May 2016
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The 16 channel bi-directional STL

As a part of our studio build out in Walton, we had to install a high capacity STL system between the studio and transmitter site. Basically, there are five radio stations associated with this studio and the satellite dish and receivers are going to be located at the transmitter site.

The audio over IP gear is getting really sophisticated and better yet, more reliable.  For this application, we are using a Cambium networks (Motorola Canopy) PTP-250 radio set and a pair of Wheatstone IP88 blades on either site.  Since there is quite a bit of networked gear at the transmitter site, the IP88’s will live on their own VLAN.  The PTP-250’s will pass spanning tree protocol, rapid spanning tree protocol, 802.1Q and other layer two traffic.

The Wheatsone IP88A blades are the heart of the system.  Not only do they pass 16 channels of audio, we can also pass 8 logic closures bi-directionally.  This is key because we are shipping satellite audio and contact closures back from the transmitter site.  The IP88A set up is fairly easy, once the IP address is entered.  The web GUI is used for the rest of the configurations including making the connections between units.

Pair of Wheatstone IP88A AoIP interfaces

Pair of Wheatstone IP88A AoIP interfaces

The switches are managed units.  The switchports need to be set up via command line to pass VLAN traffic.  There is an appendix in the IP88 manual that outlines how to do this with various manages switches.  This is the most important step for drop out free audio.  The switchports that connect to the two radios are set up as trunk ports using either VTP or 802.1Q.

Cambium PTP-250 5.8 GHz out door units

Cambium PTP-250 5.8 GHz out door units

The PTP-250 radios were already on hand, new in box.  They are built really well and look like they should not break in a year or so.  These particular units are connectorized, therefore an external antenna was needed.  There are many such antennas, this system ended up with a RF Engineering & Energy 5150-5850 MHz dual polarized parabolic dish with RADOMES.  RADOMES are necessary to prevent ice or snow build up in the winter.

RF Engineering & Energy 5150-5850 MHz dual polarized parabolic dish with LMR400 jumpers

RF Engineering & Energy 5150-5850 MHz dual polarized parabolic dish with LMR400 jumpers

STL link dish installed

STL link dish installed

1 1/2 inch EMT going from TOC to roof

1 1/2 inch EMT going from TOC to roof

Since the path is only 3.37 miles (5.43 kilometers), I set them up with a 40 MHz wide channel.  This is a rural, small town setting.  When I looked at the 5.8 GHz band on a spectrum analyser, it looks fairly uncongested.  These are MIMO single or dual payload selectable.  I will try them as single payload units, since the path is short and the band uncongested.  This should keep the throughput high.

Studio to transmitter site LAN extension

Studio to transmitter site LAN extension

The PTP-250’s use POE injectors in mounted in the rack rooms.  CAT5e shielded cable with the proper connectors properly applied is a must for lighting protection.  The PTP-250 units came with Cambium PTP-LPU lightning protectors.  I also installed Polyphaser AL-L8XM-MA type N surge suppressors on each RF port of each PTP-250.

Engineers hate this

Apparently, this coaxial cable has a hot spot:

7/8 inch air dielectric coax with jacket melting off

7/8 inch air dielectric coax with jacket melting off

The back story:

I received a text this morning that one of our clients station “had a lot of static on it, it might be off the air.” Upon arrival, I found the Nautel VS2.5 transmitter with 0 watts forward power and an output network fault. Reset the transmitter and the forward power and reflected power increased together, triggering another output network fault. I was able to turn the transmitter power down to 100 watts, at which point it stayed on, with 50 watts reflected power.  I also noted the dehydrator running continuously and 0 PSI line pressure.


I wandered around the back of the building where the coax goes out to the tower and discovered the dripping plastic from the melted jacket.  I reached up and first checked the cable to see if it was warm (it was not).  Then I shook it and heard what I thought was water sloshing around inside.  This is the original Andrew 7/8 inch cable from when the station signed on in 1972 or so.  Very likely that further up the tower, something has chaffed through the outer jacket and shield, allowing water into the cable.

