Communication - Lander to Satellite Data Size
The design specifications for our seismometer show that it is sensitive to about 30 Hz as an upper bound on frequency. For this reason, we choose to budget for sampling the analog output of our seismometer at 100 Hz to surpass the Nyquist frequency and account for potentially increased sensitivity of the physical device. By assuming 16-bit quantization, we can calculate an upper bound on the amount of data collected and how much data will need to be transmitted from the lander to the orbiting satellite as shown below.
The orbit of the communication
satellite is designed so that
it completes an orbit of Venus three times per Earth Day, meaning that
we can
transmit data from the landing probe approximately every 8 hours. The
total
number of bits to be transmitted each communication period is the sum
of the
number of bits collected by each of the three channels of our
seismometer:
where,
This gives us that
Using the seismic data compression algorithm described in [Zheng and Liu, 2012], we can achieve approximately a 10:1 compression ratio. After including compression and accounting for up to 20% variation, we estimate the maximum amount of data that needs to be transmitted every 8 hours to be 1.659*107 bits. This estimate also allows for status information about the lander to be transmitted.