The Answer to Ailing Copper

I don’t know how things are in your neck of the woods, but here in the Northeastern US, our old copper TELCO networks are on their way out.  This is a problem for broadcasters who still rely on POTS lines (Plain Old Telephone Service) for transmitter remote controls, studio hot lines, etc.  The vast majority of my transmitter site access is through dial up remote controls.  There are a few locations that have web based remote controls, but to be honest; the phone part of my smart phone still gets a lot of use.  There are several locations where the old copper is just failing outright and not through a lack of effort by the repair techs.  Generally, the copper pairs get wet and develop a loud hum, which makes the remote control unit either hang up or become unresponsive to touch tone commands.

The best course of action is to get some type of VOIP line installed.  Here is the rub; many transmitter sites are nowhere near a cable system.  Several times, I have contacted the cable company to see if they will provide a VOIP phone line at a certain site.  The response is usually; sure, we can do that!  However, it will cost  you (insert some ridiculous amount of money) to extend the cable to your transmitter site.

LAN extensions to the transmitter site are a useful for a number of reasons.  More and more transmitters are equipped with web interfaces as are processors, UPSs, transmitter remote controls, security cameras,  etc.  LAN extensions can also be used for backup audio in case of STL failure.  Finally,  an inexpensive ATA (Analog Telephone Adaptor) and DID line can replace a POTS line for a lot less money.  One example; voip.ms has the following plans as of this writing:

Plan type Per month per DID number (USD) Incoming call rate (USD) per minute Outgoing call rate (USD) per minute
Per minute $0.85 $0.01 (USA) $0.009
Unlimited $4.25 $0.00 $0.009
Toll Free (800) $0.99 $0.019 $0.009

Any of those plans surely beats the standard TELCO rate of $40-50 per month per line.

Design criteria for a wireless LAN system needs to take into account bandwidth, latency and reliability.  Each VOIP phone call takes anywhere from 28-87 Kbps depending on the protocol being used.  If the wireless LAN is being used for other things such as back up STL service, access to various GUI’s, etc then the total bandwidth of all those services need to be considered as well.  Do not forget ethernet broadcast traffic such as DHCP requests, ARP, SMB, etc which can also take up a fair amount of bandwidth.

For LAN extensions, I have been using a variety of equipment.  The older Moseley 900 MHz LAN links still work, but are slow in general.  The Ubiquiti gear has proven to be both inexpensive yet reliable, a rarity to be sure.  There are several links to various transmitter sites running on various types of Ubiquiti gear, usually without problem.  One simply needs to remember to log into the web interface once in a while and make sure that both ends have all the firmware updates installed.  They are cheap enough that a couple of spares can be kept on the shelf.

The following diagram shows how I replaced all of the copper pots lines at various transmitter sites with VOIP:

Diagram of LAN extensions to various transmitter sites
Diagram of LAN extensions to various transmitter sites

List of equipment:

Nomenclature Amount Use New or used
Ubiquiti Rocket M5 3 AP and station units New
Ubiquiti AirMax 5G-2090 90 degree sector antenna 1 AP point to multi-point antenna New
Ubiquiti Rocket Dish 5G-30 2 Station antennas New
Ubiquiti ETH-SP-G2 3 Lightning protection New
Trastector ALPU PTP INJ 6 Lightning protection out door units New
Cambium PTP-250 2 Point to Point link Existing/Used
Motorola Canopy 900DA PCDD 1 AP point to multi point Existing/Used
Motorola Canopy 900DA PCDD 2 Station Existing/Used
Microwave Filter #18486 diplexer 3 Diplexer 900 MHz ISM band and 944-952 STL band Existing/Used
Cisco SPA122 ATA 9 Dial tone for remote controls New

The main studio location has the gateway to the outside world. This system is on a separate subnet from the automation and office networks. From that location a point-to-multipoint system connects to the three closest transmitter sites.  This setup uses the Ubiquiti Rocket M5’s with various antenna configurations.  Then, from one FM transmitter site, there is an existing 5.8 GHz path to another set of transmitter sites.  This uses Cambium PTP-250s.

The next hop rides on the STL system, using Motorola Canopy 900 MHz radios and Microwave Filter Company #18486 dilpexers.  These are long paths and the 900 MHz systems work well enough for this purpose.  The main cost savings comes from reusing the existing STL system antennas which negates the cost of tower crews to put up new antennas and or rent on the tower for another antenna.

There is a smaller sub system many miles away that is connected to the outside world through the cable company at the AM transmitter site.  Unfortunately, due to the distances between the main studio and those three stations, there was no line of site shots to these sites available on any frequency.

When installing the 5.8 GHz systems, I made sure to use the UV rated, shielded cable, shielded RJ-45 connectors and Lightning Protection Units (LPUs).  Short cuts taken when installing this equipment eventually come back in the form of downed links and radio heads destroyed by lightning.

Regardless, I was able to eliminate seven POTS phone lines plus extended dial tone service to two sites that previously did not have it before.  In addition to that, all of the transmitter sites now have Internet access, which can be useful for other reasons.  All in all, the cost savings is about $310.00 per month or $3,720.00 per year.

Bucket Trucks and Landing Craft

Hopefully that title is descriptive enough:

ATT bucket trucks, , mobilized via landing craft to Pleasure Beach
ATT bucket trucks, , mobilized via landing craft to Pleasure Beach

We loaded a couple of ATT bucket trucks on a landing craft and waged an assault on Pleasure Beach.  This is to finalize the repair work from Hurricane Sandy last year.  The other factor is the construction taking place on the Island.  The City of Bridgeport is constructing a park, which involves extensive repairs and renovations to the buildings.  Construction vehicles driving under the old lines have ripped them down several times, thus repairing the lines on the new utility poles was necessary.

ATT truck offloading
ATT truck offloading
ATT truck offloading
ATT truck offloading

ATT is the LEC for the Bridgeport area, something they don’t do in most other parts of the country, from what I am told.

Landing Craft Challenger
Landing Craft Challenger

It took approximately four hours to complete this work and reload the trucks back on the landing craft.  The boat itself looks like a slightly modified LCM (Landing Craft, Mechanized), which were produced from 1943 onward.  This is an LCM-8.

WICC towers
WICC towers

WICC towers almost in line, I was about one second too late with this shot. This would be “down the bore” of the daytime pattern into downtown Bridgeport.

WICC towers
WICC towers

Another shot of the WICC towers. These were designed to hold up a horizontal T top wire antenna strung between the two of them.  At some point in the early thirties, somebody realized that the tower itself could be excited as a vertical radiator and the antenna configuration was changed. Up until the mid 1970’s there was a horizontal wire which supported third wire element hanging between the two towers, making it a three tower directional array.  This was removed and it was then that the current phasor and two tower DA-2 system was installed.

All in a day’s work.

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.