I drilled a small 5/32 inch hole at the lowest point in the cable before it enters the building.  The result was a steady stream of water, which was aided by some additional pressure from a spare N2 tank.  I let it drain while I ran down to town and got some lunch.  I came back a half an hour later, turned the transmitter on and was satisfied to see 100 watts forward power with 1 watt reflected.  I ran the transmitter up to full power for a while, then deciding discretion is the better part of valour, turned it down to half power; 820 watts which nets 8 watts reflected power.

Needless to say, the transmission line needs to be replaced as soon as possible.

Came as a stock item

So, I wore out another car and it was time to get a new one. Unexpectedly, the new car came with one of these fancy gizmos:

HD Radio as a stock item

HD Radio as a stock item

This is not the first HD radio I have owned, the Jeep Cherokee had one that I install myself. This is the first time it came with the car and I didn’t even mention it to the sales guy.

A few observations:

  • Many stations’ HD1 channels don’t sound very good, they are either shrill and tinny, or not synced with their analog counterpart.
  • There still aren’t very many station transmitting HD Radio; FM stations are either NPR affiliates or belong to a few larger corporate owners.  The AM stations are few and far between.
  • AM HD Radio still has numerous problems in the mobile listening environment.
  • Many of the HD 2/3 don’t sound very good; low audio levels, muffled modulation, low bit rate audio, etc.  The only exception that I have found so far is Vermont Public Radio’s classical format, transmitted on the HD2 of WVPS, Burlington.
  • HD2/3 channels mainly serve as “translator loophole” stations, AKA “Metro Stations”

As far as the new ownership by DTS goes; I will reserve judgement until they do something with it.

Common’ Baby

Who is that old guy standing next to Chubby Checker?

Chubby Checker and yours truly

Chubby Checker and yours truly

Hey, that’s me!

And never will you meet a nicer gentleman than Chubby Checker.

Studio Buildout, Part II

Some pictures of the studio build out in progress.

Counter top mounted

Counter top mounted

This is the counter top, mounted on a riser with the wire way cut into it. These counter tops will have AudioArts Air4 consoles installed on them.

AudioArts Air4 console with microphones

AudioArts Air4 console with microphones

Studio is taking shape. Console mounted with microphones. The rack mounted equipment goes in the Middle Atlantic rack under the counter top to the left of the console.  That rack is on casters so it rolls out to get access to the back of the equipment.  We have pretty much done away with cart pods or other counter top equipment housings.  The automation and other computers will be mounted in the rack room and extended to the studio with IP KVM extenders.

Sub Panel with manual transfer switch

Sub Panel with manual transfer switch

We installed a small Square D sub panel and manual transfer switch. This is to prevent the “Space Heater” outages, you know, when the morning show guy plugs a space heater into the same circuit as the console or computer, trips the breaker, then calls you because they are off the air. Yeah, good times.

In addition, the manual transfer switch will allow them to use a good portable generator if there is a prolonged power outage. On the bottom of the switch I installed a 30 amp twist lock input receptacle.

Since the building is older, the grounding buss was installed and wired directly to the ground at the service entrance panel.   The building sub panel for this floor is using conduit for the ground conductor back to the service entrance panel, which used to be code compliant but no longer.

5.8 GHz dish with non-penetrating roof mount

5.8 GHz dish with non-penetrating roof mount

STL/LAN extension dish installed on roof top. I used an old non-penetrating roof mount for a four foot satellite dish.  The building owner was very specific about not having anything puncture the new rubber membrane roof.  Thus, the heavy rubber mats and sand bags instead of cinder blocks.  These stations will be using a Cambium PTP-250 system for STL/TSL and LAN extension. This will haul program audio for five radio stations plus satellite backhaul and remote control. It is a relatively short path with the FM tower visible from the roof top.

