Recently I build a circular polarization feedhorn to try to do EME in 1296 MHz. The hint was that it have very easy to build and cheap. I was looking some designs based in ual mode septum designs from N2UO and RA3AQ but they not are easy to build for me. My idea has been use fireplace pipe and a dielectric depolarizer.
1296 Dual mode feedhorn
To build the feehorn I have used fireplace inox pipe of 150mm and a galvanized reduction from 250 to 150mm. The dielectric depolarizer is a piece of Rogers Duriod 5880. To try to minimize the number of sma connectors, I used a small piece of Suhner .141 as a probe that will connect directly to the LNA saver switch.
Building the RX probe
RX port probe
In the TX port I used a standard N connector. I measured the RL in the lab, but have to measure the RL in the dish for this reason the bottom plate not is soldered yet, it is glued using metalic tape, until the RL is adjusted on the dish.
Measuring return loss
Feedhon on the dish
Tonight, I was recording the Graves radar frequency (143.050 MHZ) to see I can detect the 2014 RC asteroid without success. But over a nice meteor has crossed Catalonia at the 04:56:50 UTC and has ben detected
The signal not is specially strong, because the target was very near from me. Using the Graves radar is more easy see meteors that are impacting from more remote locations of France or Italy
Other meteors can be observer before and after the target
The Graves radar uses a multibeam antenna system that is switched every 0.8 seconds. When a meteor is detected and prints a large trace, is easy to see the beam switching after the meteor.
Graves beam switching
As the Graves radar system uses the transmitter and receiver in different geographic locations, is easy to think that they are synchronized the the UTC.
To check if it is true Miguel EA4EOZ and me are doing stereo recordings stereo of the Graves radar in one channel and a 1PPS signal from a GPS receiver in the other channel. And efectively they are locked to the UTC
Graves radar 1PPS correlation
The coincidences to UTC are in the second 0,4,8,12,16,etc.. of every minute.
Some usefull info can be readed on the PE1ITR website.
PE1ITR, Greaves beam diagram
According to our team “The frequency offset is ~18025 Hz on Spectravue, so it looks likely. He’s tuned to XB, so just seeing the very tip of the PM carrier.”
Phil Karn KA9Q
Thank you for the timestamp, qth etc, and the info about the Spectravue
I examined the file anyway and worked out that a “stereo” signal was I and Q,
16-bits each, LSB first.
I confirm the signal as you found. I averaged small and large numbers of
FFTs. This showed that the signal strength varied, between approximately
11 to 16 dB-Hz. The spacecraft is spinning at about 3 rpm, so this may be
Attached is a typical plot from my my own software. This is not the strongest
signal display; the largest I found was a signal = -45.7 dB over the
noisefloor = -53.8 dB, or SNR = 8.1 dB.
With a bin bandwidth of 0.124 Hz, this equates to a CNR of 16.4 dB-Hz.
73 de James G3RUH
ISEE-3 signal processed by G3RUH
Finally after four days of attempts I detected the ISEE-3 / ICE space probe
I used the LHCP channel that is at 2217.5MHz becuse I have a lot of noise in the RHCP channel. I used a can feddhorn and a plexiglas depolarizer.
The signal is very weak and impossible to see without time integration. The offset reported by the Arecibo guys of 7202Hz has been very important to locate the probe. In my case I’m getting the probe with a carrier offset of 6035Hz from 2217.5MHz.
Here the first detection:
ISEE-3 / ICE Dection
After the detction, to confirm that I moved the dish 18deg, and the signal disappears:
ISEE-3 / ICE off center
To confirm again the signal I stoped the doppler compensation:
ISEE-3 / ICE no signal without the doppler compensation
Finally I started to compensate the doppler again and the signal is acquired again:
ISEE-3 / ICE with doppler corrected
To finally confirm at 100% a offline signal process without doppler compensation to see doppler signature. I used the amazing baudline autodrift option, it is a great feature to see signals with doppler:
ISEE-3 / ICE baudline autodrift
Here the IQ recording from Spectravue without the doppler compensation used in the baudline analysis. The sample rate is 8138 samples/sec:
The wind season is finishing, and now looks a good time to se new challenges. After a lot of years receving weak signals, looks that is a good time to try to transmit to the air my own signals. One of the most nice challenges for a amateur radio is bounce his signals to the moon, and do it in he microwaves segment looks more cool
Prodelin 1251 with 1296MHz feedhorn
Before to transmit something, I’m looking if I can receive signals. My first attempt has been in 1296MHz. I was build a feedhorn for with a bit of junk, use a LNA used before and a AOR AR5000 receiver with the WSJT software.
I1NDP left and HB9Q right signals and WSJT
The result was amazing, receiving nice signals. I was receive the big gun HB9Q with a very loud signal, audible in the receiver speaker!
After some hours finally I was copy this stations:
Now looks that will start to build a more efficient feedhorn and build the transmission side.
Detected the GAIA spacecraft travelling to the L2 point.
ESA GAIA Mission
The frequency is 8465 MHz and for the moment don’t have ephemeris from the JPL/Horizons or spice kernels. For the moment using the ephems from GBOT getting a aprox RA and DEC and using my own tools for full tracking.
Integrating the Yutu using baudline the signals recorded during the seperation from the Chang’e 3 you can see two signal variations. At the 20:27:31 UTC during two minutes aprox the signal was more weak and scince the 20:35:40 UTC the signal was boosted. Then the separation was before of the 20:40 UTC ?
Signal integration from the Yutu landing
Yesterday the Chang’e3 spacecraft andt the Yutu rover was landing successfuly. I was start to track the moon since the 18:30 to the 22:30 UTC. And I was listen Yutu from the start of my window and the signal was over 15dB of SN at 1Hz of BW. The frequency of the rover is 8462.08000MHz with the moon doppler of -0.6Hz/s of aprox. The signal was easy to listen in the earphones, and sounds like a some kind of morse.
For this event I was setup two receivers, as main a AOR AR5000 and Rfspace SDR14. As second receiver a rtl-sdr doongle with r820t tuner and baudline.
Yutu rover, using AR5000 + SDR14
Yutu rover using rtl-sdr + baudline
The command line to use rtlsdr with baudline was:
rtl_fm -g 44 -d0 -f$1 -s 250000 -F -U | ./baudline.static -stdin -samplerate 250000 -channels 1 -session rtlsdr1chUSB0 -basefrequency $1
Yutu rover using rtlsdr + baudline
Now you can listen how sounds the data stream from Yutu. A short audio record of the signal demodulated: