Friday, April 4, 2014

Visit to Arecibo Observatory

TRIP TO ARECIBO 

We had an opportunity to spend couple days in Puerto Rico last week and I wanted visit the Arecibo Observatory that is located about 1 1/2 hours drive from San Juan.  I did some research and found out that the visitor center  is open on Sundays.  After reading a very interesting QST article about 432 MHz  EME moon bounce ham radio event I decided to send an email to Angel WP3R  to find out more details on ham radio related activities in the Arecibo ham radio club station KP4AO.   I was positively surprised to get a quick reply from Angel, and even more happy that he was willing to organize a visit for us to see the Arecibo control room  and the antenna system.   After a few email exchanges our visit was confirmed for Sunday March 31st.   We left our hotel in San Juan at 8 AM on Sunday morning  and arrived to Arecibo around 9:30 AM.  Norberto  Despiau  and Dana Whitlow K8YUM greeted us upon our arrival.

ANTENNA 

Dana gave us an excellent introduction to the observatory. He started by explaining the design features of the 1000 ft diameter main reflector. It has spherical shape and is constructed from some 38,778 perforated aluminium panels. These are mounted with +- 2 mm accuracy making this antenna system usable up to 10 GHz frequency band. There is a  moving platform 500 ft above  the main reflector suspended by 18 cables from three towers surrounding the dish. This design enables to track targets +/- 20 degrees off from the zenith.  The two main antenna systems visible on the moving platform are for both transmitting and receiving signals. See Figure 1.


Figure 1. Dana K8YUM explains the antenna systems on the moving platform
The long pole with circular tapered rings is the antenna optimized for 430 MHz band. The white dome contains secondary and tertiary reflectors as well as 6 different antenna systems for various bands between 430 MHz and 10 GHz. These can be swapped in 6 seconds from the control room.

The 18 cables holding this 100 ton platform up in the air are expanding during hot sunny days and contracting during night. To maintain antenna in focus there is an automated system keeping the tension stable. We saw the system as we walked down underneath the main dish. Dana also explained the importance of keeping some vegetation growing under the main dish.   Since the dish is over a natural karst sinkhole it would fill up quickly with mud without vegetation removing the moisture.  Keeping the vegetation under control is another challenge. Cutting weeds on deep slopes of the sinkhole under the main dish is a difficult job.

TRANSMITTER

Arecibo Observatory has capability to provide planetary scale radar imaging.  They have 2  powerful transmitters and combined with very high gain ( 72 dBi at 2.38 Ghz) the effective radiated power can be up to 20 TW at 2.38 GHz.  This power is needed to produce detailed radar images from planets, moons and asteroids. The radar transmission can last for several minutes and is modulated with pseudorandom noise. Signal processing and correlation methods are used to extract data from received echoes. Arecibo can track objects up to Saturn orbit in our solar system, beyond that the echoes come back too late to fit in the observation time window.   

Dana took us to the transmitter room where they had two huge klystron amplifier tubes under repair - black horizontal tube produces 1 MW CW power at 430 MHz and red vertical klystron 1 MW at 2.38 GHz. (see figure 2 below). The grey big box at the center is the 430 MHz transmitter. 

Figure 2.  Transmitter room and klystrons

CONTROL ROOM 

Figure 3 shows the control room where the antenna system is operated. In many cases both research and antenna tracking is done remotely over the Internet. The staff is monitoring the system to ensure safety and address any issues.  One of the biggest problems is radio frequency interference (RFI). Receiver pre-amplifiers are kept cold at 15 K with liquid helium and they are very sensitive so even a tiny RFI source creates a problem. Dana explained that they have a specially equipped van to track down RFI sources, often more than 10 miles away from the observatory. They are also coordinating with air traffic control radar systems during some especially sensitive observations.  

Figure 3.  Marja AB1NL in the control room

RECEIVER SYSTEMS

Received signals are amplified at the antenna platform and brought to the control room either via low loss waveguides or via optical fibers. Figure 4 below shows racks full of advanced receivers and spectrum analyzers. As many principal investigators are operating the radio telescope remotely the digitized signals are available via the Internet. Arecibo has 250 Mbps link which is burstable to 500 Mbps rate as needed. The blue rack on the right side is part of world wide VLBA system  (Very Long Baseline Array). It has large disk arrays that are frequently swapped and shipped to central location for analysis.   


Figure 4. Receiver systems

LOCAL FOLKLORE 

In nearby villages the Arecibo Observatory is called "El Radar".  Locals are convinced that the staff at the observatory are talking to aliens on frequent basis.  In fact  Norberto instructed Dana to show us everything "except the bunkers where they keep the aliens" with a smile on his face.  


Figure 5. Norberto Despiau at control desk
There may be some truth in these beliefs.

Arecibo Observatory was used in SETI (Search for Extra Terrestial Intelligence) project in 1999 to collect data from nearby stars.   It was also used to send the famous Arecibo message (see Fig 6.)  designed by Frank Drake and Carl Sagan.  The message was sent on on 16 November 1974 and it was aimed at the globular star cluster M13 some 25,000 light years away.  

Dana did not confirm or deny  having received any response back yet.  On the other hand he has been working at the observatory only for 7 years.  We may not know the answer before the next 49,960 years.  

I would like to thank Dana, Norberto and Angel  for organizing this very enjoyable visit to the observatory. Special thanks to Dana K8YUM who  spent 3 hours of his Sunday morning with us - very much appreciated.  