5.8 GHz path to FM tower

5.8 GHz path to FM tower

It was kind of hazy when I took this picture, but if you look really close, you can see the FM tower out there on the hill top.  The path is 3.37 miles (5.43 KM).  With a 40 MHz channel width, that should net about 175 Mbps bi-directionally, which is more than enough to do what we want.  This set up will require a pair of managed switches and some VLAN configuration, which I will post separately.

No, this time we really mean it

The FCC is stepping up enforcement on pirate radio. They have released an enforcement advisory, which you can read here.

The advisory starts out like this:

WARNING: Unauthorized Radio Broadcasting is Illegal
Persons or Businesses Operating “Pirate” Broadcast Stations
Are in Violation of Federal Law and Subject to Enforcement Action

Okay, so when you stop laughing, here is what will really happen: They will go out, bust a few pirates, issue larger than normal Notices of Apparent Liability, collect none of the money from them and call it a huge success.  I doubt very much that the FCC or congress has the wherewithal to wage an all out effort against pirate broadcasting. This is the same FCC that eliminated most of its field enforcement agents and closed most of their field offices.  But that doesn’t matter either, because the NYC field office is still open and within a ten mile radius of that, there are likely a dozen or more unlicensed broadcasters.

In the mean time, if you are a licensed broadcaster, God forbid you accidentally miss a Required Monthly Test or have an unlocked tower fence.

It is like the city police force that sits on a stop sign writing tickets to otherwise law abiding motorists when the next block over, kids are out in the street openly selling bricks of heroin.  Meanwhile, the chief of police sits in his office furiously typing blistering memos saying that the sale of heroin is illegal.

Comacho 2016

I know who I am voting for:

President Dwayne Elizondo Mountain Dew Herbert Camacho

President Dwayne Elizondo Mountain Dew Herbert Camacho

If you have not watched Idiocracy yet, Netflix it (or youtube it).

Seriously, I can’t see anyone worth voting for, I suppose I will have to Johnson it again.

Studio Buildout, Part I

We are in the process of building a couple of new studios for one of our clients. This one involves a small market combo of one AM and four FM stations.  These stations were formerly located at one of the transmitter sites, two miles outside of town on top of a large hill.  That site could be difficult to get to during the winter and the building itself was not in the best of shape.  Thus, plans were made to move the studios to a better location.  Fortunately, we discovered that right in the village there are several suitable office buildings.

Any worthwhile project needs to be planned for.  The first consideration is the Studio to Transmitter Link (STL) paths.  Since this is a radio studio, it makes sense to located it where viable RF STL paths exist.  One might be surprised by the number times the issue of bad or non-existent RF STL paths has come up during these types of projects.

Studio to transmitter site LAN extension

Studio to transmitter site LAN extension

The next thing to check is the satellite path.  The plan right now is to keep the satellite dishes at the transmitter site, however, at some point in the future we can relocated the satellite dish to the roof of the studio building if desired.

AMC-8 satellite path

AMC-9 satellite path

The floor space was measured out and I drew out a floor plan:

Walton Studio floor plan

Walton Studio floor plan

Before we started work, all of the walls were painted and new carpeting installed.

Almost nothing at the old studio is worth keeping. Thus, all of the furniture, consoles, racks, STLs, and other equipment needed to be ordered.  A local kitchen company traded out the counter tops, which we picked up at their facility and delivered to the studio ourselves.

Studio counter top

Studio counter top

We will build risers for these on site then mount the consoles and such.

New Studio Equipment

New Studio Equipment

In the mean time, most of the new studio equipment has been ordered and delivered. There are still some outstanding items that have not arrived, but I am assured that those are in process and should be showing up shortly.

Used equipment racks

Used equipment racks

These equipment racks came from another market, but are in good shape.

I had a good meeting with the building owner regarding roof access, a sub panel for the racks and studios and other issues.

For those concerned people

I have received a few comments and off line inquiries about my well being and the status of the Engineering Radio blog in general.  First, let me say; thank you for your concern.  There are many things going on right now, both professionally and personally.  Some of those things are good and some are bad.  In other words; typical life stuff.

