HFLINK is
the international resource for ALE Automatic Link
Establishment High
Frequency Communications - HF Digital Messaging - HF
Interoperability - Emergency / Disaster Relief - High Frequency
Interoperable Communications - Ham Radio
October
2018 - Hundreds of ham radio operators around the world
have been active for the past several weeks, testing
their radio techniques for interoperability. They're not
competing in a contest or trying to win awards. They have
been participating in the High Frequency Interoperability
Exercise 2018 (HFIE-2018), an operating event that takes
place on the airwaves every few years, sponsored byHFLINK.
Dialing
Up A Ham Friend On HF
The
ham operators are initiating contact by dialing up each
other's call sign using selective calling (Selcall) and
Automatic Link Establishment (ALE). They are making
informal calls to engage in voice or texting
communications on High Frequency (HF) in the international
Amateur Radio Service frequency spectrum.
Instead
of dialing a telephone or using the internet, the direct
calls are initiated on their HF radio transceivers, which
are independent of land infrastructure or satellites.
Simply dialing a call to a friend may seem like an
ordinary task on a mobile phone, but it is surprisingly
unusual on ham radios. Most HF ham operators are more
accustomed to randomly calling "CQ" or gathering together
in scheduled "skeds" and meeting group "nets" to share a
frequency together.
HFcommunications
depend on bouncing signals off the ionosphere, which is
prone to the variability of solar influence and the
changing conditions of the earth's geomagnetic field. It
has been particularly difficult with the solar cycle at
its minimum this year. This variability has led to a wide
variety of reliable operating techniques, procedures, and
radio systems designed to benefit from the shortwave
spectrum.
HFLINKCoordinator,
Bonnie Crystal KQ6XA, remarked, "We are seeing a lot
of recent interest in selective calling. The statistics we
gathered during HFIE-2018 show an increase of about 350
percent. There are now about 5000 registered ALE and
Selcall callsigns globally in the net."
Kurt
KJ4AYT's solar-powered ALE-Selcall HF mobile 4WD.
Max
Haselbach HB9ZEIin Switzerland,
commented about the exercise, "I didn't know much about
ALE at the beginning of this event. While operating and
chatting onhflink.net,
I met a lot of very helpful operators. I made links toCed
F4GFZ, and exchanged AMD texting and received
calls fromThorsten
DK1ESD. They guided me through on how to do it
better."
Selcall
and ALE are slightly different formats that achieve a
similar purpose: call up a specific ham operator or group
of operators over the air using incidental tones. Both
selcall and ALE are common in the radio equipment of HF
commercial, governmental, or non-governmental
organizations (NGO) ; but, amateur radio equipment
manufacturers have traditionally been slow to advance
their technology in the area of selective calling
features. So, many of the operators working the HFIE-2018
event are utilizing commercial land mobile HF SSB radios
with built-in ALE and Selcall, that have been adapted for
ham radio service. Most are using computer-connected ham
transceivers, running program apps such as PC-ALE,
MARS-ALE, MULTIPSK, or HamRing.
Tei
JH1ESB's ALE-Selcall station with 2 Icom
IC-F8101 radios, in a synchronized system.
Antennas
for ALE and Selcall
While
any type of antenna system can be used for ALE and
Selcall, the techniques of HF scanning and frequency
agility often leads to a different approach from
traditional amateur radio single-band or slowly-tuned
antennas. Broadband antennas are the choice of many ALE
operators, especially the T2FD broadband folded dipole orBBTD
antenna, which can cover the whole HF spectrum
without needing a tuner. Autotuners are very popular for
mobile HF operation, as well as base stations. The
objective for the system is to constantly scan receive
channels at about 1 or 2 channels per second, and then be
able to respond to a call on any given HF frequency within
2 or 3 seconds.
Hams
have been using the HF Selcall standard, which is known as
CCIR493-4 Selective Calling, for about 25 years. It
consists of incidental tones in the audio range that can
selectively call, trigger an alarm tone, or open the
squelch. It was originally developed in the early 1970s by
CCIR (Consultative Committee on International Radio), a
forerunner group for ITU (International Telecommunication
Union) advisory and technical standards. This selcall
system became the basis of the Global Maritime Distress
and Safety System (MDSS DSC) which is now widely utilized
in ships and boats. The HFLINK information resource has
supported it since 2003 as implemented in4-digit
(Open Selcall) and 6-digit (United Nations Selcall)
format, and has published the open standards on the web.
