Cute-1.7 + APD II Project - Amateur Radio Service -

Small Satellite Program (SSP)

Laboratory for Space Systems (LSS), Tokyo Institute of Technology

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Top Cute Digipeater Service

About the use of amateur radio frequency band

In Tokyo Tech's CubeSat projects, Amateur radio band are used for communication between the satellite and the ground station. Cute-1.7+APD II also uses two uplinklines, 144MHz band and 1200MHz band, and two 430MHz downlink lines.

We recognize that these amateur bands are widely opened to amateur radio operators all over the world, in order to accomplish the following amateur radio operations.

1. Not for the purpose of pecuniary gain.
2. For those who are interested in radio technique.
3. To achieve the technical research of communication.

Overview of amateur radio service

In Cute-1.7 + APD II, we provide the following services using 1200MHz uplink and 430MHz downlink, on a trial basis.

1. Real-time relay communication service
2. Message box service

1267.6MHz high-speed packet communication (GMSK-9600bps) is used for uplink. 437.475MHz high-speed packet communication(GMSK-9600bps) is used for downlink.

SRLL version2.0 is usable for message bos service, as well as AX.25. Information about SRLL2.0 is mentioned below.

These service missions will be achieved in the normal operation phase. We will notify the information about this service by updating website.

Necessary equipment

Following equipments are nesesarry for this service.

1. Transceiver and TNC compatible with high-speed packet communication (GMSK 9600bps)
2. 1200MHz band transmitting set, high-gain antenna
3. 430MHz band receiving set
   

   In addition the following equipment would be helpful.

4. satellite tracking equipments (for antenna rotation control and Doppler shift control)

Please use the following numers for communication circuit design.
We estimate that the antenna gain should exceed the constant value, depending on the communication distance, in order to achieve a steady communication by 10W transmission. For example, transmission antenna gain should exceed 10dBi to communicate 1000km far, and 18dBi to communicate 2500Km.

Receiving antenna peak gain	-2	dBi
Receiver's amplification gain	0	dB
Antenna noise temperature	300	K
Feeder line loss	1	dB
Receiver's noise figure	12	dB

Real-time relay communication service

This is a real-time communication by using the satellite as a relay. The following figure shows the concept of this service.

Conceptual image of real-time relay service

This service uses functions in AX.25. Please assign the satellite's call sign JQ1YTC as VIA in AX.25 when uplink by 1267.6MHz GMSK, and the satellite will relay all the flames. The downlink will be achieved by 437.475MHz GMSK.

Who succeeded in communicating with/via Cute(2010/2/1 Updated)

Uplink Achieved			Downlink Achieved
[1]	JA5BLZ	Mr. Noguchi	[1]	JA6PL	Mr. Iji
[2]	JH4BTI	Mr. Yamashita	[2]	JH0JMA	Mr. Iwashita
[3]	JA0CAW	Mr. Sato	[3]	JE9PEL/1	Mr. Wakita
[4]	JH1BCL	Mr. Sekine	[4]	JA1GDE	Mr. Kasei
[5]	JA6PL	Mr. Iji	[5]	JA0CAW	Mr. Sato
[6]	JH0JMA	Mr. Iwashita	[6]	JH1BCL	Mr. Sekine
[7]	JE9PEL/1	Mr. Wakita	[7]	JH4BTI	Mr. Yamashita
[8]			[8]	JA5BLZ	Mr. Noguchi

Message box function service

The satellite has a message box inside of its PDA, and we will throw is open to amateur radio operators. The following figure shows the concept of this service.

Message box function concept

In order to register a message or send a command, please send satellite a UI flame in which you assign the satellite's call sign as a destination. Or please send by SRLL protocol.

The command list is as follows.

Command list

requestID ：Specify the massage number, and downlink the massage.
requestmycall ：Downlink the massage which was destined to the call sign of the command sender.
removeID ：Specify the massage number, and delete it.
multicast ：Downlink the massages sequencially which are saved in the box.
countmsg ：Return the number of saved massage.
timeplease ：Return the satellite time.

Who succeeded in communicating with/via Cute(2009/9/1 Updated)

Uplink Achieved			Downlink Achieved
[1]	JH1BCL	Mr. Sekine	[1]	JH1BCL	Mr. Sekine
[2]	JA0CAW	Mr. Satou	[2]	JE9PEL/1	Mr. Wakita
[3]	JA5BLZ	Mr. Noguchi	[3]	JA5BLZ	Mr. Noguchi
[4]	JE9PEL/1	Mr. Wakita	[4]	JA6PL	Mr. Iji
[5]	JA6PL	Mr. Iji	[5]	JH0JMA	Mr. Iwashita
[6]	JH0JMA	Mr. Iwashita	[6]

About SRLL version2.0

In Cute-1.7+APD II, we communicate by SRLL version2.0 as well as AX.25.
SRLL version2.0 has some modifications from SRLL version1.0, shown as follows.

• Selectable three kinds of packet length, 32bytes, 64bytes, 96bytes.
• Add call sign.
• Convert into NRZI.
  

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