73
Mauri  AG1LE   


Figure 6.  Arecibo Message








Tuesday, December 31, 2013

New Morse Decoder - Part 3

New Bayesian Morse Decoder 

In my previous blog entry I shared the first test results using Bayesian CW decoder integrated to FLDIGI.  As I indicated the software has still bugs but when it works the accuracy improvement compared to the legacy FLDIGI decoder was pretty impressive.  I was testing again tonight as ham bands were full of CW stations working in ARRL Straight Key Night.  I made also many audio file captures to be used as  additional testing material.

However,  as my alpha testers have also noticed the current decoder is very sensitive to proper audio signal settings.  In order to analyze this problem a bit more details I re-implemented FLDIGI audio processing chain from audio file playback to the decoder (including the FFT filtering in CW.CXX) in a standalone version of the Bayesian Morse Decoder.  It was easier to run a series of tests by just varying command line variables and WAV audio files  and capture the results for analysis & plotting the data.

After running a series of tests I compared the signal amplitude against decoder errors and found a very sharp non-linear behavior related to speed estimation algorithm.  By increasing signal volume by only 0.06% I was able to re-produce this event that alpha testers found and also capture the dynamic behavior of various parameters, including <spdhat>  that I used below to plot the speed estimate over time.

Figure 1. below shows that initially the speed tracking is trying to find the correct speed (in this case 40 WPM) but fairly soon it goes down below the lower limit 10 WPM  and is not able to recover from this error situation. This is similar behavior that alpha testers have seen.
Figure 1.  Speed estimator bug

I  scaled down the signal strength by only 0.06% and now the speed estimator works much better.   In Figure 2. below  the speed tracking fluctuates between 13 and 48 WPM until it settles to about 38 WPM.   Despite this tracking behavior the decoder produces  correct results from a noisy test file.

Figure 2.  Normal speed estimator behavior




I am very thankful for those brave hams who took this first  (broken) alpha release and provided me not only good  feedback but also some WAV file examples  that I have been able to use to track down these problems.

I have also converted all the files from C  to C++  to make it easier to re-integrate to FLDIGI.  I will continue cleaning up the code and keep working to improve the speed estimator.  Once I have the next alpha release ready for another set of tests I will announce it in the fldigi mailing lists and eham.net CW forum.

73 and Happy New Year

Mauri  AG1LE



Tuesday, December 24, 2013

New Morse Decoder - Part 2

New Bayesian Morse Decoder 


In my previous post I shared initial results of the new Bayesian Morse Decoder.  I have worked a bit more on this topic to integrate the decoder software to FLDIGI v3.21.75.   Dave  W1HKJ provided me some space on his web server so I posted full source code including all changes and new source files related to Bayesian Morse decoder in here.

To demonstrate the Bayesian decoding capability I tuned my KX3  on W1AW frequency 3.58105 Mhz  at 8:00 PM EST today and let two identical FLDIGI copies of the same v3.21.75 software running from the same audio source.  I have a SignaLink USB connected between KX3  and my ThinkPad laptop running Linux Mint OS.

On Fig 1. below  I have the legacy SOM decoder on the left side and the new Bayesian decoder on the right .  The legacy decoder makes a lot of errors and CW bulletin is not really readable.  On the right side I have enabled Bayesian decoder and you can actually read the bulletin, though the lack of proper word spaces make this still a bit difficult to read. In any case Bayesian decoder provides significant accuracy improvement with real life noisy CW signals.

Figure 1.  FLDIGI running legacy and Bayesian Morse decoder





If you choose to  compile FLDIGI from the sources yourself  please see Figure 2. below.  When you go to menu item Configure / Modems / CW / General  and click the tick box "Bayes decoding"  that will enable the new Bayesian decoder (and disables legacy decoder).  You will also notice that CW RX speed indicator  (Fig 1. bottom left corner of FLDIGI window)  will change more rapidly - this is a feature of the new decoder.  It evaluates the instantaneous speed continuously and uses this information as part of the decoding process.

Figure 2.  Enabling Bayesian decoder. 



I would be interested in getting your feedback and suggestions how to improve this software.  Current version is buggy  and it does crash occasionally.  Also, I still have not found the root cause of the problem that causes approximately 3% base error rate.

There are number of improvement areas that need work. For example noise estimator ("noise.c") does not seem to be able to keep track of the real noise level. This noise power information is later used by Kalman filters  ("kalfil.c") in estimating likelihood of keystate given the observed signals. Bayesian inference is then used in updating posterior conditional probabilities for each new path in ("probp.c"). I am getting intermittent overflows in this section of the code. Any help in this area would be very welcome.

However,  given the visible improvement in the decoding accuracy at least during certain conditions  (when you have the signal level correct, not too much noise etc.) I am now posting this for alpha testing with hopes that I could get some more eyes to look at the code and find those bugs.

Happy Holidays!

73
Mauri AG1LE  




Friday, September 27, 2013

New Morse Decoder - Part 1

NEW BAYESIAN MORSE DECODER

I have been working on a new Bayesian Morse decoder algorithm.  This work is based on Dr. Bell's  doctoral thesis  that is one of the best and most comprehensive documents on this topic I have found so far. While it contains a lot of advanced mathematics this thesis has also very thorough description of the problems related to automatically transcribing the hand-keyed manual Morse signal with acceptable error rate.  This thesis covers a lot of ground and describes with mathematical rigor how to model and solve each of the problems. It has also software examples (in Fortran)  and test results comparing to theoretically optimal solution as well as to human performance under different conditions.

