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Systems

Communications Subsystem - Big Pico

For the communications subsystem, we decided to continue using the transmitter and power amplifier circuitry used on the small pico. Since the big picos would take the scientific data, we needed a modem to modulate the data and a receiver to pick ground commands telling the satellites to collect lightning data. The modem chip is the Texas Instrument TCM3105 and was discontinued a couple of years ago. You might ask, then how did they get the TCM3105? Well, you still might find them in a Packet Radio Kit made by Ramsey Electronics (model number P-IBM), which are found at your local electronic surplus store. We used the chips and the crystals, that came with the kit, and modified the modem circuitry for our comm subsystem.

Here is one of the test comm boards for our big picosatellite.

We needed a receiver that was easy to implement with little time. Initially, we looked at Motorola and RF Micro Devices for receivers but realized we did have the experience nor the knowledge to test and debug the circuitry. Then we looked at RF Monolithics single-chip receiver. These receivers are low power, running off 3.0 volts and 1 mA. The RX1000 uses OOK (on-off keying) or ASK (amplitude shift keying) modulation.

Please see the comm schematics and trade-off sheet.

Please view the information on the comm system of Small Pico.

For the communications subsystem, we decided to continue using the transmitter and power amplifier circuitry used on the small pico. Since the big picos would take the scientific data, we needed a modem to modulate the data and a receiver to pick ground commands telling the satellites to collect lightning data. The modem chip is the Texas Instrument TCM3105 and was discontinued a couple of years ago. You might ask, then how did they get the TCM3105? Well, you still might find them in a Packet Radio Kit made by Ramsey Electronics (model number P-IBM), which are found at your local electronic surplus store. We used the chips and the crystals, that came with the kit, and modified the modem circuitry for our comm subsystem.	Here is one of the test comm boards for our big picosatellite.
We needed a receiver that was easy to implement with little time. Initially, we looked at Motorola and RF Micro Devices for receivers but realized we did have the experience nor the knowledge to test and debug the circuitry. Then we looked at RF Monolithics single-chip receiver. These receivers are low power, running off 3.0 volts and 1 mA. The RX1000 uses OOK (on-off keying) or ASK (amplitude shift keying) modulation.
Please see the comm schematics and trade-off sheet.