Monday, April 15, 2013

A Few More EME Contacts on 144 MHz

This weekend was a good one for EME (earth-moon-earth) contacts with my small two-yagi station!  On Saturday I managed to make 19 EME contacts, 16 of which were stations I hadn't contacted before.  Almost all of the stations contacted were 4-yagi stations.

UA3PTW KO93 Russia
KB8RQ EM79 USA - Ohio
RT4I LO43 Russia
ES3RF KO29 Estonia
RA6A KN96 Russia
UY0LL KN79 Ukraine
G4ZFJ JO01 United Kingdom
DL1RNW JO62 Germany
DK4RC JO60 Germany
DK2PH JO41 Germany
DL9GS JO31 Germany
DL4KUG JO64 Germany
DJ9MG JO52 Germany
SP4KM KO03 Poland
CT1HZE IM57 Portugal
VE2JWH FN35 Canada - Quebec
N7NW CN87 USA - Washington
WA3QPX FM29 USA - Maryland
JR3REX PM94 Japan

One thing that helped to make contacts this weekend was the presence of a 2 meter EME DX-pedition on 144.134 MHz: station 9G5EME has set up portable operation in Ghana.  This brought out a lot of EME operators, so with more people watching the moon this weekend, there were simply more out there to make contact with.  Conditions for EME were also pretty good:  the moon's elevation is fairly high above the horizon, and the moon comes up early enough (late morning here in California) that the European stations are still awake and active.

Some screenshots of the contacts are below.  Going clockwise around the desktop, in the upper left is the MAP65 spectal display, showing activity on the entire EME band from 144.106 MHz to 144.166 MHz.  To the right is the MAP65 stations window, showing what stations have been heard by that software.  Right of that is the astronomical data window, showing the position of the moon for my station and the DX station.  Below that is the spectral display for WSJT9 software, displaying a high-resolution spectrum on the frequency I'm actually operating on.  To the left is the MAP65 main window, showing stations decoded.  And to the left of that is the WSJT9 window also showing stations decoded.  The MAP65 software listens to the FUNCube Dongle Pro+ software-defined radio (SDR), and the WSJT9 software listens to the FT-817ND analog radio.  By using two separate radios (one SDR, one analog) it's possible to view the entire band activity at once, and still have high-quality decodes.

Here's KB8RQ, a very large station with 24 yagis:

And ES3RF, a 4x18 yagi station:

And CT1HZE, a very strong station:

Finally, I've updated the EME station block diagram:

Tuesday, April 2, 2013

Satellite AO-07 Spectrum Plots

Following on the screenshots of satellite VO-52's downlink spectrum (previous post), here are some photos of what Oscar 7's downlink looks like when viewed with a software-defined radio (the FUNCube Dongle Pro+).  AO-07 was in Mode B (UHF up, VHF down) at the time.

This particular pass (4/2/2013 1315z) was North to South:

And I started taking the screenshots when AO-07 was already high in elevation towards the east.   You can see the three strong "noise" bands (145.926, 145.941, and 145.958 MHz) of the satellite within the transponder downlink (145.924-145.964 MHz):

In this photo, a station can be seen calling CQ at around 145.950 MHz.  It's interesting to see how the SSB transmission affects the three noise bands.  We hear how excessive uplink power can cause the transponder to start "FMing", and this is a mild example of how a transmission in one part of the passband can affect signals in another:

In the next frame, you can still see the SSB transmission at 145.950 MHz, but you can also see an interesting "glitch" that affected the whole passband for around 15 seconds:

Some sort of signal (rapidly increasing in frequency) was heard by the satellite in the next photo, and you can see how it disrupted the three noise bands as it went by.  This is possibly another example of how the whole transponder passband can be affected by a single signal.  The "offending" signal is the orange diagonal line:

As AO-07 continued south, it's signal started to become weaker.  You can see my SSB CQ calls at 145.949, followed by a call in CQ below:

As the satellite got lower, signals were weaker, but my SSB CQ calls were still clearly visible:

Eventually the satellite was just a degree above the southern horizon:

And even then my SSB CQ call and CW ID is visible in the spectral plot:

When Oscar 7 got to -0.6 degrees (below the horizon), the three "noise bands" are entirely gone, along with any trace of signal from my uplink:

Monday, April 1, 2013

Satellite VO-52 with the FUNCube Dongle ProPlus

Tonight I took some screenshots of the SDR (software-defined-radio) that I use during the U/V satellite passes.  Since the VHF receive line is split between the FT-817ND and the FUNCube Dongle Pro+, I can run both radios at once and see (visually)what the entire downlink passband looks like during the pass.

