By Gary Agranat, with Myron Babcock and Glenn Davis.
On Saturday October 10, 2020 we succeeded in making our first Earth-Moon-Earth (EME) Moon Bounce communications. We succeeded at our first attempt. This accomplishment was several years in the making, thanks to the work of many members, past and present.
We did this participating in the annual ARRL EME contest held on the weekend of October 10-11, 2020 GMT. (That’s Friday 6 pm to Sunday 6 pm local time.) The frequencies available for this contest were in the ham radio bands from 50 to 1296 MHz. We used our 60-foot dish antenna at Haswell, CO, with a 1296 MHz feed with dual circular polarization, installed 2 weekends earlier.
EME Moon Bounce communications is directing a signal to the Moon. The Moon’s surface simply reflects the signal back to Earth. If the Moon is above your horizon, if you have suitable equipment, and if you know enough about what to do, it would be possible for you to receive the signal and communicate back. You could communicate to your neighbor or across continents. The signals, however, are extremely weak, having to travel back and forth the Earth-Moon distance, over 238,000 miles. EME generally requires efficient directional antennas to sufficiently increase the signal gain. Amplifiers can be used too. And the antennas have to point to the Moon. Also, radio signals sent through the ionosphere experience a rotation in their polarization. And there is some effective rotation from other causes, including from the changes in orientation from the Moon and from operating on different points of the Earth’s globe. Our solution is to circularly polarize our signals. And also, there is a Doppler shift between transmitted and received signal, mostly due to the Earth’s rotation, causing a difference in velocity between the Moon and our location on Earth. All of these are challenges to deal with.
Our team for the EME operation were Ray Uberecken AA0L, Myron Babcock KL7YY, Gary Agranat WA2JQZ, and Glenn Davis. Bill Miller KC0FHN also came on Saturday morning.
The team arrived Friday evening October 9, while we still had daylight, to set up and test. Testing included making pre-arranged tropospheric scatter contacts, which were successful. We also attempted to complete set-up of a Hughes Internet antenna, to give us Internet access, but that was not successful. We instead sometimes connected to the Internet using cellphones. Although the contest began at 6 PM local time, we had to wait for the moon to rise above the horizon. Moonrise for us was at about 11:30 PM local time, and the Moon was above our horizon until about 2 PM local time the next day Saturday. We chose to stay for just this one Moon pass, and not continue through Sunday, in order to not knock ourselves out on this first attempt.
After we completed our testing, we relaxed until we were ready to start. Looking outside, we had an exceptionally deep starry sky. We could see the Milky Way clearly arching overhead through Cygnus. Jupiter and Saturn were bright to the south, and Mars was very bright, rising in the east. Glenn Davis experimented with his camera and took some nice time exposure photos with the dish antenna, the stars, and the Milky Way.
I (Gary) meanwhile got some rest. This enabled the others to get some rest later in the morning while I continued.
Myron KL7YY wrote and emailed an update about our operations to the DSES membership on Saturday morning at around 4 AM. It provides a good narrative of how we were doing until that point, and his update follows next:
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Summary of DSES first attempt at EME, Earth Moon Earth, contacts using the 60 foot dish:
On Friday evening, October 9 we started with a few nearby Tropospheric Scatter contacts around 7 PM with DSES member KL7IZW, Steve in Monument, CO, and W6OAL Dave in Parker. Around 9 PM we talked to N0YK in Scott City KS, These contacts ranged from 110 to 130 miles and confirmed that our system was working.
When the moon came over the horizon at midnight we tried to listen to the ON0EME moon beacon in Belgium but couldn’t hear it. About 45 minutes after moon rise we started to hear JT-65 digital signals. 10-15 minutes we started to hear CW signals. Glenn Davis made a few corrections to the tracking program and signals increased in strength. At times it sounded like a 20 meter CW contest pileup with all the loud signals bouncing off the moon all across 100 KHz of band (1296.0 to 1296.1 MHz). After about 90 minutes without hearing our own signal we rechecked the power to the amplifier at the feed horn and everything appeared to be normal. A few moments later we finally heard our own signal 2.5 seconds later on CW off the moon and the Belgium Moon Beacon. I made several calls on SSB and heard our echo really loud. We went back to CW and Gary proceeded to start making CW contacts. The first almost contact, a German station, abruptly dropped out so no official contact was completed. Our first official station worked on CW was with OH2DG in Finland. England was next followed by Italy, Poland, Denmark, Sweden and with DSES member Skip Macaulay, VE6BGT, in Alberta Canada.. Also made our first voice SSB contact with him as well. Seems that with every new contact we make it is with a new European country. In order to correct for Doppler shift and with no RIT we are changing VFO’s from Receive to Transmit by several KHz or more. Lots of CW signals being heard and we still have 12 more hours of moon to bounce signals off of… We are hearing our own echo and we have lots of hours to go. We plan on Digital mode later in the day but for now there are more than enough signals to hear on CW.
