Emergency Info – Page 2 – Engineering Radio

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.

The Emergency FM Replacement Antenna

Hurricane season is here. This time of year makes me fondly remember hurricanes of the past and the things we had to do to get stations back on the air; walking a mile down a sandy spit of land, wading through swamp water to get to the transmitter shack, being threatened with arrest by the Connecticut National Guard, blow drying RF modules with a hair dryer, sleeping in a camper for a week… Ahhhh, good times, great times!

The one thing that I did learn if the disaster is big enough, expect none of the normal services to be functioning. That includes things like gas stations, fuel delivery, grocery stores, restaurants, hotels, UPS, roads, bridges, telephone service, internet service, etc.

It is not a far-fetched scenario for the main FM transmitter site to be out of commission and will not be available or accessible for some prolonged period of time. There might also be mitigating circumstances such as catastrophic tower failure, destruction of the transmitter building, flooding, or other major infrastructure disruptions. In those situations, calling the broadcast supply vendor of choice for a replacement might not be an option.

It has happened before…

All of these things got me thinking about how to fabricate a reliable FM broadcast antenna from simple materials available on hand. The FCC allows for temporary operation with an emergency antenna in part 73.1680, which reads:

(a) An emergency antenna is one that is erected for temporary use after the authorized main and auxiliary antennas are damaged and cannot be used.

(b) Prior authority from the FCC is not required by licensees and permittees to erect and commence operations using an emergency antenna to restore program service to the public. However, an informal letter request to continue operation with the emergency antenna must be made within 24 hours to the FCC in Washington, DC, Attention: Audio Division (radio) or Video Division (television), Media Bureau, within 24 hours after commencement of its use. The request is to include a description of the damage to the authorized antenna, a description of the emergency antenna, and the station operating power with the emergency antenna.

(1) AM stations. AM stations may use a horizontal or vertical wire or a nondirectional vertical element of a directional antenna as an emergency antenna. AM stations using an emergency nondirectional antenna or a horizontal or vertical wire pursuant to this section, in lieu or authorized directional facilities, shall operate with power reduced to 25% or less of the nominal licensed power, or, a higher power, not exceeding licensed power, while insuring that the radiated filed strength does not exceed that authorized in any given azimuth for the corresponding hours of directional operation.

(2) FM, TV and Class A TV stations. FM, TV and Class A TV stations may erect any suitable radiator, or use operable sections of the authorized antenna(s) as an emergency antenna.

(c) The FCC may prescribe the output power, radiation limits, or other operating conditions when using an emergency antenna, and emergency antenna authorizations may be modified or terminated in the event harmful interference is caused to other stations or services by the use of an emergency antenna.

In this situation, making a circularly polarized antenna would be overly complicated, so either a horizontally or vertically polarized antenna would be the most likely scenario. There are a few antenna types that readily lend themselves to field expedient fabrication.

These are, in no particular order:

1/2 wave wire dipole
1/2 wave tubing dipole
1/2 wave folded dipole
1/4 wave vertical ground plane
3/4 wave J-pole (end fed 1/2 wave antenna with 1/4 wave tuning stub)

Of these, the 1/2 wave wire dipole is the easiest to construct. Cut two wires, length (in feet) determined by the formula 234/Frequency (Mhz). Attach one wire to the center conductor and one to the shield, stretch to the wires out and tune for minimum SWR by cutting or adding small lengths to the ends. The total length for such an antenna would be approximately five feet and it could be mounted horizontally or vertically. The issue with a wire dipole would be bandwidth and power handling capability.

A 1/2 wave dipole made from tubing would have better bandwidth and power handling, but tubing is a little harder to work with when it comes to tuning the antenna.

Frankly, if one is going to go through the trouble of using tubing to create an emergency antenna, the J-Pole (end-fed antenna with a 1/4 wave matching section) is probably the best. This antenna is easier to tune, does not need to work against a ground plane, and has good bandwidth and a low take-off angle, meaning more power is radiated out toward the horizon, giving it a good deal of gain over both a ground plane and dipole antenna. Additionally, when using standard RG-8, RG-214, LMR-400 or another similar transmission line, a well-matched antenna might be able to accept about 1 KW of input power, which would net approximately 4.4 KW ERP. Not an insignificant sum, especially in an emergency situation.

Vertical radiation pattern for J-pole (1/2 wave end fed) antenna

1/4 wave ground plane vertical radiation pattern

There are many J-Pole antenna calculators available online, but many of them include a 20-inch or so section of tubing below the tuning stub that can be electrically coupled to the supporting structure. This configuration defeats the main advantage of the antenna, creating a good deal of upward radiation. It is a better idea to use a non-conductive support piece and keep any conductive materials at least 1/2 wavelength or greater from the radiating portion of the antenna.

