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




Japanese Version This Page is English Version
Copyright(C) 2000,2001 -CubeSat- All rights reserved.
Tokyo Institute of Technology    Laboratory for Space Systems (LSS)
TITECH CUBESAT PROJECT TEAM
Contact : Tomoyuki Urabe