Friday, November 22, 2013

Having Fun with FUNcube!



Yesterday marked a successful launch of the UK's FUNcube amateur radio satellite.  The satellite contains both educational experiments and a linear transponder, and for these initial orbits the satellite is relaying telemetry containing data about the satellite's status (voltages, temperatures, etc).  The FUNcube designers have built software that will automatically read and decode the telemetry from an attached software-defined radio (the FUNcube Dongle Pro+), and relay this telemetry to a central data warehouse.  This way, students in the UK (and around the world) can see the status of the satellite in almost real-time!


Right before launch, I set up my home station with the software to record and upload the telemetry, and configured my satellite tracking program (SatPC32) to steer the antennas (a pair of VHF yagis) and track the satellite in the expected orbit.


The first visible pass of the satellite over California was around 9:30am yesterday morning, and all systems worked great!  Not only was the satellite operating perfectly, but the home station was able to decode and transmit its telemetry to the warehouse.  After the pass, I could see on the website that KB5WIA had uploaded 121 frames of data to the warehouse.



I'll leave the system tracking FUNcube for the next while, to add to the pool of satellite data that's being collected right now.  It's nice to be part of a truly global effort to help out with this satellite.  Fun stuff!

More details on the data being received at:
https://warehouse.funcube.org.uk/

And lots more details on the FUNcube project itself at:
http://funcube.org.uk/



Monday, November 18, 2013

Installing MAP65 and the FUNcube Pro+ for JT65 EME, Part II

Here is an updated article for installing the FUNcube Pro+ receiver and MAP65, this time without using Linrad.  In this article, we'll see how to install the system with the receiver providing direct input to the software.  The advantage?  Faster and much easier installation!


SUMMARY

A software-defined receiver coupled with MAP65 software will allow the amateur radio EME (Earth-Moon-Earth) operator to visualize the entire EME sub-band at once. This can be a great benefit to both small and large stations, since monitoring the entire spectrum simultaneously will tell you exactly where other EME stations (strong enough for your system to decode) are located.

This article describes how to install a FUNcube Pro+ (FCDPP) software defined radio (SDR) into an exisiting EME station.  It assumes that the operator is already familiar with EME exchanges using the JT65B protocol, has experience with WSJT software, and has basic EME station hardware.


HARDWARE

A typical EME-capable station will have a mast-mounted preamplifier, sequencer, and separate transmit and receive lines.  For my 144 MHz EME, I use two M-Squared (M2) 2M7 antennas coupled with a M2 power divider, feeding an Advanced Receiver Research (ARR SP144VDG) GAsFet premplifier with +24dB gain.  Received signal is sent through a separate receive coax (75' of RG-8/U) to a hybrid splitter combiner (ie. Mini-Circuits ZFSC 2-2 Power Splitter, 10-1000 MHz).  The FunCube Dongle Pro+ is connected directly to the output of the splitter, the other port goes directly to the analog radio.


Appropriate coax relays are controlled by a dedicated sequencer and protect the mast-mounted preamplifier and switch between the separate TX/RX lines.  I also found it helpful to add a dedicated coax relay to switch the input of the splitter to a 50-ohm dummy load during transmit; this also helps to prevent spurious JT65B decodes.  The main hardware list is as follows:

- Antenna(s)
- Sequencer
- Mast-Mounted LNA
- A/B coaxial RF relay at mast (high-power)
- Separate RX / TX lines.  RG-213 or RG-8/U is OK for RX side.
 - High power amplifier
- A/B coaxial RF relay in shack (low-power)
- 2 port hybrid splitter
- SDR (in this case, the FUNcube Dongle Pro+)
- Traditional transceiver and WSJT9 software
- Multi-Core CPU (MAP65 is more CPU intensive than WSJT)
- Second 1080p monitor (optional, but recommended)

If separate transmit and receive lines are not used, careful attention needs to be placed on protecting the FCDPP receiver from damage during transmit.  The configuration settings described below will likely need to be optimized if station hardware differs significantly from the above.  It should, however, provide a good starting point.


COMPUTER SETTINGS

A reasonably fast computer is required, and modern multi-core processors should be fine.  These instructions are written with the Windows 7 operating system in mind.  It helps to disable power saving options on the computer used to run the SDR.


INSTALLING THE FUNCUBE DONGLE PRO PLUS

Read the user manual for the FUNcube Dongle Pro+ (FCDPP) and install the software according to directions.  The main steps will be:
  • Obtain documentation at http://www.funcubedongle.com/?page_id=1225
  • Download FCHid (called FCD+ Frequency Control Program v2.002)
  • Download SDRSharp
  • Install both programs
  • Verify the FCDPP demodulates signals
  • Update the FCDPP firmware to latest
  • Verify (again) the FCDPP demodulates signals
The FUNcube Dongle can be attached directly to the computer's USB port, but some operators have reported that it's better to use a short USB extension cable.  This allows the FUNcube to be physically separated from the computer (reducing RF ingress) and also takes some of the strain off of the USB connector.  I have not seen any RFI issues myself, but use a 3-foot USB extension cable with a ferrite core.


Re-read your FCDPP user manual, and re-verify that it can hear signals with the SDRSharp software.  There's no point in continuing any further if you haven't got your receiver working!


CONFIGURING THE FUNCUBE DONGLE PRO+

You'll run the FUNcube Pro+ receiver using the FCHID program.  This program is the one you downloaded  earlier, called "FCD+ Frequency Control Program v2.002".  Start the program and enter your center frequency in the big black box in the upper left:




Next, boost up the IF gain a little (like 10dB), by clicking on the up-arrow next to the IF gain window.  Your FUNcube Dongle Pro+ is now sending an RF stream out via the soundcard port.