Our Moon bounce station consist of an older Yaesu FT-736R with 10 watts feeding almost 180 feet of half inch hardline into a 200 watt amplifier at the antenna feed horn. The receiver pre amplifier is a 30+db gain with a noise figure of minus .35. Our Effective Radiated Power (ERP) is over 6 million watts.
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We operated with our club call sign K0PRT.
A short video of Myron KL7YY calling CQ. You can hear the echo of his signal coming back from the Moon a couple of seconds later. (Video length 35 seconds)
Because the signals are extremely weak, and there can be fading, there is a standard protocol for exchanging messages for EME contacts. This is intended to ensure as much of the message as possible can be copied and acknowledged on both sides. The basic format is simple, and one repeats a lot. One first exchanges call signs, then the signal reports, and then finally if that worked, an acknowledgement all that was copied correctly. If one only completes part of the contact, one should still log that, as that is an accomplishment. If using Morse Code, the standard is to send at 15 words per minute, but spacing out the characters longer than usual. The faster sending and spacing is to help one copy complete characters if there is fading. If one misses a character, one still has a high chance to get the character with the many repeats.
In order to have the proper frequency offset for the Doppler shift, we referenced the WSJT 10.0 software, at the suggestion of Steve KL7IZW. The software has an astronomical data section that calculates and displays the frequency offset. The higher the frequency, the more significant the offset. At 1296 MHz we had a difference of as much as 3 KHz between transmit and receive frequencies. The software also displays other useful data like local Moon rise and set times (based on Grid Square location).
The WSJT 10.0 software also can be used for JT65C digital EME communication. However, we didn’t figure out how to configure that in time with our setup, and so we didn’t do any digital contacts this time. We could tell we were hearing JT65 signals. They were present from 1296.05 to 1296.1 MHz, and we almost always could hear those signals while the Moon was up.
Glenn stayed up until about 3 AM, when we were sure our antenna azimuth alignment was correct and would continue to point accurately to the Moon. His work was invaluable in troubleshooting the azimuth offset, which turned out to be about 1.5 degrees, and honing in on the Moon once we heard CW signals.
Since the Moon rises in the east, our signal paths at first are to the east. That is to Europe and the North American east coast. As Myron mentions, once we started receiving the signals, we were hearing many European stations, and we were busy. Through the morning we made 14 contacts to Europe, to 8 European countries. We also made the contact to our DSES member Skip Macaulay VE6BGT in Alberta, Canada, on CW and then phone. W4OP in North Carolina, hearing us on SSB, then gave us a call on SSB too.
Ray AAOL brought a CW keyer that can send Morse Code with either a keyer paddle or a keyboard. It can store pre-programmed messages, like a CQ call. I (Gary) decided to use the keyer paddle, as that gave me more flexibility — I could quickly adjust for conditions — and I felt more comfortable as I am used to the key. Meanwhile, it seemed to me also that some of the CW contacts we made used software to send their messages. Those didn’t have good spacing between words or call signs. And that made copying slightly more challenging. A keyboard though can enable any of us to send, even if we don’t have practice sending Morse Code. Most of the contacts we made were with CW Morse Code.
At around 6 AM, when the Moon was high enough so that we no longer had a path to Europe, we took a break for breakfast and to rest.
In earlier discussions we thought we might have many more contacts across the Pacific and to the North American west coast, when the Moon was sufficiently to the west. But it turned out we had very few contacts that way. We made just two contacts to Japan. Our first was at about 9 AM local time, to JH1KRC. Our second was three hours later to JA6AHB. Instead we made a few more contacts to the US, a few to Canada, and one to Mexico. These other stations we heard were searching around too. That led me to believe that if there were any other signals out there, we likely would have heard them.
Our contacts included:
- K2YUH Alan Katz in NJ, who runs the 432 MHz and Above newsletter: http://www.nitehawk.com/rasmit/em70cm.html
- W5LUA Albert Ward in TX, who some in our group know for EME. (He at first thought I was Ray, when I contacted him on CW. Myron then contacted him on SSB.)
