HFLINK - ALE Ham Radio USA - FCC - HF Automatic Link Establishment HF ALE HF Network Ham Radio Amateur Radio HF Emergency Disaster Relief Communications.

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 development of 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 practice 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 data subbands. One of the aspects of operation using digital technology in Amateur Radio is navigating the complexities of the arcane, and sometimes contradictory maze of FCC rules regarding content, modes, bauds, emission types, and subbands. Currently, many countries of the world have easily understood bandwidth-based Amateur Radio rules where most of the protocol and features of ALE can be utilized freely on any frequency with any type of content at any moment. The USA Amateur Radio Service has been somewhat more limited in this respect, due to its more antiquatedcontent-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.

What subbands should be used with ALE for DATA content?
While 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 channel list 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 188-141B or 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 transmission 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 the number of state changes the transmitted signal makes per second. The ALE signal is 8FSK (8ary Frequency Shift Keyed). 8 discrete tone frequencies are 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 symbol represents three bits of data, resulting in an over-the-air data rate of 375 bits per second (375bps) using "125 baud".

Does the ALE modem signal bandwidth comply FCC rules?
Yes. The FCC does not currently specify an occupied bandwidth limitation for DATA emission, other than the stipulation 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 somewhat resistant to noise, QRM, passband tilt, group delay, and phase distortion. It is designed to be run through typical SSB transceivers (even with speech compressors) on transmit and various AGC characteristics on receive.

The ALE modem using MIL-STD 188-141B or FED-STD-1045 does not use excessive bandwidth to obtain sufficient signal 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 Amateur Radio Service. The ALE signal bandwidth is suitable for transmission via HF transceivers 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 keyed, the bandwidth spreads out slightly, to an occupied bandwidth (-23dBc) of 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
Currently, USA 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 demodulated 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 station initiates the calling, the 2nd station ACKs (acknowledges) the reception 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 exchange, there are parts of the ALE protocol that can include "incidental" types of very limited text/status sequences and Link Quality signals, AMDs, or MOTDs that are carried along incidentally embedded in the selective calling and alerting sequence.

The question then is:
"Where do we draw the line between Automatic Link Establishment for selective calling operation as a PHONE mode, and make the conceptual "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.

The complex language of FCC rules are attempts at drawing clear lines between what is allowed and not allowed, but technology often outpaces rules, or turns the clear lines fuzzy. If the "spirit of the rules" are to be our guide for clarification, once the selective call or ALE exchange happens, 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.

Limiting procedures for ALE operation as a Phone signal
When the ALE or Selcall system is 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 signals to set up a voice or image contact for QSO with other station(s).
5. Alerting another station to talk on voice.
6. Alerting another station to QSY.
7. Sending an alerting or selective calling signal to break the link.

ALE use when linked in the Phone SubBands
The ALE protocol and most ALE controllers, have features that provide an easy way for operators to make the fuzzy line 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 software 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 station(s). 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 exceptions to this are:
1. A selective call signal that alerts the other station 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 attempt to call yet another station to join the QSO.
3. A selective call that alerts another station to talk on voice or image.
4. The limited orderwire that gets a free ride as part of the selective calling and alerting signalling protocol sequence.
5. Some bands such as 160 meters which do not have phone subbands.

FCC Rules for ALE in the Phone Bands
Here are some excerpts of present Amateur Radio Service FCC rules permitting to the use of ALE and SELCALL for Selective Calling and Alerting in the PHONE sub-bands. Please note the last sentence in §97.3(c)(5) which is the definition of Phone mode. At the bottom are the URLs for §2.201 of FCC Rules which define emission type designators.

"§97.3 Definitions.
...[extraneous text deleted]
(c) The following terms are used in this Part to indicate emission types. Refer to §2.201 of the FCC Rules, Emission,
modulation and transmission characteristics, for information on emission type designators.
....[extraneous text deleted](5) 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 as 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 telegraphy practice interspersed with speech. Incidental tones for the purpose of selective calling or alerting or to control the level of a demodulated signal may also be considered phone."
[---emphasis added]

What About Sounding?
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:

1. Soundings enable ALE stations to meet station identification requirements while initiating or maintaining contact with other stations.
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 ham station.
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 other operator(s).
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