INSTALLING MAP65

Download and install MAP65 from Joe Taylor's website at http://www.physics.princeton.edu/pulsar/K1JT/map65.html.  Comprehensive installation directions (and a great manual!) are included on Joe's webpage, just follow them step by step.  Be sure to install to the path [C:\MAP65\].




CONFIGURING MAP65

Well next set up MAP65 to listen to the output from the FUNcube Dongle Pro+.  Start MAP65 and go to Setup > Options > I/O devices.




















Make sure the radio button next to SoundCard is selected.  Next, select the output from your FUNcube Dongle in the drop-down list.   Make sure the sample rate is set to 96000 Hz.

Now make sure that your MAP65 wide graph display shows the right frequency.  Check the Force Center Freq checkbox and enter the same value you had in your FUNcube control application (144.137).


Next, check to be sure MAP65 is receiving data.  You should see the bar graph on the left have some sort of display:


Verify your noise floor.  On my system, at this point, the noise floor on MAP65 will fluctuate around +21dB with antennas pointed away from noise sources into a cold sky.  It's also normal to see the noise levels go up by +8dB when the antennas are pointed towards the horizon in a suburban environment.

If your noise floor with the antennas pointed at cold sky is high (higher than +25dB), you should next to to the Windows audio control to turn down the audio gain of the FUNcube.  Choose Windows Start > Control Panel > Sound > Recording, and look for your FUNcube:




















Select this by double-clicking, then choose the Levels tab and decrease the audio level so that your MAP65 signal reads in the +20 to +30dB range.  I have my "gain" set to "6":




















Next, verify your preamp is functioning.  Turn off the mast-mounted preamplifier and verify that the noise floor drops significantly (at least 10dB, preferrably 20dB).  On my system, the noise floor drops to around +7dB when power to the external +24dB preamplifer is removed.

Adjust the NAvg on MAP65 to a value of 10, so that 1 minute of time corresponds to approximately 1cm of vertical space on the waterfall.  Averaging the lines (a slower waterfall) will help you see weak traces.

Zero the MAP65 waterfall brightness.  After zeroing, the waterfall should be a blue color.  I'll typically zero the waterfall with antennas pointed at the cold sky, so the color of the MAP65 waterfall can tell me how much local noise I'm seeing at any point in time:  Blue = nice and quiet; Green = Marginal; Orange and Red = only the big guns will get through!

Increase the gain on the MAP65 waterfall to 5 or so to get more "snow".  This will help you visualize weak traces better.

You can turn on MAP65's noise blanker if you'd like.  Personally, with my local noise environment, I don't see much impact one way or the other.  Keep the blanker from "eating" too much signal, so adjust it so it's less than 5 to 10%.

Verify the frequency display is correct.  Look for a birdie (or set of birdies) on the MAP65 wide screen waterfall.  Take a note of the frequencies, then tune your analog radio to the same frequency.  Verify that you can see the same birdies on both radios.  On my system, they are pretty close, about 40Hz apart.

Configure the MAP65 output to your analog radio (transmitter).  You'll need to specify the sound card output, and the COM port used to key the PTT line.  These should be the same settings that you are using in WSJT9 software.  Try calling CQ on an open frequency and verify that the MAP65 transmissions and levels seem correct.


IMPORTANT: Update MAP65's call3.txt.  Download the latest from http://www.mmmonvhf.de.  The program WSJTMerge from http://www.k2txb.com/WsjtMerge.htm can be used to merge an existing call3.txt file with the new one.  Also, if you're not in the Make More Miles on VHF Database http://www.mmmonvhf.de/dbase.php already, then you're potentially missing out on +4dB of coding gain because other EME stations may not have you in their own call3.txt files.  Be sure your call is in the call3.txt from this site.  It's difficult to stress how important this is -- if you're a small station, and you're not in the other station's call3.txt file, it's going to be much, much more difficult to have a QSO.

Make sure to turn on aggressive deep search in MAP65.

MAP65 has a Setup option to reduce the font size in the Astronomical Data window. Set it to something like 12 or 14 pt so you can see everything in the window.


USING THE SYSTEM

By now you have a system that is decoding JT65B signals on two separate radios:  the FCDPP and your traditional analog radio.  With the settings described above, the FUNcube Dongle Pro Plus should be about the same sensitivity (able to decode JT65B signals about as well) as your analog radio.


By running both MAP65 and WSJT9 simultaneously, you now have an even better ability to decode signals on the frequency you're looking at.  For example, if one of the two radios misses a decode (random noise, etc), the other one may pick it up.  You can also use one radio to check on the decodes of the other -- for example, seeing both radios decode the same message virtually rules out the chance of a false decode.

Moreover, you can now visualize the entire EME sub-band on the MAP65 waterfall, so you can quickly check other frequencies for active EME activity.  Even better, MAP65 has the band map / message list, and will decode stations that you're not even looking for (albeit, with slightly reduced sensitivity).



Importantly, using MAP65 you're no longer limited to finding stations calling CQ on the internet chat rooms.  You'll find stations that *your* station can hear, since by definition MAP65 is only going to report to you the stations that you're capable of receiving.  As a bonus, you can also quickly use MAP65, which displays the last 5-10 minutes of spectrum activity, to zero in on a station that you saw calling CQ in an internet chat room to see if you can find any traces of signal.

You can also use the two radio systems (analog and digital) for optimizing one or the other.  For example, you can experiment with different Linrad settings, or different filters, on the SDR side and make A/B comparisons with the decoding on the analog side.  Given the high degree of variability of EME decodes, having a direct A/B comparison greatly improves your ability to optimize one or the other.

Overall, the incorporation of an SDR and MAP65 into your station should greatly enhance your ability to make EME contacts, even with a smaller station.



