- omnirange indicator
- on condition
- optical transmission
- optical tuning
- optical wavelength
- optimal control
- optimal path
- optimal program
- optimal sampling
- optimization
- optimization control
- optimum bunching
- optimum height
- optoelectronic chip
- optoelectronic receiver
- optoelectronics
- orbit altitude
- orbit congestion
- orbit correction
- orbit division
- orbit generator
- orbit inclination
- orbit node
- orbit number
- orbit parameters
- orbit period
- orbit prediction
- orbit segment
- orbit sharing
- orbit time
- orbit trimming
- orbital arc
- orbital capacity
- orbital elements
- orbital position
- orbital slot
- orbital spacing
- orbital velocity
- orbiter
- orbiting satellite
- order sample
- order structure
- order wire
- ordinary line
- ordinary wave
- originating junctor
- originating traffic
- oscilloscope photograph
- oscilloscope trace
- OSI layers
- osillographic display
- ordinary overtime
- ordnace devices
- orientation control
- originating centre
- originating exchange
- originating point
- originating register
- orthogonal antennas
- orthogonal polarization
- orthogonal signals
- orthogonal transmission
- orthomode junction
- out-port
- outage time
- outboard
- outbound trajectory
- outdated data
- outdoor aerial
- outer planet
- outer space
- outgate
- outgoing line
- outgoing procedure
- outgoing pulse
- outlays
- outline
- output
- output amplifier
- output attenuation
- output attenuator
- output buffer
- output cavity
- output divergence
- output element
- output feedback
- output instruction
- output message
- Output OPAC
- output order
- output power
- output quantity
- output sample
- output sequence
- output stage
- output stream
- output syntax
- overall calibration
- overall distortion
- overall selectivity