The most important role of the Communication subsystem is to communicate
with groud station, which is one the most important subsystem in the satellite.
Cute-1.7 + APD uses amateur 144MHz and amateur 1200MHz frequency for thr ground
to the satellite link, and uses 430MHz band for the satellite to the ground
link. The satellite is an amateur satellite whose frequency was coordinated
by International Amateur Radio Union (IARU), and was licensed by the Ministry
of Internal Affairs and Communications in Japan. The Callsign is "JQ1YPC"
and controled from the operation center at Tokyo Institute of Technology "JQ1YCZ"
in Tokyo, Japan. Cute-1.7 + APD amateur missions are based on the acknoledgement
of CUTE-I and are developed with Japanese radio amateurs. The objectives of
communication subsystem in the satellite are as follows.
1. To create a higher functioned amateur satellite using
micro/pico satellite with new design methodology
2. To share radio experiment opportunities with radio and
satellite amateurs
To receive the telemetry and use digital repeater, please see Cute-1.7
Amateur services.
Cute-1.7 + APD communication subsystem has following functions,
Cute-1.7+APD has following transceivers
4 transceivers are equiped
| Frequency (MHz) |
Moduration | Protocol | Transceivers | Power (mW) |
Consumption (mW) |
|
| Command | 144MHz | AFSK 1200bps / GMSK 9600bps, DTMF | AX.25/SRLL, DTMF | DJ-C5 (ALINCO) |
?? | |
| Uplink (Digipeater) |
1200MHz 1268.5MHz |
GMSK 9600bps | AX.25/SRLL | TH-59 (KENWOOD) |
?? | |
| Telemetry | 430MHz 437.505MHz |
AFSK 1200bps / GMSK 9600bps | AX.25/SRLL | DJ-C5 (ALINCO) |
300 | ??(MAX) |
| Beacon | 430MHz 437.385MHz |
CW | CW | (INVAX) |
100 | ??(MAX) |
Cute-1.7 + APD antennas are the same as of CUTE-I. Amprifier is used
for 1200MHz receiver to make stable communication. Antennas are made of
steal tape(0.2mm thickness, 3mm wide) covered by PTFE. While the satellite
in the rocket, antennas are coiled. They are deployed after the satellite
is separated from the rocket. The movie file is about deployment of antennas.
Antenna deployment
(quicktime, 20.8MB)
4 mono-poles
Communication controller handles packet assembling and disassembling.
Controller has 2 micro-computers, one of which handle the transmit data,
and the other handles receive data. They are connected by RS-232 serial
line. Because the MPU can handle only serial communication, to communicate
with PDA, USB-serial converter. And also, MPU and APD unit directly connected
by serial line in order to conduct APD science mission even if PDA didn't
work. Micro-computer is H8S/2328 FlashROM type, which has 128kB ROM and
8kB RAM, and was tested by Gamma-ray radiation.
If PDA didn't work in the orbit, micro-computers in the Communication subsystems would control the whole satellite.
The development team has considered what service using amateur radio would be fun and interesting for both amateurs and universities. The team has discussed with Japanese radio amateurs from its early stage of development. Cute-1.7 + APD provides digipeater service to all amateurs in the world.
This is the image of Cute Digipeater operation. The satellite has 2 modes,
which are "Multi-cast mode" and "Uplink mode". Cute-1.7
+ APD usually operates in Multicast mode. All registered messages will be
sent sequentially. Anyone who has Cute-1.7 + APD telemetry decodable radio
transceiver can listen these messages. In Uplink mode, 1200MHz receiver for
Cute Digipeater mission is ready for accept your message to register. When
Cute-1.7 + APD accept your message, satellite will reply acknowledge signal
imediately in 437.505MHz telemetry link. Anyone can listern this reply signal.
detailed information, please see amateur
service section.
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