ACKNOWLEDGEMENTS

Much assistance from the W6YX team is appreciated with regards to getting this system working!


REFERENCES AND NOTES

[1]  Ordering a FUNcube Dongle Pro Plus:  Howard Long G6LVB has ordering instructions on his website at http://www.funcubedongle.com/, look for the tab called "The New FUNcube Dongle Pro+", you can find out about how to order it right there.  When I ordered mine, there was a waiting list of a few weeks -- put in your name and Howard will send you an email telling you when yours is ready to order.  Pricing is on the website also, and proceeds from these units go to AMSAT-UK's FUNcube satellite project, so it's also for a very good cause.

[2]  The original version of this article, designed for those wishing to install Linrad as an intermediary between the FUNcube Dongle Pro+ and MAP65, is located here:  http://kb5wia.blogspot.com/2013/01/installing-map65-and-funcube-dongle-pro.html

[3]  I've written about optimization tips that have really helped me, as a small EME station, make contacts.  That article is located here: http://kb5wia.blogspot.com/2013/06/a-checklist-for-optimizing-small-144mhz.html







Thursday, October 31, 2013

EME: 28 Grids in 36 Hours!



This last weekend was the first (144 MHz leg) of the 2013 ARRL EME Contest.  The contest scores 100 points for each two-way QSO via the earth-moon-earth pass, multiplied by states / provinces / countries.  For this contest, I used the regular EME station (FT-817ND running WSJT9 software and the FunCube Dongle Pro Plus running MAP65 software), relying on MAP65 to find other stations across the EME sub-band (144.100 to 144.160 MHz).  It worked out pretty well!

The moon didn't rise above the local noise (= RFI from neigbor's houses) until 1:30am both days, so I worked at trying to make contacts from 1:30am to 6:30am, then again from 9:00am to moonset.  Staying up all night doing radio was rough, but still pretty exciting to be making so many EME contacts!  

Here's the list:

Num Call Grid Location
1 I2FAK JN45 Italy
2 PI9CM JO22 Netherlands
3 RU1AA KO48 Russia
4 OK1UGA JO80 Czech Republic
5 K9MRI EN70 USA - Indiana
6 UX0FF KN45 Ukraine
7 OK1DIX JN79 Czech Republic
8 UR7D KN18 Ukraine
9 3Z4EME KO03 Poland
10 DK9ZY JO40 Germany
11 DK3WG JO72 Germany
12 KB8RQ EM79 USA - Ohio
13 WS3Z FN20 USA - Pennsylvania
14 K1JT FN20 USA - New Jersey
15 AA4SC EM94 USA - South Carolina
16 AD4TJ FM08 USA - Virginia
17 KE7NR DM33 USA - Arizona
18 7K3LGC QM06 Japan
19 K6MYC DM07 USA - California
20 SK6EI JO68 Sweden
21 YT1AR KN03 Serbia
22 RK3FG KO86 Russia
23 SP2OFW JO82 Poland
24 VE1KG FN84 Canada - Nova Scotia
25 AA7A DM43 USA - Arizona
26 PA5MS JO21 Netherlands
27 K3RWR FM18 USA - Maryland
28 W2DBL FN20 USA - New Jersey
29 W7MEM DN17 USA - Idaho
30 NT0V EN08 USA - North Dakota

30 contacts beats my previous weekend record by 1 contact (previous was the DUBUS EME contest in the summer, there I managed to log 29 QSO's over the weekend).  What's interesting is the DUBUS contest allows station operators to find stations by any means (email, internet spotters, chat rooms, etc) ... yet I was actually able to make one more contact by completely relying on my own station.  Comparing the two contests, it seems that with a well-functioning station, the use of chat rooms / internet spots can become a distraction, rather than an aid.

A number of highights from the weekend:  Seeing K1JT Joe making contacts -- he's the Nobel Prize winner who developed the software that allows small stations like mine to "see" the signals reflected off the moon. Working K6MYC Mike, and seeing both his direct signals from a few hundred miles away, as well as his moon reflection at the same time.  Also making a few new contacts with stations that I hadn't worked before (SK6EI, 7K3LGC, W2DBL, OK1DIZ, 3Z4EME, PI9CM) was quite enjoyable.

I was discussing weekend's contacts with a neighbor, and they asked what the furthest station I had contacted was -- I answered either Russia or Japan, I'm not sure which is actually further from California.  To me, however, what's far more amazing than contacting another station several thousand miles away, is that these contacts were all made completely via moon reflections.  So -- the signal received in Japan actually went from my backyard, 250,000 miles through space, then reflected off the rocks and dust of the moon, then travelled 250,000 miles back through space, to be reached on the other side of Earth.  That's a half-million miles that the signals travelled!

Overall, it was a fun weekend.  It's pretty amazing to see how well earth-moon-earth communication works!

Dave

Sunday, September 15, 2013

September ARRL VHF Contest - Mt Vaca


For this year's ARRL September VHF Contest, I set up the portable system near the summit of Mt Vaca.  Mt Vaca is close to 3,000' in elevation and is located west of Sacramento in grid square CM88.  The mountain has good radio views of the surrounding San Francisco Bay Area and the Central Valley.  The ridgeline is accessed by the 5-mile long narrow, winding, Mix Canyon Road; near the top, a private road turns to the south to access the commercial radio towers, and I turned north for another mile along the dirt road to a relatively open spot along the ridgeline.