Using the thesis as a starting point I implemented the algorithms in C language. Current version has some 3335 lines of code and is posted in Github as open source with verbal permission from Dr. Bell. I managed to get the software working to the degree that I am able to run some performance tests.  There is still a lot of work ahead to improve and clean up the code but I decided to publish some early results for those who might be interested in this work.

CORRELATOR-ESTIMATOR TESTING

As described in the thesis this algorithm represents a "correlator-estimator" technique in which a sequence of all possible keystate transitions are hypothesized and correlated with the incoming signal, and the most likely sequence is output as the best estimate.  To illustrate this point I plotted a segment of incoming signal with letters "QUICK B" as shown on figure 1. below.  The probability estimates of various keystates [P(dit), P(dah), P(el-spc), P(chr-spc), P(wrd-spc), P(pause)] are plotted underneath the incoming signal.  I used Kst Data Viewer to create this plot.


Figure 1.  Correlator-estimator probabilities




























The Morse audio file used in this test had Signal-Noise Ratio (SNR) of 8 dB @ 2 kHz bandwidth. This figure shows nicely the time variant probability values of each keystate, as well as how a particular keystate correlates with "mark"/"space" changes in the incoming signal.

CER vs. SNR  TESTING 

To test the decoder performance in the presence of noise I created a set of Morse sound files with -10 dB to +20 dB SNR @2kHz bandwidth using modified version of Rob Frohne KL7NA morse.m Octave software.  These files contain 200 words with 5 random letters and numbers each.  The sound files are available here: Morse sound files -10 dB ... 20dB SNR @2kHz BW  For algorithm testing I also created corresponding text files where is each sample is a real number on separate line. These are easier to manipulate and plot using standard Linux tools, like gnuplot.

I ran the algorithm using files with different SNR levels and saved the decoder text output. To get the Character Error Rate (CER) I created a small utility program to calculate Levenshtein  distance using this algorithm.  Comparing original text to decoded text gives the character error rate.  When plotting the results it was quite interesting to see a deep reduction in CER with SNR over 6 dB.  Note that SNR figure contains noise for the whole 2kHz bandwidth.  

Figure 2.  CER to SNR test results


































The CER should go down to zero as SNR improves - however the graph shows some base error rate ~ 3 %.  I need to study this a bit more in detail to find the root cause.  At higher noise levels the curve shape looks a bit closer to what I expected.

NEXT STEPS 

As mentioned before there is still a lot of work ahead to make this software useful.

I did some initial testing to integrate this decoder to a modified  FLDIGI package and got the software partially working as an external program connected to FLDIGI via a Linux FIFO pipe.

I am also trying to figure out automated test scripts for timing and speed variance testing.  I would really like to find the limits where the algorithm breaks. This requires more work in creating synthetic tests similar to what is described in the thesis.

Third  area of work is testing the algorithm performance against signal fading. This would provide limits on real world signals and help to optimize the model parameters.

If you are interested in advancing the state of the art in Morse decoding feel free to download the software, work on testing & improving it. Please provide your feedback and post comments below.

73
Mauri AG1LE




Sunday, April 21, 2013

E51DXX DX-Pedition

LOCATION





Our  DX-Pedition / vacation to Rarotonga was very enjoyable and successful.  We spent almost two weeks on South Cook Islands including a day trip to Aitutaki.  Rarotonga is located in South Pacific between Tonga islands and French Polynesia.  It is in the same time zone as Hawaii (UTC -10h).  Rarotonga is part of South Cook Islands.




We stayed at Sea Change Villas located on the south coast of Rarotonga, almost opposite side to Avarua, the chief town in Rarotonga.

Figure 1.  E51DXX location on Rarotonga









Sea Change Villas has excellent 5 star ratings in Tripadvisor  and after spending there 2 weeks I can assure that the place is just wonderful. When booking the villa back in December 2012 I was corresponding via email to Christina and Deb.  I asked if it was possibile to setup a ham radio antenna.  They responded that if I don't interfere with the Wifi internet service I am welcome to setup my antenna.   It turned out to be a very ham friendly location and I got even some help to pull the coaxial cable. 

There are multiple villas on this well maintained property, including two that are right at the beach (Fig 2.).  We opted for unit #7 that is approximately 150 meters from the beach on a sloping terrain. 

Figure 2.  Sea Change Villas
We arrived to Rarotonga with a direct Air New Zealand flight from Los Angeles around 6:30 AM local time on April 1st.  Upon arrival the warm southern pacific air smelled really good and there was a nice breeze coming from the ocean.   We had a driver waiting for us and he gave us white flower leis and took our luggage.  On the way to the villas James told us about Rarotonga. He explained that the main road Ara Tapu goes along the coast around the island and is about 32 km. There are clockwise and counterclockwise bus routes that go around this road.  There are also plenty of places to rent a scooter,  a bicycle or a car.  We passed by many hotels on the west coast as well as several shops and restaurants.  In about 20 mins we arrived to Sea Change Villas and James helped to unload our luggage. 

Figure 3. Sea Change Villas 




















We were positively surprised of the villa - it was very spacious and very well maintained.  We had a nice view to the ocean as well as our own private pool backside. We also found that the refrigerator was well stocked with food so I prepared some eggs and toast for breakfast.  There was also a letter on the kitchen table explaining that the reception opens at 9:30 AM.  

