Emergency radio communication falls into three classes:
Many amateurs are covering voice requirements with good results but over the past three years I have yet to observe much success on the data side in our area. I'll restrict my interest to digital data transmissions that have error correction schemes, (ARQ). Usually this just means automatic retransmission with a failed check sum. PSK31, RTTY, CW and some new HF schemes will not be considered because of this weakness. Some use FEC (Forward Error Correction) as an attempt to correct a few characters but unless the entire message is correct, it doesn't pass the test.
Excluding Canadian stations, the North Olympic Pennisula AX.25 VHF packet performance is dismal.. a joke. The so called EOC packet stations that are operated during a SET (Simulated Emergency Test) usually don't even pass messages...... they often can't seem to get the station on the air and if they do, they're trying to operate with poor and unneccesary practices such as digipeating. Stations are not maintained or set up correctly with individual ownership. This observation led me to think about a portable station rather than fixed. People must be totally familiar with the tools. Don't tell someone to start sending messages in time of emergency when the last time they used the terminal and software was a year ago. When we have an emergency theirs no time for training.
If an individual literially "owns" it, he's more inclined to maintain in an operational status and its familiar to him. He's more inclined to operate, particularly if its useful in non-emergencies. Being portable with its own power source and antenna means its not limited to one location.....it can go anywhere theirs a need.
Plain old AX.25 VHF packet radio was the first consideration but as
above, its a disaster from the networking and operational point
view. I had a message delivered to me from a local ham who
received it via HF and VHF packet that was sent two months
previous. We all had a good laugh over that one but its down right
embarassing to deliver those to non-hams.
HF data is a solution that many try to adopt. Sure,
its good for sailors at sea but is it really reliable overall for land
based emergencies? Many EOC managers will try to argue that they
need a system to cover several hundred miles by radio. Thats good
but is the solution HF? I think
these people are smoking something? Reliability of passing
messages on HF radio is a function of many factors:
A complete HF radio station will generally be more expensive than
VHF/UHF. If you notice over 50 years or so that
radio has migrated to higher frequencies for some of the same reasons
mentioned above. To me, HF is a backup solution if all else
fails. Unlike many, I feel the most reliable radio solution is
An observation I feel is important, "Whatever tools used
must be familiar to the operators". This includes
and software. Hint, hint: Most people are now comfortable with
The Internet is ubiquitous. Wherever we go we find its
presence. In fact, I would have trouble not having it around.
grown so accustom to sending information to others in business and
pleasure via email that it has become a natural way we
communicate. Thats an important consideration we can't
ignore. In times of emergency, we want to be familiar with the
tools used to get to others. We'll be
under enough stress and don't need new ideas thrown at us, new
forms to fill out or other mandated ideas that have not been
practiced. In short, an emergency communications system should
look just like what we normally would use in our day to day
activities. No need for lots of practice sessions on
interfaces as we use them daily. Thats another reason
wanted to build a portable station that could go on
camping trips, cruises or other destinations where I could set it
up in 10 minutes for communications to the world. Have some fun
and use it often
So, are we looking at a radio based internet "look alike"?
The objective is to be able to pass "email like" messages by amateur radio to nearby internet gateways in time of emergency. Must be bi-directional so messages can be passed in the opposite direction as well. It must also have a peer to peer capability when the internet gateways are out of range or inoperatable for whatever reason.
The main problem to solve is "local" Internet access may be taken out in a disaster. In fact, thats a promise! By its nature, its redundant and distributed so only sections would be down but outside the immediate area operations should be unaffected. Lets take advantage of this observation in designing a backup system. What I've developed is a portable solution that uses a radio based link to cover the connection of the "last 50 miles or so". Its foundation has been around for a number of years and is called WINLINK 2000.
I'm not going into the details of WINLINK because much has been written about it. I will cover those points that are relavent to this station. If you want to know more, two sites are a good starting point:
Winlink has an HF following as well as VHF/UHF. It
originally got its start by serving sailors on the high seas using HF
radio and thats still very popular today and important for certain
applications and extensions. Some EOC's (Emergency
Operations Centers) would argue that HF stations are important to
communicate out of the area and to state EOC offices. With the
exception of HF voice communications, I disagree as eluded to
above. Their are many reasons that an HF strategy
will fail in a real disaster... too bad many EOC managers follow
like sheep and don't give it serious thought. The
key is to give VHF priority but having one fixed HF station is OK but
probably won't need it. HF, VHF and Telnet WINLINK
all talk to each other and are part of the same system so you could
consider it redundancy.
considered is OUTPOST. In short, this is an
attempt to automate the BBS process on the VHF packet network. Its a
recent development with few advantages over WINLINK AIRMAIL. As far as
I'm concerned packet BBS's have been superseded by
Recently, is NBEMS, (Narrow Band Emergency
Messaging System). It just had a beta release: 1/3/08.
