tech stuff – Page 28 – Engineering Radio

Moving and upgrading a translator

Something that I eluded to in a previous post, we finalized the move of the WSBS translator, W231AK, from the Fairview Hospital in Great Barrington to the side of the AM tower.

Tower crew hanging translator antenna on AM tower

The move was started by hanging a new Shively 6812B antenna from the side of the AM tower, located off of US 7, north of Great Barrington. This is a half-wave-spaced circularly polarized antenna.

While this work was going on, some guy from OSHA showed up and started taking pictures without asking permission or telling anyone who he was. We informed him that he was on private property and asked him his reasons for being there. He got in his car and left, no doubt to a parking lot down the road so he could keep the tower climbers safe… mostly from themselves… by levying huge fines for free climbing… Wasn’t there something in the news about the government running out of money? Anyway…

WSBS had been using this translator for a few years. The advantages for the station from the translator move are greater power output (from 35 watts to 250 watts ERP) and less operating expenses in the form of TELCO line charges and roof top rental at the Hospital.

In addition to that, the reliability of the translator should increase, as there have been several instances in the past when TELCO line problems have taken the translator off the air for days at a time.

W231AK new transmitter, WSBS base current meter below

The transmitter for W231AK was changed from a Crown 35 watt unit to a BW Broadcast T600. These units are made in the UK and it is an all-in-one processor/exciter/transmitter. We took the cover off to make a few configuration changes and the entire unit is very well made.

One of the nice features of this particular transmitter is the screw-down clamping method of connecting the RF devices. Lets face it, unsoldering MOSFETS is a PITA. This screw down clamp eliminates all that.

The audio input and processing board is pretty neat too.

There are several different processing settings which we played around with. All in all, it seems like a pretty solid unit and I would recommend it to anyone looking for a low to moderate power transmitter.

Goodbye, ISDN

The imminent demise of ISDN has been talked about for some time. There now appears to be a date attached which makes it semi-sort of official. As of May 18, 2013, Verizon will no longer accept orders for new ISDN lines. They will also not make any changes to existing lines and will start charging more for the service.

Taking the place of ISDN will be a variety of Ethernet/IP-based audio transmission methods. As technology evolves, this makes sense. The quality of ISDN and the bidirectional nature was a vast improvement over the old system 5/7/10/15 KHz point to point analog lines. The one downside, ISDN equipment was expensive and the service was expensive to install and operate.

High-speed internet is available in almost every business and venue. Many times, there is no cost to access it and equipment is relatively inexpensive. Depending on the equipment, CODEC, and speed, it can sound almost as good as ISDN. For those opposed to using the public network due to reliability issues, there is always frame relay.

Time moves on, so buy your IP CODECS now.

Undersea Cable Map

With the advent of fiber optic cables starting in the 1980s, the majority (one estimate says 99%) of this country’s overseas communications are carried by undersea cables. These are interesting system constructions, being first redundant and second, self-healing. Glass fiber stands themselves are fairly fragile. Bundling several together and then sinking them in the ocean can create mixed results. Deep ocean bottoms are often very rugged, containing mountains, canyons, and fault lines. Thus the submarine cables used have to be pretty rugged.

There is a common misconception that fiber optic cables do not need repeaters. That is not true, while they do not need as many repeaters as copper cable, repeaters are still required approximately every 40-90 miles (70-150 km) depending on the cable type. These active devices are another failure point. Overall, it is a complex system.

Submarine Fiber Optic Cable cross section — Submarine Fiber Optic Cable cross-section, courtesy of Wikipedia

Cross-section of a submarine fiber optic communications cable:

1. Polyethylene
2. Mylar tape
3. Stranded metal (steel) wires
4. Aluminum water barrier
5. Polycarbonate
6. Copper or aluminum tube
7. Petroleum jelly
8. Optical fibers

It weighs about 7 pounds per foot, which is pretty hefty.

There are a couple of interactive maps online that have detailed information about where these cables go, date in service, and data capacity. My favorite is Greg’s Cable Map which is a Google map with cable data overlayed with a downloadable KML file:

This shows a new cable called the “Emerald Express” which is going into service in 2013. Throughput is reported as 60 Tbps, which is moving right along. As noted on the map, this is more of a schematic diagram connecting two shore side points. The path the cable takes is an estimate and the actual geographical location may (is likely to) be different. Click on any line on the map for cable information. Most cables have their own web page and Wikipedia article.

Another undersea cable map is the Telegeography Submarine Cable Map, which has many of the same features noted above:

China US submarine Cable network diagram

Just in case you were wondering, as I often do, how a TCP/IP connection is being routed to any given place. For fun, I tried a trace route to a known server on Guam and found the results interesting:

Approximately 231 ms round trip route from NYC to LA to Guam and back, which is over 8,000 miles (12,850 km). A few of the intermediate routers did not answer and I tried this several different times; the same routers time out. This missing information looks to be small steps, not large ones. So, which cable goes directly from LA to Guam? Possibly the China-US Cable Network (CHUS) (picture above). At 2.2 Tbps and landing at San Luis Obispo, that is the likely candidate for the cable that carried my data.

As a general exercise, it is kind of fun, although it may be harder to figure out a particular route to say London or Berlin because there are many more different possibilities.

Route latency is something to keep in mind when planing out AOIP connections for remotes and other interactive type connections between studio and remote location. Almost nothing is worse than that half second delay when trying to take phone calls or banter back and forth with the traffic reporter.

h/t: jf

The NASH: WNSH, Newark, NJ

Lately, I have been working at a site in West Orange, NJ connecting various parts and pieces, and thought that this was interesting:

WNSH 94.7 MHz, Newark, NJ main antenna (top)

That is the main antenna for WNSH, 94.7 MHz Newark, NJ, aka “Nash-FM.” Below that is the backup antenna for WEPN-FM (98.7 MHz), WQHT (97.1 MHz) and WFAN-FM (101.9 MHz). More on those stations later.

This is the WFME studios, located off of NJ Route 10. It is kind of hard to see the call letters behind all those trees and whatnot. There is an older picture from 1999 floating around, which shows the studio building in better condition. This is a better angle:

I believe WFME is still originating its programming here, now being broadcast on WFME 106.3 MHz, Mount Kisco. I had to use the facilities there, the interior is like a way back 80’s time machine, which is kind of cool. If I owned a radio station, I would go for the 70’s office decor; dark wood paneling, shag carpets, bright blue bathroom tile and avocado green appliances, but hey, that’s just me.

This is the WNSH backup antenna, mounted on top of a UHF slot antenna for WFME-TV. There is an LP TV antenna mounted there also, but I don’ t know who it belongs to. Overall, it is an interesting transmitter site on “First Mountain” in West Orange, NJ. Also located here, WFMU-FM, an old ATT microwave site, now owned by American Tower and several cell carriers. In other words, it is just like most other mountain top transmitter sites, except there is a shopping plaza across the street.

I gave a listen to the NASH while driving there. For where it is, it seems to have a pretty good coverage area. As for the music, well, I am not sure how a Manhattenite will relate to Tracy Byrd’s “I’m from the Country” wherein:

Everybody knows everybody, everybody calls you friend
You don’t need an invitation, kick off your shoes come on in
Yeah, we know how to work and we know how to play
We’re from the country and we like it that way

Being from upstate NY, I get it. Perhaps the Manhattan salary man will too. There are no DJ’s on air quite yet, just music, some commercials and a few “Nash-FM” liners that sound slightly distorted.