After settling in  and exchanging more comfortable clothes I walked down to beach to check water temperature.  The morning mist was still visible around the mountains as visible in Fig 3. 
During the two weeks we stayed in Rarotonga the weather was really nice and temperature was around 30 C  (day time) to 23 C (night time).   

When the office opened in the morning John came to provide us orientation to Rarotonga.  We discussed about various activities and locations that we wanted to experience.  John was very knowledgeable and helped us to rent a car  and get our first scuba diving scheduled.   He also provided a really good overview of restaurants, beaches,  shopping and other activities we were interested.  

E51DXX STATION DETAILS 

John also helped me to setup the Buddipole antenna next to the pool and to pull the coaxial cable inside. The telecom office was closed on April 1st as it was a public holiday in Rarotonga but I did erect the antenna to listen the HF bands in the afternoon and evening.

Figure 4. Buddipole antenna
I had two radios with me  - Elecraft KX3  and  Flex-3000.

I had also Powerwerx SS-30DV portable 30 Amp power supply with me.  I had also two adapters to plugin to local 230V AC but I realized later that they were lacking the grounding pin.

It took me a while to assemble the station and connect to Flex-3000.  My trusty old Thinkpad T60 laptop had latest and greatest PowerSDR software that I did test before our departure to Rarotonga.

I had also an Array Solutions AIM UHF antenna analyzer to help tuning the Buddipole antenna to different bands.  I  tested the Buddipole in different configurations such as
  • horizontal dipole
  • vertical dipole
  • L-shaped dipole 
I had a portable mast to erect the antenna up to 18 feet. I had also guy wires to keep the antenna straight.

First day was filled with other activities as well.  I went to get a rental car, we visited the scuba diving place to schedule some dives  and  finally took our snorkling gear to explore the blue lagoon a bit closer.


In the evening I was listening the ham bands  - 20m was wide open and I heard many VK and ZL stations as well as North American stations.  I also heard a few European stations later in the evening via long path.  The sunset was around 6:40 PM local time and eventually the sky turned pitch black.  I went out a few times to adjust the antenna and I was amazed to see Milky Way and Southern Cross. With almost zero light pollution in Rarotonga the sky was really black and I saw many unfamiliar constellations.

Figure 5. E51DXX license

Next morning we headed with my wife Marja (AB1NL) to Avarua  - the small town on the northern coast of Rarotonga. I got my Cook Islands drivers licence at the Police station - a dark gray building next to a gas station.  They also instructed me to go the Telecom office to pickup the E51DXX ham licence.  Telecom has a nice modern air conditioned office  and I asked for Mr. Katoa Banaba to whom I had emailed copy of my passport and U.S. ham licence in advance.  He had prepared my licence  so I walked out of the office in about 15 minutes with a fresh new E51DXX amateur licence in my hand.

We bought some groceries from CITC supermarket near the airport and headed back to the villa.  There are many smaller stores around the island but CITC store is well stocked and had everything we needed. There is also locally grown fruits and vegetables.

After dinner I opened the radio and starting working QSOs.  I was struggling a bit as the station setup was not very stable initially.  I got some signal reports where NZ  hams indicated that I might have some RF in the shack. I had some extra ferrite cores with me so I re-arranged the cables.  I also realized that the missing grounding pin on the AC adapter might be part of the problem. However,  I was able to fix most of the issues and adjust the settings in Flex-3000 / PowerSDR to eliminate the problem and I started getting better quality reports.

As discussed earlier I also experimented with different Buddipole configurations.  It was very easy to bring the antenna down,  adjust settings, measure with AIM UHF analyzer  and lift the antenna up again. As I got better feel of the bands and different antenna configurations I settled with the L-shaped configuration (see Figure 6. below) that seemed to work extremely well.  I used this setup both at the beach near water front as well as at the villa. Chris W6HFP and Tom K2GSJ have a neat Youtube video that explain how to do the antenna setup.

In the following days there were several great 28 Mhz openings  so I took my Elecraft KX3  and set the antenna right at the beach.  I made many great SSB contacts to Europe,  USA and Japan with only 5 Watts.  Many hams were amazed how well they heard my QRP station.  In many cases they had multielement Yagi and 1 kW amplifier on their side, and they gave me 56 to 59 signal reports. KX3 has excellent receiver and I did hear more stations than I could work with.

Figure 6.  Buddipole in L-shaped configuration.













I needed some power adapters  and I was wondering if there is anything available in such a remote South Pacific island.  I called Jim E51JD who we had already met at lunch in Avarua. There is a fairly new electronics store near the airport called JayCar.  I visited the store and talked to Denny who is the store manager.  He was very helpful  and not only had exactly what I needed but he also helped to test that everything worked. See figure 6 below - he is testing my Powerpole connections.

The store itself is like a very well equipped RadioShack. He had everything from connectors, batteries, solar panels to actual electronics components.  Denny mentioned that even the telecom engineers visiting from New Zealand find some components they need as they are installing a new 3G network on the island. I did visit the store couple times  during this DX-Pedition. I wish my local RadioShack store near Lexington would be as well equipped as this one.    

Figure 7.  Denny  from Jaycar is helping to fix a new power adapter. 

SCUBA DIVING 

We did multiple scuba diving trips during this vacation.  We used Pacific Divers - their office is located on the east side of the island.   
Figure 8. Marja returning from a dive
Figure 9.  From left: Alex, dive master Hayley, Marja, Mauri and Mitch
 Most of the trips started from Avarua harbor as the wind was blowing mostly from south west during the first week.  The conditions were good - sea was calm and visibility was  around 30 meters (100 feet).

