Guide for USA operators using ALE
under FCC Rules for Amateur Radio Service
This information has been prepared to help answer some of the
questions that USA ham radio ALE operators may have about ALE regarding
FCC Amateur Radio Service rules and regulations, and to help guide the ALE operator in maintaining full compliance. Ham radio
operators in USA have been using ALE in an organized
way on HF for domestic and international communications for at
least 7 years. Prior to that, most ALE use in ham radio was
unorganized, somewhat more sparse, and used randomly chosen frequencies. The
ham-friendly ALE standards and coordinated frequencies has not
only ensured that hams using ALE comply with FCC rules (as well as
other national rules or ITU region IARU bandplans); it has enabled
ham radio ALE operations to be in harmony with good amateur radio
and band use patterns, while providing interoperability and
emergency/disaster relief communications
service without interference problems or complaints for many years.
Hams are widely encouraged to use common voluntary ALE standards,
and the majority of hams on the air with ALE today are using them.
ALE compliance with FCC's Content-Based rules
USA hams can use ALE's Selective
Calling and Alerting features in the phone subbands,
and all of the features of ALE in the
One of the aspects of operation using digital technology in Amateur Radio
is navigating the complexities of the arcane, and sometimes contradictory maze of
rules regarding content, modes, bauds, emission types, and subbands. Currently, many
of the world have easily understood bandwidth-based Amateur
Radio rules where most of the protocol and features of ALE can be
freely on any frequency with any type of content at any moment. The USA Amateur Radio Service has been somewhat more limited in
respect, due to its more antiquated content-based
rules. Thus it is important for USA hams using ALE to be aware of the
type of content they are transmitting (voice, data, image, or text) in
order to comply with these content-based rules.
be used with ALE for DATA content?
ALE is most widely known as a selective calling system and a way of
intitiating and maintaining communications on HF, the ALE standard also
includes the ability to send/receive short text or data using the same
"ALE modem". The ALE modem uses an 8FSK signal, and it may be used
within FCC rules to transmit anywhere in the RTTY/DATA sub-bands when the content of the transmission is data or text messaging.
Also, within the RTTY/DATA segment,
are sub-bands for automatically controlled data stations. An ALE "Pilot Channel"
frequency exists within the automatic sub-band of each HF ham band. The ALE
includes these as Pilot Channels, and the repetitive sounding
(station ID) activity for
hams usually occurs on these Pilot Channels. The main reason for using
the automatically controlled data station subbands for most repetitive
sounding is because these band segments traditionally have stations
with similar signals and fast time-sharing methods as ALE, and thus ALE
operation fits well in these segments. A secondary reason is to enable
easy interoperation with automatically controlled data stations that
are using ALE. Additional frequencies for data are available in the ham
radio ALE channel list for texting, keyboarding,
and digital messaging. It is important that operators follow the
guidelines for use and to avoid interference. If one ALE channel is
busy, operators can usually find a clear spot on one of the other
channels to communicate by keyboarding or data transfer. Keep in mind
that although the ALE "channels" have existed for a long time and are
widely recognized by ham operators worldwide, there is no special
"ownership" of any particular frequency on the ham bands or right to
use it more than any other, and that courtesy and cooperation is the
cardinal rule that we should all operate by.
Does ALE modem comply with the "300 baud rule" for Data?
Yes. The ALE (MIL-STD
FED-STD-1045) signal is transmitted at
125 symbols per second. It complies with FCC
Rules for use in the Amateur Radio
Service for DATA MODE
on HF in the DATA sub-bands. Current FCC Rules in USA allow DATA modes up to 300 baud (300 symbols per second) in HF data subbands. Symbol rate (baud) is
number of state changes the transmitted
makes per second.
signal is 8FSK (8ary Frequency Shift Keyed). 8 discrete tone frequencies
spaced 250 Hz apart from 750 Hz to 2500 Hz at audio baseband. A single
tone is being transmitted at any given instant on any one of these 8
frequencies. No more than one tone is transmitted at a time. Each
represents three bits of data, resulting in an over-the-air data rate
375 bits per second (375bps) using "125 baud".
Does the ALE modem signal bandwidth comply FCC rules?
