BOTAN Comms | CIT-GARDENs

Frequencies

Band	Frequency	Use	Modulation
VHF	145.825 MHz	APRS	AFSK 1200 bps / AX.25
UHF	437.375 MHz	CW beacon	CW
UHF	437.375 MHz	Downlink of HK, images, gyro and APRS logs	GMSK / AX.25

The callsign is JS1YPT

CW beacon

Format: BOTAN JS1YPT <SI + RSSI> <16 hex digits>

The 4 hex digits after SI are the received RSSI The 16 hex digits are 64 bit of HK

bit	Item	Note
0–7	BATT_V	Battery voltage
8–15	BATT_I	Battery current
16–23	BATT_T	Battery temperature
24–31	BPB_T	BPB temperature
32–39	RAW_I	RAW current
40	LCL_5V0	5V0 latching current limiter
41	LCL_DEPANT	Antenna deployment LCL
42	LCL_COMPIC	COM PIC LCL
43–47	SAP −X, +Y, −Y, +Z, −Z	1 bit per face
48–51	RESERVE_CMD_COUNTER	Counted by the OBC
52–54	GMSK_CMD_COUNTER	Counted by the COM
55	KILL_SW
56–57	KillCounter
58	MISSION_PIC_ON/OFF
59	MIS_CANCEL_FLAG
60	MIS_END_FLAG
61	APRS_FLAG
62–63	CURRENT_MIS	Mission in progress

GMSK downlink packet

AX.25 UI frame; the first 22 bytes are a common header

byte	Content	Value
0–6	Destination callsign + SSID	`JS1YMY` + 0x30
7–13	Source callsign + SSID	`JS1YPT` + 0x30
14	Control	0x3E
15	PID	0xF0
16	SAT ID	0x42
17	PCKT ID	0x11 data, 0x33 COM status, 0xAA ACK / NAK, 0xCC CAM
18	Reserve	0xFF
19–21	Packet sequence number	Camera packet number for CAM
22–	Payload	64 byte for data, 61 byte for CAM
last 2 bytes	CRC

Packet	Length
Data, address management	88 byte
CAM	85 byte
ACK / NAK, COM status	32 byte

The COM status packet carries the RSSI and radio temperature An address management packet sends the start address of each data area

HK format

64 byte, generated every 90 s

byte	Item	Note
0	Header	0x33
1, 2, 3	sec, min, hour	On-board time
4–5	day
6–7	+X Temp
8–9	−X Temp
10–11	+Y Temp
12–13	−Y Temp
14–15	+Z Temp
16–17	−Z Temp
18	CIS Temp	CIGS cell temperature
19–20	BPB Temp
21–22	−X Voltage
23–24	+Y Voltage
25–26	−Y Voltage
27–28	+Z Voltage
29–30	−Z Voltage
31–35	−X, +Y, −Y, +Z, −Z Current	1 byte each
36	Battery Temp
37	Battery Voltage
38–39	Battery Current
40	FAB RAW Voltage
41–42	FAB RAW Current
43	SRC Voltage
44–45	SRC Current
46	Kill Status	Upper 4 bit FAB, lower 4 bit MAIN
47	RESET RAW Voltage
48, 49	3V3#1, 3V3#2 Current
50, 51	unreg#1, unreg#2 Current	UHF-COM, DEPANT
52	5V Current
53–54	RESET_SW_STATUS	See table below
55	1h RESET Counter
56	RSSI
57	COM Temp
58	CMD Counter
59	MIS ACK
60	Current Mission
61	MIS_COUNT
62	APRS Flash Remain
63	CRC	XOR of bytes 0–62

Bit assignment of RESET_SW_STATUS

bit	byte 53	byte 54
7	RESET_RAW_V_MON	DCDC_3V3_2
6	LCL_UHF_COM	LCL_COMPIC
5	LCL_5V0	LCL_MAINPIC
4	DCDC_FAB	—
3	LCL_DEPANT	—
2	LCL_3V3_2	—
1	LCL_FAB	—
0	DCDC_5V0	—

Main flash memory areas

Area	Start address	Size
SATLOG	0x00060000	128 KB
HK	0x00080000	64,000 KB
CW	0x03F10000	2,624 KB
High-rate HK	0x041A0000	25,984 KB
APRS received messages	0x05B10000	64 KB
APRS mission log	0x05B30000	64 KB
Thumbnails, corn / aurora / pumice	0x05B61000 –	5,388 KB / 3,424 KB / 3,424 KB
RGB images, corn / aurora / pumice	0x069F3000 –	3,200 KB each
GYRO log	0x07367000	640 KB

APRS

Format      : AX.25
Frequency   : 145.825 MHz
Callsign    : JS1YPT
Modulation  : AFSK 1200 bps
TNC         : TinyTrak4

Mode	Operation
Digipeat	Sends back a message received from the ground as it is
User message	Triggered by data received from the ground, returns one of the preset phrases
TRX	Sends one of the preset phrases from the satellite on its own

At start-up it sends Hello World!! This is JS1YPT BOTAN. 5 times and then waits Passed a continuous operation test of 8 hours, 5.3 orbits Received logs are stored on board and downlinked over UHF

The TinyTrak4 digipeats packets containing JS1YPT The PIC extracts the input text and sends it as a message from BOTAN

Received packet	Response from BOTAN
Contains JS1YPT	① Digipeat by the TinyTrak4 ② A packet from BOTAN with the same text
Does not contain JS1YPT	② only

Received logs are published as the APRS digipeat sample