We had scuba diving scheduled typically in the morning and we explored the SS Mai Tai shipwreck near the Avarua harbor.  We also visited Edna's achor on this dive trip.  During the following 12 days we visited few other dive sites around the island.

Coral Gardens was an impressive dive site and I did capture on video some strange creature that might have been a big octopus hiding under a big rock.

We also learned some new tricks.  Diving backwards over the side of the boat was a new experience for me. The first time felt pretty awkward but it was really the only practical way to get into water with air tank and all the other gear as the boat was pretty tightly packed as you can see from Figure 8.

Figure 10.  Marja coming to surface

Unfortunately I did have some trouble equalizing my ears so after my 4th dive trip I had blood in my mask and had to stop and focus on snorkeling. My both ears were pretty clogged for the rest of the vacation.   However,  I did have a lot of fun and got to play with my new GoPro2 camera.  I still need to edit all those underwater video clips - I have literally Gigabytes of video and pictures.

Scuba diving in Rarotonga was a lot of fun but I also enjoyed snorkeling.  For example in the place called "Fruits of Rarotonga" there is a lot of tropical fish and corals if you swim past the big red buoy.

On our day trip to Aitutaki we had also opportunity to snorkel in the lagoon. What a fantastic place - the natural beauty of this lagoon must be experienced - photographs won't do it.  We finished our lagoon journey to One Foot Island (Tapuaetai) where we had lunch and got our passports stamped.
Aitutaki has also been used as the location for US TV program Survivor:Cook Islands.    


SOCIAL ACTIVITIES 

On Friday April 12th I had also a very nice lunch with Jim, E51JD and Here (friend of Barb, N1ICQ) at Tamarind restaurant. I learned quite a lot about the island, its history and the people.  Jim has been living in Rarotonga for 40 years and Here is native resident so they were both very knowledgeable. The island has changed over these years,  quality of housing has improved and tourism has become the biggest source of income. Many people have also moved to New Zealand and Australia, especially from more remote islands of Cook Islands group.  In Rarotonga there is about 10,000 residents and on annual basis they have some 100,000 tourists visiting these islands. When the new airport was opened in 1974 it brought many new visitors to these southern pacific jewels. 

Figure 10. Lunch with Jim E51JD and Here.





We did also some antenna tuning at Jim's place.  He has an impressive station on the north east corner of Rarotonga with antennas covering almost every band. I heard Jim E51JD multiple times on the air during my visit to Rarotonga even though I was on the other side of Rarotonga mountains. His 30m/17m/12m vertical antenna was a little bit out of resonance so we took it down and adjusted the upper element.  While we had the antenna analyzer available I measured all his other antennas as well and they got a perfect score.  Jim is fairly close to the beach and he explained that winds are bringing salt everywhere so corrosion is a big problem.

WORKING DX STATIONS
As this DX-Pedition was really a vacation I was not too worried about working around the clock or trying to maximize number of contacts. I worked at a leisure pace and did not spend all nights chasing for DX stations.  However,  I did have a couple good pileups  and I am very grateful for the patience of fellow hams who were calling me.  In several cases I worked a station and they gave up their frequency and put me on the DX cluster.  This did help a lot as I spent quite some time calling CQ  without success as my signal was pretty weak in Europe and USA. Once I was spotted on the DX cluster a big pile up developed and I could work over 100 stations in a short period of time.

It was also  interesting to hear how the band conditions changed pretty quickly. After sunset in Rarotonga I could work stations around the Pacific rim. I also participated the ANZA net almost every day  at 14.183 Mhz at 05:15 UTC.  I got many good contacts through the net.

Figure 11. E51DXX working a pile up 

LOG SUMMARY 

As discussed earlier many of these contacts were made with only 5W with Elecraft KX3  and L-shaped vertical dipole near the beach.  As many hams have discovered earlier a vertical dipole near large body of salt water is an excellent antenna for DX work.  In my case I tested various Buddipole configurations and finally decided to stick with L-shaped vertical dipole (see figure 6. above). It was very easy to tune to accurately to resonance, it provided really good signals on reception and I got great signal reports even from stations 10,000 miles away.  I was literally blown away how well this QRP setup (see Fig 12. below) worked.

Figure 12. Elecraft KX3 - 5 Watts and vertical dipole at the beach












With Flex-3000 my transmit power was around 50-70 W. As the villa was about 150 meters from the beach I used the Buddipole antenna at maximum height of 18 feet and carefully tuned it to resonance. I did notice about 2 S units difference on several stations compared to reports by Jim E51JD - he was located on the north side of the island. Jim was  using a 3 element Yagi  that may explain part of the difference. I also worked Jim a few times - he was only 5 - 6 km away but we had Te Manga,  a 652 meter (2139 ft) high mountain between us. I am not exactly sure how and where the radio waves reflected but they certainly did not pass the solid rock between us.

Total number of QSOs  was 776 and they are mostly on 20m and 10m bands. I did spend time also on 15m and 17m bands but to my disappointment I did not hear much activity and got only a handful of contacts on these bands. 10m band openings were totally unexpected and a great experience.

10M 362
15M 5
17M 7
20M 402
TOTAL 776

I was positively surprised how well my simple station performed. I worked total of 49 DXCC countries listed below. There was a couple new ones for me like Samoa and Fiji. I was also very happy to get 10 stations from Finland in my log, as the distance is over 9700 miles and my VOACAP propagation prediction did give only a slim chance to make these contacts with QRP power levels.  Out of blue also Nick RI1ANP called me from Antartica on 10m band.

