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Amateur Satellite FAQ

Amateur Satellite FAQ

Having recently started to get into Satellites, I asked MANY people what it took to get started and what to do. I found few people who could offer all the information necessary to start. I have attempted to compile this information for future newbies. If I have missed something, please ask and I will attempt to add it to the collection. Any comments can be sent directly to me, [email protected] Copies of this article should be available in the following locations:


	oak.oakland.edu:/pub/hamradio/docs/faq 	ftp.cs.buffalo.edu:/pub/ham-radio 	Clear Skies BBS (608)249-7130 

Also, if you really want to get serious about satellites, I would STRONGLY recommend joining AMSAT to help promote the satellite hobby. AMSAT.... is a volunteer organization that works for the interests of amateur satellites. Dues are only US$30 per year and you will receive a subscription to "The AMSAT Journal". For US$80, you will receive first year dues and a copy of Instant Track computer tracking software which is a top-notch program. Instant Track was donated to AMSAT by its author and its sales account for a considerable portion of AMSAT's income. AMSAT-NA, 850 Sligo Avenue, Silver Spring, MD 20910-4703. (301) 589-6062. Credit cards welcome.


NOTE: I am in no way connected with AMSAT-NA, other than I have found their publications quite useful.



The following text was compiled from the following sources and from comments from many operators:


  • "How to use the EZSATS pass tables by N9LTD" and "Hamsat aliases" reprinted with permission. Full text, tables, and lots of other useful information can be obtained by sending a SASE to David Mullenix N9LTD, 2052 Brentwood Pkwy, Madison, WI 53704 or call the Clear Skies BBS at (608)249-7130.
  • "Amateur Radio Satellite Frequencies" This file can be obtained from the ARRL e-mail server. For information on the server, send an e-mail message to [email protected] with 'HELP' in body of message.
  • "Summary - Getting onto the Hamsats" This was an article posted to rec.radio.amateur.misc newsgroup by Stephan Greene ([email protected]) on 20 Mar 1992. The article is also available via anon ftp from ftp.cs.buffalo.edu or Australian mirror at grivel.une.edu.au as file pub/hamradio/ham_sat_sum.
  • "An Amateur Satellite Operation Upgrade Path" from the AMSAT Journal, September/October 1993, pp. 24-26.


The combination of uplink freq, downlink freq, and transmission mode are all lumped together into standardized satellite MODES. Here is a list of common satellite modes used by satellites covered by this article:


This mode requires a 2 meter SSB/CW transmitter and a 10 meter SSB/CW receiver and supports CW and voice.
This mode requires a 70 cm SSB/CW transmitter and a 2 meter SSB/CW receiver and supports CW and voice. Some satellites also support RTTY and SSTV in this mode.
This mode requires a 15 meter SSB/CW transmitter and a 10 meter SSB/CW receiver and supports CW and voice. This mode is unique in that it can be done with a simple HF rig.
This mode stands for J Analog and requires a 2 meter SSB/CW transmitter and a 70 cm SSB/CW receiver and supports CW, voice.
This mode stands for J Digital and requires a 2 meter FM transmitter and a 70 cm SSB/CW receiver and supports packet.
This mode requires a 70 cm SSB/CW transmitter and a 2.4 GHz SSB/CW receiver and supports CW and voice. Many people use a 2.4 GHz to 2 meter converter with a 2 meter SSB/CW receiver instead of buying a 2.4 GHz SSB/CW receiver.
This mode requires a 15 meter SSB/CW transmitter and a 2 meter SSB/CW receiver and supports CW and voice.

Some satellites have dual modes that operate simultaneously. For example, AO-13 can operate in mode BS which means that it can do both mode B and mode S simultaneously. Other common dual modes are KT and KA.


Also, satellites have 3 basic types of retransmissions: beacon, transponder, and repeater.


Most satellites have a fixed Morse beacon at the lower end of the satellites band-pass transponder. This is useful to detect when the satellite has crossed the horizon and is in range for operation. It can also be used to determine doppler shifts.
A transponder is a band-pass repeater. It accepts a range of frequencies on the input and retransmits the entire range on the output. All offsets within that range are preserved. NOTE: since the satellite is transmitting many signals at the same time, it is dividing its output power amongst all of these signals. If someone transmits a very powerful signal into the satellite, it will spend most of its power retransmitting that signal and all of the other signals will drop in power. This is NOT a way to earn friends and people who overpower the satellites input are called "alligators" and are not very popular.
This closely resembles a land-based repeater. It listens for signals on one frequency and retransmits it on another frequency. All satellite repeaters (and transponders) are full duplex, meaning you can (and should) listen to you signal on the downlink (with headphones) while you are transmitting.... more follow this link......


