Radio Receiver Design
This reference focuses on understanding and designing radio receivers and systems, presenting the characteristics of individual receiver components and their interaction in cascade.
TABLE OF CONTENTS Radio Receiver Design
1.3: Energy, Power, Voltage and Current
1.3 Energy, Power, Voltage and Current
A transmitter produces a given amount of energy per unit time. We are interested in collecting this signal energy and making the best use of it. However, the signal energy competes with the noise energy also present in the signal path. As receiver designers, we are interested in received signal energy and noise energy, and we are not interested in voltage, current or power, except as they apply to received energy.
Jupiter Probe
Consider a space probe circling Jupiter. In order for a receiving system on earth to receive data from the probe, the probe must send out enough signal energy to overcome the noise energy we will also receive. Since
| (1.1) |  |
the probe can send out either a large amount of power for a short period of time or it can transmit a smaller amount of power for a longer period of time (for a fixed amount of energy).
Many common signal quality measurements, such as signal-to-noise ratio and bit error rates, are measurements of signal energy versus noise energy that was received over a period of time. But since the signal and noise are processed over the same period of time, the time in Equation 1.1 becomes irrelevant, and we can meaningfully speak of received signal power and received noise power.
Copyright Noble Publishing Corporation 2000 under license agreement with Books24x7