ALASKA 1 COLOMBIA 1 HAWAII 11 NETHERLANDS 6 SERBIA 1
ANTARCTICA 1 CROATIA 1 HONDURAS 1 NEW ZEALAND 18 SLOVAK REP. 3
ARGENTINA 2 CZECH REP. 3 HUNGARY 1 NORWAY 1 SOUTH KOREA 1
AUSTRALIA 74 DENMARK 3 INDIA 2 PAPUA NEW GUINEA 1 SPAIN 14
AUSTRIA 4 ENGLAND 5 ITALY 18 POLAND 4 SWEDEN 4
AZORES 1 FIJI 2 JAPAN 80 PUERTO RICO 2 SWITZERLAND 3
BELGIUM 2 FINLAND 10 LITHUANIA 3 RUSSIA (ASIATIC) 2 TRINIDAD AND TOBAGO 1
BRAZIL 12 FRANCE 9 MADEIRA ISL. 1 RUSSIA (EUROPEAN) 1 UKRAINE 1
CANADA 5 FRENCH POLYNESIA 1 MARTINIQUE 1 SAMOA 2 USA 171
CANARY ISL. 3 GERMANY 20 MEXICO 2 SCOTLAND 1

I have uploaded my log to eQSL.CC  and to LoTW.  I already had a stack of QSLs waiting in my mail when I returned home from this trip. Creating a printed QSL card  and sending  them out will take few months so please be patient with me.

Update May 11, 2013:  QSL cards arrived (see Fig 13. below) and I sent the first batch to those who send me QSLs directly.

Figure 13.  E51DXX QSL card front













73
Mauri  E51DXX  /  AG1LE 

Tuesday, March 26, 2013

DX-Pedition to Rarotonga, Cook Islands


I will be active from Rarotonga, Cook Islands  IOTA OC-013  from April 1 to April 13, 2013.
This DX-pedition will be mostly a vacation but I hope to make a few contacts as well.  My call sign will be E51DXX and I will be working mostly SSB and digital modes.  I created this filter in DX cluster to check for possible spots.

I used VOACAP propagation planner and online tools to predict propagation from Rarotonga to various other  locations.  As a starting point I made some assumptions on antennas and transmit power.  I will carry a Buddipole antenna and two radios (Flex3000 and Elecraft KX3) with me.  Prediction was done assuming 100W transmit power, vertical antenna  and SSB transmit mode from Rarotonga.  For the other stations I assumed 3 element Yagi at 50ft and 100W.

The propagation prediction tables below show that 20M, 17M and 15M HF bands look like the most promising bands this time of the year.  The tables show the % probability of the contact and estimated S-unit signal strength for each ham band  over 24 hours (Raro / UTC timezones).  The best case to US East coast will be S4 signal strength and 28% probability at 20M  @07:00 UTC so bare with me and follow the DX Code of Conduct please.

I will be working mostly between 18 - 24 Rarotonga time which is 4:00 - 10:00 UTC.   Let's see how well this propagation prediction will match with reality.

I hope to make a QSO with you from Rarotonga, Cooks Islands.  Thanks for reading this blog. Feel free to leave feedback below.

73
Mauri AG1LE


Here is the CQ Zone map for reference (from EI8IC website).


Figure 1.  CQ Zone Map  by EI8IC 















For CQ Zone 5  - US East Coast 

Raro UT 80M 40M 30M 20M 17M 15M 12M 10M
15 1 0 -   -  -  -   -  -  -   -  -  5  26 S1 27 32 S1 44 36 S2 44 36 S2
16 2 0 -   -  -  -   -  -  -   -  -  23 31 S2 39 34 S2 23 23 S0 23 23 S0
17 3 0 -   -  -  -   -  -  0  12 S1 35 33 S2 23 23 S0 -   -  -  -   -  - 
18 4 0 0  06 S1 0  06 S1 0  20 S3 27 26 S1 -   -  -  -   -  -  -   -  - 
19 5 0 0  13 S3 0  13 S3 1  25 S3 20 21 S0 -   -  -  -   -  -  -   -  - 
20 6 0 0  17 S3 0  17 S3 3  27 S3 14 17 S0 -   -  -  -   -  -  -   -  - 
21 7 0 0  18 S3 0  18 S3 5  28 S4 13 15 S0 -   -  -  -   -  -  -   -  - 
22 8 0 0  19 S3 0  19 S3 6  28 S3 11 14 S0 -   -  -  -   -  -  -   -  - 
23 9 0 0  19 S3 0  19 S3 7  28 S3 -   -  -  -   -  -  -   -  -  -   -  - 
24 10 0 0  17 S3 0  17 S3 6  26 S3 -   -  -  -   -  -  -   -  -  -   -  - 
1 11 0 1   18 S2 1   18 S2 2   23 S3 8   09 S0 -   -  -  -   -  -  -   -  - 
2 12 0 0   12 S1 0   12 S1 0   20 S2 25  26 S1 -   -  -  -   -  -  -   -  - 
3 13 0 0   00 S0 0   00 S0 0   16 S1 51  38 S3 28  30 S1 -   -  -  -   -  - 
4 14 0 -   -  -  -   -  -  0   01 S0 19  20 S0 11  13 S0 -   -  -  -   -  - 
5 15 0 -   -  -  -   -  -  -   -  -  14  17 S0 9   12 S0 -   -  -  -   -  - 
6 16 0 -   -  -  -   -  -  -   -  -  1   24 S1 42  36 S2 8   10 S0 8   10 S0
7 17 0 -   -  -  -   -  -  -   -  -  0   14 S0 32  35 S2 39  34 S2 39  34 S2
8 18 0 -   -  -  -   -  -  -   -  -  0   09 S0 13  31 S1 47  37 S2 47  37 S2
9 19 0 -   -  -  -   -  -  -   -  -  -   -  -  0   21 S0 42  36 S2 42  36 S2
10 20 0 -   -  -  -   -  -  -   -  -  -   -  -  0   19 S0 30  33 S1 30  33 S1
11 21 0 -   -  -  -   -  -  -   -  -  -   -  -  0   15 S0 37  35 S2 37  35 S2
12 22 0 -   -  -  -   -  -  -   -  -  -   -  -  0   19 S0 29  33 S1 29  33 S1
13 23 0 -   -  -  -   -  -  -   -  -  0   09 S0 1   22 S0 34  34 S2 34  34 S2
14 24 0 -   -  -  -   -  -  -   -  -  0   16 S0 10  27 S1 43  36 S2 43  36 S2
  

