850 Sligo Ave. Suite 600
Silver Spring, MD 20910
fahnen/13.jpg AMSAT - AMSAT-OSCAR-51
Launch Pad Return

Satellite Summary

Pre-Launch Designations: AMSAT-Echo, AMSAT-OSCAR E
NASA Catalog Number: 28375
Callsign: Broadcast: PACB-11; BBS: PACB-12
Launched: June 29, 2004
Launch vehicle: Russian Dnepr LV (SS-18)
Launch location: Baikonur Cosmodrome, Kazakhstan
Weight: 11.14 kg
Size: 25cm x 25cm x 25cm (9.5" x 9.5" x 9.5")
Orbit: 817km x 697km (510 mi x 435 mi)
Inclination: 98.3 deg
Period: 99.97 min


  • Voice
    145.920 MHz FM (67.0 Hz PL Tone)
    1268.700 MHz FM (67.0 Hz PL Tone)
  • Data
    145.860 MHz FM (9600 bps AX.25)
    1268.700 MHz FM (9600 bps AX.25)
  • 28.140 MHz USB (PSK-31)
  • Voice
    435.300 MHz FM
    2401.200 MHz FM
  • Data
    435.150 MHz FM (9600 bps AX.25)
    2401.200 MHz FM (38,400 bps AX.25)


  • UHF LHCP (Transmitter A, normally packet and TLM)
  • UHF RHCP (Transmitter B, normally voice repeater)
  • Dual band L/S Open Sleeve (1/4 wave stub)
  • VHF 1/4 wave whip


  • FM Repeater
  • Digital PACSAT BBS
  • PSK-31 Uplink


AO-51 contains an FM repeater with both a 144 MHz and 1.2 GHz uplink and 435 MHz and 2.4 GHz downlinks. Additionally AO-51 contains a digital subsystem that transmits TLM on 70cm and provides complete PACSAT BBS that can be configured on both V and S band uplinks. There is also a 10 meter PSK uplink.

Experimenter's Wednesday is an idea that has been put into action with the Echo Project. Every Wednesday (0001 - 2359 UTC) the satellite is placed into a special mode of operation. Experimenters can use their equipment to communicate with the satellite in various modes including V/U, L/S, HF/U, and others. AO-51 supports digital store-and-forward at speeds upto 76.8 kbps, and a contains a wideband SQRX Receiver. A current schedule of operation is kept up-to-date by the AO-51 Control Team.

With four VHF receivers, two UHF transmitters, six modems, fifty-six channels of telemetry, and various other subsystems AO-51 is quite a complex spacecraft. The two UHF transmitters are connected to four antennas, two in the right-hand circular polarization (RHCP) and two in the left-hand circular polarization (LHCP). Transmitter A is connected to the LHCP antennas and is often used for digital modes. The transmitter often used for analog is connected to the RHCP antenna.

Last update 12 Jan 2004 - KF4OTN and W0EEC

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