FCC does not
an occupied bandwidth limitation for DATA emission, other than the
that bandwidths must not be excessive for the data rate used. In this
case, the bandwidth of the ALE modem is not excessive, especially since
the objective of the signal is to provide
a robust, fast selective calling signal, enable many stations to share
the same frequency with time division intervals, and provide some
limited but fast texting or data transfer capability. The design
of the 8FSK signal enables economical decoders and encoders that can
work with almost any transceiver. The signal is
to noise, QRM, passband tilt, group delay, and phase distortion. It is
designed to be run through typical SSB transceivers (even with speech
and various AGC characteristics on receive.
ALE modem using
or FED-STD-1045 does not use excessive bandwidth to obtain sufficient
quality bit error rates to establish linking through difficult HF noise
conditions while stations are rapidly scanning a large number of channels.
The bandwidth is similar to PACTOR, SSB voice, SSTV, MT63, and many of the other common digital and analog waveforms in current
use in the
Radio Service. The ALE signal bandwidth is suitable for transmission via HF
through generic SSB audio/RF chains with an IF bandwidth of about 2.5
kHz. The 8aryFSK tones take up about 1750 Hz, and when the FSK is
the bandwidth spreads out slightly, to an occupied bandwidth (-23dBc)
approximately 2kHz. In practice, for demodulating, amateurs have
been able to use receive IF filters as narrow as about 1800 Hz with the
passband centered at 1625 Hz. Successful ALE operation requires
accurately tuned transceivers, and thus encourages operators to
maintain high standards for equipment calibration.
ALE use in the Phone Bands
Amateur Radio Service
operators have been utilizing ALE in the "HF phone bands" for many years without problems. ALE transmissions
in the phone bands comply with FCC rules: "Incidental tones for the purpose
of selective calling or alerting or to control the level of a
signal may also be considered phone."
ALE controller units
use very brief handshake
signals to make selective calls which set up communication links between stations... The operator of the 1st
initiates the calling, the 2nd station ACKs (acknowledges) the
of the call and alerts the operator, and the 1st station ACKs the 2nd station's ACK... in other
words, it is a 3-way exchange of selective calling and alerting signalling to set up the voice or image communication
to be in a linked status. Within this 3-way linking signal
there are parts of the ALE protocol that can include "incidental" types
of very limited text/status sequences and Link Quality signals, AMDs,
MOTDs that are carried along incidentally embedded in the selective calling and alerting sequence.
The question then is:
"Where do we draw the
Automatic Link Establishment for selective calling operation as a PHONE mode, and make the
"content-based rule" jump that the ALE modem signal would be considered a DATA transmission under the FCC rules?"
The simple answer is:
If the content of the ALE
modem signal contains an exchange of DATA content or text messaging,
then we need to use the DATA subbands. If we are just using it to
selectively call operators or alert them for a voice or image QSO, we
can do that in the Phone subbands.
of FCC rules
are attempts at drawing clear lines between what is allowed and not
but technology often outpaces rules, or turns the clear lines fuzzy. If
the "spirit of
rules" are to be our guide for clarification, once the selective call
or ALE exchange
and the LINKED status is established, the operators should cease the
transmissions of the ALE selcall encoder/decoder and should engage in
the voice or image QSO.
for ALE operation as a Phone signal
When the ALE or Selcall
used as a "PHONE" emission under the selective calling FCC rules, (in the "phone bands"),
operators need to limit the transmissions to:
1. ANYCALLS or NETCALLS
(the ALE selective calling
equivalent of a group CQ with a forced answer, for calling up a group of multiple stations simultaneously)
2. ALLCALLS with voice (the ALE
selective calling and alerting equivalent
of a QST)
3. INDIVIDUAL CALLS (ALE
direct selective call to link and alert another station)
4. Selective calling
set up a voice or image contact for QSO with other station(s).
5. Alerting another
station to talk
6. Alerting another
station to QSY.
7. Sending an alerting
calling signal to break the link.
ALE use when linked
in the Phone
The ALE protocol
and most ALE controllers, have features that provide an easy way for operators to make the fuzzy
of rules interpretation between PHONE and DATA a little clearer! In the ALE protocol, there is
a point during the "handshake" between two stations when the ALE
or the ALE controller tells the user that the station is LINKED.
Being linked, It means that you have succeeded with Selective Calling and/or alerting of the other
We can use this LINKED status indicator as a dividing line between what
the FCC defines as PHONE and DATA operation. If we use the AMD or data
modem after the indicator says we are LINKED, we are probably stepping
out of the PHONE mode and into DATA mode, and thus should continue the QSO with text or data only in the DATA subbands.