The basic j-pole antenna looks like this:

J Pole (1/2 wave vertical antenna) diagram

The radiating part of the antenna starts above the tuning stub. Basically, the 1/4 wave stub is shorted at the bottom, the feed point is adjusted away from the shorted end until a 50-ohm impedance point is found. The center conductor of the coax is attached to the 3/4 wavelength section, while the shield is connected to the stub. The critical distances are the tuning stub length and the distance of the feed point from the shorting section. I created an excel spreadsheet (.xls) that can be used to create all the lengths required to fabricate one of these antennas. That spreadsheet can be had here: J Pole Calculator

Having a few moments of time to spare, I thought it would be fun to build one of these and put the analyzer to it. I think testing things in the real world is a good exercise and I always enjoy working with antennas anyway. Looking in the basement, I found some 3/4 inch copper tubing, a tee, an elbow, and a few end caps. The complete list of parts is thus:

Part	Amount	Use
¾ copper tubing	78-96 inches (196-244 cm) (frequency dependent)	Main section
¾ copper tubing	26-32 inches (66-82 cm) (frequency dependent)	Tuning stub
¾ copper tubing	2.5-3 inches (6.35-7.62 cm) (frequency dependent)	Tuning stub short
¾ copper tubing	2 inches (5.08 cm)	Mounting section, bottom of T to MIP threaded adaptor
¾ copper T section	1 each	T section for joining main section to tuning stub
¾ copper 90 elbow	1 each	Elbow
¾ copper end cap	2 each	End cap on tubing
¾ to 1 inch copper MIP threaded adaptor	1 each	Antenna Mounting
1 inch PVC FPT threaded adaptor	1 each	Insulating mounting connection
1 inch PVC	Approximately 20-25 inches (50-65 cm)	Insulating mounting material
1 inch stainless steel hose clamps	2 each	Attaching the coax to the antenna feed point
RG-8, RG-214, LMR-400 or other transmission line	As needed, including 5-6 turns, six inches in diameter to form RF choke at feed point	RF choke needed to keep RF off of coax shield

One important detail to remember when using the above spreadsheet, the measurements are to the closest side and not the center. Thus, if something measures 2.5 inches, it is metal to metal. Some basic soldering skills are required, but assembly is relatively straightforward. In a pinch, almost any conductive material could be used including aluminum, brass, steel, EMT, rigid conduit, or even iron pipe.

Parts cut to size for j-pole antenna on 87.9 MHz — Parts cut to size for J-pole antenna on 87.9 MHz

j-pole antenna assembled — J-pole antenna assembled

J-pole antenna on the antenna testing range

I made this particular J-pole antenna on 87.9 MHz because I didn’t feel like chopping up all my 3/4-inch tubing. Cutting and soldering the tubing took about half an hour. Designing and fabricating the feed point system for another half an hour. I’ll throw another hour in for rounding up the parts, tools, etc. Thus, the entire antenna was constructed in about two hours. I used my AIM 4170D to find the proper feed point. If I were going to actually use this antenna, it would then be a matter of finding a mounting location and running the transmission line.

Actually, I was less than happy with this. While the antenna is nice and broad across several channels, there are 16 ohms of inductive reactance that is impossible to get rid of. That gives an SWR of 1.4:1, which is not great. With that kind of load, I would be reluctant to run more than a couple of hundred watts into this antenna. The interesting thing is, that graph is the first one, with everything set as calculated in the spreadsheet. After that, I could make the impedance and reactance worse, but not better.

Still, in a pinch, I would use this antenna until something better could be found.

Update:

As promised, a picture of the feed point:

The hose clamps are not optimum, I am sure a better way to attach the feed line to the antenna can be fabricated, but again, I was thinking of an emergency situation and the parts which may be available from local sources.

The efficacy of the computer generated voice

I was just listening to the latest broadcast of severe thunderstorm and tornado warnings rolling in across WXL-37 for upstate NY:

It looks a little bit hairy to the north. There is a lot of rumbling around to the west of us and we are prepared to head for the basement in event of a tornado in this area.

At some point in time, somebody decided that computer-generated voices were exactly right for emergency communications. Never mind some of the quirks that can be encountered. These are mostly pronunciation errors for places like Saugerties, normally spoken as Saw-ger-tees but the NOAA computer voice says S-ouw-jer-tees. That is understood well enough, but frankly, there are other place names that go by so fast that I cannot make sense of what the computer is saying.

Another good example of this is the Coast Guard’s computer voice confusion around the word “November.” In the military (NATO) phonetic alphabet, November is the word used to express the letter N. For some reason, the word itself seems to be a bit of a mystery to the computer, which sometimes renders the word November as “NOVEMBER OSCAR VICTOR ECHO MIKE BRAVO ECHO ROMEO.” For those of us who have been in the military, this makes perfect sense. Why just say “November” when you can say much more, waste time, and confuse the un-aware? This particular computer voice is nick-named “Iron Mike.”

Computer-generated voices can be hit or miss.

