TOP.03 // COMMS
RF Communications, Link Budgets & Antenna Deployment
UHF, S-band, and X-band link budgets, FSK/GMSK and LoRa CSS modulation, NiTi superelastic tape-spring antennas, and non-pyrotechnic Dyneema burn-wire release actuators.
1. SatWiki Encyclopedia Specifications (4)
- SQ-SS-004
Communications (COMMS)
Carries telemetry, telecommands and payload data between spacecraft and ground. Small satellites span VHF and UHF amateur bands, S, X and Ka band and optical links; the link budget decides whether a link closes.
- SQ-SS-009
Antennas & deployment mechanisms
Quarter-wave and half-wave UHF tape-spring antennas, S-band patch arrays, UHMWPE thermal-knife hold-downs and deployment verification switches on picosatellites.
- SQ-SS-012
Telemetry framing & protocols
AX.25, CubeSat Space Protocol (CSP), CCSDS reed-solomon/convolutional coding, Morse CW beacons and Kaitai Struct decoders for small-satellite downlinks.
- SQ-OP-004
Frequency coordination & licensing
ITU Radio Regulations, IARU amateur-satellite coordination, national administration filings (API/CR/N) and UHF/S-band allocations for PocketQubes and CubeSats.
2. Interactive Lab Calculators & Workbenches (3)
3. Technical Notes (4)
- NL-TN-2026-013
LoRa from low Earth orbit
LoRa chirp spread spectrum (CSS) demodulates signals 7.5 to 20 dB below the thermal noise floor, enabling PocketQube reception on simple omnidirectional ground antennas. However, high spreading factors (SF11–SF12) at narrow bandwidths suffer symbol-bin drift when the orbital Doppler rate peaks near zenith. We derive the sensitivity, link margin and maximum tolerable Doppler rate across SF7–SF12.
- NL-TN-2026-019
Scaling from 437 MHz UHF to S-band and X-band high-rate CubeSat downlinks
A 9.6 kbps UHF downlink transfers at most ~3–4 MB per day—sufficient for housekeeping telemetry on a 1P PocketQube or 1U CubeSat, but four orders of magnitude below the output of a multispectral imager. We compare link budgets across 437 MHz UHF, 2.2 GHz S-band (2 Mbps), and 8.2 GHz X-band (100 Mbps DVB-S2) into a 2.4–3.7 m parabolic dish.
- NL-TN-2026-009
How much data can a PocketQube download per day?
We compute the daily contact time of a single ground station for a 525 km Sun-synchronous orbit across station latitudes and elevation masks, apply framing efficiency for AX.25 and CSP, and tabulate the net payload volume delivered per day at 1200 to 9600 bit/s.
- NL-TN-2026-002
A UHF downlink budget for a 1P PocketQube
We compute, line by line, the downlink budget of a 1P PocketQube transmitting telemetry at 437.2 MHz from a 500 km Sun-synchronous orbit with 0.5 W of RF. At 10° elevation, 9.6 kbit/s non-coherent FSK closes with only +0.1 dB of margin, while 1.2 kbit/s keeps more than 5 dB even at the horizon. Integrating over passes shows that low passes deliver almost nothing at 9.6 kbit/s. We then recompute the budget of Grizu-263A, whose 20 dBm EIRP and dual 4800/2400 Bd modes reproduce the margins reported in the PocketQube review, and argue for adaptive data rates and forward error correction.
4. Research Monographs (3)
- SQ-R-004
Materials-initiated failures and screening gaps in CubeSat and PocketQube missions
- SQ-R-003
Non-pyrotechnic antenna deployment in PocketQube-class satellites: strain and thermal budgets for NiTi tapes and release actuators
- SQ-R-001
PocketQube picosatellites: A review of standards, mission trends and miniaturization constraints, with lessons learned from Grizu-263A, Türkiye’s first PocketQube
5. Engineering Course Modules (2)
- MODULE 06
UHF / LoRa Link Budgets, Antennas & Doppler
Closing a 437 MHz downlink with +22 dBm RF power, tape-spring dipole deployment, Eb/N0 vs. LoRa chirp spread spectrum, and ±10 kHz Doppler tracking.
- MODULE 12
3U/6U CubeSat 3-Axis Reaction Wheels, Star Trackers & S/X-Band Downlinks
Scaling from 1P magnetic detumbling to arcsecond star trackers, reaction wheel momentum desaturation, deployable 20–60 W solar wings, and 50–150 Mbps X-band Earth observation downlinks.