|Satellite Frequency Chart||RS-12||RS-13|
|15m Uplink (Modes K&T)||21.210 - 21.250 MHz||21.260 - 21.300 MHz|
|2m Uplink (Mode A)||145.910 - 145.950 MHz||145.960 - 146.000 MHz|
|10m Downlink (Modes K&A)||29.410 - 29.450 MHz||29.460 - 29.500 MHz|
|2m Downlink (Mode T)||145.910 - 145.950 MHz||145.960 - 146.000 MHz|
|10m Beacons||29.408 & 29.454 MHz||29.458 & 29.504 MHz|
|2m Beacons||145.912 & 145.958 MHz||145.862 & 145.908 MHz|
|ROBOT Uplinks||21.129 & 145.831 MHz||21.139 & 145.840 MHz|
To operate in "Mode A" you would require a 2 meter SSB or CW transmitter and a 10 meter receiver. For "Mode K" you would need either two radios with two antennas or one radio with the capability to switch between two different frequencies on two seperate bands. Those bands being 15 meter transmit and 10 meter receive. The more rare "Mode T" requires a 15 meter transmitter and a 2 meter capable receiver. Sometimes the modes and thusly the frequencies are combined; those being "Mode KT" and "Mode KA". (It is important to note that in the US, Technician and above licensees can utilize Mode A, but to use Mode K or Mode T, an Advanced or Extra class license is required.)
Many hams work the RS-12/13 satellites with little more than a dipole or
vertical antenna. In fact, I have had many QSOs with 5 watts and a vertical,
but it does take a little practice. On Mode A, 25-50 watts is usually
sufficient into an omnidirectional antenna. A dipole will work just fine for
reception, but many have found a full wave horizontal loop to be the best. A
beam is a plus, but it also requires learning how to turn the rotor in QSO.
No "special" equipment is required other than a computer to figure the
satellite's "track" or 'when the satellite will be in range'. Running the
"keplerian elements" or the numbers to calculate position is the same as for
any other satellite. Or you can get them e-mailed to you from the NASA website.
They have a service called J-Pass. Just click on the link below to go there and
sign up. You will need to know your latitude and longitude, (which can be obtained
from Buckmaster's or
QRZ callsign servers) if your city or one close
to you is not listed. Also you will have to enter your time zone and some e-mail
preferences. You will need to choose the RS-12/13 satellite and any others you may
wish to track. Then J-Pass will send you e-mail updates of the satellite's passes
over your location.
CLICK HERE TO REGISTER WITH J-PASS E-MAIL SERVICE
Which leads us to awards. The reason for exchanging grid squares is that many stations are competing for awards for a certain number of grid squares, usually 100 or more for VUCC (VHF UHF Century Club). Its very similar to DXCC when chasing DX. Others may be trying for Worked All States, or any one of many specialized satellite awards offered by various AMSAT clubs. But many just enjoy the thrill of working another station through a man-made object, completely independent of propagation! However, sometimes propagation does come into play since these satellites utilize HF frequencies! More on this exciting facet later...
One note on QSLing. When sending a QSL for a satellite QSO, it is considered a courtesy to write in your grid square, if it is not already printed. And to state the satellite name and mode of operation. For instance, on my cards I write in 21/29 under MHz signifying Mode K, or I could just write in "Mode K". And under Mode, I write CW/RS-13 or whatever is appropriate.
Doppler Shift happens to radio waves just as it does to a train whistle or a siren as they pass by. It causes the frequency to rise and fall. With the satellite, it just seems like the other guy has an older radio with a real bad drifting problem! But seriously, as a signal goes up to the satellite it is affected and again as it is retransmitted back down it is affected, so it is not as simple as the siren or train whistle analogy. Suffice it to say that frequencies tend to drift as the satellite passes over, and stations constantly have to adjust frequency. But which frequency do you adjust?!! Back to that in a bit.
