Day 5 -6 Flashcards
What compares the level of desired signal to the level of background noise?
SNR (Signal to Noise Ratio)
Rate at which transmitted segment of data received with incorrect bits compared to the original message
BER (Bit Error Rate)
What is a common means of encoding data to determine if any errors have been introduced through interference?
Error Detection
Method of adding redundant information to data stream that allows for ID and correction of errors.
FEC (Forward Error Correction)
What is FDMA?
Frequency Division Multiple Access. Assigned bandwidth is divided into segments. Users operate at the same time, using different frequencies (different frequencies, same time).
What is TDMA?
Time Division Multiple Access. The allocation of specific time slots for transmission. Users operate on same frequencies at different times (same frequency, different times).
What is CDMA?
Code Division Multiple Access. All users transmit signals simultaneously on the multiple access channel.
What is the process of combining signals into a composite baseband in order to modulate on to a single carrier?
Multiplexing
What is Spread Spectrum?
A modulation technique that encodes a digital signal in a manner that distributes transmissions over a greater bandwidth than the information signal would naturally require. (information is spread over a wide frequency band, much wider than the bandwidth required to send the message).
What technique results in a signal having a low probability of detection, a low probability of interception, and a reduced susceptibility to interference?
Spread Spectrum
How does PRN help hide our signals?
Pseudo-Random-Noise spread sequence is a digital sequence that resembles a random succession of ones and zeroes. Helps hide signals from adversaries.
What is FHSS?
Frequency Hopping Spread Spectrum. Carrier frequency of the transmitted wave changes at regular intervals.
What is DSSS?
Direct Sequence Spread Spectrum. Uses a PRN sequence to allow user to operate below the noise floor.
