1. Communication System
DINO Peer Review
July 9, 2003

2. Subsystem Block Diagram

3. Power Requirements Daytime Operation
Receiver: 0.54 W (6 V, 90 mA) always.
TNC: 5.52 W (13.8 V, 400 mA) always.
Transmitter: 8.4 W (6 V, 1.4 A) for approx. 2 minutes, otherwise same as Receiver (0.54 W).

4. Power Requirements Nighttime Operation Safe Mode
Receiver: 0.54 W (6 V, 90 mA) always.
TNC: 5.52 W (13.8 V, 400 mA) always.
Transmitter: 8.4 W (6 V, 1.4 A) for approx. 4 seconds, otherwise same as Receiver (0.54 W).
Safe Mode
Same as nighttime.

5. Calculating Transmission Time
Time needed to send one packet:
10 bits/byte * 256 bytes/packet  9600 bits/sec = sec/packet
Total transmission time (assuming 50 kB per pass during daytime):
0.267 sec/packet * 50 kB/pass
 256 bytes/packet
= 52 sec/pass

6. Transceiver Trade Study: Four Choices
ICOM IC-ID1 1.2 GHz digital
Pros
Allows for small antenna
Built-in TNC with kbps baud rate
USB interface
Cons
Expensive
Only one frequency band: need half-duplex comm.
Newly released, untested, unlicensed by FCC
Needs new ground equipment

7. Transceiver Trade Study
Kenwood TH-D7 dual band 70 cm/ 2 m
Pros
Operates in 2 frequency bands
One third of the cost of the ICOM radio
Compatible ground equipment already set up
Previous experience from other missions
Cons
Max. baud rate of 9.6 kbps.
Requires larger antenna than ICOM
Uses RS-232 interface

8. Transceiver Trade Study
TEKK SD-5200 synthesized radio and TEKK KS-960 crystal radio
Pros
Can be set to one frequency by the manufacturer: no actual programming required (unlike Kenwood)
Currently being proven in space flight on Stanford’s Quakesat mission
Significantly cheaper than the Kenwood radios
Cons
Only UHF version available: so we would need a different radio for VHF (no longer advantageous)

9. Design Decision
Two Kenwood TH-D7 radios: one for uplink, the other for downlink.
Reasons
Only choice that allows two distinct channels for uplink and downlink, respectively.
Much better to use same model for both channels
9.6 kbps should be a sufficient baud rate for the purposes of this mission
No idea when the ICOM 1.2 GHz radio will ever be available for our use.

10. Antenna Trade Study Monopole Pros Cons Simple design
Does not take up space on the satellite’s surface
Cons
Deployable
Could be very long (~50 cm)

11. Antenna Trade Study Patch Pros Cons Preferable gain pattern
Non-deployable
Cons
Could occupy a lot of space on nadir surface
More complicated design process
More expensive