The equipment I used was the same as in the June 2013 VHF contest:  the Yaesu FT-817ND QRP all-mode transceiver, connected to a 2-element Diamond 6 meter beam for 50 MHz, a 4-element Arrow VHF yagi for 144 MHz, and a 15-element Diamond  UHF yagi for 432 MHz.  All three antennas were mounted on a 20-foot Buddipole mast that I set in the bed of the pickup truck.  I also brought along the Yaesu VX-6R and a 5-element 223 MHz yagi for 1.25m FM contacts.  Power came from the 6.4 Ah LiFePO4 battery that I've used for contesting in the past; four hours of operation didn't deplete the battery enough to need the solar panels that I normally use.

This contest was just casual operating -- in that I set up around 1pm on Saturday, and took the station down just after 5pm.  There were quite a few other stations out there.  Some of the best contacts were KK6BQU in the South Bay (he was with me in the June Diablo contest), and AL1VE and others on Mt Shasta in the relatively rare grid CN81.  It was also great to hear quite a few of the contest regulars out there!

BandQSOs Grids
50 21 7
144 31 8
223 11 4
432 21 7

The weather was just about perfect -- temperature in the low 80's and virtually no wind.  All in all, it was a fun day to be doing radio on top of a mountain!






Tuesday, August 6, 2013

RF Maps of the Sky, Continued...

Here are a few more of the RF Noise Maps that I have been creating.  Each one is made by sweeping the 2m antenna array in a grid pattern across the sky, and recording the absolute level of RF noise seen by the antennas and SDR receiver.  The noise is measured in decibels (dB), with an arbitrary setpoint of roughly 21dB for the lowest noise seen (the "cold sky").

The first map shows a typical morning.  In the lower left is a bright red blob, corresponding to high noise coming out of a neighboring house (across the street, a few houses down).  In the upper right, there's a mild source of noise centered exactly around where the sun is located in the sky.  The cold sky in the upper left, away from most noise sources, is in the low 20's.


The next one was recorded during an evening when many TV's, fluorescent lamps, microwaves, and toaster ovens must have been running - there's very high noise near the horizon in all directions.


Next we have a nice morning with very low noise levels.  The sky is a very dark blue, indicating low RF signals at higher elevations.  Even the lower elevations have a nice (relatively!) low noise level.  My radios (and associated computer equipment) are located at 270 degrees azimuth on this map, and it's possible to see the orange "blob" from the RF that the computers, internet router, etc give off.


Next is a map created just as the sun appeared over the hills to the east in a July morning.  Accompanying the sunrise was a huge amount of radio noise that obliterated all EME reception right away.  Notice the huge red blob surrounding the sun in the sky, as viewed by the antennas:


One could argue that it's not sun noise at all in the lower right of the above plot.  Maybe it's my neighbor's TV?  Well, if we hypothesize that the noise is coming from the sun, then if we look at the same sky a few hours later, the noise should have moved and followed the sun.  This is exactly what we see, in the following plot from later on that morning:


Was the sun that noisy all day?  I took a reading a few hours later, and while there is still noise centered around the sun, the level has gone down quite a bit.  You can also see that my RF-generating neighbors at 248 degrees still have their noise going, and my neighbors to the south have turned something on as well:


The last plot is from a later July morning, with sun just coming over the hill but with little associated noise on that day.


The neighbor to the south at 180 degrees has whatever RF-noise box running, but on the whole noise levels are fairly low across the sky at 40 degrees elevation and above.

By way of reference, to hear a 4-yagi EME station, I pretty much need to have the Rf noise levels at that azimuth and elevation to be at 24dB or below (green or blue in the above plots).  When the noise is above 24dB (yellow, orange, and red in the plots above), I can only hear the strongest of the EME stations.

One nice thing about these plots is it lets me compare the local RF-noise environment from day to day, on a more or less absolute basis.  It helps to identify sources of noise, and to determine which noise sources are constant and which change over time.  It also helps to predict the best times and directions with which to listen for EME signals. Finally, it serves as a "reality check" that helps to verify system performance -- even if there's high noise that suddenly appears in one direction, by mapping the sky and seeing the rest of the noise levels are as expected, I can attribute the noise to a particular source rather than a system malfunction.

An example Excel 2003 spreadsheet that has these maps, and the macro that generates the color coding, is available here.  My previous post on this subject is located here.

Thursday, August 1, 2013

2013 Digital EME Contest



This was my first EME (earth-moon-earth) contest and I had a lot of fun but not much sleep!  The moon rose above my local hills past midnight local time, so on both days I was up the whole night long trying to make contacts.  The contest involved trying to make as many different contacts on the 2-meter (144 MHz) band as possible, using digital modes, and with one strict requirement:  all contacts must be complete two-way exchanges using only signals reflected off of the moon.

Out of the 29 QSO's, eight were new initials (stations not previously worked), including a new country (Uruguay) and two US states.  The most exciting contact was a local California station (Stanford W6YX), with very strong direct signals but also with a very weak lunar echo trace visible. Once the lunar echo was strong enough to decode, we could complete the QSO!

Below is the contest log:

