Radio link
| Frequency (downlink and uplink) | 435.500 MHz, requested and pending IARU coordination |
|---|---|
| Band | 435–438 MHz, amateur-satellite service |
| Modulation | 2GFSK, 9600 baud, ±2.4 kHz deviation (modulation index 0.5) |
| Doppler shift | Up to about ±10 kHz during a pass |
| When it transmits | Only during scheduled windows over Honduras and Central America. Outside them, radio silence. |
| Encryption | None |
Transmissions
| Transmission | When | Packet data |
|---|---|---|
| Text beacon | Every 5 s, during mission windows | AX.25 UI frame whose text is the satellite's callsign |
| Telemetry beacon | Every 15 s, during mission windows | AX.25 UI frame: destination CQ, source HR0UNA-1, PID 0xF0. 73-byte information field (telemetry table) |
| CW beacon | Together with the text beacon | Text: [TBD]. Speed: 25 words per minute. Keying: tone over FM |
| QSL image (SSDV) | Scheduled broadcast passes | One standard SSDV packet without FEC (type 0x67, 72 or 128 bytes) per radio packet. SSDV callsign: HR0UNA. The image repeats in a loop during the pass. |
| Data files (weather) | Scheduled broadcast passes | 128-byte “MF” fragments (fragment table) |
| SSDV satellite image | Scheduled broadcast passes | One standard SSDV packet without FEC (type 0x67, 72 or 128 bytes) per radio packet. SSDV callsign: HR0UNA. The image repeats in a loop during the pass. |
AX.25 frames carry 0x7E flags, bit stuffing, NRZI encoding and the G3RUH scrambler (1 + x¹² + x¹⁷) within the radio packet data. Any 9600-baud G3RUH decoder, such as Dire Wolf or gr-satellites, can receive them. The text beacon carries a 4-byte header followed by the ASCII text, terminated by 0x00.
Telemetry: 73-byte information field
| Bytes | Type | Field | Unit or values |
|---|---|---|---|
| 0 | u8 |
Frame type | 0x01 (version 1) |
| 1 | u8 |
Sequence | Wrapping counter (detects lost frames) |
| 2 | u8 |
Operating mode | 1 SAFE, 2 SAFE_ENTRY, 3 SAFE_CONTROL, 4 SAFE_NO_CONTROL, 5 IDLE, 6 MISSION, 7 DATA, 8 HELL, 9 DATA_UPLINK, 11 MISSION_PHOTO, 12 MISSION_QSL |
| 3–4 | u16 |
Validity | A bit set to 1 means that group carries fresh data (bit table) |
| 5–8 | u32 |
OBC uptime | s |
| 9–10 | u16 |
OBC resets | Total |
| 11–12 | u16 |
Battery voltage | mV |
| 13–14 | i16 |
Battery current | mA |
| 15–16 | i16 |
Battery temperature | 0.01 °C |
| 17–18 | i16 |
EPS MCU temperature | 0.01 °C |
| 19–30 | 6 × u16 |
Panel current X−, X+, Y−, Y+, Z−, Z+ | mA |
| 31–34 | u32 |
Packets received by the radio | Counter |
| 35–38 | u32 |
Packets received with a CRC error | Counter |
| 39–42 | u32 |
Packets transmitted | Counter |
| 43–44 | i16 |
Radio temperature | 0.01 °C; −32768 = no data |
| 45–50 | 3 × i16 |
Angular rate X, Y, Z | 0.01 °/s |
| 51–56 | 3 × i16 |
Magnetic field X, Y, Z | 10 nT |
| 57–68 | 6 × i16 |
Panel temperature X+, Y+, Z+, X−, Y−, Z− | 0.01 °C; −32768 = no data |
| 69 | u8 |
Attitude control status |
Bits 0–3: state (0 ROOT, 1 RUN, 2 TRIGGER, 3 IDLE, 4 NOT_INIT) Bit 4: B-dot Bit 5: backup B-dot Bit 6: nadir pointing |
| 70 | u8 |
Radio beacon status |
Bit 0: identity written Bit 1: failed to write it Bits 2–3: profile (0 off, 1 text, 3 not applied) Bit 4: configuration failure Bit 5: callsign read from the SD card Bit 6: beacon window open Bit 7: configuration in progress |
| 71–72 | u16 |
Camera offset from nadir | 0.01°; 0xFFFF = no data |
*Integer values are little-endian.
Validity bits: 0x0001 OBC · 0x0002 battery · 0x0004 EPS temperatures and panels · 0x0008 packets received · 0x0010 CRC errors · 0x0020 packets transmitted · 0x0040 radio temperature · 0x0080 gyroscope · 0x0100 magnetometer · 0x0200 panel temperature · 0x0400 nadir.
MRZN technical parameters
All of MRZN's transmissions are unencrypted. This page publishes what you need to receive and decode each one. Contact for these formats: Fernando Zorto, HQ1FJZ (fernando.zorto@unah.edu.hn).
Open-source decoders: https://github.com/MRZ-N/MRZN-RadioAmateur-Resources