CCIR493-4
Selcallis available in many
different types of equipment suitable for ham radio use.
Selcall is an embedded feature in HF land mobile radios
such as: Codan (all models), Barrett (all models), QMAC
HF-90, Vertex VX-1210, Icom IC-F series, and Micom Z. The
SC2 selcall microphone by Jenal can be adapted to most ham
radios to easily.
A
new computer app calledHamRing,
has just been released for Selective Calling, in an
experimental demo version, coinciding with the HFIE-2018.
Devin K6DRS developedHamRingin
collaboration with Bonnie KQ6XA.HamRingis
available for download athttp://hflink.com/hamring
HamRing
developer,Devin Butterfield K6DRSin
California, commented, "HamRing is focused on an intuitive
user interface and easy set-up. In a pinch, it even works
with good old acoustic coupling, where you hold the mic up
to the speaker. Many innovative features are planned
beyond the normal selcall."
Varuliantor
YD0OXHis Coordinator of a
large group of active ALE stations for the HF Emcomm ALE
net, which covers many islands of Indonesia.
Photo:
courtesy of Varuliantor Dear YD0OXH
About
ALE in Ham Radio
Ham
operators have been utilizing ALE in the Amateur Radio
Service for about 20 years, since the late 1990s. The ALE
standard was developed in the early 1980s in USA as
MIL-STD 188-141 / FED-1045, and is known internationally
as2G-ALE.
It grew out of an effort to improve interoperability of
selective calling radio equipment made by various
manufacturers. It became the de facto standard for
adaptive HF radio systems, which keep track of HF
propagation and available frequencies to improve the
dependability and speed of calling stations. An active
international net of ALE ham operators was formed in 2001
and has been in continuous 24/7/365 operation since
2007.
Steve
N2CKH,Developer of
PC-ALE, at his home station
PC-ALEis
a very popular computer program (Windows) among ham
operators that provides a world-class ALE controller when
combined with an amateur HF SSB transceiver. The scanning
capability and a wide array of advanced features found in
PC-ALE can basically turn a ham radio into an ALE radio
system. PC-ALE is available for free and was created byCharles
G4GUO, with new development and improvements
bySteve
N2CKH. TheMARS-ALEprogram
by Steve N2CKH, is also utilized by hams who areMARSmembers
and operate ALE on the MARS systems.
MULTIPSKbyPatrick
F6CTEis an advanced ham
computer program that also provides excellent ALE calling
operation and other functions.
This
year, Brian had some sage advice for some of the other
operators in the HFIE exercise: "So, just having an HF
station on-the-air, or even in a go-box, doesn't make you
part of an effective communications solution... You also
need to know how to get another station at the other end
set up and interfaced with the people on the other end
that need to communicate back to where you are. Only then
do you become an effective component in a disaster and
relief communications process."
Brian
WB6RQNwith the Dominica
AirliftAngels To Edenflights
brought relief supplies and communication after
hurricane Maria in 2017.
HFLINK
Recognizes Operators
High
regards, thanks, and recognition goes to the
operators of following stations, for their work in
providing real-time receiver reporting to the HFLINK. NET
system during HFIE-2018.
The
HFIE 2018 went from 12
to 22
October. For more information about upcoming events,
please check the HFLINK websites and forums.
Amateur
Radio Service operators in the event activated their
stations on the air using the same standards as
non-governmental (NGO) and government organizations
worldwide for interoperable HF communications. The focus
of operation during this exercise was ALE (Automatic Link
Establishment) and SELCALL (HF Selective Calling).
Ham
operators in the exercise were invited to participate at
any time during the 10 days of the free and open informal
event. Operators got real-world experience and become
proficient in HF Interoperability communications using the
following suggested methods:
Initiating and responding to ALE calls
Initiating and observing ALE soundings
Linking up with fellow operators for texting
Linking up for SSB voice QSOs
Sharing helpful information on setting up ALE
Initiating and responding to SELCALL calls
Sharing information on setting up SELCALL
Exchanging local status and infrastructure reports
There
are thousands of amateur radio operators worldwide with
ALE-capable and SELCALL-capable stations. All are invited
to discuss, learn, and ask questions using the HFN Comm
Centre chat room onHFLINK.NET.