How to operate the RS Satellites

by Paul Willmott, VP9MU

If you have been following my little series of articles on satellites then you should be just about ready to make your first contact via a spacecraft. There are several satellites, built and launched by Russia (formally the USSR), which are called the RS-Series satellites or sometimes the Easy-Sats. RS either means Radio Sputnik or Radio Sport, depending upon which books you read. The RS-Series satellites operate in low Earth orbit (LEO), and can be operated using very simple equipment. In this article we will look at how to operate these birds. You may find it beneficial to re-read my previous articles before starting this one - just as a recap.

Before trying to make a contact, listen for a few passes first. Make sure that you are receiving the bird well before you start transmitting. Listen to the operating style of those working the bird. Remember that receiving successfully is the key to success in satellite operation - listening for a few passes is not a waste of time, it will be extremely beneficial.


All the RS satellites, are capable of operating in several different modes. Mode in satellite terms means which pair of uplink and downlink passbands are used for the communications link; e.g. Mode A is 2m (145 MHz) up and 10m (29 MHz) down. The schedule for mode changes is never officially published by the Russian ground controllers, however it appears from experience (and some unofficial rumours), that the birds will stay in their current operating modes for some time to come. RS-12 & RS-13 were launched on February 5, 1991 and are two separate packages piggy-backed on the Cosmos 2123 navigation satellite. Currently only RS-12 is in operation, it is understood that RS-13 is an in-orbit spare for RS-12.

Let’s first have a look at the possible modes that RS-12 and RS-13 can operate in. The following tables list of all possible transponder passband combinations and beacon frequencies.


Mode A (CW/SSB)

Type: Linear, Non-Inverting

Beacon/ROBOT 29.408 MHz

Beacon/ROBOT 29.454 MHz

Mode A Uplink 145.910-145.950 MHz

Mode A Downlink 29.410-29.450 MHz

ROBOT A Uplink 145.831 MHz

ROBOT A Downlink 29.408 or 29.454 MHz

Mode K (CW/SSB)

Type: Linear, Non-Inverting

Beacon/ROBOT 29.408 MHz

Beacon/ROBOT 29.454 MHz

Mode K Uplink 21.210-21.250 MHz

Mode K Downlink 29.410-29.450 MHz

ROBOT K Uplink 21.129 MHz

ROBOT K Downlink 29.408 or 29.454 MHz

Mode T (CW/SSB)

Type: Linear, Non-Inverting

Beacon/ROBOT 145.912 MHz

Beacon/ROBOT 145.959 MHz

Mode T Uplink 21.210-21.250 MHz

Mode T Downlink 145.910-145.950 MHz

ROBOT T Uplink 21.129 MHz

ROBOT T Downlink 145.912 or 145.959 MHz


Mode A (CW/SSB)

Type: Linear, Non-Inverting

Beacon/ROBOT 29.458 MHz

Beacon/ROBOT 29.504 MHz

Mode A Uplink 145.960-146.000 MHz

Mode A Downlink 29.460-29.500 MHz

ROBOT A Uplink 145.840 MHz

ROBOT A Downlink 29.458 or 29.504 MHz

Mode K (CW/SSB)

Type: Linear, Non-Inverting

Beacon/ROBOT 29.458 MHz

Beacon/ROBOT 29.504 MHz

Mode K Uplink 21.260-21.300 MHz

Mode K Downlink 29.460-29.500 MHz

ROBOT K Uplink 21.138 MHz

ROBOT K Downlink 29.458 or 29.504 MHz

Mode T (CW/SSB)

Type: Linear, Non-Inverting

Beacon/ROBOT 145.862 MHz

Beacon/ROBOT 145.908 MHz

Mode T Uplink 21.260-21.300 MHz

Mode T Downlink 145.960-146.000 MHz

ROBOT T Uplink 21.138 MHz

ROBOT T Downlink 145.862 or 145.908 MHz

Recently RS-12 has been operating exclusively in Mode K and RS-13 is switched off. But things can change very fast in the satellite world.

