Downgrading an AM radio station

WGHQ in Kingston, NY has been downgraded from a 5KW DA-1 to a 1KW non-DA system.  This was done because two of the three towers in the directional antenna array dated from 1960, were in very rough condition and needed to be replaced.  The remaining tower (furthest from the transmitter building) had been replaced in 1994, is in good condition, and is being kept as the non-directional radiator.

Here are a few pictures:

WGHQ 3 tower directional antenna array, Port Ewen, NY
WGHQ 3 tower directional antenna array, Port Ewen, NY
More deferred maintenance
More deferred maintenance
RF and tower light feed disconnected from tower base
RF and tower light feed disconnected from tower base
Second tower base vegetation not as bad, tower disconnected
Second tower base vegetation not as bad, tower disconnected
WGHQ transmitter and original Collins phasing cabinet
WGHQ transmitter and original Collins phasing cabinet

First tower video (sorry, I appear to have no idea what I am doing with the camera):

Second tower video, this one is better:

Towers on the ground:

I made measurements on the third tower and constructed a temporary ATU with parts on hand to get the station back on the air. They are now running 1 KW day, 38 watts night, as per their CP. I will be going back up to finish the job once the brush has been removed from around the existing tower and the ATU building has been repaired.  The coverage with 1 KW is not bad, actually:

Predicted coverage map from FCC website
Predicted coverage map from FCC website

The translator is on the way.

The Ubiquiti Nano-Beam

I installed one of these wireless links between two transmitter buildings recently.  The Ubiquiti gear is not my first choice, however, the client insisted that we use this equipment likely because of its inexpensive nature (less than $65.00 per unit).  My overall impression is so-so.  They are fairly easy to set up; the AirOS is intuitive and easy to navigate around.  I had to upgrade the firmware, change the default user name and password, assign IP addresses, subnet mask, gateway information, SSIDs, security parameters, etc.  All of that was very easy to figure out.  My grip is this; it seems the hardware is a bit plastic-y (e.g. cheap).  I know some of the Ubiquiti models are better than others.  I hear good things about the airFiber units but they still don’t compare to the Cambium/Canopy gear.

For this installation, I used the shielded Ubiquiti “Tough Cable” with the shielded Ubiquiti RJ-45 connectors and Ubiquiti Ethernet Surge Protectors.  When making the Ethernet cables up, I made sure the shield drain wire was connected to the metal body on the RJ-45 connector.  I tested everything with my trusty Fluke Microscanner cable verifier which also shows continuity for the shield.  I am still not completely confident that the outdoor units will survive a lightning strike on the 898-foot (273.7 meter) guyed tower nearby.  Time will tell.

The system has a wireless path length of about 200 meters plus another 60 meters or so of Ethernet cable.  Latency when pinging the gateway across the entire network is about 3 to 4 ms (laptop>switch>nanobeam<->nanobeam>switch>gateway).  The network is being used for remote control/monitoring of transmitters and backup audio via Comrex Bric link II IP CODECs.

screen shot; Nano Beam Air OS
screenshot; Nano Beam Air OS v7.2.2

On the plus side, the 802.11ac link is very fast; 650+ Mbps unwashed link speed is pretty impressive.  Strip off the wireless LAN headers and that likely translates to greater than 500 Mbps goodput.  Also, the inexpensive nature of these units means that we can keep a few spares on hand in case something does suffer catastrophic damage due to a storm.  The AirOS v.7 is pretty cool with the RF constellation and other useful tools like airView (spectrum analyzer with waterfall display), discover, ping, site survey, speed test, traceroute, and cable test.

After installing the updated firmware, which fixes a major security flaw with the web interface, the link was established with three mouse clicks.  After that, I ran speed tests back and forth for several minutes.  Basically, the speed on the LAN is reduced because of the 100 Mbps switch.  Even so, that should be more than enough to handle the traffic on this segment of the network.

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 IP88s will live on their own VLAN.  The PTP-250s 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 setup 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 managed 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 the 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 an 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 analyzer, 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 is uncongested.  This should keep the throughput high.

Studio to transmitter site LAN extension
Studio to transmitter site LAN extension

The PTP-250s 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.

Emergency Communications

In this modern day and age, we take electronic communication for granted. Imagine being plunged into a world where 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 1980s and early 1990s, 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 girlfriend 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 to 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 is 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 a 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 by any number of national or global situations.  Shortwave receivers are not only for listening to international broadcast stations but also for tuning into 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 no 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 the battery is moderate, as receivers do not use much current.

Another option is a wide-band USB radio for a laptop computer like a WinRadio WR-G315e.  These devices can be powered by the USB outlet on the computer while the computer itself is charged with a solar panel.  For this route, some research on laptop solar chargers is needed.  The DC power requirements vary from laptop to laptop, 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, but they will also likely track you down and report you to the FCC.  That is the nature of the hobby, like it or don’t.

Amateur radio setups can be very simple and not terribly expensive.  A 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 backhaul, 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 lightweight, simple index page containing vital information, news, weather, etc can be set up on a laptop and all HTTP traffic is directed to the default index page.  This type of setup 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.