The experience gained by operator participation in the
exercises can also be useful for HF Emergency/ Disaster
Relief communications (EMCOMM).
HFIE 2018 HF Interoperability Exercise
12~22 October
ALE and SELCALL
HFIE, the international ham radio
HF Interoperability Exercise is sponsored by HFLINK.
Amateur Radio Service operators in the event activate their
stations on the air using the same standards as
non-governmental (NGO) and government organizations
worldwide for interoperable HF communications. The focus of
operation during this exercise is ALE (Automatic Link
Establishment) and SELCALL (HF Selective Calling).
Ham operators are invited to participate at any time during
the 10 days of this free and open informal event. Operators
get real-world experience and become proficient in HF
Interoperability communications using the following
suggested methods:
Initiate and respond to ALE calls
Initiate and observe ALE soundings
Link up with fellow operators for texting
Link up for SSB voice QSOs
Share helpful information on setting up ALE
Initiate and respond to SELCALL calls
Share information on setting up SELCALL
Exchange local status and infrastructure reports
Join the growing thousands of amateur radio operators
worldwide with ALE-capable and SELCALL-capable stations.
Participants may discuss, learn, and ask questions using the
HFN Comm Centre chat room on HFLINK.NET. The experience
gained by operator participation in the exercise is also
useful for HF Emergency/ Disaster Relief communications
(EMCOMM).
HFIE 2018 SCHEDULE Start: 12 October 2018 at 0001 UTC
End: 22 October 2018 at 2359 UTC
HFIE was previously called
ALE On The Air Week (AOTAW)
ALE Operators
Support Dominica Airlift Humanitarian Relief Operations
2017
ALE Operators in
North and South America are mobilizing to provide HF support
for the Dominica Airlift - "Angels To Eden" flights. The
airlift in early October assists humanitarian relief in the
Caribbean island that was hit with the full force of
category-5 Hurricane Maria in late September. Several ALE HF
portable base stations are being set up at areas where all
the other land communications have failed. ALE Operators who
want to help with the airlift can check in at the HFLINK.NET
chat room.
Brian Lloyd WB6RQN Completes Historic
Earhart Flight with ALE HF Radio
Brian Lloyd WB6RQN Flying Round The World in
His Mooney M20K 231 Airplane Spirit Equipped with Micom 3 ALE HF Radio.
Texas, USA: On May 31, 2017, pilot and ham operator
Brian
Lloyd WB6RQN embarked to retrace the historic
worldwide equatorial flight route, commemorating 80 years since Amelia Earhart's famous attempt
at circumnavigating the world in 1937. He completed the
solo flight in August. Brian's aircraft is equipped with
HF Automatic Link Establishment, and is active on the ham
radio ALE channels during the flight. Ham operators
worldwide can connect directly with Brian WB6RQN/AM Air
Mobile on High Frequency SSB, ALE and AMD text messaging
during the flight. The 125 Watt radio system is equipped
with an under-fuselage HF antenna and SGC SG-237 antenna
tuning unit. See the WB6RQN
ham radio schedule.
Brian
Lloyd comments, "At this point the planning
shows that longest leg of the flight will be from Fiji,
across Howland Island (where Amelia and Fred disappeared),
and then on to Kauai, Hawaii. That leg is 2,788 nm
(3,208mi or 5,163 km) long. The flight time for that leg
will be about 15 hours." See Project
Amelia Earhart.
The BBTD Antenna
Broadband Butterfly Terminated Dipole: New Antenna Articles for 2017
The Broadband
Butterfly Terminated Dipole antenna (BBTD) was
invented by Bonnie Crystal (KQ6XA). It is a type of
traveling wave antenna, similar to a terminated folded
dipole antenna (T2FD or TFD). But, the BBTD antenna is
constructed of triangular or irregularly-shaped elements,
instead of narrow rectangular elements. The triangular
geometry has many structural and electrical advantages
over... read
more...
13
May 2017. The USA Armed Forces
Day Crossband Military/Amateur Radio Communications
Test, is an annual HF interoperability event. The
US Army, Air Force, Navy and Coast Guard sponsored the
annual military/amateur radio communications tests in
celebration of the 67th Anniversary of Armed Forces Day
(AFD). Ham operators participate using ALE, especially
onthe
USA 5 MHz ALE simplex frequency 5371.5 kHz USB. It
is on a common frequency that many hams already have
programmed for ham radio HFN and HFL ALE nets.
