EME operations

Home Procedure by G3SEK

EME Operating Techniques (1988 ARRL HANDBOOK)

Unfortunately, there is no universal agreement as to procedures for all the bands, although there is similarity. Two-meter operators generally use the "T M O R " system, while those on 432 MHz use a similar system but applied at somewhat different levels of readability. The meanings and typical use of each part of the sequence are given in Tables 11 through 14.

At the moment, there is no uniform system in use for EME operation on all bands. The 432-MHz procedure is used on 432 MHz and above. It has also become the preferred system on 220 MHz, although the 144-MHz procedure is sometimes used on this band.

In the schedule sequence for both 144 and 432 MHz, the initial period starts on the hour, but because of the difference in sequence lengths for the two bands,schedules starting on the half hour will not be the same. On 2 meters, there are 15 sequence periods to the half hour, which make the period 0030 to 0032 an "even" sequence. This could make a difference, depending on which operator was assigned an "odd" or "even" sequence. Note that odd or even refers to the sequence number, not the minutes designated within that sequence.

On 432 MHz, there are 12 sequence periods to the half hour. The eastern-most station from the international date line usually calls first, and since two 2~2-minute periods fill a 5-minute space, it works out conveniently that the eastern (or first) station will call starting with every five minute mark, and start listening 2%-minutes later. Thus a schedule starting at 0030 would be an "odd" period, although operators on 432 MHz seldom label them as such. It is convenient for the operators simply to start with the eastern-most station calling on the hour or half hour, unless arranged otherwise.

Of course there is much room for change in these arrangements, but they do serve as vital guidelines for schedules. As signals become stronger, the rules can be relaxed to a degree, and after many contacts, stations can often ignore them completely, if the signals are strong enough.

Calls are often extremely difficult to hear in their entirety. A vital dot or dash can be missing, which can render a complex call unreadable. To copy both calls completely requires much patience and a good ear. Both calls must be copied, because even though most work is by timed schedules, there can be last-minute substitutions because of equipment trouble at one station, unexpected travel, changes in plans or the like, which make it impossible for the scheduled station to appear. Thus, rather than have one station spend the entire period listening, only to find that no one is there, a system of standby stations is becoming more popular. This is good, because nothing will demoralize a newcomer faster than several one-sided schedules.

An exchange of signal reports is a useful and required bit of information: useful because it helps in evaluating your station performance and the conditions at the time, required because it is a "non-prearranged" exchange, thereby requiring that you copy what was sent as part of the contact. Obviously, other things could be included in an "exchange of unknown information," and when conditions permit stronger signals, many operators do include names, elaborate on the signal reports, arrange next schedule times, and so on. Unfortunately, such exchanges are rare.

Confirmation is essential for completion of the exchange. There is no way that you can be sure that the other operator copies what you sent until you hear him say so. The final R or ROGER means that he has copied your information, and your two way contact is complete.

Sending speed is usually in the 10- to 13-WPM range, although it can be adjusted according to conditions and operator skill. Characters sent too slowly tend to become chopped up and confusing. High-speed CW is hard to copy at marginal signal levels for most amateurs, and the fading that is typical of an EME path can make it nearly impossible to decipher the content.


Other Modes: Only a few stations have the capability of sending (and receiving) signals of a strength sufficient to allow experimentation with other than CW. SSB contacts are now common. In general, only the stations with large antennas try the more difficult modes for EME work. Such installations are often "borrowed" from some research program for the amateur endeavors.


Frequencies: EME contacts are generally made randomly or by prearranged schedule. Many stations, especially those with marginal capability, prefer to set up a specific time and frequency in advance so that they will have a better chance of finding each other. The larger stations, especially on 144 and 432 MHz where there is a good amount of activity, often call CQ during evenings and weekends when the moon is at perigee and listen for random replies. Most of the work on 220, 12% and 2304 MHz, where activity is light, is done by schedule.

Most amateur EME work on 144 and 220 MHz takes place near the low edge the band. Activity is found 50 kHz or higher in the band during peak hours. Generally, random activity and CQ take place in the lower 10 kHz or so, and schedules are run higher in the band.