Date            Time    Call    Grid    Sent    Rec'd
7/27/2013       6:50    UA3PTW  KO93    "O"     "O"
7/27/2013       7:56    I2FAK   JN45    "O"     "O"
7/27/2013       8:14    EB5EEO  IM98    "O"     "O"
7/27/2013       8:51    I3MEK   JN55    "O"     "O"
7/27/2013       8:57    DD0VF   JO61    "O"     "O"
7/27/2013       9:15    DL4KUG  JO64    "O"     "O"
7/27/2013       9:51    CX2SC   GF25    "O"     "O"
7/27/2013       10:05   WZ5Q    EM30    "O"     "O"
7/27/2013       10:18   CT1HZE  IM57    "O"     "O"
7/27/2013       10:49   K3RWR   FM18    "O"     "O"
7/27/2013       10:55   NZ5N    EL96    "O"     "O"
7/27/2013       11:06   AD4TJ   FM08    "O"     "O"
7/27/2013       13:43   K9MRI   EN70    "O"     "O"
7/27/2013       14:05   VK5APN  PF95    "O"     "O"
7/27/2013       15:01   W8WN    EM77    "O"     "O"
7/27/2013       15:25   KD9NH   EN44    "O"     "O"
7/27/2013       16:50   HL5QO   PM42    "O"     "O"
7/28/2013       7:18    HB9Q    JN47    "O"     "O"
7/28/2013       8:16    RU1MS   KO48    "O"     "O"
7/28/2013       9:01    OK1KIR  JO70    "O"     "O"
7/28/2013       9:11    UR7D    KN18    "O"     "O"
7/28/2013       9:15    F1DUZ   IN97    "O"     "O"
7/28/2013       9:44    G4SWX   JO02    "O"     "O"
7/28/2013       10:19   SM4GGC  JO69    "O"     "O"
7/28/2013       13:53   KE7NR   DM33    "O"     "O"
7/28/2013       14:00   VE1KG   FN84    "O"     "O"
7/28/2013       15:41   JA5EEU  PM63    "O"     "O"
7/28/2013       16:49   K5DNL   EM15    "O"     "O"
7/28/2013       17:36   W6YX    CM87    "O"     "O"

Here is a screenshot from a typical QSO.  This one is with VK5APN in Australia.  At 1402z you can see the trace that decoded as KB5WIA VK5APN PF95, when he replied to my CQ call.  At 1404z you can see the characteristic shorthand notation of "RO", where he acknowledged my OOO signal report.  And at 1406z you can see the shorthand notation for "73", indication completion of the QSO.  The lower left window is the WSJT9 software display from the FT-817ND analog radio, and the middle window is the MAP65 display from the FunCube Dongle Pro+ software-defined radio.


And next is a screenshot of the W6YX QSO.  In the SpecJT waterfall window, you can see the strong direct terrestrial JT65B signals clearly at about DF=80Hz.  At around -285Hz you can see a very faint trace, which decoded as KB5WIA W6YX CM87 at time 1731z.  The dT of the decoded trace is 2.0 seconds, in line with the expected 2.5-second round-trip of radio signals to the moon and back (the WSJT9 software clock is about 0.5 seconds behind the MAP65 clock, you can see this in the VK5APN windows above).  The Astronomical Data window in the upper right shows that the expected doppler shift between KB5WIA and W6YX was -369Hz at that instant.  The observed doppler shift of the faint trace is -285Hz - 80Hz = -365Hz, pretty much exactly as expected and further confirming the weak trace as a lunar echo.  Also of interest is the diagonal trace at 1733z, veering off the main sync line to the upper left; this is likely an airplane echo, doppler-shifted by the relative speed of the aircraft between the two stations.  To me, these QSO's are even more fascinating than EME DX contacts to the other side of the world -- since you can literally "see" the radios hearing signals coming direct through the air, the signals bouncing off of airplanes, and signals literally bouncing off the moon.















The MAP65 waterfall display (receiving signals from the FunCube Dongle Pro+) was really useful -- it helped to keep an eye on what signals were strong enough for easy decodes, and at times the messages display was full of QSO information.



All in all, it was a fun contest!  I'm pretty happy to make 29 unique QSO's via radio signals reflected off the moon, all in a single weekend!



Saturday, June 29, 2013

A Checklist for Optimizing JT65B and WSJT9 144MHz EME Stations

Introduction

A year ago I would not have believed it to be possible to work over a hundred different EME stations in a span of 8 months, all with just two short yagis.  I have worked ham radio satellites for a number of years now, and have recently become active in 144 MHz EME (Earth-Moon-Earth) radio contacts.  Each one of these contacts is exciting, since it involves signals carried all the way from my backyard, to the moon, and then back to some distant point on earth.  Since I don't have much physical space for antennas, I have had to spend much time optimizing my small JT65B / WSJT9 EME station for maximal performance (with the valuable assistance of the W6YX team).  I have listed many of the optimization tips below.  By following these guidelines, it should be possible to work many dozens of EME stations, even with a small station.

I have ordered the optimization tips spatially, to preserve clarity and flow.  The tips start with antennas, then move to the feedlines, then to the transceivers, then to the computer and software, then to the human side of operating the software and attempting EME.  For each tip, I have included my own personal "ranking" as to how important they are.  Some are nice-to-have (Very Useful), whereas others are so important that if you skip them, you will certainly miss out on many contacts (Critical!!).  As with all lists, this one too will be subject to change.  It's based on what I consider important after learning enough to contact the hundred-plus EME stations so far; I'm far from finished learning, so no doubt the list will change in the future.

Enjoy!

Dave KB5WIA



















Hardware: Antennas: Gain
Importance:  Very Important
Use the maximum antenna gain possible.  Why?  EME signals are weak!  Every additional dB of gain you can obtain from the antennas will help out.   Use modern antenna designs, pay careful attention to the manufacturer's recommendations for spacing and mounting, and avoid interactions with crossbooms, other antennas, or the feedlines.

Hardware: Antennas: Polarization
Importance:  Very Important
Use linear polarization.  Why?  On bands 432 MHz and below, the convention is to use linear polarization, not circular polarization.  Circular polarization results in a 3dB reduction in signals of linear polarization.  Unless you are using dual horizontal / vertical polarization, you will need to wait for Faraday rotation to line up signals for optimum reception, this will take from a few minutes to an hour or more.  Patience is a virtue with EME.

Hardware: Antennas: Preamplifier
Importance:  Very Important
Use a low-noise preamp (LNA) at the antenna if possible.  Why?  By boosting the signal immediately after the antenna, you can reduce or eliminate the effects of cable losses on your received signals.  Keep the preamp at the antenna, since any loss between the antenna and the preamp will add directly to your noise figure.