Okay, it's time for the satellite to come over the horizon. You will begin to hear a very weak CW signal that gets gradually louder. Now not real loud. Even if it were overhead it may not get more than S7 or so, depending on your receiver setup. If you have a high noise level at your location, you may not be able to hear the satellite at all, but lets say you can. Now tune up the band a bit. In the lower half of the passband 29.460-475 you will generally find the CW signals; in the upper half 29.475-29.500, the voice. You will notice that no one is any stronger than the beacon. To understand why, lets take a look at how the "transponder" or satellite repeater works.
A transponder has a "passband" or a frequency section on its receiver that it will hear signals from the ground. It then takes ALL those signals and 'translates' them to a transmitter frequency section in a 'proportionate' amount. This means that if one signal is louder in the receiver, it will be louder coming out of the transmitter. You see, the satellite transmitter is only 8 watts and all the signals coming back down have to SHARE that 8 watts of power. It is common courtesy to turn your own transmit power down so that you are no stronger than the beacon, or else you will use more than your fair share of the signal. You will be really strong and no one else will be heard. When a strong DX station comes on frequency, they sometimes come through the satellite, unknowingly of course, and cause all the other signals to "take a fade" as it is called.
OK, so now you hear a fellow calling CQ RS CQ RS on about 29.465. "What do I do?" you ask. Well, here's a rule of thumb for these particular satellites or "birds" as we like to call them. The last two digits will be pretty close to the same. Meaning, try tuning up on 21.265 or 145.965 (listen first so you don't interfere with a "terrestrial" or non-satellite QSO). See if you can hear your own signal, by sending a series of dits. If you can hear your own signal, then he should be able to as well. If you are using just one radio and switching bands, just try winging it. Maybe try just a little higher in frequency (21.265.4 or 145.965.4) to offset the Doppler shift and give him a call. When he comes back to you, (notice I said when not if!) you will be copying what he is sending and he will start drifting. That means that when he turns it over to you, you have drifted as well! How do we compensate for that?!! Well, the standard practice with satellites is that we always adjust the higher frequency. If you transmit on 15 and listen on 10, you adjust your receive so that you can keep hearing him. (You don't want to change transmit frequencies as you may drift into an ongoing terrestrial QSO!) If you are running 2 up and 10 down, you would adjust your transmitter frequency, WHILE TRANSMITTING, so that you continue to hear yourself in your receiver.
I know it sounds complicated, but you get the hang of it pretty quick. If you listen to other QSOs in progress, you'll hear some of the stations constantly adjusting frequency. And you may think, "But they aren't even on the same frequency as each other," but that is how it sounds to YOU. They have adjusted their radios to hear each other just fine. It's that the Doppler is different for you at your location... Don't worry you'll get it.
After you make contact, he will call you and send his info. Then you do likewise. Send him an RST (never 599, be honest) your state and your name and then a break, like so: AA0PW de AC5DK GM TU UR RST 559 559 ARK ARK OP KEVIN KEVIN HW? BK. Then he will probably say 73 and thanks and sign off. You will do the same and THAT'S IT! You did it! Your first Satellite QSO. Now that wasn't really so hard was it?
Something else of interest is the effect of propagation on satellite signals. Sometimes in the spring when the MUF gets high and the "skip" starts coming in on 2 meters, you may notice that SOME of the signals on the satellite sound all warbly and funny, almost like the effect the Aurora Borealis has. It is caused by the 2 meter signals bouncing around through the ionosphere.
On 10 and 15 meters the propagation has an even greater effect. Sometimes, stations on the other side of the world may be "skipping" around the ionosphere and "bouncing" into the satellite, and their signals can be heard in the downlink, even though when you turn on 15 meters, you don't hear a thing. In fact, it is possible to have a QSO through the satellite when it is BELOW the horizon of one or both of the stations. This is called "Over the Horizon" technique (or OTH for short). Some stations have used this method to achieve DXCC through the RS-12 satellite, but that's a little complicated for right now. Suffice it to say, it can be done.
There is also something called the ROBOT. It is a computer circuit that can copy your CW signal, (with limitations), and respond to you with your callsign and a QSO number. You can even send for a QSL card for such contacts. I have never been able to make one of these QSOs myself, but I know that it can be done. Perhaps in the future I can add another page with more detailed information about this and OTH technique for the experienced operator.