Formal schedules (that is, schedules ranged well in advance and published in "432 and Above EME Newsletter published by Al Katz, K2UYH) are run on 432.000, 432.025 and 432.030 MHz. Other are normally run on 432.035 and up to 432.070. For this band, the EME random calling frequency is 432.010 with random activity spread out between 432.005 and 432.020. Random SSB CQ calling is at 432.015. Terrestrial activity is centered on 432.100 and is by agreement, limited to 432.075 and up in North America.

Table 11 - Signal Reports Used on 144 MHz EME

T-- Signal just detectable

M-- Portions of call copied

O-- Complete call set has been received

R-- Both "O" report and call sets have been received

SK-- End of contact

[It seems that lately on 2 meters, most of the time only "O" is used]


Table 12 - Signal Reports Used on 432 MHz EME


T-- Portions of call copied

M-- Complete calls copied

O-- Good signal--solid copy (possibly enough for SSB work)

R-- Calls and reports copied

SK-- End of contact



Table 13 - 144-MHz Procedure -- 2-Minute Sequence

Period 1 minutes            30 seconds

1 Calls (W6XXX DE W1XXX)    Calls

2 W1XXX DE W6XXX              TTTT

3 W6XXX DE W1XXX             OOOO

4 RO RO RO RO                 DE WlXXX K

5 RRRRR                       DE W6XXX K

6 QRZ                         DE WlXXX K


Table 14 - 432-MHz Procedure –- 2 - Minute Sequence


Period 2 minutes       30 seconds



3 VE7BBG DE K2UYH        T T T T

4 K2UYH DE VE7BBG        M M M M

5 RM RM RM RM            DE K2UYH K

6 R R R R R                DE VE7BBG SK


[End of ARRL Handbook excerpt]

EME RST Signal Report

Readability: 1 - Unreadable (copy < 5%)

             2 - barely readable (5% < copy <25%)

             3 - readable with considerable difficulty (25% < copy <75%)

             4 - readable with practically no difficulty (75% < copy <95%)

             5 - perfectly readable (copy > 95%)

Strength: 1 - barely perceptible

          2 - very weak

          3 - weak

          4 - fair

          5 - good

          6 - very good


4.14 Improving 70cm EME Operating procedure, Joe Reisert - WIJR – February 1982

70 CM EME has now matured and many QSOs are somewhat routine. This wasn't true 10 years ago. The principal reasons are improvement in antennas, power amplifiers, receivers and operating procedures. We have now developed antennas that have high gain and some are quite large! 1000 W Power Amplifiers using various tubes and circuitry are available. Preamplifiers using relatively inexpensive GaAsFETs are almost as quiet as the sky behind our antennas. However, some of our operating procedures could still use improvements to further increase our QSO rates.

Let's talk a moment on operating procedures. A valid QSO consists of an exchange of calls, signal reports and R's. On HF the RST System has long been used as the signal report. Signals can be quite strong and it usually isn't difficult to copy a 229 report if the QRM doesn't get you. However, on EME the signals are seldom strong (except from the very large stations). Add to this the non-reciprocity Faraday rotation and libration fading and you have a situation were everything must be just right for a QSO. Realizing this the TMO code (in its various forms) was developed in the 60's by EME operators to replace the RST type of report in the exchange because the longer DAHs are much easier to read than the DITS in the normal RST report.

So you say, "Why are you bothering me with all this information that I already know?" The reason is that if signals are weak (a common situation for those who can't rotate polarity) the exchange can be quite difficult unless you use a procedure that is understood by both operators. Timing is just as important as to what we are attempting to exchange for information. If we improve timing, send only information that is necessary and send it in a format expected by the receiving station, we can use the human brain as a "matched filter" and thereby improve copy as well as QSOs without increasing power or antenna gain! Let me give a few examples. It is common procedure on 70 cm to send only signal reports in the last 30 seconds of the 2 1/2 minute transmission period. However, I consistently hear stations sending call sets in this time frame and I would have known that he was not hearing me at all instead of thinking I may be getting a signal report. If you are not sending reports leave this time period blank.