This makes it really easy to see who else is on the satellite.  Without having to tune the main radio, I can just watch the waterfall display to see what activity there is.  It's simple to identify CW stations, stations tuning up, and SSB transmissions.

Here's a radar plot of tonight's pass (AOS at 4/2/2013 02:42z):

And here is the console display of the SDR program HDSDR.  Frequency control is in the lower left, the main waterfall is on the top, and the waterfall of decoded audio signals (a close-up of the main waterfall) is on the lower right.  The main waterfall covers from around 145.840 to 145.940 MHz.  The solid vertical traces are the local "birdies" coming from various sources of RFI in my area.  The waterfall flows from bottom to top, so the whole display is constantly "flowing" upwards.  Newest signals are at the bottom, and the vertical span of the waterfall covers around thirty seconds.

At the start of the satellite pass, the downlink is very quiet.  You can see my CW identification as a vertical streak around 145.905 MHz.  It's actually easy to identify, since it does not extend all the way from top to bottom like the birdies do.  VO-52 is only about 2 degrees above the horizon in the south at this point.

As the satellite gets up in elevation a few more degrees, you can now see me calling CQ in SSB around 145.905 MHz.  There's also a noise burst around 145.925 MHz.
The satellite is up around 10 degrees at this point, and my CQ calls in SSB are clearly visible:
Now that the satellite is around 25 degrees above the horizon, my CQ call in SSB (top) is followed by a CW ID (vertical line), and then another station answers my CQ but is slightly off frequency (about 3kHz below me).

It takes a little while for the other station and I to get lined up, you can see the patchy transmissions.  At this point the satellite is at a really high elevation and is moving pretty fast overhead, so doppler is playing a significant role.  The sloping vertical line on the left side of the waterfall is VO-52's CW beacon, slanted due to doppler shift.
We're now lined up, and have good strong signals.  You can clearly see the noise floor of VO-52's passband, it's the yellow-orange patch in the center of the waterfall from about 145.870 to 145.910 MHz:
As VO-52 continues north and descends towards the horizon, signals start to fade out:
Near the end of the pass, I spun the tuning dial as I was sending a string of dashes in CW, you can see the zig-zag pattern it makes.  This is typical of what a "tuner-upper" will look like on an SDR -- their CW will zig-zag through the passband until they (hopefully!) zero in on themselves:
As the satellite continued even lower towards the horizon (about 10 degrees by now), signals were pretty weak.  My SSB call is the smudge at around 145.903, and my CW ID's are the orange vertical lines below that.
This was a pretty quiet pass (only myself and one other station), but hopefully it will give you an idea of what a typical linear transponder satellite downlink "looks" like on an SDR display.

EME Progress - First Six Months

Here's a quick report as to how my small EME station is doing so far.  I started in October of 2012, and over the first six months of EME attempts I've been able to make 76 two-way contacts so far.  The contacts have included 58 "initials" (stations I haven't worked before), representing 19 countries, 13 US states, and 55 unique grid squares.

All contacts have been on 2 meters (144.110 to 144.160 is the EME sub-band), and using the JT65B digital protocol.  Software and hardware details are in the postings below, but mostly I use MAP65 for the contacts now.

With the small 2 x 2M7 antennas, I seem to be able to work stations as small as 4-yagi stations, although I've made contacts with two 2-yagi stations and one 1-yagi station.  Signal reports received at my end range from -16dB for the huge stations to -28dB for the smaller ones, but typically contacts are made at around the -22 to -25dB range.  Signal reports for my station coming back from the DX station's side ranged from -19 to -27dB, typically in the -23 to -25 dB range.

Most contacts have been made during the two weeks of the month when the moon is at elevations.  This seems to be primarily for two reasons:  1) there are more stations on when the moon is at higher elevations, and 2) my station sensitivity is much improved when the moon is above 40 degrees in elevation (due to local noise at the horizon).  QSO rate has ranged from zero over two weeks to several per hour during optimal conditions.

