RF 3 Flashcards
Lower RBW
- Lower noise floor
- Higher sensitivity
Aspects of Digital
- Square signal
- Can’t be demodulated
Most common impedance
50Ω
Most directional antena
Horn
Does a carrier current require 60 Hz?
No
If I talk louder in FM
Signal gets wider
If I talk louder in AM
Signal gets taller
Up-converters overcome
Equipment weakness and lower frequencies
Up-converters compensate for
Receiver sensitivity and frequency response near DC
Medium/channel is targeted
Because it is the least controlled
Impedance (defined by capacitance and inductance) considerations
- diameter of conductors
- distance between conductors
- dielectric between conductors
Transition point from Near to Far Field
5 wavelengths (λ)
Inverse Square Law
Signal falls 6 dB for every distance doubled, from the transmitter
Physical barriers’ effect on sound propagation
1) Reflection
2) Refraction
3) Diffraction
Modulation
1) The Process of putting information onto a high frequency carrier for transmission
2) In order to be used by the receiving person it must be DEMODULATED (stripping away the carrier)
14-sided box
- 6 interior
- 6 exterior
- everything inside
- everything outside
30 dBm
1 W
How do cell devices talk to the base station?
- Frequency division duplexing (FDD)
- Time division duplexing (TDD)
Cellular generations
- 1G: AMPS
- 2G: GSM/CDMA one
- 3G: UMTS - CDMA2000; 3GPP
- 4G: LTE
- 5G: NR
AMPS
- 30 kHz
- voice
GSM
- 200 kHz
- voice
CDMA
- 1.25 MHz
- voice & data
UMTS
- 5 MHz
- voice & data
LTE
- 1.4 - 20 MHz
- data
NR (VoLTE)
- 100 MHz
- data
Unmodulated sine wave BW
0
Amplitude Modulated sine wave
2 times baseband BW; maximum
Frequency Modulated sine wave
2 times baseband BW; minimum
Analogue to digital conversion
- Filtering
- Sampling
- Quantizing
- Encoding
- Streaming
Components of cellular
a) Mobile devices
- cellphones
- credit card readers
- rental cars
- IoT
b) Base station
c) Central controller
