that means the signal is listenable for a good, long ways. Maybe less so when listening inside the home, but definitely while listening in a car.

We haven't started formal signal drive-testing yet, but anecdotal tests by friends & family indicate 102.9 is listenable as far north along I-95 as the I-295 interchange in Attleboro, and as far south along I-95 as the Rt.4 split (maybe even to Exit 5, depending on your radio). Reception seems pretty good through Barrington into Warren, and east well into Seekonk. We'll post the results of more formal testing here when we get it done.

Most importantly, so far it's pretty good over downtown Providence and College Hill; two places neither our 89.3FM nor 88.1FM signals have been very strong in.

What happened to WELH 88.1FM?

In October of 2011, then-Rhode Island Public Radio brought a local public radio service to Providence via a ten-year lease of The Wheeler School's WELH 88.1FM. While that was a major win, there were some significant compromises involved.

First, it's a signal we only leased, we did not own it. That effectively meant we couldn't expand or modify it. And while it has decent power (4000 watts) it broadcasts from a comparatively low height (130ft above ground level), and generally height matters more than power. So while 88.1 did provide an FM service to Providence, it was inconsistent where in Providence it could reliably be heard. That's why we eventually acquired 89.3FM and, now, 102.9FM as well.

Second, it's a lease with an annual rent payment. It's a fairly reasonable rent payment, all things considered. But it's still roughly equivalent to a full-time reporter's salary. With the addition of 89.3 and 102.9, it was very hard to cost-justify that rent anymore.

Certainly WELH will always have a special place in our hearts, but it was definitely time to move on. Still, a big, big, BIG thanks to Dave Schiano, Allison Gaines Pell, Gary Esposito, Dan Miller and everyone at The Wheeler School for being such great broadcast partners over the last ten years.

Over the course of Thursday September 30th, there will be several interruptions as our engineers remove TPR's equipment from the WELH transmitter site, and help prepare it for broadcasting content from The Wheeler School's own students; that begins October 1st.

Getting into the (technical) weeds of 102.9FM

What is this weird "W275DA" thing? They're call letters! Just like "WNPN" for 89.3FM or "WNPE" for 102.7FM. But why the odd alphanumeric combination? It's because it's a particular "Class" of license as determined by the FCC. While WNPN is "Class B FM" (regional / 50,000 watts @ 500ft), and WNPE is "Class A FM" (local / 6000 watts @ 300ft), W275DA is "Class D Translator FM".

Side note: What about Class C, you ask? "Class C FM" (super-regional / 100,000 watts @ 2000ft) stations do exist but most of New England doesn't have them. The FCC divides the USA into two "Zones": Zone I and I-A, and then Zone II. It's all about population density. Zone I-A is Puerto Rico & most of California, while Zone I is Illinois east through New England (excepting the northern edge along Canada), and down to Delmarva. Both Zones are relatively high-population density areas, so the smaller Class B is the maximum station size; serves lots of people, but still allows for more signals to be packed in. Zone II is everywhere else, and generally people are more "spread out" in Zone II so the larger Class C is the norm.

Back to Class D Translators: these signals operate under different rules in the Code of Federal Regulations (CFR): Part 74 instead of Part 73 for the rest of the FM's. They are considered a "secondary" service, meaning they cannot ever cause interference to "primary" signals...though they are allowed to receive interference; something "primary" signals cannot willingly do (except in very specific circumstances). So sometimes they can be "squeezed into" the dial where a primary station wouldn't fit. And translators cannot originate their own programming; meaning they have to repeat or "translate" another signal, from the original frequency to a new frequency. And they get different call letters: W for east of the Mississippi River, K for west. Then the channel number (each FM frequency is assigned a number from 200 (87.9) to 300 (107.9)) for the frequency in question...275 = 102.9 MHz...and then two letters that are issued alphabetically based on the number of applications for that frequency on that day to the FCC. The first is "AA", next is "AB", then "AC", etc. So yes, by extrapolation, there were a whopping 104 applications for translator stations on 102.9FM across the entire United States on the same day we filed for W275DA.

Fortunately the rules stipulate that we must only include 102.9 in our official "legal ID" (normally at the top of every hour) three times daily: once in mid-morning, once just after lunch, and again in early evening. That's why sometimes you'll hear "W275DA" mentioned and sometimes you don't.

What does W275DA "translate"? By the terms of the FCC's "AM Revitalization" efforts, W275DA is permanently connected to WPVD 1290AM; it must always "translate" (e.g. "relay" or "repeat") whatever 1290 is playing. Ordinarily translators that broadcast in the non-reserved (e.g. "commercial") band of 92.1 to 107.9 FM, as W275DA does, must use "off the air" reception of the primary signal. But AM Revitalization waives that requirement, lest you be forced to broadcast an AM-quality audio on a higher-fidelity FM signal. In our case, we use over-the-air reception of WNPN 89.3FM, which is allowed because WNPN and WPVD are 100% simulcasts of each other.

Why does W275DA have this oddly-lobed antenna pattern? As you might imagine, the FM dial is very crowded. We had to find a tower site that accommodated:

  • Be within 25 miles or inside the 2 mV/m contour of WPVD 1290AM.
  • Being high enough up in the air to prevent our 100dBu contour from touching the ground.(and thus cause undesired interference to WKLB 102.5 and WBGB 103.3 from Boston)
  • Avoid undesired contour overlap with existing WFPR-LP on 102.9FM in Franklin, MA.
  • Avoid undesired contour overlap with WDRC 102.9FM in Hartford, WPXC 102.9FM in Hyannis, and our own WNPE 102.7FM in Narragansett Pier.
  • Complement our WNPN 89.3FM signal wherever possible, especially in downtown Providence, Olneyville & Federal Hill (esp along the Woonasquatucket River & Rtes 6/10), College Hill, and - to a somewhat lesser extent - along 95 thru Cranston and Warwick.
  • Provide a viable replacement for WELH 88.1FM wherever possible.

In the end, a complicated four-antenna (Kathrein-Scala CL-FM/SRM) array was used (mounted between the WPRO-FM main and aux antennas) with two antennas per array. One array of two CL-FM's were aimed northeast towards Providence. The other array of two more (at the same height) antennas were aimed south towards Cranston. Each of the two arrays had their antennas spaced 0.9 lambda (wavelength) apart to manage downward radiation. A hefty Shively 2916-3 bandpass filter was used to minimize involvement between W275DA and WPRO-FM (the filter reduces signal on 92.3 MHz by -81.7dB!).

Technically we could have had a more "expansive" antenna pattern. We could have put more signal to the west-northwest (towards Scituate). And towards the southwest (towards West Greenwich). And even towards the southeast (towards Bristol). Maybe even just more signal southwards in general, really. Why didn't we? Physics, mostly! We needed a very sharp null northwards to protect WFPR-LP, but still wanted to put a solid signal over Providence. That largely required the use of a log-periodic antenna like the CL-FM; they have a pretty narrow pattern. Sort of like a tight-beam flashlight. To use any additional antennas, you have to account for how they interact with each other. It's very easy to get into situations where your antennas are putting out signals that starts interfering with themselves. Combine that with very limited physical space available on the tower in question, and how the WPRO-FM tower was one of very few that really met all our needs, and we had room for one more antenna direction and only one. And even then, this second antenna (array) needed to be pointing more or less in the opposite direction as from Providence. Hence, the antenna aimed south towards at least 102.9 covers the I-95 corridor fairly well.