AMSAT-LU SSTV and Crossband Repeater on Glider and Balloon


View of communications experiment: Below is the plate of the repeater. Top left is the SSTV camera and top right is the GPS receiver module. Image credit LU7AA

An SSTV and crossband repeater payload developed by AMSAT-LU will be flown on a Glider and a High Altitude Balloon on March 3 and 17.

AMSAT-LU LU7AA report:

We are pleased to inform next Saturday March-3 2012 (if weather permits) from 12hs (GMT-3), Amsat-LU and friends will be flying from Zarate (Route 193, km 19 from Buenos Aires) an UV repeater including APRS + SSTV + CW + DTMF thru several flights aboard manned glider, as test for LUSEX (LU Satellite Experiment), being developed by AMSAT-LU.

Afterwards on Saturday March-17 from 12hs-LU on (GMT-3), a free Balloon will fly same payload from the city of Junin (Club of Gliders, Lagoon of Gomez), 250Km west of Buenos Aires City.

Payload will operate as an UHF to VHF crossband repeater, with CW tlm, APRS location and SSTV emissions in local and space frequencies.

According to estimates Balloon could reach 100,000 feet (30 km) in height, travelling from 50 to 100 miles towards east.

Thus allowing contacts between stations located in provinces of Buenos Aires, Santa Fe, Entre Rios, Cordoba, La Pampa, San Luis and Uruguay.  See coverage map on and possible trajectory in .

For these experiences, Amsat-LU works with and it is thankful to hams of Radio Clubs of Junin, QRM Belgrano, APRS Group, Don Bosco Ramos Mejia School, gliders Clubs of Zarate, Junin and Cañuelas, and the twelve Amsat-LU members development team as well as those who have actively participated and sent their reports in previous experiences.

More information at



Several flown experiments have been successfully operated during 2011 in manned-gliders, airplanes, captive and free Balloons allowing operational & practice for hams contributing to platform validaton of LUSEX satellite (LU Satellite EXperiment) on development by Amsat Argentina. More on

In order to monitor the payload (if you are within 400 miles of launch area) you need just an FM receiver either handy or base, in 145.950 for repeater and/or 144.930 for APRS. The repeater, that is activated via 123 Hertz subtone, operates receiving voice FM in 435.950 Khz (-112dbm, 0,56 uV) and emits with 2W the received audio live on 145.950 Khz.

Simultaneously APRS data will be sent in Packet at 1200 bauds in 144.930, and also in 145.950.

The DTI APRS symbol would change from a Balloon (/O) during the ascent to a glider (/g) during parachute descent.

Payload would operate as voice repeater activated by 123 Hz subtone during 1 minute, a warning bip at 40 seconds will indicate telemetry is coming, which is emitted if the repeater is not in use, if in 20 seconds more voice repeater still in use a two bips will be heard signaling that short APRS packages will begin in the different frequencies, also every 5 minutes CW (telegraphy with tones of audio) with CQ + callsign (LU7AA), sequence#, ext. and int. centigrade temperatures and voltage of batteries, after which the cycle will repeat.


The system board containing RF transmitter module, receiver module, level adjustments, duplexer and antenna connector. Image credit LU7AA

Experiment for the first time in these flights will emit SSTV pictures in ROBOT-36 (36 seconds) in real time, showing what glider/Balloon sees. Every 5 minutes during ascent/descent and more spaced at high altitudes. (It can be received among others with MIXW, MMSTV & RX-SSTV ).

Payload would also carry on board two TV cameras (one towards earth and another towards horizon) recording video and sound during the flight. These captured videos could be recovered when payload is recovered.

APRS trajectory could be seen every minute, including speed, height, external and internal temperatures and 7.2v battery voltage using UI-View ( download from the UI-View official site on ) and/or to see/follow from Internet connecting to or locally via Packet at specified frequencies.

There are georeferenced Maps for UI-View in,,,, and . Download and place them in directory Program Files/Peak Systems/UI-View32/MAPS and rename files .txt to .inf.

The experiment in 435.950 KHz besides voice, receives and accepts DTMF sequences commands on demand, I.E. sending B* (DTMF with handy keyboard on UHF) will return S5 … ….. in 145,950 VHF CW, reporting in CW signal strength received from your station, if S9+10 will returns P10.

There are also DTMF commands qualifying emission of CW tlm or APRS beacon or SSTV emission, commands that allows remote release of payload, mode changes, timers control, energy, power, etc.

Frequencies for previous coordination, announcements and flights will be 7090 Khz LSB +/-10 Khz and local repeaters.

During the flights will remain active wide coverage AMSAT-LU APRS Igate LU7AA-10 on 144.930 and 430.930 KHz, operating from the Constituyentes Investigation Center transferring whatever is received towards Internet.

For being an experiment oriented to a next satellite, the contacts made between stations via this payload will be considered valid for the recently announced permanent, gratuitous and applicable Satellite Certificate that AMSAT-LU and RClub QRM Belgrano grants, more info on

During the Balloon flight, amateur groups will chase the payload, aiming to locate and recover. Trapping ventures holds on this activity, as in the case of the Pampero 15 Balloon sent from San Miguel del Monte which landed in the middle of the Magdalena’s state prison … See

All reports welcome. If you wish or can organize or want be part of control, or like to pursuit and recovery, or like operating and capturing data as an independent station, and/or wishes to join us personally in this adventure from the launching places email us to parapente at

We appreciate reading of this information and thankful if distribution possible.

73, LU7AA, Amsat-LU, aiming at the future by making the present funny.
info at