Hardware: Rotator Type
Importance:  Important
Try to use a two-axis rotator.  Why?  If you don't have elevation control on your rotator, you are going to be limited to attempting EME with the moon close to the horizon, typically where most environmental RF noise is located.  By being able to elevate your antennas towards a high moon elevation, you can significantly extend your moon operating time, and therefore improve your chances of EME contacts.

Hardware:  Feedline Quality
Importance:  Important
Use the lowest loss feedline you can afford with a minimal number of connectors.  Why?  Again, on EME, every dB counts.  You do not want to lose signal in the feedline.  Note that if you have a LNA at the antenna, the effects of feedline losses on receive are minimized.  Unless the amplifier is at the tower, however, using high-quality low-loss feedline will prevent your transmitted signal from being wasted as heat.

Hardware:  Separate Feedlines and Sequencer
Importance:  Very Useful
Use separate RX and TX feedlines with a dedicated sequencer if you can.  Why?  Having a dedicated RX feedline will let you split off some of the received signal to a SDR (software defined radio) if you desire.  Having a dedicated TX feedline and sequencer will let you bypass the preamplifier and SDR entirely on transmit, to prevent system damage.

Hardware:  Transmitter:  Stability
Importance:  Very Important
Avoid frequency drift in your transmitter.  Why?  Transmitters will change in frequency as they heat up, and JT65B transmissions can generate a lot of heat.  Frequency drift can make decoding impossible, or force both stations to have to turn on AFC which results in a modest reduction in coding "gain".  By having a stable frequency (install a TCXO if necessary) you can improve chances of decodes.

Hardware:  Transmitter:  Power
Importance:  Very Important
Have the ability to use as much power as possible to complete the contact.  Why?  Since every dB counts, the more power you have, the more chance of successful decodes at the DX station.  A 600W amp will improve your signal at the other station by 3dB over a 300W amp, all other things being equal.  A 1.2kW amp will improve your signal by 6dB.

Hardware:  Receiver:  Noise Blanker
Importance:  Important
Use your receiver's noise blanker.  Why?  EME signals are very weak, and using your receiver's noise blanker can help remove interfering signals that could reduce your receiver's sensitivity.  If your noise blanker has variable settings, use a "light" setting to prevent blanking out the desired signals.

Hardware:  Receiver:  Software Defined Radio (SDR)
Importance:  Very Useful
Use a SDR if possible.  Why?  With an SDR and MAP65 software, you can monitor the entire EME sub-band (144.105 to 144.165) at once, allowing you to immediately spot stations that your antennas can hear.  This can multiply your chances of a successful EME QSO, since you will be less likely to miss seeing another station calling CQ.  Quality SDR's are relatively inexpensive these days.  [Example: The FunCube Dongle Pro+, can be installed with Linrad and MAP65].

Environment:  Obstructions
Importance:  Important
Be aware of nearby objects that will block the antenna's view of the moon.  Why?  If the antennas can't see the moon, they can't see EME signals!  Obvious factors are mountains and neighboring houses.  Less obvious factors are trees, which can significantly attenuate the already weak EME signals.

Environment:  Background Radio Noise:  Your own home
Importance:  Critical!!
Turn off all devices that cause RFI.  Why?  Any devices adding to your baseline noise level will directly reduce your sensitivity.  For weak EME signals, a simple defective switching power supply can completely destroy your ability to hear other stations.  Almost every home has devices that cause radio interference.  Turn off circuits one-by-one to find these devices.  Eliminate the noise by shutting them down, replacing them, or adding ferrite chokes to the input/output leads.

Environment:  Background Radio Noise: Nearby Noise
Importance:  Very Important
Know your surrounding radio noise levels.  Why?  You can't eliminate RFI coming from your neighbors, but you can avoid it.  Watch your meters as antennas are raised above horizon, and take note of how different antenna directions and elevations relate to your ambient noise levels.  Plan for best operating conditions when the moon is high enough that your antennas can be up and out of the noise.

Environment:  Ground Gain
Importance:  Important
Understand ground gain and how you can use it to your advantage.  Why?  You can pick up an extra few dB by capturing the signals reflected off the ground at low moon elevations!  This is potentially equivalent to doubling your power output, or doubling the size or number of your antennas.  Of course if you have high RFI at the horizon, you can't take advantage of your own QTH ground gain ... but you can still use the DX station's. Simply use the Astronomical Data in WSJT9 or MAP65 software to monitor the DX station's moon elevation.  Very often you'll see signals come up when the DX station has low moon and is experiencing ground gain effects.

Protocol:  Communications Mode
Importance:  Important
Plan to operate with mode JT65B rather than CW or voice when starting out.  Why?  EME signals are extremely weak, and a small EME station will only be able to hear (by ear) the largest of the EME stations.  This pretty much entirely rules out SSB voice communications, and also rules out CW communications.  The JT65 modes by Joe Taylor K1JT provide 10 to 15 dB better signal-to-noise than CW, and are what make small-station EME possible.   (That being said, once you have experience, go ahead and try for the thrill of working the big stations by CW.  It's not easy, but it's possible!).

Computer:  Sound Card Interface
Importance:  Important
Ensure that robust audio signals are reaching the computer's sound card.  Why?  You want to have your radio's audio signals significantly above the background noise level of the computer's sound card.  Feeding too low an audio level to the PC will result in more difficult decodes.

Computer: Clock Synchronization
Importance:  Critical!!
Ensure your computer clock is accurate to within a fraction of a second.  Why?  If your clock is off, you will have difficulty identifying valid decodes (which will have a dT of approximately 2.6 seconds).  In addition, your CQ calls will not be published by the automated spotting network LiveCQ.eu, which uses the dT value to differentiate between EME and tropo spots.  BKtTimeSync by IZ2BKT works well to keep your clock synchronized, set your time server to pool.ntp.org with a sync of every 15 mins.