Information is still limited but it works with PSK type
signals up to PSK250 using a sound card. Its intended for both VHF and
HF (NVIS). No apparent interface to the internet and has a difficult
access approach. So far, it has so many things against it that I
don't feel it stands a chance for what I'm trying to do. I do like
the idea of an ARQ feature combined with tolerant S/N of
What about client software? Winlink is the architecture and defines
interface but has nothing to do
with the software that runs on your terminal. Their are two ways
to go at present, Packlink and Airmail. I've ruled out OUTPOST as
||Must be running WIN 2000 or XP
||Running WIN95 or better
||Will run one of many popular
||Must use Airmail's built in
program but can deploy built in servers to reach others
||Can be up to $25
||Advanced users suggested.
Can get complex
||Experienced users, fussy, some
hacks needed for certain TNC's
||Preferred by advanced users,
flexible but can crash more often and troublesome at times. Capable of
||Simple once operating, good
introduction to WINLINK
|Peer to peer operation
||HW or SW for VHF.
Expensive Pactor modem for HF
|Usually, Hardware only TNC's.
AGW has been reported to work with hacks.
Expensive Pactor modem for HF
||Available but not for the "faint
||Available, but not well
coordinated. Starting to improve, however
I choose AIRMAIL version #3.3.081 as the client program mostly
simplicity. Like everything, it has its pros and cons. It has a
commercial version for non-ham operators called SAILMAIL which is used
on the high seas.
Without going into technical detail, a RMS station and its SW is what interfaces a radio channel to the internet in the WINLINK world. Most often this is done through a high speed connection such as DSL. The radio side only needs a common TNC. A PC running free software turns it into a RMS station. I have eight RMS stations within single hop radio range and many more using digipeaters which are discouraged but can be used. Since the RMS make up the other end of the reliability equation, the more you have available the better; your reliability of success goes up. RMS don't need to be manned which means that this can easily be a single operator system. Most amateur emergency communications links require operators on both end of the link.
The real test of reliability is when we have a mini disaster such as
a big windstorm which is common where I live. How many RMS's
can you reach after the storm hits? The worst storm over the last two
years took out three RMS stations. I was still on the air and
reach the world! Our biggest concern is probably an earthquake
can cover a much larger area. One RMS within radio range is nearly
70 miles distant...probably far enough away that a big earthquake
wouldn't cover that far?
The local internet service does go out all the time which helps
need for this station.
But what if all RMS's are unreachable? Thats where the peer to peer capability comes into play. AIRMAIL provides this mode which allows you to avoid the internet all together or transport the messages whatever distance needed to reach a working RMS. Even HF or conventional packet if you must. Many addressing combinations are available. Most stations can hold messages in a "transient" folder until a link is available.
Several important considerations for the station are needed:
A full printable page (PDF) of the schematic-block diagram can be obtained here.
The TNC is a Kantronix KPC 3+. Works great but AIRMAIL needs a couple of "hacks" in the airmail.ini file for proper operation. They have to do with stabilizing the XMITLVL value. Stock Airmail wants to override the value most optimum and I had to force it to accept my value. Improper XMITLVL level is one of the most common mistakes that packet operators make. A good discusion of this problem can be found at: http://www.febo.com/packet/layer-one/transmit.html
The self powered Real Time clock (RT clock) option is handy as the TNC needs power to run the regular internal clock. But, most of the communications are time stamped by the Laptop so its clock is the most important one to maintain. You want messages to be accurately dated and stamped. Its always a good idea to verify clock accuracy when you boot up.
The laptop computer is an old DELL Inspiron 4000 running Windows ME. It works well but isn't upgradable to a later operating system for running Packlink so I'm forced to stay with Airmail. It has a Eithernet port built-in so I can connect it to my home network or, in an emergency situation, an agencys (ie EOC) internal network assuming the IP staff will allow you a username and password? I could never understand why many WINLINK aficionados want to gain access through the firewall? This station is intended to back up communications in the case of the loss of the internet. You don't need WINLINK if the internet is up and running ! Keep it independent!
I will usually carry an outboard mouse and keyboard if operation appears to be extended. Never did like built-in versions.