First, from the professional side:  The company (?) I work for has undergone some internal changes. We are, in general, very busy and I myself have at least five or six irons in the fire when it comes to projects.  These include things like two complete studio projects, a couple of transmitter site rebuilds, some STL installation work, a couple of new IP data links, etc.  On top of this there are, of course, maintenance issues and emergency calls, irate general managers, frugal owners, old equipment, and so on.  We have had a pretty good cold snap over the last weekend (-10 to -15F), which has lead to numerous failures; pipes freezing, diesel fuel gelling, UPSs quitting, etc.  <s>All in, it has been so much fun I cannot believe I actually get paid do to this </s>.  If you have worked in the business for a while, none of this should surprise you.

When I get time, I will put together some posts on the above projects, as some of them are quite interesting or at least somewhat entertaining.

Secondly, from the personal side:  Youth hockey season is here and I have been carting my son around to practices and various hockey games in upstate NY and western Massachusetts.  Last weekend, his team played in the Empire State Winter Games in Lake Placid, New York.

Lake Placid hand shake

End of game hand shake, USA rink, Lake Placid, NY

For any fan of Hockey, a trip to the Herb Brooks Arena can be a semi-religious experience.

In addition to this, another common radio engineering problem has occurred; marital discord.  So much so that alternate living arrangements have been considered.

Thus, my time and very often my mood has been constrained.  Hopefully, after youth Hockey season ends in next month, I will at least have more time to do some quality posting.  Your patience is appreciated.

Emergency Communications

In this modern day and age, we take electronic communication for granted. Imagine being plunged into a world were there are no phones, cellphones, internet, email, television or even radio. Back in the day when I served aboard ships, we called that being underway.

Way, way back in the late 1980’s and early 1990’s, those that served at sea were at the mercy of the Fleet Post Office.  I will say, the FPO did a very good job routing the mail to the appropriate place, however, sometimes weeks or even a month would go by without mail.  When the mail finally did arrive, it all smelled the same.  Everyone’s wife or girl friend put some sort of scent on the outgoing, but since those letters mingled tightly packed in the same bag for weeks, often in hot humid tropical Pacific air, those scents blended together and became the Westpac Mail Smell, which permeated everything, even the letters from my father.

What will happen if people can’t sign on Facebook?

Fortune favors the prepared.

Communications loss in ordinary circumstances

Loss of utility company power, phone service and internet service can happen at any time for a variety of reasons.  The worst case scenario will occur when such loss is coupled with a natural disaster, which are often a major disruption of normal life.  Loss of information, especially at critical moments, can make a bad situation much worse.  In a situation where all normal means of communication are not functioning, something will fill that void, most likely the rumor mill.  That could be bad.

For information gathering, there are many options.  A good AM/FM shortwave radio is a decent start.  I would recommend a quality shortwave radio that has AM/USB/LSB options.  During run of the mill storms and power outages, many radio stations will remain on the air with emergency generators.  The key is to figure out which stations are staffed and offer good timely information.  NOAA all hazards radio can be good source of weather information, however, their transmitters can remain off the air for weeks or months at times.

One might ask “Isn’t this overkill or alarmist?”  I suppose that depends.  In the December 2007 ice storm, we had no power for seven days. In the aftermath of several major Northeast hurricanes and winter storms, some people had no power for more than two weeks.  Not only no power, but no cable, phone or internet either.  In situations like that, having some form of connection to the outside world can make a big difference.