Upper Sideband (USB) is utilized on all frequencies for
transmit and receive. More
information, seeHFLINK.COM page
about AFD2016.
Solar Cycle Peaked Already.
Next Cycle Starts in 3 Years With Less Sunspots, Peaking
in 2022-2025
Solar Cycle 24 Was
In Its Last Peak in 2015
2015 - The solar cycle was on its second and strongest peak.
The levels of moderately high solar activity with occasional
solar flares were expected to continue through end of 2015
and then subside dramatically over the next 4 years. Then we
should see the solar minimum for 3 years. An upswing of the
next solar maximum, Cycle 25, is predicted to peak between
year 2022 and 2025, but be somewhat less potent than our
present cycle. The following chart shows our present
position in the cycles.
(Prediction Source: Bonnie Crystal KQ6XA, HFLINK)
US Ham Operators and Government Test HF
Radio Communications
Disaster
Communications Compatibility Exercise Uses Automatic Link
Establishment
Washington, DC, and San Francisco, CA – 27 March 2014 - US
Amateur Radio operators (ham operators) and Federal
Government radio stations engaged in a nationwide test of
their capability to communicate with each other by shortwave
radio, in case of an emergency or disaster. They
participated in a 12-day joint readiness exercise which ran
from 27 March through 7 April, covering all areas of USA,
using a digital High Frequency (HF) radio system known as
Automatic Link Establishment (ALE). This High Frequency
Interoperability Exercise 2014 (HFIE-2014) ran concurrent
with the federal National Exercise Program (NEP) 2014.
ALE is a standardized digital signaling protocol used by
each radio service, ham and government, to establish HF
communications between their own stations. For the first
time, the government regulatory agencies (FCC and NTIA) have
authorized these stations to communicate with each other
using ALE. HF radio enables long distance communication
independent of terrestrial communications infrastructure,
internet, or satellites.
To facilitate the communication testing, the Federal
Emergency Management Agency (FEMA) secured temporary
authority from the National Telecommunications and
Information Administration (NTIA) and the Federal
Communications Commission (FCC). Federal Government radio
stations and hams are allowed to communicate with each other
using ALE during the exercise. Under existing rules, hams
have secondary access to 5 HF radio channels on which
Government stations are the primary users.
HF radios used by Federal Government stations have the ALE
capability built into the hardware. Amateur Radio operators
have implemented the same ALE protocols using their personal
computers with ham radio equipment and software. The Special
Temporary Authority allows for on-the-air testing of
interoperability between the hardware and software-generated
ALE implementations.
Participation in the interoperability exercise was open to
all ALE-capable Federal Government radio stations and to all
ALE-capable US Amateur Radio stations. While five channels
are available if needed, the test plan called for using only
two of the channels in order to minimize impact on other
stations not participating in the exercise. Specifics of the
STA were as follows:
(1) Temporary
modification of the authority granted at NTIA Manual
section 7.3.8(4), which authorizes Federal Government
stations to communicate with stations in the Radio Amateur
Civil Emergency Service, to allow communications with any
Amateur Radio station utilizing Automatic Link
Establishment, limited to the five channels in the 5 MHz
band which are available to the Amateur Radio Service on a
secondary basis, for the period March 27th through April
7th 2014.
(2) Concurrent waiver by the FCC of that part of FCC rule
97.111(a)(4) which limits communications with US
Government stations to transmissions necessary to
providing communications in RACES, limited to the five
channels in the 5 MHz band which are available to the
Amateur Radio Service on a secondary basis, for the period
March 27th through April 7th 2014.
The HFIE-2014 is a semi-annual ham radio readiness exercise
coordinated by the HFLINK organization http://hflink.com and
the Global ALE High Frequency Network http://hflink.net
It is open to all ALE-capable ham radio stations. Technical
and operational guidelines for ham and federal government
stations are available at: http://hflink.net/hfie2014
National Exercise Program (NEP) 2014 is a complex emergency
preparedness exercise with activities sponsored by
government departments and agencies, designed to educate and
prepare the whole community for complex, large-scale
disasters and emergencies. As part of the National
Preparedness Goal (NPG), it enables a collaborative, whole
community approach to national preparedness that engages
individuals, families, communities, the private and
nonprofit sectors, faith-based organizations and all levels
of government.
