A Portable Emergency Communications Station
Battery operated data terminal connected by VHF radio to one of many Internet gateways
by Neil Robin, WA7NBF
Last Revised: Oct. 24, 2008

mergency radio communication falls into three classes:

  1. Voice for time critical simple messages that many amateur radio operators are good at.

  2. Data communications which is best at transporting complex detailed information that would be time consuming by voice and prone to error.  They usually are not quite as time critical and often require good records.  Sending charts, maps, photos  plus detailed inventory lists would fall into this category.  I have not been impressed with amateur activity in this area.

  3. CW: Its over!  Great for the Titanic but not in modern day.

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 mentioned above, its a disaster from the networking  and operational point of 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:

  1. Limited bandwidth available on HF, cramped space. Petitions have been submitted to the FCC to limit BW.  Fights between old school and new unsettled.
  2. Propagation conditions with time of day considerations
  3. The bigger the event the more everyone else will be trying to do the same thing
  4. Bigger antennas needed for HF, poor portability. Often due to space restrictions they use a compromised antenna. Array of NVIS common which limits range to solve fade problems
  5. Best and fastest modems expensive and proprietary, ($1,000), compatability issues. Still evolving
  6. Complex software that is harder to master, often crashes or locks up
  7. Overcoming QRM. Finding out that other stations want to use "your" frequency that you thought you owned
  8. Most HF transceivers and TNC's are power hungry....less attractive  for battery power
  9. Receivers more prone to local EMI....usually don't find out until emergency occurs. Transmitters also tend to generate more EMI  at least at the higher power levels which are attempted to drive away QRM.  rarely are these stations checked for bi-directional EMI

A complete HF radio station will generally be more expensive than VHF/UHF.  If you notice over 50 years or so that commercial/government 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 better served with VHF/UHF.

Where does this leave us?

An observation I feel is important, "Whatever tools used must be familiar to the operators".  This includes hardware and software.  Hint, hint: Most people are now comfortable with the internet.

The Internet is ubiquitous. Wherever we go we find its presence. In fact, I would have trouble not having it around. We've 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 strange interfaces as we use them daily.    Thats another reason I 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

winlink logoThe solution

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 others 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 you 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.

Another solution 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 email.

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 PSK. 

Why select WINLINK?

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 mentioned above.

I choose AIRMAIL version #3.3.081 as the client program mostly because of 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.

A word about RMS stations (Remote Mail Servers)

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 could reach the world!  Our biggest concern is probably an earthquake which 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 justify the 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.

Putting it all together

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.

First Dry Run

Rudy Goldberg set upIts 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.

Second Dry Run; First packaging

EOC WINLINK setup at 2007 fairOn 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 the 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  suitcase if 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 charged battery. 

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.

Suitcase Photos

Electronics package-WINLINK station

Photos show 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.

Rear view

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 two 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.

Solar and back-up power

Having a large 12 VDC power source in constant state of readiness is something few amateurs seem to be doing effectively.  How do you expect 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 of emergency.

In my opinion, the biggest need for amateur emergency communications will be in the first 24 hours after a disaster hits.  Thats why I orientated this station for portable use (assuming you can travel).  You need to be able to move the station to where it will be effective.  Being able to communicate, reliabiliy to anywhere in the world is a very powerful approach.  If the station required operation over days, a re-charging method is obviously needed. A multi-battery recharging system in a vehicle would work but you can't count on it.  For a long term disaster, generators will start to become available.  I've  included a 120 VAC to 12 VDC battery charger.  Another option is a 20 watt solar panel but you do need to have some sunshine to be effective...... sometimes infrequent in the Pacific Northwest.

Staying ready; inventory of my "ready to go" station:

Setting a staging area is important so you have everything inventoried and ready to go.  I do pull the suitcase and battery out often and use it in my home station just for practice and verification.

A word about forms

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 and distributed by courier to nearby participants.  Thats obsolete today for digital modes.  We work over great distances where its 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.



I see a station like this as having three important uses in emergencies:

  1. Its available to support emergency operations centers (EOC's, Red Cross, etc.) for delivery of "email" type messages including photos and other attachments if internet access is down.  It can be at the center, in the field or both if multiple stations are available.  Having  more than one portable station in an area is powerful.

  2. This station can stand alone and be an equal to standard internet connection efficiency. Most amateur solutions require at least two participating  stations with human operators at each end.  With the automation here,  only one operator is needed.  A single operator in the field can provide bi-directional communications to the world and directly to the decision maker.

  3. In an emergency, their will be many citizens that would like to contact friends and relatives to say "I'm OK"!  Setting up a station like this near a large gathering of people will have enormous benefit to the average citizen and be much appreciated. A great way to show what ham radio can do!  Trying to use a cell phone or telephone will almost always be jammed or not working.  Once these facilities are working, our usefullness is diminished but thats the way it should be. 

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.