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Math Help - Can anyone help

  1. #1
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    Question Can anyone help

    A typical sensor node has a transmit duty cycle of 3% and draws a current of 1.53 mA while it is in the active part of the duty cycle, and negligible current while in the inactive part of the duty cycle. On average, the node sends 375 bits of data per transmission and each transmission takes 33.0 ms.
    • i.How long does each node transmit for in every hour? Express your answer in seconds.
    • ii.If each sensor node has a battery with a capacity of 2510 mAh, how long a transmission is this battery capable of powering before it must be recharged or replaced? Express your answer in seconds in scientific notation.
    • iii.At what data rate is data transferred in each transmission? Express your answer in kbps.

    Give all your answers to 3 significant figures.
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  2. #2
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    Re: Can anyone help

    Since the sensor transmits 3% of the time, it transmits for 3600 * 0.03 seconds each hour.

    For the second question, see this thread. Note that the word "transmission" is used in two different senses in the problem, as that thread says. There was an almost identical question in this thread, which used the phrase "for how long can the sensor continue to operate" (intermittently, as I see it) instead of "how long a transmission is this battery capable of powering". This makes more sense because it avoids that ambiguity.

    Try to answer the third question yourself and describe any difficulty if you need help.
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  3. #3
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    Re: Can anyone help

    This Question has been bothering me for some time. I've ask around my friends if they could shed some light on it, but all they could answer was the first question. When I look at it now nothing makes any sense. Like I say I would be gratefull if you could help me to answer the question
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  4. #4
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    Re: Can anyone help

    The light as finaly come on in regards to Qu. 1+2 thankyou What would I have to do to work out the data rate in Qu.3
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  5. #5
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    Re: Can anyone help

    Quote Originally Posted by fatherjack View Post
    What would I have to do to work out the data rate in Qu.3
    How do you determine car speed in miles per hour? You divide the number of miles by the number of hours. Similarly, how do you determine transmission speed in bits per second?

    Note that kbps is 1000 bits per second.
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