For CQ Zone 15  - Finland 
Raro UT 80M 40M 30M 20M 17M 15M 12M 10M
15 1 0 -   -  -  -   -  -  -   -  -  -   -  -  -   -  -  -   -  -  -   -  - 
16 2 0 -   -  -  -   -  -  -   -  -  -   -  -  -   -  -  -   -  -  -   -  - 
17 3 0 -   -  -  -   -  -  -   -  -  -   -  -  -   -  -  -   -  -  -   -  - 
18 4 0 -   -  -  -   -  -  1  21 S2 6  07 S0 -   -  -  -   -  -  -   -  - 
19 5 0 -   -  -  -   -  -  0  05 S0 9  11 S0 -   -  -  -   -  -  -   -  - 
20 6 0 -   -  -  -   -  -  0  09 S0 14 17 S0 -   -  -  -   -  -  -   -  - 
21 7 0 -   -  -  -   -  -  0  03 S0 27 26 S1 9  11 S0 -   -  -  -   -  - 
22 8 0 -   -  -  -   -  -  -   -  -  25 25 S1 18 20 S0 -   -  -  -   -  - 
23 9 0 -   -  -  -   -  -  -   -  -  23 25 S1 18 20 S0 -   -  -  -   -  - 
24 10 0 -   -  -  -   -  -  -   -  -  28 28 S1 17 19 S0 -   -  -  -   -  - 
1 11 0 -   -  -  -   -  -  -   -  -  28  28 S1 18  19 S0 -   -  -  -   -  - 
2 12 0 -   -  -  -   -  -  -   -  -  28  27 S1 18  20 S0 8   10 S0 8   10 S0
3 13 0 -   -  -  -   -  -  -   -  -  28  27 S1 16  18 S0 -   -  -  -   -  - 
4 14 0 -   -  -  -   -  -  0   04 S0 22  24 S1 13  15 S0 -   -  -  -   -  - 
5 15 0 -   -  -  -   -  -  0   07 S0 9   12 S0 -   -  -  -   -  -  -   -  - 
6 16 0 -   -  -  -   -  -  0   02 S0 6   08 S0 -   -  -  -   -  -  -   -  - 
7 17 0 -   -  -  -   -  -  -   -  -  12  15 S0 13  16 S0 -   -  -  -   -  - 
8 18 0 -   -  -  -   -  -  -   -  -  9   12 S0 8   10 S0 -   -  -  -   -  - 
9 19 0 -   -  -  -   -  -  -   -  -  5   06 S0 -   -  -  -   -  -  -   -  - 
10 20 0 -   -  -  -   -  -  -   -  -  -   -  -  -   -  -  -   -  -  -   -  - 
11 21 0 -   -  -  -   -  -  -   -  -  -   -  -  -   -  -  -   -  -  -   -  - 
12 22 0 -   -  -  -   -  -  -   -  -  -   -  -  -   -  -  -   -  -  -   -  - 
13 23 0 -   -  -  -   -  -  -   -  -  -   -  -  -   -  -  -   -  -  -   -  - 
14 24 0 -   -  -  -   -  -  -   -  -  -   -  -  -   -  -  -   -  -  -   -  - 


