| s | second |
| S+DX | Speech Plus Duplex |
| SA | Selective Availability |
| SABM | Set Asynchronous Balanced Mode |
| SAC | Satellite Access Controller |
| SADA | Solar Array Drive Assembly |
| SADE | Solar Array Drive Electronics |
| SAGR | Supergroup Automatic Gain Regulator |
| SAN | Satellite Access Node |
| SAO | Signatory Affairs Office |
| SAP | Second Audio Program |
| SAR | Search and Rescue |
| SAS | Subscriber Authorisation System |
| SAT | Supervisory Audio Tone |
| SBAI | Selective Backward Alarm Indication |
| SBC | SC Bit Map Creation |
| SBCA | Satellite Broadcasting and Communications Association |
| SBS | Satellite Base Station |
| S/C | Spacecraft |
| S/C | Suppressed Carrier |
| SC | Satellite Channel |
| SC | Service Channel |
| SC | Subscriber Communicator |
| SCADA | Supervisory Control and Data Acquisition |
| SCART | Syndicat des Constructeurs d'Appareils Radio Recepteurs et Televiseurs |
| SCC | Satellite Control Centre |
| SCC | System Control Centre |
| SCCN | System Co-ordination and Control Network |
| SCF | Satellite Control Facility |
| SCPC | Single Channel Per Carrier |
| SCPDM | Suppressed Clock Pulse Duration Modulation |
| SCR | Silicon Controlled Rectifier |
| SCS | System Control Segment |
| SCTO | Stalled Call Timed Out |
| SCU | Satellite Communications Unit |
| SD | Speech Detector |
| SDC | Secondary DAMA Controller |
| SDCU | Satellite Delay Compensation Unit |
| SDF | Supergroup Distribution Frame |
| SDH | Synchronous Digital Hierarchy |
| SDL | Specification and Description Language |
| SDLC | Synchronous Data Link Control |
| SDMA | Space Division Multiple Access |
| SDPSK | Symmetrical Differential Phase Shift Keying |
| SDS | Satellite Data Services |
| SDTV | Standard Definition Television |
| SDU | Satellite Data Unit |
| SECA | Société Européene de Controle d'Access |
| SECAM | Système Electronique Couleur Avec Mémoire (TV standard) |
| SEM | Space Environment Monitor |
| SEP | Spherical Error Probability |
| SES | Satellite Earthstations and Systems |
| SES | Severely Errored Seconds |
| SES | Ship Earth Station |
| SES | Standard Earth Station |
| SF | Single Frequency |
| SFD | Saturation Flux Density |
| SFDR | Spurious Free Dynamic Range |
| SGDF | Supergroup Distribution Frame |
| SHA | Sidereal Hour Angle |
| SHE | Spacecraft Handling Equipment |
| SHF | Super High Frequency |
| SI | Speech Interpolation |
| SIA | Satellite Industry Association |
| SIM | Subscriber Identity Module |
| SIMP | Satellite Interface Message Processor |
| SIT | Satellite Interactive Terminal |
| SIU | Signalling Interface Unit |
| SiS | Sound in Synch |
| SLIP | Serial Line Internet Protocol |
| SLL | Satellite Line Link |
| SLS | Sidelobe Suppression |
| SMA | Search Mode Acquisition Procedure |
| SMA | Semi Major Axis |
| SMATV | Satellite Master Antenna Television |
| SMC | Sheet Moulding Compound |
| SMC | System Monitor Console |
| SMG | Special Mobile Group |
| SMS | Satellite Multiservice System |
| SMS | Short Messaging System |
| SMS | Subscriber Management System |
| SMT | Surface Mount Technology |
| SMTP | Simple Mail Transfer Protocol |
| SMY | Solar Maximum Year |
| S/N | Signal to Noise Ratio |
| SNA | System Network Architecture |
| SNF | System Noise Figure |
| SNG | Satellite News Gathering |
| SNMC | Service Provider Network Management Centre |
| SNMP | Simple Network Management Protocol |
| SNMS | Satellite Network Management System |
| SNR | Signal to Noise Ratio |
