Test 2 Flashcards
What are 4 advantages to spread spectrum systems?
Resistance to Narrowband Interference
Security
Multiple Access Capability
Low POI
What are two types of spread spectrum modulation
Direct Sequence (DSSS)
Frequency Hopping (FHSS)
Explain PCM encoding.
Sampling - signal is sampled at regulat intervals.
Quantization - each sample is assigned a digital value.
Encoding - Quantized values are encoded into a digital format
How many bits per byte?
8 bits per byte
What is meant by 16 bit PCM?
16 bits per sample
Draw 10110 in Unipolar
Draw 10110 in Polar
Draw 10110 in Bipolar
Draw the following in Manchester Encoding
Draw the following in Differential Manchester Encoding
Explain the FM Capture Effect
When two FM signals are received simultaneiously, the stronger signal dominates and the receiver will only tune to the stronger signal.
What is the difference between Narrowband and Wideband FM signals in terms of Beta?
Narrowband: 0.5 < B < 1
Wideband: B > 1
Narrowband vs Wideband advantages
Narrowband: Uses less BW
Wideband: Better SNR
Identify the equation to calculate the BW of an FM signal
How does a Coherente receiver work?
The receiver local oscillator must be synched with the carrier frequency.
Carrier frequency is removed by the local oscillator and the two sidelobes are then combined.
How many bits per symbol?
With 16 levels:
How do you calculate the modulation index of an FM signal?
