Cute_Comm

Function
Sequence
Transceiver
Antenna
DTMF
TNC
CW Morse Code
System Block Diagram
Balloon Experiment

Function

   Receive a series of DTMF control commands from Titech Ground Station.
   Send FM-telemetry packets.
   Send CW-telemetry data.
   Change the Communication Protocol

Comm. Sequence

   Receive CW-telemetory from CubeSat.
   Send DTMF commands of "FM transmitter Power ON".
   Check CW-teremetry whether DTMF commands are received.
   Send DTMF commands. （Sensor Select Command,Protocol Change command etc.）
   Receive FM-telemetory.
   Send DTMF "FM transmitter OFF"command.

  We use "CW " as a beacon to find the CubeSat, so CW transmitter is always "ON".
  The power consumption of FM transmitter is so large, so it is usualy "OFF".
  We could turn on and off the FM transmitter using DTMF command.


The details of "OBC" is here.
The details of "Titech Ground Station" is here.

Transceiver

Freq.
(MHz)

Form

Tranceiver

Power output
(mW)

Power consumption
(mW)

Uplink

144MHz Band

DTMF

DJ-C1
(ALINCO)

100

Downlink

430MHz Band

Packet
(Ax.25 or SRLL　Protocol)

DJ-C4
(ALINCO)

350

1100(MAX)

Downlink

430MHz Band

CW

Order 1, 2
( Maki Denki)

100

400
（以下）

Antenna

Antenna configuration of "CUTE" balloon model

Freq.
(MHz)

Antenna length
(mm)

Antenna width

Uplink

144MHz Band

500
(1/4 wave length)

less than 4mm

Downlink

430MHz Band

170
(1/4 wave length)

less than 4mm

Downlink

430MHz Band

170
(1/4 wave length)

less than 4mm

"Antenna deployment" page　is here.

DTMF

  We use the DTMF signals to control CubeSat

     　 CM8870 　　2.7～3.6V Supply Voltage(California Micro)

  This devices have ever been used in Space.

TNC

   Functions of "TNC" are "Packetizing,modulation,demoduration".
   and we add the "Protocol change function".

   Ax.25 protocol　　Popular Amature packet communication protocol
   SRLL　　　　　　　 Titech Radio Club original protocol

   TNC Specification



   Devises

   　CPU 　　　　H8/ 3334Y (Hitachi)



   　 Modem IC 　MX614（MX_COM）



Details of SRLL Protocol and TNC

Morse Signal

   　
   Devises
　　PIC16LC73A-04I (Microchip)



   Function

   　 Transform serial data from OBC into Morse Code.
   　 Even if OBC does not send any data for some reasons , send the "CUTE" and "TITECH" message.


The detailes of CW data format are here.

System Block Diagram

Balloon Experiment

We conducted "ISAS Balloon Experiment"
The details of this experiment is shown here
Cute Balloon Experiment Model
1,2,3
Balloon Experiment
1,2,3

	Freq. (MHz)	Form	Tranceiver	Power output (mW)	Power consumption (mW)
Uplink	144MHz Band	DTMF	DJ-C1 (ALINCO)		100
Downlink	430MHz Band	Packet (Ax.25 or SRLL　Protocol)	DJ-C4 (ALINCO)	350	1100(MAX)
Downlink	430MHz Band	CW	Order 1, 2 ( Maki Denki)	100	400 （以下）

	Freq. (MHz)	Antenna length (mm)	Antenna width
Uplink	144MHz Band	500 (1/4 wave length)	less than 4mm
Downlink	430MHz Band	170 (1/4 wave length)	less than 4mm
Downlink	430MHz Band	170 (1/4 wave length)	less than 4mm