Here's the list of stations worked so far:

10/11/2012 HB9Q JN47 -19dB DX 120az/42el Switzerland
11/8/2012 DG9YIH JO32 -22dB DX 112az/32el Germany
11/8/2012 EA2AGZ IN91 -20dB DX 115az/35el Spain
11/10/2012 KB8RQ EM79 -16dB DX 119az/24el USA - Ohio
11/11/2012 WA3QPX FM29 -22dB DX 123az/21el USA - Maryland
11/11/2012 K1OR FN42 -24dB DX 135az/28el USA - Massachusetts
11/12/2012 W7GJ DN27 -21dB DX 127az/17el USA - Montana
11/26/2012 RK3FG KO86 -21dB DX 89az/23el Russia - Moscow
11/27/2012 UA3PTW KO93 -22dB DX 89az/28el Russia - Moscow
11/27/2012 I3MEK JN55 -22dB DX 104az/45el Italy
11/28/2012 K6MYC DM07 -26dB DX 92az/35el USA - California
12/1/2012 K9MRI EN70 -21dB DX 86az/28el USA - Indiana
12/1/2012 K1JT FN20 -25dB DX 109az/52el USA - New Jersey
12/2/2012 RX1AS KO48 -25dB DX 90az/30el Russia  
12/2/2012 DK3EE JO41 -18dB DX 104az/44el Germany
12/2/2012 DK3BU JO33 -21dB DX 107az/47el Germany
12/2/2012 W6BBS DM06 -23dB DX 268az/28el USA - California
12/16/2012 W7IUV DN07 -21dB DX 186az/39el USA - Washington
12/22/2012 OK1UGA JO80 -26dB DX 97az/31el Czech Republic
12/23/2012 KG7HF FN70 -29dB DX 210az/64el USA - New Hampshire
12/24/2012 S52LM JN65 -27dB DX 91az/29el Slovenia
12/25/2012 NC2V EL98 -25dB DX 88az/29el USA - Florida
12/25/2012 SM5CUI JO89 -25dB DX 91az/33el Sweden
12/31/2012 DK3WG JO72 -22dB DX 104az/36el Germany
12/31/2012 OK1RD JN79 -19dB DX 120az/49el Czech Republic
1/2/2013 PA0JMV JO21 -22dB DX 110az/29el Netherlands
1/2/2013 DK5SO JN58 -24dB DX 113az/31el Germany
1/13/2013 I2FAK JN45 -22dB DX 116az/14el Italy
1/13/2013 K5GW EM13 -20dB DX 173az/41el USA - Texas
1/17/2013 JE1TNL PM95 -25dB DX 241az/38el Japan
1/19/2013 SP4K KO03 -25dB DX 91az/27el Poland
1/19/2013 RU1AA KP40 -24dB DX 96az/33el Russia
1/20/2013 VK2KU QF55 -24dB DX 249az/49el Australia
1/21/2013 N9XG EN60 -22dB DX 161az/69el USA - Indiana
1/28/2013 DH3YAK JO31 -26dB DX 99az/25el Germany
1/28/2013 ES6RQ KO28 -20dB DX 102az/29el Estonia
1/28/2013 SP4MPB KO03 -27dB DX 104az/31el Spain
1/28/2013 SM7GVF JO77 -24dB DX 112az/39el Sweden
2/16/2013 G4SWX JO02 -23dB DX 93az/32el United Kingdom
2/16/2013 SM5DIC JO89 -24dB DX 98az/38el Sweden
2/17/2013 UR3EE KN88 -23dB DX 92az/34el Ukraine
2/18/2013 SM5CFS JO99 -23dB DX 77az/16el Sweden
2/20/2013 K5QE EM31 -23dB DX 124az/63el USA - Texas
3/3/2013 NZ5N EL96 -26dB DX 175az/32el USA - Florida
3/3/2013 NR5M EM10 -23dB DX 130az/33el USA - Texas
3/16/2013 AA7A DM43 -22dB DX 91az/31el USA - Arizona
3/16/2013 PA1GYS JO22 -24dB DX 93az/33el Netherlands
3/16/2013 PA2CHR JO32 -20dB DX 94az/34el Netherlands
3/16/2013 F1DUZ IN97 -25dB DX 95az/36el France
3/16/2013 OH7PI KP32 -23dB DX 99az/41el Finland
3/16/2013 R3BM KO85 -23dB DX 101az/43el Russia
3/16/2013 OH4LA KP20 -25dB DX 103az/45el Finland
3/16/2013 EA1YV IN52 -24dB DX 104az/46el Spain
3/16/2013 DD0VF JO61 -26dB DX 117az/56el Germany
3/16/2013 S51ZO JN86 -23dB DX 119az/57el Slovenia
3/16/2013 ON4KHG JO10 -25dB DX 122az/59el Belgium
3/17/2013 K9CT EN50 -26dB DX 88az/29el USA - Illinois
3/19/2013 JH8CMZ QN12 -23dB DX 198az/71el Japan

So far, I'm pretty happy with the performance of the system!  Thanks much to the W6YX team for all the tips in getting me started.