The possible allowable
to this are:
1. A selective call signal that alerts the
to start re-scanning (or QSY) because you are going to try another selective call for it on another channel.
2. A selective call made while already in a link with one station to
call yet another station to join the QSO.
3. A selective call that alerts
to talk on voice or image.
4. The limited
that gets a free ride as part of the selective calling and alerting
signalling protocol sequence.
5. Some bands such as
which do not have phone subbands.
Rules for ALE
in the Phone Bands
Here are some excerpts
Amateur Radio Service FCC rules permitting to the use of ALE and
for Selective Calling and Alerting in the PHONE sub-bands.
note the last sentence in
§97.3(c)(5) which is the definition
of Phone mode. At the bottom are the URLs for
of FCC Rules which define emission type designators.
(c) The following terms
in this Part to indicate emission types. Refer to §2.201 of the
for information on emission type designators.
Phone. Speech and other sound emissions havingdesignators with A, C, D,
F, G, H, J or R as the firstsymbol; 1, 2 or 3 as the second symbol; E
the thirdsymbol. Also speech emissions having B as the first symbol; 7,
8 or 9 as the second symbol; E as the third symbol. MCW for the purpose
of performing the station identification procedure, or for providing
practice interspersed with speech.
Incidental tones for the purpose
of selective calling or alerting or to control the level of a
signal may also be considered phone."
What About Sounding?
is ALE jargon for "Station ID" and it is simply a 10
second transmission of the station ID (your callsign). In ALE, the
interesting thing is that a simple station ID sounding transmission can
be used in many different ways by the station receiving it or sending
it, and for many different purposes or intentions. Thus, depending upon
how the sounding is used at any particular time, it complies with
various aspects of FCC rules. Here are some of the purposes and ways
that sounding is used as part of ham radio ALE 2-way communications:
Soundings enable ALE stations to meet station identification
requirements while initiating or maintaining contact with other
2. In ham-friendly ALE, a sounding is usually transmitted every hour or
so, usually in the HF automatic sub-bands, by ALE operators who are
in the process of maintaining intermittant or ongoing communications
with each other as part of
a network of stations, or individually from one ham station to another
4. Soundings are also brief transmissions utilized for the purpose of
establishing 2-way communications between ham radio ALE operators, and
are necessary for Automatic Link Establishment to function efficiently.
5. A sounding can indicate that the sending station is now ready to
receive a call on this frequency, and the operator desires to be called
back by other operator(s). In this case, the sounding can serve as an invitation for other stations to communicate or continue communications. Soundings are thus similar to the traditional ham radio CQ, for initiating communications.
6. Sounding is different from an ALE Selective Call, Group Call, or
NETCALL, in that a sounding does not force all other stations' ALE
controllers to respond. Instead, sounding invites a manual reply or
manual call to link up with another station as needed or desired by the
7. Soundings are initiated by the
operator while their station is on the air, as needed, in the process of using
ALE efficiently for selective calling or alerting.
8. Soundings enable stations to tune accurately to the same frequency for communications.
9. Soundings alert other ALE stations that your station is on the air,
and which frequency(s) you are listening and now ready for replies on,
or available to be selectively called or alerted on.
10. Sounding can be manually sent at the push of a button, or programmed by the operator for repetitive intervals.
11. A sounding can also be sent in response to selective calling signals.
12. Ham radio ALE operators normally use channel-occupancy and
collision detection checking prior to transmitting each sounding, so as
not to interfere with other ongoing communications. The occupancy
checking utilizes the ALE receiver to detect signal activity.
13. The ALE controller used by the operator of the transceiver of each
ham station with ALE is a 2-way communication device that receives
other ALE signals; it is constantly "listening" for replies and calls,
as well as transmitting occasional brief sounding transmissions.
14. Another intent of ALE with sounding is to establish a 2-way communications link on the best frequency for any given moment.
15. Sounding when used at the end of a QSO, can signal the end of that
sequence of communications, and alert the other station's ALE
controller that it is OK to scan again or look for another selective
call on another frequency. More information about soundings.
Manual, Automatic or Remote Control of a Station:
FCC Rules §97.109 Station control