The INVERTER is a standard 75 watt unit designed to power a Laptop computer from an automobile. I kept the cigarette lighter plug in place so it still can be used for that purpose if need be. My first approach was to design a power supply that goes from 12 VDC to the computers 18 VDC. It would be more efficient but not all computers use 18 VDC so I would loose flexibility with a direct approach. Best to stay with standard stock equipment..... replacement becomes much easier when caught in the field.
1.5 watts from the ICOM-2AT would seem to be very low power by many but I have to pay attention to battery life. With a good directional antenna you can increase the effective radiated power up to about 10 watts. At least three of my targeted TELPAC stations are across the Strait of Juan de Fuca and no more than 20 miles away as the sea gull flies. This is a line of sight path. 1.5 watts into an omni antenna does just fine. Realizing that not all situations will be ideal, I decided to add the optional power amplifier when needed. An RF concepts unit gives 30 watts into the Omni. Well over 100 watts ERP when using the yagi. Power drain increases to about 6 amps but that's the price you pay. On the otherhand, packet transmissions have low duty cycle. ICOM 2AT's cost about $35.00 on ebay. They also make good transmitters for ARDF sources. One negative is they require about 8 volts maximum so I included simple regulator to handle that.
The speaker with volume control is optional but valuable. I always like to have the ability to listen to the received signal quality and activity. I find that I usually set it so I can just barely hear signals in normal operation. Since AIRMAIL doesn't have a "Monitor" or "PASSALL" function, its very handy to judge if you're getting "resend" requests. An experienced packet operator can make that determination by just listening to incoming signals. I hope the designer of AIRMAIL includes a MONITOR function in future versions.
Its always a good idea to test things out in field conditions before you complete the packaging. As it turned out, on February 28, 2007 Clallam County had a communications simplex drill. We couldn't use repeaters for voice or data so this was a perfect opportunity to test parts of the system. As mentioned above, I have direct access of seven RMS stations so no digipeaters are needed.
I literally thru everything in the back of our Explorer and headed off to the parking lot outside the EOC. It doesn't look pretty but the photo shows the equipment as it was for the test.
Lower left is a 75 AHR trolling battery plus charger. Radio and TNC are in the lower right. The laptop sits on the DOMEX box and was operated from the rear seat. Normally, I would have put it on the tailgate but with the threat of snow in the air, I went for the comfort of the vehicle. Antenna was a 5/8 wave magmount on the roof. My yagi, as mentioned above required I bring the stand which I didn't want to mess with for this simple test. The radio was an old Heathkit at about 10 watts because I was afraid the ICOM 2AT "barefoot" would not have enough punch to get through from this location. After sending four messages, I tried it and it worked fine but that was with the "close in" RMS at 20 miles. My 30 watt amplifier was incapacitated at the time.
I was expecting noise from the inverter or computer getting into the receiver but my filtering must have solved the problems. The system worked flawlessly in moderately heavy traffic. Next step is to see if I still get that performance when they sit side by side in the suitcase. It was operational for 2 hours when the drill ended.
Current draw on the battery was 2.5 amps when in receive and 4.6 amps during transmit. This should give nearly 24 hours of service from a full capacity battery or longer with the lower power radio. The 2AT would have significantly less current drain at about 0.5 amps in transmit but the 30 watt amplifier would increase it to about 7 amps transmitting.
Things learned? Most were convenience. A Power-pole connection block in the back of the suitcase is a must. A 10 amp fuse would be fine but I'll still hold out for a breaker. It was fun to take it in the field and the folks I wanted to receive messages did so and had very positive comments. The real strength of digital data transmission is for complex messages that complement voice traffic. I sent the EOC a photograph of earthquake damage and a long list of supplies that might be needed in the real thing. Something that voice can't do effectively.
On August 17, 2007 I set up the first packaged system at the Clallam County Fair EOC booth. Operation was from 14:00 to about 18:00 hours. I used my homemade "J pole". The fair location has excellent propagation to at least three RMS stations so extra gain is not needed. All worked flawlessly. Messages were both sent and received during this time as well as firming up a visit the next day to Victoria for a foxhunt.
Lessons learned: The station can be transported as three pieces with one trip using a handtruck. The three pieces include:
I had to transport the station about 1/8th mile from my vehicle to
EOC booth and the handtruck works just fine.
You only need about 2' x 2' of table space but should be at a
comfortable working height for the keyboard. The laptop computer
is designed with long cables so it can be moved out of the
more flexibility is needed.
