A miniaturized communication sub-system, essentially the same as the one aboard the Mercury Freedom 7 spacecraft, again provided the communication link for America's astronaut in the nation's second down-range manned space flight.

 Designed and supplied by Collins Radio Company, in co-operation with a team of eight subcontractors, the Mercury spacecraft communication subsystem included the following:
(1) Transceivers to provide voice communication in both flight and rescue operations.
(2) Command receivers with a substantial number of on-off channels providing remote control for various functions within the capsule during the launch, flight and re-entry phases when desired.
(3) Telemetry transmitters were provided to transmit scientific, operational and aeromedical data from the spacecraft to the ground.
(4) Radar transponder beacons in the microwave frequency range were used for precision tracking during flight.
(5) Two rescue beacons operating on international distress frequencies to determine the capsule's bearing during retrieving operations at sea.

 Collins designed and built equipment .included the UHF voice transceivers, the HF voice transceivers, the communication control panel, the UHF rescue antenna, the Bicone isolator, the UHF voice power amplifier, the HF diplexer, the telemetry line filter and the HF antenna Z-match.

 While responsible for the integration of the complete communications subsystem within the spacecraft, Collins subcontracted function packages to the following companies: command receivers, Motorola, Inc.; telemetry transmitters, Texas Instruments, Inc.; microwave radar transponder beacons, Electronics Division of ACF; rescue beacons, Simmonds Precision Products, Inc., radar beacon antenna system, Melpar, Inc., multiplexer, Microphase Corporation; audio center, Andrea Radio Corporation; and coax switches, Transco Products, Inc.