Computer:  Read the manual
Importance:  Absolutely Critical!!
Read the WSJT9 manual.  Once you've read it, read it again.  Why?  The WSJT manual is a great resource that covers in great detail how the software works and how to use it.  Small stations need every advantage they can get, so don't shortchange yourself by missing out on knowledge that's located in the manual.

Computer: WSJT9 Software: Sampling Rate
Importance:  Very Important
Ensure no sampling rate errors.  Why?  If your computer soundcard has problems with sampling rate, you will have significant problems decoding stations, and other stations may have significant problems decoding you.  The sampling rate values in the lower left of the software should be in the range of 0.9995 to 1.0005.

Computer: WSJT9 Software: Noise Floor
Importance:  Important
Adjust the slider on waterfall to zero the RX noise floor.  Why?  You need to keep the decoder working within a reasonable signal range.  Adjust the slider to zero depending on your ambient RF noise conditions.

Computer: WSJT9 Software: Waterfall Speed
Importance:  Very Important
Adjust the waterfall speed in the WSJT9 software to "3".  Why?  JT65B is a visual mode, so you need to optimize your software display for the best visual signal-to-noise possible.  Using a slower waterfall speed will help you identify EME traces.  Also be sure to select "Flatten Spectra" in the SpecJT options, it's not set by default and helps improve your ability to see signals.  These steps are often overlooked, so spend time adjusting the waterfall settings for maximum visual sensitivity; a properly optimized waterfall will have snow and a light green tint to it.

Computer: WSJT9 Software: Sync Value
Importance:  Critical!!
Set the Sync Value to 0 or below.  Why?  Values equal to or less than zero set maximum Sync sensitivity.  If you do not have maximum sensitivity, you will see traces but miss decodes.  All values from 0 and below are technically equivalent, so any number -1 or less will work.  Some operators set a large negative number here, just to avoid the chance of accidentally clicking this value upwards past zero.

Computer: WSJT9 Software: Deep Search
Importance:  Critical!!
Turn Deep Search on.  Why?  Deep search decoder provides an additional +4dB of coding gain.  Without it you are seriously limiting your chances of a successful EME contact.  Once you become familiar with discriminating real from false decodes, turn Aggressive Deep Search on for further sensitivity.  And remember that for Deep Search to work, you must have an updated call3.txt file (see below).

Operating:  Practice files
Importance:  Critical!!
Practice using WSJT9 software using the practice JT65B .wav files.  Why?  It's very important to know how to use the software.  WSJT9 is powerful and not immediately intuitive, but with practice (and careful attention to the free manual) you can be comfortable using it.  Learn how to use the Freeze, the Tol, the AFC and the ZAP functions.  Learn how to read the short-hand signals for RO, OOO, and 73.  If you don't know how to use the software, there is no point in attempting EME.

Operating: Your call in the call3.txt file
Importance:  Critical!!
Make sure you're in the other party's call3.txt file.  Why?  If you're not in the other station's call3.txt file, you're effectively losing over half (-4dB) of your transmit power via the missing coding gain at the receive station.  Be sure to register at Make More Miles on VHF and add your call to the call3.txt database.  It's hard to stress this enough:  be sure to register your call, grid, and check the box that says you're an EME operator.

Operating: Update your call3.txt file frequently
Importance:  Critical!!
Be sure to update your own call3.txt file immediately after installing WSJT software, and frequently thereafter.  Why?   If the other station's call and grid is not in your Call3.txt file, you'll lose -4dB of coding gain, equivalent to more than cutting your antennas in half.  The default call3.txt file in the WSJT9 download is very much out of date, so frequently download the latest call3.txt file from www.mmmonvhf.de or www.livecq.eu/call3.  To keep your own call3.txt file up to date without losing the calls you've manually added, use wsjtmerge.exe to merge the new call3 to your existing call3.

Operating: Check your call3.txt file for every QSO
Importance:  Critical!!
Always make sure other station is in your call3.txt.  Why?  Many stations who you see on the moon may not have added themselves to the mmmonvhf.de database, so they won't be in your call3.txt.  You don't want to accidentally lose that 4dB of coding gain!  If you are calling another station, check to be sure they're in your call3.txt file by looking them up in the "To Radio" box of WSJT9 software.

Operating:  Know how to  adjust for Doppler  on 432 and 1296 MHz
Importance:  Critical on 432MHz and above!!
Be sure to follow the proper Doppler adjustment convention on 432MHz and above.  Why?  If you don't adjust for Doppler, you may not be looking in the right place and may miss callers entirely.  In the  Main  WSJT window, click View > Astronomical Data.   The "Self Dop" value is  how many Hertz away from your transmit frequency you should be receiving. This is offset is also  referred to as your self  echo frequency. You may use your RIT or split  A/B  VFO  to achieve this.   (On 144 MHz, Doppler will not shift received signals out of the audio passband of your transceiver, so it's not as much of a concern.)

Operating:  Start thinking in dB
Importance:  Very Useful
Stop thinking of signals in terms of S-meter readings and instead in terms of dB.  Why?  Decibel units, displayed for decoded signals in the WSJT9 and MAP65 software, have real-world value!  For example, if you just barely work a station at -27 dB signal strength, then you can imagine if you double your antennas (adding 3dB) you could have worked that station much easier at -24 dB.  Or, if you see on a spotter that your CQ was decoded at -25 dB and you're running 300W, if you went to 600W (3dB more) you'd likely have been decoded at -22 dB.  Thinking in terms of dB helps put many aspects of EME operation into perspective.