The simplest way to start working RS-12 Mode K, is to use your HF transceiver in split frequency mode. Set one VFO to 21 MHz for transmit, and the other VFO to 29 MHz for receive. Tune your antenna for the transmit frequency, and don’t worry about tuning for receive; the signals coming back from RS-12 are very strong. Using this arrangement you will be able to work the satellite in simplex mode, but you will not know if you are succeeding until someone returns your call. This is because you can’t hear the downlink while you are transmitting. To do this you will need separate transmitters and receivers. If you have two transceivers then use them, assign one to the uplink and one to the downlink. In this configuration you will be able to work full-duplex, and fully control your activity on the satellite.

As has already been explained, satellites carry transponders. Transponders are devices which take a slice of RF spectrum in one band, amplifies it, then re-transmits that slice in another band. The transponders on the RS series satellites are linear and non-inverting. The linear part means that any signal in the uplink passband will be faithfully be reproduced in the downlink passband. The non-inverting part means that no frequency inversion is performed in the amplification section of the satellite. Many Amateur satellites carry inverting transponders, this is done to reduce the effect of the Doppler shift. Without going into the mathematics of the whole thing, the end result of an inverting transponder is that you when you transmit on the low end of the uplink passband, your signal will appear in the high end of the downlink passband. Also if you transmit LSB up, you will hear USB down. For the RS series frequency-inversion is not an issue, and with RS-12 in particular the Doppler shift is so small that we can ignore it - which is why it is possible to work simplex with a standard HF transceiver.....for tons more go to this link.....http://www.qsl.net/kd4cga/howtos.htm

An optimum radio amateur satellite receiving system consists of antennas, rotor, preamplifier, receiver, and a modem for the digital modes. The receiver is usually the most expensive piece of equipment, so let's start by analyzing the characteristics an ideal receiver should have. The table lists types of receivers and all of the satellites that can be received with each receiver.

  • It should cover 135-145MHz, 435-437MHz, 1.2GHz.
  • If it's a transceiver, it should be able to receive and transmit simultaneously.
  • Tune increments of 10-20Hz should be available.
  • The microphone should have UP/DOWN button tuning.
  • It should have a 9600 Bps digital I/O connector.
  • Non standard FM offsets should be available.
  • You should be able to change the IF filters to wider ones if necessary.

The receiver doesn't have to have all of the above characteristics, but the more it has, the more modes and more data you'll be able to copy.

Table 1. Receiver Types and the Satellites You Can Work With Each Top ^
10-meter SSB ReceiverRS-10/11, RS-12/13 and RS-15 using Voice and CW
2-meter SSB ReceiverAO-13, AO-10 using Voice, CW, RTTY and SSTV with 400 BPS PSK modem: AO-13 telemetry with 1200 BPS Bell 202 modem: UO-1 1 data and telemetry
2-meter FM ReceiverMIR, DOVE, SAREX using Voice with 1200, BPS AFSK AX.25 modem: DOVE, Mir, SAREX and AO-27 digital data
70cm SSB ReceiverFO-20 Voice and CW; with 1200 BPS PSK AX.25 modem: AO-16, WO-18 and LO-19 digital mail and experimental data
70cm FM Receiver (with 430-440 MHz coverage) AO-27 in digital voice mode; with 9600 BPS FSK modem: UO-22, KO-23 and KO-25
2.4 GHz SSB Receiver or Receive ConverterAO-13 using Voice and CW

Preamplifier Top ^

Adding a preamplifier at the bottom of your antenna is an easy and cost effective way of improving your satellite reception. As the received frequency increases, so do the losses in signal strength caused by the coax cable connecting the antenna with your receiver. A preamp placed just underneath the antenna will amplify the signal received making up for the losses induced by the coax cable.

Antennas Top ^

There are several types of antennas that may be used to work with amateur satellites, such as turnstiles, eggbeaters, helixes. The most used one for frequencies below 1.2GHz is the cross Yagi, with both horizontal and vertical elements. To work digital satellites a 12-14dB gain antenna is preferred, for FO-20 a 14dB gain is fine, and for the AO-10 and AO-13 satellites the longer the antenna the better…

A rotor capable of azimuth/elevation movements is also a desirable thing. You are then capable of aiming the antennas at the satellite as it passes overhead.

Currently LogSat supports the Kansas City Tracker, an interface card which is mounted inside your computer. This card acts as an interface between the rotor and the computer. Using this card LogSat can automatically control the rotors and move the antennas for you, tracking in real time any satellites you select.