Media and Technical Contact: Bonnie Crystal, KQ6XA,
HFIE-2014 Coordinator
Email: hfie2014@hflink.net
International ham radio HF
Interoperability Exercise sponsored by HFLINK
and HFN.
Ham operators were invited to participate at any time during
the 10 days of this free and open informal exercise. Operators
can look forward to certificates
and wallet cards showing they are qualified in ALE.
They will continue to keep track of each other on the air
and by using an inter-connected chat room with a map feature
that picks up their transmissions.
Non-governmental and government organizations worldwide use
ALE for HF interoperability communications. This
Interoperability Exercise covers standard ALE (Automatic
Link Establishment), NALE (Non-Automatic Link
Establishment), and SELCALL (HF Selective Calling).
Operators get real-world experience and become proficient in
HF Interoperability communications. They initiate and
respond to ALE calls, link up with fellow operators for text
or SSB voice QSOs on HF, and share helpful information about
setting up ALE stations. It's not a contest, and many just
do it for fun.
Join the thousands of amateur radio operators worldwide with
ALE-capable stations. Participants discuss, learn, and ask
questions using the HFN ALE
COMM CENTRE chat room.
HF Interoperability
Exercise 2014
2014 HF Interoperability Exercise
Starts:1200 UTC 27 March 2014
Ends: 2359 UTC 07 April 2014
The HFLINK 2013 Antenna Poll
Results are in...
The 5000+ member HFLINK forum was asked: "What
type of antennas do you use for ALE?"
Operators responded to the poll with many different types of
HF antennas. As the above chart shows, autotuners and
broadband antennas tend to be used most often by ALE
operators. Autotuners mounted at the antenna feedpoint (32%)
are deployed slightly more often than broadband antennas
(31%) or autotuners at the radio. The single most popular
type of antenna is the T2FD (14%). Click on the chart to
zoom in for a more detailed analysis of poll results for all
the popular ALE antenna types.
HF
Interoperability Exercise
Gobble Gobble:
The Sound Of ALE
If you tuned into
your shortwave radio in October 2013, you may have heard a gobble-gobble
noise. What may seem like a flock of wild turkeys were
actually the sounds of the HF
Interoperability Exercise, and it was in full swing.
It started Friday the 4th of October, and ran for 10 days.
Ham operators all over the world were on the air for this
international communications preparedness exercise, using
Automatic Link Establishment (ALE). The innovative ALE
system is a digital selective calling method, enabling radio
users to ring each other up on High Frequency shortwave
using their callsigns like a phone number. HFIE, as it is
known among hams, happens several times per year and is
sponsored by HFLINK.COM and the Global ALE
High Frequency Network (HFN) organization.
Kurt Stephens KJ4AYT, a radio operator in Florida, had this
to say: "I use ALE a lot, both in my professional career and
as a ham. I'm really excited to be participating in HFIE.
Within the first hour, I was able to easily get signals to
three different continents with my Micom 2 radio. I recently
designed a new antenna for my station and I'm checking the
performance of it in this exercise. I call it the WOLF
antenna. It has good broadband SWR on all the HF bands,
perfect for ALE. I look forward to making lots of new
contacts with it."
Another ham, John Lawson W4JML, commented, "I'm in Wyoming
and I need to use ALE with Army MARS, so I decided to get
some more experience with it during this exercise on the ham
bands. I downloaded the free
PCALE software and hooked the computer up to my Icom
IC-765, running into an 80m delta loop antenna. Amazingly,
within a few minutes after setting it up to scan, I made my
first ALE contact when Kurt KJ4AYT called me on 7 megahertz,
and did some texting. I'll be on this again tomorrow for
sure."
Over three thousand ALE stations have registered so far, and
many of them are on-the-air this week talking by single
sideband (SSB) analog voice or digital texting. Some use the
exercise to provide training or maintain their proficiency
in HF Interoperability; an important issue these days, due
to the new digital standards for governmental and
non-governmental organizations in emergency and disaster
communications.
The distinctive turkey gobble sounds of ALE can
usually be found on the following frequencies.