Operating:  Best days to operate
Importance:  Important
Learn how the moon's position in the sky during a month affects EME activity.  Why?  Some days have many EME operators who are calling CQ or listening to the moon, other days have very few.  If you try to operate on high activity days, you will significantly improve your chances of hearing or being heard.  The moon's orbit is inclined relative to the earth's, so the moon alternates from being low in the sky to being high in the sky every two weeks.  There are many more operators out in the two weeks of high moon elevations.  Similarly, at new moon (next to the sun), many operators avoid EME, as well as when the moon is near high galactic noise sources.  Such physical conditions don't diminish a small operator's chances of EME nearly as much as the reduced turnout of EME operators does.  [Reference: The MMMonVHF EME Propagation Predictor has a nice graph of moon declination]

Operating:  Best hours to operate
Importance:  Important
Learn how EME activities vary during the day.  Why?  You will have much more success finding stations when they're a) awake and b) can see the moon!  For example, Europe has many active EME operators, but they naturally will be mostly asleep at 2300z to 0600z.  In addition, as the earth rotates "underneath" the moon, some regions will lose moon visibility and some will gain it.  Activity on EME will ebb and flow during the day according to sleep and visibility patterns.

Operating:  Understand the impact of the degradation value
Importance:  Important
If you're a single polarity station, don't worry much about the Degradation number in the software.  Why?  The calculated degradation in the moon signals varies by just a few dB for most days of the month.  On the other hand, your signals can vary up to -20dB due to polarity mismatches between you and the DX station.  Since the effects of Degradation are small with respect to the effects of Faraday Rotation, don't let the Degradation values scare you away from operating.

Operating: Finding active stations
Importance:  Very Important
Use the LiveCQ.eu spotter to find active frequencies and relative signal strengths.  Why?  Unless you are running MAP65 and can monitor the whole EME band for yourself, it's fruitless to try to scan across the band tuning for JT65B signals; they're too weak to hear.  If you stick to LiveCQ.eu, you can see who is "on the moon" in real-time, what their calling frequencies are, and how strong they are heard at other stations.   Use caution when looking for stations calling CQ via an EME chat (ie. N0UK EME Logger).   Chats may have very small stations advertising calling CQ (that you're unlikely to hear), or operators with incorrect settings, or operators who announce calling CQ but then discontinue without updating the chat.

Operating: Recognizing EME traces
Importance:  Very Important
Recognizing EME traces is a useful skill.  Why?  It allows you to tighten the decode window around the particular trace, improving decodes by eliminating interfering signals.  EME traces have a characteristic start (:00 seconds) and stop (:50 seconds) times, a characteristic brightness (varying brightness over time), a characteristic width (about 3 to 5 Hz), and a characteristic period (every second minute).  Skill in identifying potential EME traces (and differentiating them from noise) will help you to find signals.

Operating:  Traces that won't decode
Importance:  Very Important
Know what to do when seemingly strong EME traces don't decode.  Why?  Strong EME signal traces that don't decode are most commonly caused by three things: 1) the message is part of a QSO between other parties (ie. N1XYZ observes W6YX KB5WIA CM88 OOO) and does not invoke Deep Search.  2) operator error on the other end.  3) operator error on your end.  If you recognize an EME trace and it unexpectedly does not decode, it should be a big clue that you need to go back and check your settings!

Operating:  Recognizing false and true decodes
Importance:  Very Important
Knowing the difference between true and false decodes is important.  Why?  You don't want to waste time calling a station who never called you in the first place!  When you see a decode, ask yourself:  a) do I expect to see the other station calling me? b) does the other station see the moon at this time?  c) does the dT of the signal match  an EME signal (2-3 seconds)?  d) does the width of the trace match an expected EME signal (3-5 Hz)?  If in doubt, simply wait one more cycle and see if the same decode comes up.  The odds of a false decode are slim, and the odds of two identical false decodes are virtually nil.

Operating:  Persistence
Importance:  Critical!!
Be persistent when trying to contact another EME station.  Why?  EME propagation is not like terrestrial VHF!  EME propagation changes from minute to minute, is often unpredictable, and can include "one-way" propagation.  Just because you call someone five times and do not hear back from them does not necessarily mean that they cannot hear you, nor that you will not hear them on the next cycle.  Sometimes it takes many cycles of calling before conditions (ie. Faraday rotation) line up favorably for you to make a contact.

Operating:  Don't be afraid to call CQ
Importance:  Very Important
Call CQ as much as you can.  Why?  Just because you don't see other stations calling CQ yourself, or on the Internet, doesn't mean that there aren't other stations listening to the moon.  It is guaranteed they will never hear you if you don't call CQ!  Call CQ often, since there are very frequently many more stations listening than you will be aware of.

Operating:  Chat rooms
Importance:  Important
Don't become reliant on chat rooms to complete your QSOs.  Why?  First, exchanging any information about your QSO prior to completion will invalidate the QSO.  Secondly, if you have to depend on the other station telling you about the QSO status via the internet, then you aren't doing EME communications.  It's fine to announce that you're calling CQ in the chat room, and to give the other station a signal report after the QSO is finished.  Finally, all hams can relate to the unexpected thrill of having a DX station unexpectedly replying to your CQ -- don't let internet chat rooms diminish this joy!


Summary

It's quite possible for ham-radio operators to make contacts via the Earth-Moon-Earth path, even with a smaller station of no more than a 10-foot yagi and 100 watts of power.  However, since with small stations there is very little margin for signal reductions, no stone should be left unturned when attempting to optimize the station.

My own experience has shown with the above optimization tips, a small station with two ten-foot yagis and 500 to 1000W of power on 144MHz is capable of working at least 100 different EME stations in a relatively short period of time.