Modems Top ^

As you can see from Table 1, each digital satellite mode usually requires a different kind of modem ($100-$150). If however you buy a DSP modem you'll pay more, but you'll have all the modes in one box.

What do Amateur Satellites Transmit? Top ^

The analog satellites have voice and CW (Morse code) signals, as well as occasional RTTY (Radio TeleType) and SSTV (Slow Scan Television) signals. All satellites also transmit telemetry signals, such as how much power the satellite is using to transmit, the satellite's temperature, solar cell current and many other interesting things. This telemetry is transmitted as AX.25 (packet data). Some data is also sent using ASCII, CW or RTTY.

Receiving Pictures from Weather Satellites Top ^

There are two kinds of weather satellites. They can either be geostationary or spinning in polar orbits around the earth. Geostationary satellites are satellites 36000km above our heads, whose position in space relative to us on earth never changes. Once you point your antenna at them you won't have to move it again. The European Meteosat satellite and the American Goes satellites are geostationary weather satellites. Meteosat transmits continuously on 1.69GHz, and can be received using small satellite dish, a receive converter which converts the 1.67GHz into 137MHz, a receiver capable of receiving 137MHz with a 30KHz bandwidth, a simple interface to convert the receiver's analog data into digital data which is fed into the computer through the serial port. Shareware software like JVFAX 7.0 will then decode these signals and give you a photo on screen just like those in the weather forecasts you see on TV. The dish runs for $50-$100, the receive converter is about $150-$200, the receiver ranges from $100 to $500, and the software is shareware.

There are also polar weather satellites. Among these are the Russian Meteors and the American Noaas. These satellites have very low orbits (~1000Km) compared to those of geostationary satellites (~36000Km). Their photos are thus a lot more detailed, but will cover only a small portion of the earth. They transmit at around 137MHz, and can be received using a couple of simple round dipole antennas. The equipment needed is the same as for the Meteosat, with the difference in antennas and the unnecessary receive converter.

Tracking Satellites With Your Bare Eyes Top ^

It is possible to watch satellites with your bare eyes, given the right conditions. Using LogSat just select a very low orbiting satellite, as could be the Russian space station MIR, or the space shuttle during one of its flights, see when it passes overhead, go outside and with a bit of luck you should be able to spot it. The key is choosing a good time of the day. The best chance of seeing one is a little after sunset, when you're in the dark, but the satellite is still illuminated by the sun, which will reflect onto the satellite body, allowing you to see it.

Table 2. Uplink/Downlink Frequencies for Amateur Satellites Top ^
SatelliteUplink DownlinkBeacons Notes
OSCAR 10435.025-175 145.83-98145.81/987  
OSCAR 11 (UoSAT 2)  145.826
Experimental beacon on 2401.5 MHz
OSCAR 13 (Mode B)
(Mode S)
OSCAR 16(PACSAT)145 90-96 437 051437.026/051 S beacon 2401.143
OSCAR 17(DOVE)  145.825 S beacon 2401.221
OSCAR 18 (WEBERSAT)  >437.102 spare TX on 437.075
OSCAR 19 (LUSAT)145.84-90 437.126437. 126/154 CW on 437.l27
>OSCAR 20 (Fuji)145 9-146 435.8-.9435.797/91 .797=CW, .910=packet
OSCAR 22 UoSAT 5145.9/.975 435.120435.120 
OSCAR 23 KITSAT 1145.85/90 435.175435.175  
OSCAR 25 KITSAT 2145,87/98 436,500 spare TX 435.175
OSCAR 26145.875/90/925/95 435.822 secondary TX 435.867
OSCAR 27 AMRAD145.850 436.797  
RS 10 (Mode A)
(Mode K)
(Mode T)
145. 86-90
29 36-40
29 36-40
29 357/403
Robot uplink 14S.820
Robot uplink 21. 120
Modes KA & KT also
RS 11 (Mode A)
(Mode K)
(Mode T)
145 91-95
21.2 1-25
145,9 l -95
Robot uplink 145.830
Robot uplink 21.130
Modes KA & KT also
RS 12 (Mode A)
(Mode K)
(Mode T)
145 91-95
Robot uplink 145.831
Robot uplink 21.129
Modes KA & KT also
RS 13 (Mode A)
(Mode K)
(Mode T)
145 96-146
145 96-146
Robot uplink 145.840
Robot uplink 21.138
Modes KA & KT also
RS 15 (Mode A)145.85-89 29 36-4029.353/398