For CQ Zone  25  - Japan 
Raro UT 80M 40M 30M 20M 17M 15M 12M 10M
15 1 0 -   -  -  -   -  -  -   -  -  0   11 S0 9   31 S1 46  37 S2 46  37 S2
16 2 0 -   -  -  -   -  -  -   -  -  0   15 S0 3   28 S1 51  38 S2 51  38 S2
17 3 0 -   -  -  -   -  -  -   -  -  0   23 S1 14  32 S2 68  42 S3 68  42 S3
18 4 0 -   -  -  -   -  -  -   -  -  2  28 S1 49 38 S3 66 42 S3 66 42 S3
19 5 0 -   -  -  -   -  -  0  05 S0 22 34 S3 69 42 S3 77 45 S3 77 45 S3
20 6 0 -   -  -  -   -  -  0  14 S1 54 39 S3 68 43 S3 74 48 S4 74 48 S4
21 7 0 0  09 S0 0  09 S0 1  23 S2 70 43 S4 82 48 S4 78 50 S4 78 50 S4
22 8 0 1  20 S2 1  20 S2 10 29 S4 76 45 S4 85 50 S5 80 51 S4 80 51 S4
23 9 0 9  27 S4 9  27 S4 21 32 S4 65 43 S4 71 48 S4 73 51 S4 73 51 S4
24 10 0 15 30 S5 15 30 S5 38 36 S5 66 45 S4 75 52 S5 72 50 S4 72 50 S4
1 11 0 14  31 S5 14  31 S5 44  37 S5 68  47 S5 74  51 S5 72  50 S4 72  50 S4
2 12 0 11  30 S5 11  30 S5 48  38 S5 74  50 S5 76  53 S5 71  49 S4 71  49 S4
3 13 0 8   30 S5 8   30 S5 52  38 S5 75  51 S5 76  53 S5 67  47 S4 67  47 S4
4 14 0 8   30 S5 8   30 S5 50  38 S5 67  47 S4 72  50 S4 54  40 S2 54  40 S2
5 15 0 4   27 S5 4   27 S5 46  37 S5 61  44 S4 47  37 S2 22  22 S0 22  22 S0
6 16 0 0   22 S4 0   22 S4 43  37 S5 45  35 S2 21  22 S0 -   -  -  -   -  - 
7 17 0 0   17 S3 0   17 S3 28  34 S4 28  30 S1 26  25 S0 9   11 S0 9   11 S0
8 18 0 0   10 S2 0   10 S2 2   25 S3 37  32 S2 15  17 S0 -   -  -  -   -  - 
9 19 0 -   -  -  -   -  -  0   16 S1 35  30 S2 26  25 S0 -   -  -  -   -  - 
10 20 0 -   -  -  -   -  -  0   03 S0 51  38 S3 53  40 S3 18  20 S0 18  20 S0
11 21 0 -   -  -  -   -  -  -   -  -  23  34 S2 63  43 S3 62  44 S3 62  44 S3
12 22 0 -   -  -  -   -  -  -   -  -  1   25 S1 24  34 S2 60  43 S3 60  43 S3
13 23 0 -   -  -  -   -  -  -   -  -  0   14 S0 12  32 S1 51  39 S2 51  39 S2
14 24 0 -   -  -  -   -  -  -   -  -  0   11 S0 50  38 S3 51  38 S2 51  38 S2

For CQ Zone 14 EA  -  Western Europe 
Raro UT 80M 40M 30M 20M 17M 15M 12M 10M
15 1 0 -   -  -  -   -  -  -   -  -  -   -  -  -   -  -  -   -  -  -   -  - 
16 2 0 -   -  -  -   -  -  -   -  -  -   -  -  -   -  -  -   -  -  -   -  - 
17 3 0 -   -  -  -   -  -  0   11 S0 -   -  -  -   -  -  -   -  -  -   -  - 
18 4 0 0  06 S1 0  06 S1 1  18 S1 -   -  -  -   -  -  -   -  -  -   -  - 
19 5 0 0  10 S1 0  10 S1 3  20 S2 -   -  -  -   -  -  -   -  -  -   -  - 
20 6 0 0  09 S1 0  09 S1 2  20 S2 -   -  -  -   -  -  -   -  -  -   -  - 
21 7 0 -   -  -  -   -  -  0  19 S1 -   -  -  -   -  -  -   -  -  -   -  - 
22 8 0 -   -  -  -   -  -  0  16 S1 8  10 S0 -   -  -  -   -  -  -   -  - 
23 9 0 -   -  -  -   -  -  -   -  -  34 32 S2 9  11 S0 -   -  -  -   -  - 
24 10 0 -   -  -  -   -  -  -   -  -  17 26 S1 29 27 S1 -   -  -  -   -  - 
1 11 0 -   -  -  -   -  -  -   -  -  7   26 S1 40  34 S2 9   12 S0 9   12 S0
2 12 0 -   -  -  -   -  -  -   -  -  5   23 S0 37  33 S2 15  17 S0 15  17 S0
3 13 0 -   -  -  -   -  -  -   -  -  7   18 S0 27  26 S0 12  14 S0 12  14 S0
4 14 0 -   -  -  -   -  -  -   -  -  5   05 S0 7   08 S0 -   -  -  -   -  - 
5 15 0 -   -  -  -   -  -  -   -  -  -   -  -  -   -  -  -   -  -  -   -  - 
6 16 0 -   -  -  -   -  -  -   -  -  1   18 S0 18  21 S0 -   -  -  -   -  - 
7 17 0 -   -  -  -   -  -  -   -  -  0   13 S0 11  23 S0 12  16 S0 12  16 S0
8 18 0 -   -  -  -   -  -  -   -  -  0   09 S0 7   20 S0 14  18 S0 14  18 S0
9 19 0 -   -  -  -   -  -  -   -  -  0   14 S0 5   16 S0 8   10 S0 8   10 S0
10 20 0 -   -  -  -   -  -  -   -  -  -   -  -  7   12 S0 7   09 S0 7   09 S0
11 21 0 -   -  -  -   -  -  -   -  -  -   -  -  6   11 S0 -   -  -  -   -  - 
12 22 0 -   -  -  -   -  -  -   -  -  2   07 S0 -   -  -  -   -  -  -   -  - 
13 23 0 -   -  -  -   -  -  -   -  -  -   -  -  -   -  -  -   -  -  -   -  - 
14 24 0 -   -  -  -   -  -  -   -  -  -   -  -  -   -  -  -   -  -  -   -  -