T9-1 Chapter 9 – Special Operations VHF and UHF Operation –Repeater Operations, Autopatch and Linking –APRS Operations and Digipeaters –Simplex Operation Amateur Satellite Operations Earth-Moon-Earth (EME) Communications Image Communications One-Way Communications

T9-2 Repeaters VHF/UHF repeaters extend communication range by receiving a signal and retransmitting it. A repeater receives on one frequency (input) and transmits on a separate frequency (output) at the same time. –The frequency difference between the repeater input and output frequencies is called the offset. –The standard repeater frequency offset for a repeater on the 2 meter band is 600 Khz. Some repeaters can receive on one band and transmit on another band (crossband repeaters).

T9-3 Repeaters

T9-4 Repeater Operation RX: TX: RX: TX: RX: TX: Repeater Ham A Ham B

T9-5 Band Plan – 2 meters OutInOutInOutIn Repeater CWSSB, Weak SignalFM Simplex FrequencyUsage EME (CW) General CW EME & SSB National SSB Calling SSB Operations Beacons OSCAR Subband Linear Translator Inputs Repeater Inputs Weak Signal SSB Linear Translator Outputs FrequencyUsage Repeater Outputs Misc Experimental OSCAR Subband Repeater Inputs FM Simplex National FM Calling Repeater Outputs Repeater Outputs FM Simplex Repeater Inputs

T9-6 Repeaters (Cont’d) Some crossband repeaters can operate in duplex mode to allow a user to talk and listen at the same time (similar to a telephone). Most repeaters have “open” access; however, some repeaters are operated as “closed” repeaters. Repeaters may require the transmission of a subaudible tone or tones for access to prevent interference by extraneous transmissions. –Called CTCSS (Continuous Tone Coded Squelch System) or PL (Private Line) tones.

T9-7 Repeaters (Cont’d) Repeaters identify using Morse code or voice recordings. Repeater frequencies are selected through consultation with frequency coordinators. Repeater frequencies, by geographic location, can be found the in The ARRL Repeater Directory. Amateur television (ATV) repeaters operate on the 70 cm UHF band. Most repeaters are funded by amateur radio clubs and their members.

T9-8 Rochester Voice Repeaters CallOutput (MHz)Input (MHz)Tone (Hz) VHF 2m Repeaters WØMXW/R (-)100 WØMXW/R (-)100 WØEAS/R (+)100 UHF 70cm Repeaters KGØBP/R (+)110.9 WØMXW/R (+)71.9 Not on test Note: RARC WØMXW/R repeaters and may require use of 100 Hz access tone.

T9-9 Repeater Operation Making your first transmission on a repeater is as simple as signing your call. Pause between transmissions to allow other stations to break in by giving their call sign. The repeater courtesy tone is a beep which sounds a second or two after each transmission to permit other stations to transmit their call signs. A time-out timer prevents the repeater from transmitting continuously.

T9-10 Repeater Autopatch Allows repeater users to make local telephone calls through the repeater system. Touch-tone tones are used to access, dial phone numbers, and terminate the autopatch operation. Some repeaters provide autopatch “speed-dial” numbers. Never use the repeater autopatch for business communications.

T9-11 Repeater Internet Linking Amateur repeaters can be linked together using the internet “Voice Over IP” capabilities. VOIP internet linked repeaters allow amateurs to communicate to other amateurs across the country and around the world. Echolink is a popular repeater linking technology. –KØRGR operates a Echolink node on the RARC / repeater in Rochester. –For information on Echolink and using the local Echolink node, see the Echolink page on

T9-12 Repeater Internet Linking Repeater Ham KØRGR/L Echolink Node Internet Ham VoIP Repeater Echolink Access via Internet Echolink Node

T9-13 APRS Digipeaters Digital repeaters (digipeaters) are used to relay digital packets of information between amateur radio stations. The Automatic Position Reporting System (APRS) is a digital packet system for relaying geographic position reports, messages, and weather reports between amateur radio stations. –APRS digital packets may be relayed via digipeaters, satellites, ISS, or the internet. –APRS position reports are often plotted on computer maps for tracking and messaging. Not on test.

T9-14 APRS Position Report Display APRS position report displayed on Kenwood D700 transceiver.

T9-15 Automatic Position Reporting System

T9-16 APRS Digipeaters (Cont’d) APRS gateway digipeaters are connected to the internet and relay APRS digital packets to and from the internet. APRS amateur stations and digipeaters typically use the national APRS frequency of MHz. For information on APRS and Rochester digipeaters, see the APRS page at Not on test.

T9-17 VHF/UHF Simplex Operation Stations are operating simplex when they are communication directly with each other. If two stations using a repeater can hear each other on the repeater input frequency, then they should be able to operate on a simplex frequency. National simplex calling frequencies have been defined on the VHF/UHF bands. –The national simplex calling frequency on the 2 meter band is MHz.

T9-18 Amateur Satellite Operations Orbiting Satellites Carrying Amateur Radio (OSCARs) are amateur radio satellites. Any licensed amateur can operate through a satellite using the VHF and UHF bands. A satellite’s orbit is usually shaped like an ellipse. –Perigee is the closest approach to Earth –Apogee is the farthest distance from Earth –The orbit can be mathematically calculated using Keplerian element parameters.

T9-19 Amateur Satellite Operations (Con’t) The Doppler effect shifts the apparent frequency of a satellite transmission due to the relative motion between the satellite and earth station. –As the satellite moves closer, the frequency is higher. –As the satellite moves away, the frequency is lower. The International Space Station (ISS) operates amateur stations in voice and packet modes. –Due to the fairly low, circular orbit, the ISS station can only be worked 4 to 6 minutes per pass by an Earth station.

T9-20 Earth-Moon-Earth (Moonbounce) Amateur stations reflecting signals off of the moon are using EME communications. Stations can be more than 11,000 miles apart on Earth. Due to the extremely weak reflected signals, most EME operations use Morse code. High path losses require the use of high power amplifiers and high-gain antennas (stacked Yagi or collinear).

T9-21 Amateur Television (ATV) ATV, or “fast scan television,” uses the same standards, or frame rate, as broadcast television. The 70 cm band is the lowest frequency band where ATV operations is permitted. A cable-ready television set can receive ATV frequencies on the 70 cm band. ATV repeaters are used to expand the communication range.

T9-22 Slow-Scan Television (SSTV) Images are transmitter by converting the image into transmitted audio tones. SSTV is popular on the 20 meter HF band using SSB emission. Also used on the 2 meter band using simplex or FM voice repeaters. –As a matter of courtesy, you should request permission to use a FM repeater for SSTV communication from the repeater owner.

T9-23 Beacon Stations Beacon stations are transmitters primarily used for the study of radio-wave propagation or other experimental activities. The transmitter power of a beacon must not exceed 100 watts. All technician and higher license classes can operate a beacon station. Beacon stations are limited to parts of the 28, 50, 144, 222, and 432 Mhz bands plus all bands above 450 Mhz.

T9-24 Telecommand Telecommand operation is a one-way transmission to initiate, modify or terminate functions of a device at a distance. –Controlled devices may be models, amateur satellites or remote controlled amateur stations. FCC rules do not require identification during telecommand of a model craft. –The transmitter must contain a label with the station call sign and licensee’s name and address. –Maximum transmitter power is limited to 1 watt.