Saturday, September 2, 2017

The Role Of HF Amateur Radio in Disaster Communications

Does HF still have a legitimate role in disaster communications?
High frequency, also known as shortwave, is the portion of radio frequency spectrum from 3 MHz to 30 MHz; or to describe it another way, between medium wave (including the AM broadcast band) and VHF (which includes the FM broadcast band).

HF is characterized by ionospheric skip propagation (1), where signals bounce off ionized particles in the upper atmosphere. It is this characteristic that makes HF important, and is the reason that we can tune in shortwave broadcasts from around the world. Without getting too heavily into the science behind ionospheric skip propagation, radiation from the sun ionizes particles in the F layer of the ionosphere, between approximately 100 miles and 300 miles above the earth's surface. The ionization is greatest during daylight hours at any given point. The season is also a factor, as is the 11-year sunspot cycle (2),(3).

In practice, an HF operator or frequency coordinator can choose an operating frequency based upon distance to the receiving station. The lower bands within the HF spectrum work best within a radius of zero to 200-300 miles, while the upper HF bands are better for worldwide communications. If the operator chooses the correct frequency, very little power is required to make contact. Amateur radio operators who are into QRP (low power, often simple equipment) regularly communicate thousands of miles using less than 5 watts and often even less than 1 watt of output power. The author has communicated over 1000 miles using 1 watt or less, and once carried on a two-way contact over approximately 15 miles using 50 microwatts. That's one, twenty-thousandth of a watt!

Back to the subject at hand: the majority of public service and other utility communications has moved away from HF frequencies and into trunked systems and microwave backbone links that connect local radio communication systems with others across the state and even across the country. These new systems have much greater bandwidth and can carry more information, for a greater number of users, at a faster rate than the older technology. To the end user, the new systems are easier to operate and more user-friendly, all the while providing more secure communications.

To be sure, the new systems provide greatly enhanced communications capabilities in day-to-day use. But what about during a disaster? These networks are infrastructure-intensive and cost billions of dollars to install. They're not immune to breakdowns, either. Tornadoes, hurricanes, earthquakes and other natural disasters can bring down these systems just as readily as they can bring down an HF radio antenna. And while the trunked systems can bypass damaged nodes and continue operating at a reduced capacity, such events create greatly increased communication needs. Even if the network does not suffer damage, disasters often overload the capacity of the system to maintain the flow of communications. Have you ever noticed how your Internet service slows down during times of peak usage? The same phenomenon is at work with trunked radio systems.

Consider for example, Hurricane Katrina. Here is what the Armed Forces Communications and Electronics Association had to say after Katrina: " On September 14, 2005, the 9/11 Public Discourse Project issued a report asserting that the response to Hurricane Katrina was a classic failure in command and control. It found no unity of command—or more specifically, no one in charge and no unified incident reporting system to coordinate efforts of local, state and federal agencies. Fixed communications systems failed with no ready means for their restoration. This was not surprising, given that there exists no incentive for the intensely competitive information systems industry to finance ruggedness, redundancy or rapid restoration." (4)

Here is where amateur radio comes in, with HF as well as VHF and UHF communications. From, again using Katrina as an example: "
During Hurricane Katrina, amateur radio provided volunteer operators to support
many served agencies such as Emergency Management,
National Weather Service,
Hurricane Watch and the American Red Cross. This is business as usual for many radio operators in the Amateur Radio Emergency Service, or ARES, nationwide.
After Katrina, amateur radio provided many more volunteer operators to support
an even larger host of served agencies that requested our services. The ARRL
coordinated hundreds of amateur radio operators who
traveled to the devastated
area and provided critical communications capabilities. This work continued for
many weeks. 
The sufficiency and effectiveness of amateur radio
to re-establish communications
systems with equipment they brought in, much of it
owned by these volunteers and
quickly building complete systems from scratch, was
tremendous. Amateur radio
operators themselves were part of the solution, providing experienced communications operators to replace and supplement
local public service
communications personnel in the devastated area. These systems of equipment and operators were very effective, not only for amateur purposes but in support of Emergency Management, Red Cross, Southern Baptist,
Salvation Army and many other organizations.
In each town we set up a High Frequency (HF) amateur radio station to communicate out of the area to Montgomery and the outside world. We also set up
a communications network connecting every Red Cross
facility in a town on a local
short range radio frequency. Our network included
fixed and mobile disaster
vehicle stations."(5)
Of course ham radio antennas can fail during disaster events too, and amateurs suffer power outages as well. But hams who participate in disaster relief efforts have the skills, know-how and equipment to put their stations on the air under all kinds of conditions, including portable field operations. In fact probably the most well-known amateur radio event is Field Day, in which thousands of amateurs all over the USA take to the field with their portable stations for a 24 hour emergency communications exercise.

Hurricane Harvey Amateur Radio Net

This is a bit of footage from the amateur radio HF (High Frequency) Hurricane Harvey watch net. One viewer made the comment that, "All I hear is callsigns and not much else. Do they ever actually talk about anything?" Here was my reply:

"You mostly hear the net control station. Net control is usually outside the affected area and runs an amplifier and a very good antenna setup. Stations reporting might be running low power, temporary antenna, and maybe even battery power. So you may or may not hear them. But what's important is that net control hears them, or another station is able to hear and relay to net control. This is not broadcast radio, and should not be expected to sound like it.
Also, a lot of the action is on other frequencies so as not to tie up this, the main contact frequency. Stations make contact via the net control, then move off frequency to communicate. For example, in the video you can hear net control take a checkin from a station 25 miles south of Dallas. Then you hear the National Hurricane Center (which I think is in Miami, FL) ask the net control if the station checking in has VHF or UHF contact into the affected area. VHF and UHF are used for local communications, and the Hurricane Center is well outside VHF/UHF range. The Dallas station replies that he has VHF contact only (It's a bit too far for UHF). Hurricane Center wants to talk to him further, so Net Control gives them time to make contact after which they move to a different frequency to continue their communications. While they are making contact, you can't hear the Dallas station but you can hear Net Control and you can also hear the Hurricane Center, but not as strongly."

It really is fascinating to listen to this going on, but you have to understand what is actually happening because as the viewer pointed out, you cannot hear everything. Also the video only captures a small snapshot of the big picture. In fact while I was listening, the net control announced that the hurricane was currently making landfall. Unfortunately I didn't have the camera rolling at that moment, so I started filming again and commented on that fact. This was approximately ten minutes before 9 PM Central DST.

It's worth pointing out that listeners in different areas might hear different parts of the net. A listener in South Carolina for example might hear the Hurricane Center very strongly, but hear the Net Control only weakly or not at all. The same listener might also hear the station in Dallas quite well. A listener in Houston with only a 2 Meter VHF mobile or handheld radio might hear or even be in contact with the station in Dallas and other local hams, but obviously will not hear any of the HF action.
The great thing is that any licensed ham who is interested can get involved in this sort of public service activity.