How Important are Convenient Operating Times?

Presented by Ian White, G3SEK
at 1996 International EME Conference.

Convenient operating times are becoming more of a problem when choosing sked weekends. It is especially difficult to choose weekends that will encourage intercontinental QSOs across east-west time differences. Eu-JA is 7-9 hours, Eu-W is 5-11 hours, and W-JA is 7-10 hours.

It would be very convenient to have sked weekend when the moon is up in the daytime or evening, so that nobody has to get up early or stay up late. Unfortunately when the moon is up all day there will be a strong risk of sun noise, a disturbed ionosphere and generally poor conditions.

This table expands the short format of the Lunar Weekend Calendar, and indicates typical operating times to catch the whole E-W windows on the weekends labeled Night, Day(AM) and Day(PM) in the Calendar. Note that there can be several hours variation according to latitude, summer/winter and lunar declination – the table is just to help you to think about the convenience implications.

SUN OFFSET (deg) Comments in Calendar Times of day for JA-Eu, Eu-W, W-JA windows in Calendar ( The station who has the moon earlier is #1 )
-180 Night #1 is up all night. #2 operates in evening.
-120 Night #1 is up all night. #2 stays up late.
-60 Day(AM) #1 operates in morning. #2 gets up extremely early.
-30 through +30 Sun noise #1 operates in afternoon. #2 operates in morning. Conditions will probably be poor.
+60 Day(PM) #1 operates in afternoon/evening. #2 operates mid-day.
+120 Night #1 stays up late. #2 operates in afternoon/evening.
+180 Night Same as -180


There are also other considerations in choosing sked weekends. Convenient operating times are just one of several factors we need to balance:

Apogee/perigee · Declination (further north means more moon time - much more for some people) · Sky noise temperature - Proximity of sun - Stellar background noise · Time of day - Convenience - Effect on conditions (night usually better than day).

All these factors are locked together by the moon’s motion, so we have to choose the weekends that give the best overall combination.

Best for what? Years ago, it was always ‘best for signal strength’, i.e. close to perigee. Then sky noise temperature became important. Now that most stations have some reserves of path loss performance, the most important objective is to MAXIMIZE EME ACTIVITY.

But this is still a combination of several factors. Time of day is important, but so are the all the factors affecting signal/noise ratio. It isn’t a “convenient” sked weekend if every QSO is a struggle against poor conditions. If we are trying to minimize the solar disturbance, the best time of year is in the winter when the days are short – we all know that. Because people stay up in the evening, after sunset, the most convenient E-W operating times tend to be on weekends when the Sun Offset is positive (in the lower half of the table on the previous page).


1. We need to choose sked weekends with the aim of maximizing activity.

2. Convenient operating times are important, but that can never be the only criterion.

3. The most convenient E-W operating times tend to be when the Sun Offset is positive, in the Day(PM) and early Night zones.

4. To get the optimum conditions for E-W intercontinental contacts, somebody needs to get up early and/or stay up late.

Most important of all -

5. If the other guy is staying up late, getting up early or even pulling an all-nighter in order to make QSOs with you, then YOU NEED TO BE THERE !


That’s the end of the analysis. Now we come to the judgement calls.

In the early months of 1997 the most convenient weekends are also the weekends of highest declination (18/19 Jan and every 4 weeks after that). Unfortunately these are also the weekends of highest sky noise; 2m operators might go one weekend later, but maybe we can live with the sky noise on 432MHz and above, for the sake of hopefully creating more E-W activity.

The 144/1296MHz part of the Eu/DUBUS Contest in March would have lower sky noise temperatures on the 22/23rd, a week later than the regular sequence; but the declination is low and it’s also apogee, so it may be better to stick to the regular sequence and go for March 15/16th. For the 432MHz and microwave part, the regular sequence looks best: April 12/13th. The regular sequence carries us through 10/11th May, but June, July and August will be difficult because sun noise (new moon) always forces a mid-summer jump to a different weekend.

September 27/28th gives more convenient operating hours than the 20/21st, but after that the declination on that weekend of the month is creeping lower towards the end of the year. October and November are the ARRL Contest months, so let’s forget about convenient operating hours and just go for it! The best weekends for 432MHz and above look like 18/19th October and 15/16th November, but the sky noise might be high for 2m operators; go one week later as a fallback. For December, the 13/14th weekend looks best – but it’ll be another all-nighter if you want to pass your holiday greetings to those guys a long way west.

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