Then there is the computer voice from Shannon VOLMET:

Even on HF Single Side Band, that voice is clearly more understandable than the NOAA voices in use today. The issue is, many broadcast stations now use the NOAA computer voice to broadcast weather alerts to their listeners. If I were driving in my car with lots of background noise, I likely would not get most of the information being relayed by the broadcast station via EAS. I suppose gone are the days of a professional broadcaster’s voice clearly imparting information and comforting the listeners during times of calamity. Sigh.

NAB thinks Translators offer more value than LPFM

Alternate title: “I love Stupidity,” somebody else’s, usually not my own. It’s a bit hard to reconcile the NAB’s desire for translators against the need and strong community support for local radio. The original intent of translators was to fill in coverage areas of existing FM licenses within the parent stations’ protected contour. Very few translators are actually used for that purpose today. They have, instead, morphed into vast over-the-air relay networks for NPR and religious stations or are relaying programming of HD-2 channels that would otherwise not be heard. Why we would need more of that, I don’t know.

The unfortunate part of all that stupidity is the side effects. Think of the stupid driver who cuts off a tractor-trailer on the interstate and causes a big pile-up. There are potential injuries to those involved in the accident but also the inconvenience to all those stuck in miles of backed-up traffic. That is a fairly minor occurrence.

With big corporate government, the size and scale of stupidity can reach epic proportions. To wit: During the natural disasters that overtook the northeast, indeed other areas of the country as well, local radio was proven to be a reliable, sometimes life-saving means of communication time and time again. Yet, in spite of all that, the NAB seems to think that LPFM stations (community radio) should be second to cross-band translators broadcasting AM stations and HD-2 channels. Regarding FM translators on AM stations, the NAB says:

NAB first commends and supports the Commission’s proposal to eliminate the restriction on the use of FM translators by AM stations to translators that were authorized as of May 1, 2009. FM translators enable AM stations to overcome inherent technical disadvantages that limit audio quality compared to other services, thus limiting their service to the public and even threatening their economic viability.

Oh where to begin? First of all, AM stations do not have inherent technical disadvantages, that is a myth. Off-the-shelf AM receivers are of inferior quality and make a well-designed, well-executed AM station sound like a telephone. If one were to listen to an older AM radio or AM on a receiver with variable bandwidth IF, one would find that it can sound quite good, if not very good. The problem is that the receiver manufacturers never carried through with the promise to open up the bandwidth following the implementation of NRSC-2 in 1991. One should wonder why.

Second, there are many AM stations out there that are economically viable. Those stations have local programming and serve the community of license and have not been neglected or turned into an automated syndicated radio repeater. Now, could a class C or class D AM station benefit from a translator at night, sure? That may not be a bad distinction to draw, especially for those class D stations with no nighttime operating authority.

Regarding more translators in general, it is difficult to imagine what all those new signals will be used for, other than more of the same (relaying distant, out-of-market religious stations, NPR stations, or HD-2 programming which nobody cares about). The FM band is already full of such things and could actually use less, not more.

While unfortunate, the NAB’s position is not surprising. They do the bidding of their dues-paying members, after all. The anti-competition we are a monopoly stance of the NAB members is not new either. Remember the required economic impact study required by the LCRA on the LPFM vs full power commercial FM stations. To think that a 100-watt LPFM could significantly impact the business of a class A, B or C FM station is laughable. Yet, it was a requirement stuck into the bill at the behest of the NAB.

It is up to the broadband-minded FCC to see how to slice the remaining FM spectrum up and whether the corporatist NAB’s argument holds water or the rising call of the people who want a return of local radio and local community service will be heard.

This is a video of what happened during Tropical Storm Irene in Ulster County, where I live:

We are truly fortunate that no one here was killed. In the mean time, the waters around here are still receding, we had some additional flooding Wednesday (9/7) with another 6 inches of rain from Tropical Storm Lee with flood warnings still in effect for several local creeks.

In my neck of the woods, we have nine radio stations licensed within about a 16 mile radius. One is religious, one is a college station, the other is a classical music format programmed from Albany, 90 miles away, one is a LPFM run by a local high school and two are commercial AM or FM station. The commercial stations used to be located in downtown Ellenville but moved to Poughkeepsie, about 30 miles away in 1999. The religious, college, and classical stations are small and have no backup systems or interest in emergency programming. That leaves the high school LPFM, WELV-LP.

In the height of the storm, 11.53 inches of rain had fallen in the previous 8 hours, the power was out, cable was out, the internet unavailable, the Verizon telephone company office in town was almost underwater, we had two sources of local Ulster county information; WDST (100.1 MHz, class A) in Woodstock and WELV-LP in Ellenville. WDST studios are located in Bearsville, which is about 25 miles north of here. They are a locally owned, locally programmed station with a good record of community support. They did a good job updating emergency information, flooded roadways, emergency shelter information, power restoration information, dry ice, alternate emergency numbers in case 911 went out, rallying points for local fire departments, etc. Ellenville Central School district’s WELV-LP also did a good job, although much more confined to the local area around Ellenville and have a much smaller coverage area. Still, they were live on the air with up to date information. Thankfully.

Next time, who knows?