Rechecking current drain shows about 1.8 amps when in receive with a
"topped" laptop battery. 6.8 amps when transmitting using the ICOM 2AT
and 30 watt "brick" RF amplifier . This is better than
expected and allows well over 24 hours operation on the 75 AHr fully
One addition since, I've built in a digital volt-ampmeter so that I can monitor current drain and voltage level at all times. This will allow a warning when the battery voltage is starting to drop allowing you to send a runner to find an alternative 12 VDC source or a means of recharging the battery.
the complete electronics package. At the time these pictures were
taken the box was unfinished as I wanted see if any modifications were
needed before I went to the trouble of sanding and painting.
The second picture is the rear of the box. The center section is for cable storage, including the 12 VDC, 25' power cable. All the RF equipment is on the left side and the digital/computer equipment on the right. This was an attempt to keep RF radiation and digital noise separated and not interacting with the receiver or upsetting the computer. It seems to have worked as I havn't seen any problems.
After I built it and got all the hardware inside, I realized that
its really higher than need be. I could haved shaved off at least
inches in height. Oh well, its roomy. I'll take the next
generation on the cruise
Since FOXHUNTING is one of my other hobbies, antenna construction is
dear to my heart. Particularly directional ones. The
directional antenna used for this station is optimized for small size,
3 elements, and with a good front to back ratio with minimal lobes in
the pattern. Gain is not a
priority. Foxhunting antennas must be collapsible because we
often take them on 'walk on' ferries in the Pacific Northwest.
Thats a good trait to have for a portable station as
well. Neither antenna shown requires a ground plane.
|Homemade 3 element Yagi to
add directivity when reflections (multipath) and interference are
||Modest gain homemade
pole". Very lightweight, made out of 600 ohm ladder line
in 1" schedule 40 PVC water pipe. Far easier to handle and setup over
the Yagi. Can be operational in seconds where the Yagi takes
several minutes to assemble
|The collapsable stand breaks down into a simple package. To erect, just screw in the 4 legs in the base. The antenna pole simply drops into the 1 1/4" steel pipe.|
Having a large 12 VDC power source in constant state of readiness is
something few amateurs seem to be doing effectively. How do
to have an emergency communications system ready on short notice if the
power source is not ready? Yes, you can use the vehicle battery but
thats a conflicting use of a valuable transportation resource in time
Not a technical issue but an operational one. A common topic
of discussion is the use of the ICS213 form and others for
passing messages. It comes from the dark
ages of communications where multiple copies were created
distributed by courier to nearby participants. Thats obsolete
today for digital modes. We work over great distances where
impractical to have a multilayered form. A far better solution is
to send copies of the message to whoever needs it and maintain the
records in a database. Modern communications systems have a
wealth of information automatically added in the header including
date/time stamps that make backtracking so much easier. The
problem is many havn't advanced far enough to understand how effective
it can be. Many still want to do it the same old way.
True, voice messaging
still needs some record (form filled out) but we're
talking about digital here. For digital data communications, get the
message into a transmitable form and leave it there. Translate only
once. The computer can keep much better records than human
operators if well designed in the first place
When I create an email message in drills or the real thing, I follow the ICS213 content but don't use the form, literally. Some people think they have to fill out the ICS form and then attach it to a WINLINK or packet message. Not only is this a waste of time but a waste of bandwidth. The smallest basic ICS213 form I've found which is in PDF format required 3k bytes to transport. I've seen some as high as 24kbytes. The actual content of the 213 message header can be delivered in less than 100 bytes! Join the 21st century, people!
AIRMAIL has a template feature that allows you to create predetermined fields in the message header. I use this template which prompts me for all the info that the ICS213 form requires. Simple, efficient and with the network header automatically attached, contains all the info you would ever want for traceability.
OK, I don't find them of much value but I do endorse
experimentation in ham radio so more power to them. Theirs
still plenty of room for the emergency stations that carry useful
traffic. I should mention that AIRMAIL has a provision for
sending GPS data . Undoubtably from its marine roots.
I see a station like this as having three important uses in emergencies:
Of course in normal times it works well on RV's, boats and Public
Service events......providing a practical service.
I've tried to highlight only the key details of putting this station
together. Many amateurs like to do their own thing
and will customize it to their liking. Thats the nice thing
about our hobby. Setting up a station is not trivial but don't be
discouraged if you havn't done it before.....ask for help....I'd like
to learn some new approaches, also.
Neil Robin, WA7NBF
Port Angeles, Wa.