An important procedure is the way we send call sets. Again we can improve our through put by standardization. I recommend that we send only 1 x 1 call sets as follows: DL9KR de WlJR DL9KR de WlJR etc. The "de" tells you the order (and helps ID by others listening in) and breaks up the call signs in an orderly manner. Sending 2 x 2, 3 x 3 call sets etc. is confusing and fading may cause you to receive only one call but not the other. Next is the use of RST reports. They are fine but only if signals are "0" copy. Reserve any RST reports until you have received an "O" report especially on initial contacts. Another poor procedure I have noticed is reporting. When you are sending MR, OR or R, send them at least 1 to 2 minutes, not just in the last 30 seconds. If you are sending these reports you know the other station already has call sets so a few 1 x 1 call sets at the beginning (mainly for identification) is all that is needed. Give the other station all the reporting help you can.

To sum this all up, we can improve our QSO rate if we standardize our procedures as follows: Never send in the last 30 seconds of your time block unless you are sending signal reports or "R." Use only 1 x 1 call sets. Send RST type reports only after you are sure you are "O" copy by the other station. Send MR, OR or R for longer periods of time (greater than 30 seconds). I have prepared a handout sheet on the 70 cm QSO procedure and will be happy to send it upon receipt of an SASE. I hope this write-up will improve operating techniques as well as increase your number of QSOs. Any Comments?


4.16 432/1296 MHz EME Operating Procedure Allen Katz K2UYH - October 1982


4.16.1 Introduction

EME signals tend to be weak and relatively consistent, but with a short term fading which can turn a dah into a dit or even a pair of dits. It is this mushy signal quality due to libration fading, rather than the low signal level, which makes EME communications difficult. Also signal paths are often non-reciprocal, due to polarization rotation, allowing excellent reception in one direction. but none in the other direction.

Because of these unique EME signal characteristics, operating procedures, different from those used for other forms of VHF propagation, have been developed. Unfortunately no single EME operating system has been agreed upon for all bands. The system below has been adopted for use on the 432/1296 bands. This system is designed to provide a minimum of feedback between transmitting and receiving stations and still meet the minimum requirement for a QSO as defined by the ARRL: Exchange of calls, some other piece of unknown information - usually signal report - and confirmation of information reception.


4.16.2 Procedure

Schedule periods are broken up into 2.5 minute transmission segments with the station most west of the international date Line usually transmitting first. The 2.5 minutes are further broken down into two parts: The first 2 minutes (part A) and final 30 seconds (part B). Period B is reserved exclusively for the transmission of signal reports except during the initial period.

During the initial transmission period, calls are sent repeatedly for the entire 2.5 minute sequence. Procedure for subsequent transmission periods depend on what has been previously copied and can be classified as follows:

1. Copied nothing previously: Period A - transmit calls repeatedly. Period B - transmit nothing.

2. Copied signals but not full calls or reports: Period A - transmit calls repeatedly. Period B: transmit T.

3. Copied full calls but no reports (or just T report): Period A - transmit calls repeatedly Period B - transmit appropriate signal report( M or O ). T indicates insufficient signal quality for reception of calls. M indicates signal quality just adequate for reception of full calls (never sent unless full calls have been received). 0 indicates better than marginal copy (also indicates more consistent copy). RST reports may also be used, but they are not recommended for use on initial QSOs or when there is any question that the other station is copying.

4. Copied T reports and only part of calls: Same procedure as 2.

5. Copied reports of M or better but only parts of calls: Transmit Ts for complete 2.5 minute period.

6. Copied full calls and reports of M or better: 'transmit MR or OR as appropriate for the complete 2.5 minute period.

7. Copied reports and R (assuming previous reception of calls): transmit R's (and 73'e) for complete 2.5 minute period.


Figure 4-10: A sample EME QSO

Received before: Period A: (2 min)     Period B: (30 sec)

Initial period   VE7BBG de K2UYH         VE7BBG de K2UYH

Nothing heard    K2UYH de VE7BBG         Nothing

Signal heard     VE7BBG de K2UYH         T T T T.....

Nothing heard    K2UYH de VE7BBG         Nothing

Complete calls   VE7BBG de KZDYH       M M M M.....

Calls & report   MR MR MR MR MR..      MR MR

Report R's       R R R 73 73 ...         R R R

R' s             R R R 73 73 ...       73 73