| SNT | System Noise Temperature |
| SOC | Satellite Operations Centre |
| SOC | Satellite Operation Complex |
| SOCC | Satellite Operations Control Contre |
| SoD | Services on Demand |
| SOF | Start of TDMA Frame |
| SOI | Silicon on Insulator |
| SOM | Start Of Message |
| SORF | Start of Receive Frame |
| SORMF | Start of Receive Multiframe |
| SOS | Space Operation Service |
| SOTF | Start of Transmit Frame |
| SOTMF | Start of Transmit Multiframe |
| SP | Service Provider |
| SP | Space |
| SPADE | SCPC PCM Access Demand Assigned Equipment |
| SPC | Stored Program Control |
| SPELDA | Structure Porteuse Externe de Lancement Double Ariane |
| SPI | Special Position Identification |
| SPL | Sound Pressure Level |
| SPM | Signal Processing Modem |
| SPRE | Satellite Position Reporting Equipment |
| SPS | Signalling, Protocols and Switching |
| SPS | Standard Positioning Service |
| SR | Shift Register |
| SRARQ | Selective Repeat Automatic Repeat Request |
| SRB | Secondary Reference Burst |
| SRB | Solid Rocket Booster |
| SRD | Satellite Receiver Decoder |
| SRE | Speech Recognition Equipment |
| SRF | Service Request Flag |
| SRH | Service Request Handling |
| SRP | Signal Reference Point |
| SRS | Space Research Service |
| SRT | Secondary Reference Terminal |
| SS | Satellite Switching |
| SS | Signalling System |
| SS | Speed Spectrum |
| SS7 | Signalling System No 7 |
| SSB | Single Side Band |
| SSB-SC | Single Side Band - Suppressed Carrier |
| SSB-SC-AM | Single Side Band - Suppressed Carrier - Amplitude Modulation |
| SSB-SC-ASK | Single Side Band - Suppressed Carrier - Amplitude Shift Keying |
| SSB-SC-PAM | Single Side Band - Suppressed Carrier - Pulse Amplitude Modulation |
| SSC | Satellite Signalling Channel |
| SSC | Satellite Situation Centre |
| SSC | Satellite Switching Centre |
| SSE | Spread Spectrum Encoder |
| SSFC | Sequential Single Frequency Code |
| SSG | Small Signal Gain |
| SSLO | Solid State Local Oscillator |
| SSM | Satellite System Monitor |
| SSM | Secondary Surface Mirror |
| SSMA | Spread Spectrum Multiple Access |
| SSOG | Satellite System Operations Guide |
| SSP | Signalling and Switching Processor |
| SSPA | Solid State Power Amplifier |
| SSR | Steady State Reception Procedure |
| SSRA | Spread Spectrum Random Access |
| SSS | Sun Synchronous Orbit |
| SSSF | Self Scanner Stop Failure |
| SSSO | Specialised Satellite Service Operator |
| SST | Satellite to Satellite Tracking |
| SS-TDMA | Satellite Switched Time Division Multiple Access |
| SSTM | Station to Station Traffic Matrix |
| SSU | Secondary Sampling Unit |
| SSU | Sequential Shunt Unit |
| SSU | Single Subscriber Unit |
| SSU | Stratospheric Sounding Unit |
| SSUS | Solid Spinning Upper Stage |
| ST | Standard Time |
| ST | Successful Termination |
| STA | Structural Test Article |
| STAR | Satellite Telecommunications with Automatic Routing |
| STBY | Standby |
| STC | Sub Technical Committee |
| STCC | Spacecraft Technical Control Centre |
| STDN | Space Tracking and Data Network |
| STE | Spacecraft Test Equipment |
| STE | Supergroup Translating Equipment |
| STM | Structural Thermal Model |
| STM | Synchronous Transport Module |
| STP | Space Test Program |
| STR | Symbol Timing Recovery |
| STS | Space Transportation System |
| STU | Satellite Terminal Unit |
| SVC | Switched Virtual Circuit |
| SW | Switch |
| SWOF | Switchover Operation Failure |
| SWR | Standing Wave Ratio |
| SYLDA | System de Lancement Double Ariane |
| SYZ | Synthesiser |