Over a Decade of ALE HFLINK
HF Interoperability
HFLINK
celebrated
13 years of ALE in 2014. The HFLINK forum has become a
gathering point for amateur radio operators and
professionals in HF. The organization was founded by Bonnie
Crystal KQ6XA, as a High Frequency Interoperability
international resource for ALE and Selective Calling. The
first large scale organized Ham Radio ALE nets began in late
2001, during the recovery from the 9-11 disasters. Since
then, HFLINK has grown to over 5500 members. Through
teamwork, frequency coordination, technical standards, and
protocol optimization, ALE has become a widely accepted
ham-friendly, interference-free system worldwide.
FCC
Changes 5MHz Ham Radio Rules, Adds Data Comms
In 2012, FCC adopted new rules for the 60 meter band.
How do these changes affect USA hams?
Under
the new rules, Ham Radio operators in USA are allowed to use
Data modes on 5 channels in the 5MHz band, with some
restrictions. The maximum power level is 100 Watts PEP with
reference to a dipole. One of the channels that previously
was prone to constant interference has been replaced with a
clearer frequency. For a more detailed information about
the changes, please see HFLINK
5MHz News.
Global
ALE High
Frequency Network Celebrates 7 Years of Continuous
24/7/365 All Band HF Digital Service in 2014
The
Global ALE High Frequency Network (HFN) set a new up-time
record by operating 100% continuously on all international
amateur radio shortwave bands simultaneously 24/7/365 for 7
years.
Relying on HF (High
Frequency) ionospheric communications, all radio stations
in this worldwide system scan the ham bands every 10
seconds, rapidly maintaining contact through short digital
bursts of signals using a system known as ALE (Automatic
Link Establishment). With about 4000 registered operators,
the HFN covers a vast area of the planet.
All ham operators
are welcome and invited to participate in the net on the
air at any hour of the day or night, for normal QSOs and
messages, soundings, or priority Emcomm use.
IARU
GlobalSET
EmComm Radio Events ALE operators
participate in Global Simulated Emergency Test
communications exercises sponsored by International
Amateur Radio Union (IARU)
GlobalSET
is the on-the-air international emcomm radio event sponsored
by IARU. The
objective is to promote readiness for international
emergency disaster relief communications. Operators
participate in the Global Simulated Emergency Test by
sending text messages to the central IARU GlobalSET
headquarters, relayed via amateur radio stations. Hams may
activate their ALE stations, start scanning and sounding
before the event, and send messages during the day of the
event. For more information,
please read the details on the HFlink forum. GlobalSET Objectives:
1. Increase the common interest in emergency communications.
2. Test how usable the IARU Emergency Center of Activity
frequencies are across ITU regions.
3. Create practices for international emergency
communication.
4. Practice the relaying of messages using all modes.
The
International Amateur Radio Union's Global Amateur Radio
Emergency Communications Conference GAREC-2007 was held in
Huntsville AL, USA, with international delegates from IARU
Region 1 and Region 2 attending. The focus of the GAREC
conference was: How the amateur radio service can apply
advanced technologies to emergency communications in the
service of early warning, emergency response and disaster
relief. The ALE
presentation at the conference included information
about how ALE can provide an interoperative method for all
emergency and disaster relief communicators to communicate
with each other. more...
A conference
report for HFLINK members is available on the HFLINK
forum.
BACKGROUND
ALE was originally an expensive system for government
services, but recent innovations in digital technology have
brought the cost way down. The first organized amateur radio ALE
nets began in 2001, corresponding with the release of the free
PC-ALE software controller for ham radios. Several years of
development by the 4600+ member HFLINK organization adapted ALE
to be a ham-friendly, interference-free system. In 2007, the
internet- connected HFN network
went into full scale 24-hour service. HFN rapidly expanded to
cover large areas of the earth, and it has become the prime
framework for ham radio operations using the global standard ALE
system. In keeping with its roots, ham radio ALE still maintains
compatibility and interoperability with goverment ALE radios,
many of which are also available now on the surplus market and
being used by hams. Nearly every major HF SSB radio manufacturer
in the world is now marketing an ALE radio.
Automatic Link
Establishment and Selective Calling, HF
Interoperability, Selcall,Nets, ALE, and individual
station direct HF calling. Real-time reporting of
who is on the air. Voluntary maidenhead grid geo-location. A global
network of ham stations.
A
team of ham radio operators is on the air, in a
global constellation of ALE and SELCALL stations.