Communications loss in less than ordinary situations

Other situations and scenarios may require more effort.  Prolonged information shortages could be triggered any number of national or global situations.  Shortwave receivers are not only for listening to international broadcast stations but also for tuning into the amateur radio (AKA “Ham”) frequencies as well.  Amateur radio is often used for emergency communications on a local and national and international level by governments and the Red Cross when other systems are out.  National and international communications are often heard on the HF band; 3-30 MHz.  The Amateur radio primary emergency voice nets are:

  • 3791.0 USB VOICE PRIMARY International, DX, and Emergency/Disaster Relief
  • 5371.5 USB EMERGENCY Emergency/Disaster Relief
  • 5403.5 USB EMERGENCY Emergency/Disaster Relief
  • 7185.5 USB VOICE PRIMARY International/Regional and Emergency/Disaster Relief
  • 14346.0 USB VOICE PRIMARY International/Regional and Emergency/Disaster Relief
  • 18117.5 USB VOICE PRIMARY International/Regional and Emergency/Disaster Relief
  • 21432.5 USB VOICE PRIMARY International/Regional and Emergency/Disaster Relief
  • 24932.0 USB VOICE PRIMARY International/Regional and Emergency/Disaster Relief
  • 28312.5 USB VOICE PRIMARY International/Regional and Emergency/Disaster Relief

These are voice channels from the ALE website. If there is not traffic on these frequencies, tune around a little bit.  In addition to voice nets, the amateurs also use something called ALE, which stands for automatic link establishment.  This is a data system that can be decoded on a listen only basis with a computer and some free software, for those so inclined.

For local amateur communications, 2 meter and 70 cm repeaters are often pressed into service.  For those, a VHF/UHF scanner is required.  Get a trunking scanner for 800 MHz police/fire dispatch as well.  Make sure that all radios can operate on 12 volts DC.  For this application, the size of the solar panel and battery is moderate, as receivers do not use much current.

Another option is a wide band USB radio for a lap top computer like a WinRadio WR-G315e.  These devices can be power by the USB outlet on the computer while the computer itself is charged with a solar panel.  For this route, some research on lap top solar chargers is needed.  The DC power requirements vary from lap top to lap top, so I can only offer general advice here.

With any receiver, a good antenna will greatly improve performance.  If there is room for an outdoor antenna, any length of wire strung up in a tree, away from power lines will work well.  For indoor setups, some type of receiving loop will work best.

Prolonged loss of communications in extraordinary circumstances

For longer term situations, gaining access to vital information and communications may become more problematic.  First of all, electronic communications require electricity.  Long term disruptions to the electrical distribution system could occur by either natural or man made events.  When those events happen, those that are prepared will be in a better position to survive if not thrive.  Things like ad hoc computer networks and amateur radio can facilitate two way communications.  In order to use amateur radio, one needs to get a license first.  This is a pretty easy thing to do and most other amateur radio operators won’t talk to you without a valid call sign.  Not only will they not talk to you, they will likely track you down and report you to the FCC.  That is the nature of the hobby, like it or don’t.

Amateur radio set ups can be very simple and not terribly expensive.  An used HF radio can be purchased on eBay for a moderate sum.  A simple multiband vertical antenna will serve general purposes.  For those that are interested in HF Link, a newer radio will work better.

Wireless ad hoc computer networks can be set up to establish a quasi internet over a moderate sized area.  WiFi WAN networks can be locally established using 900 MHz, 2.4 GHz, 5.8 GHz and 24 GHz license free channels.  Depending on the frequency, those links can be used for point to point medium to long haul links, or to establish local links to laptops and wireless devices:

  • 900 MHz: lower speed data rates, long haul, good to moderate building and vegetation penetration
  • 2.4 GHz: Limited channel availability, high atmospheric absorption, moderate speeds, low vegetation and building penetration
  • 5.8 GHz: High number of channels available, potential interference issue with TDWR radar systems, moderate to high speeds, line of sight only
  • 24 GHz: Large bandwidth, high speed, point to point back haul, line of sight only

Once the information is obtained, distribution to the greater public becomes a problem.  A very simple webserver (Apache, Nginx) with a light weight, simple index page containing vital information, news, weather, etc can be set up on a laptop and all HTTP traffic directed to the default index page.  This type of set up could be run off of a battery charged by a solar panel.  The issue here would be obtaining the information to put on the web page.