- W6YX, the Stanford University radio club, which was using a 28 foot dish. We contacted them first on CW. Then later when Bill was looking to record a phone QSO, which would illustrate the signal delay from the transit time to the Moon and back, W6YX just happened to call CQ on SSB on the frequency we were tuned to. We then had about a 4 minute QSO on SSB with them, which Bill recorded.
A video of Gary WA2JQZ responding to W6YX at Stanford University and having a 4 minute SSB QSO. (Video length 4:38)
We operated until about noon. We made 30 contacts in all. 25 contacts were CW (Morse Code) and 5 were SSB phone. 4 of the 5 phone contacts were with stations we also had CW QSOs with.
We submitted our contest log to ARRL the next day.
In the judgement of all of us, we had a very good EME operation. We are very pleased it worked so well on the first attempt. We clearly have a capable EME station.
Glenn and his team are continuing to follow up to investigate why we had a 1.5 degree azimuth offset.
It still takes my breath away to hear the echo of our signal coming back from the Moon, a couple of seconds later. The speed of light isn’t just a value in the books, it is something you experience viscerally first hand. It is real. EME is the longest signal path we have for communicating with others. This is fun.
These are the contacts we made. (CW = Morse Code, PH = SSB phone. Given also are the date and GMT times, the signal reports, and the other stations and their locations):
CW 10/10/2020 750 K0PRT 559 DL0SHF 559 Germany
CW 10/10/2020 756 K0PRT 559 OH2DG 579 Finland
CW 10/10/2020 805 K0PRT 559 G3LTF 579 England
CW 10/10/2020 814 K0PRT 549 I5MPK 569 Italy
CW 10/10/2020 846 K0PRT 569 SP6JLW 589 Poland
CW 10/10/2020 900 K0PRT 559 DL4DTU 559 Germany
CW 10/10/2020 912 K0PRT 579 SM4IVE 589 Sweden
CW 10/10/2020 919 K0PRT 549 DG5CST 569 Germany
CW 10/10/2020 934 K0PRT 559 VE6BGT 579 Alberta, Canada
PH 10/10/2020 947 K0PRT 57 VE6BGT 56 Alberta, Canada
PH 10/10/2020 947 K0PRT 55 W4OP 57 North Carolina, USA
CW 10/10/2020 1034 K0PRT 549 OK1KKD 569 Czech Republic
CW 10/10/2020 1043 K0PRT 599 OE5JFL 599 Austria
CW 10/10/2020 1049 K0PRT 579 W6YX 589 California, USA
CW 10/10/2020 1103 K0PRT 569 IK2MMB 569 Italy
CW 10/10/2020 1111 K0PRT 579 OZ4MM 599 Denmark
CW 10/10/2020 1149 K0PRT 549 OK1CS 579 Czech Republic
CW 10/10/2020 1153 K0PRT 569 OK2DL 479 Czech Republic
CW 10/10/2020 1201 K0PRT 559 VE6TA 579 Alberta, Canada
CW 10/10/2020 1503 K0PRT 559 JH1KRC 569 Japan
CW 10/10/2020 1526 K0PRT 549 AA4MD 559 Florida, USA
CW 10/10/2020 1533 K0PRT 569 WA9FWD 559 Wisconsin, USA
CW 10/10/2020 1540 K0PRT 569 W5LUA 579 Texas, USA
PH 10/10/2020 1547 K0PRT 569 W5LUA 579 Texas, USA
CW 10/10/2020 1652 K0PRT 539 VA7MM 559 British Columbia, Canada
CW 10/10/2020 1703 K0PRT 559 XE1XA 559 Mexico
PH 10/10/2020 1731 K0PRT 55 VE6TA 55 Alberta, Canada
CW 10/10/2020 1740 K0PRT 569 K2UYH 559 New Jersey, USA
CW 10/10/2020 1806 K0PRT 549 JA6AHB 569 Japan
PH 10/10/2020 1826 K0PRT 54 W6YX 55 California, USA
And these are summaries of our contacts from the logging program:
K0PRT’s Contest Summary Report
Total Contacts = 30
Operating Period: 2020/10/10 07:50 – 2020/10/10 18:26
Total Contacts by State \ Province: AB 4, CA 2, TX 2, BC 1, FL 1, NC 1, NJ 1, WI 1. 8 total.
Total Contacts by Country: USA 8, Canada 5, Czech Republic 3, Federal Republic of Germany 3, Italy 2, Japan, 2, Austria 1, Denmark 1, England 1, Finland 1, Mexico 1, Poland 1, Sweden 1. Total countries 13.
Total Contacts by Continent: Europe 14, North America 14, Asia 2. Total continents 3.
-72/73 Gary WA2JQZ