Deep-Penetrating Probes
A total of three probes are used to measure data entering Neptune's surface. One enters at Neptune's equator (which is in-line with the center of Neptune and the Relay Satellite), while the other two enter at 45 N and 45 S degrees Latitude. They transmit 8 kbps in real time to the Geostationary Neptunian Orbit relay satellite. Communication calculations were again performed for the worse case, providing exceptional quality and robustness.
Power
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The probes are battery powered. They require enough power to transmit for 25 hours. Upon searching for available sources, the preliminary selection was made of Sanyo Ni-H2 batteries, however the full details have been left to the power engineers. These batteries were selected based upon the results of research conducted for the Japanese Aerospace Exploration Agency. |
Communications Bandwidth
The probes will be transmitting 8 kbps of data using a rate 1/2 Turbo Code, resulting in a total of 16 kbps of information. QPSK modulation is also implemented. MATLAB (see Bandwidth.m) was used to determine the bandwidth required for this signal using the raised cosine pulse shape. This resulted in approximately 80 kHz of needed bandwidth:
Communications Block Diagram
Above is the basic communications block diagram for the probes. The probes will be transmitting using an omni-directional antenna. The following is a list of the communication components aboard the Probes (Click on the model for the Spec Sheet):
| Component | Brand | Model | Specs | Price |
| Turbo Coder | ComBlock | COM-7001 | Rate .25 - .97; 64b-4kb Block Length | $375.00 |
| PN Coder | Texas Instruments | CDMA2000 1X | Integrated Filter, Amp, and SS Encoder | Not Given |
| Modulator | Analog Devices | AD8345 | QPSK, 250-1000 MHz | $5.00 |
| Variable Gain Amp | Analog Devices | AD604 | Ultra Low Noise, 0-48 dB Gain | $17.73 |
Geometry - Probes - Relay Satellite - DSN