Day 1: RF Equipment Flashcards
Equipment in a system that supports and allows the transmission of a signal
Transmit (Tx)
Takes digital information and adapts it to propagate through free space
Transmit (Tx)
Equipment in a system that supports and allows the reception of a signal
Receive (Rx)
Usually, takes in analog information and adapts it for delivery for users
Receive (Rx)
Frequencies used to transmit signals over a distance
Radio Frequency (RF)
Can be in several bands (UHF, L, S, etc…)
Radio Frequency (RF)
Can utilize characteristics of different bands to achieve different goals
Radio Frequency (RF)
Low frequencies (UHF and lower) travel great distances more reliably but sacrifice data rate
Radio Frequency (RF)
Medium frequencies (L, S, C, and X) interact with the environment (diffract, reflect) and can be manipulated to reach mobile or challenging RXers, and have middling data rates
Radio Frequency (RF)
Higher frequencies (Ku and above) gradually can support higher and higher data rates but lose power more rapidly and are susceptible to interference
Radio Frequency (RF)
Frequencies used to standardize a transmission system
Intermediate Frequency (IF)
Can be in certain bands (L Band, 70/140 MHz)
Intermediate Frequency (IF)
Used to reduce cost and improve efficiency of a system
Intermediate Frequency (IF)
All devices can talk without the need for additional converters
Intermediate Frequency (IF)
Steps in Signal Flow
Baseband Signals
MUX
MODEM - VSG
Converter(s) - U/C, D/C
Amp - HPA, LNA
Antenna - Transmitter, Receiver
TTF
Any user original signal in its original format - i.e. prior to multiplexing and modulation
Baseband Signals
Combines baseband signals into a single data stream
Multiplexer
Can use TDM, FDM, or CDM multiplexing formats
Multiplexer
Used to generate signals or modulate existing signals
Modulator
Used to strip off modulation and FEC to reveal data
Demodulator
Modifies Carrier Wave (CW) to represent data
MODEM
Modulator
Promotes flexibility in signal characeristics
MODEM
Modulator
Adds FEC (computational gain)
MODEM
Modulator
Digital to analog conversion
MODEM
Modulator
Must match received signal modulation for lock
MODEM
Demodulator
Understands Mod scheme
MODEM
Demodulator
Recognizes and strips off FEC
MODEM
Demodulator
Can be separate from Modulator
MODEM
Demodulator
Analog to digital conversion
MODEM
Demodulator
Sophisticated radio
Vector Signal Generator (VSG)
Produces many signals of varying types/forms
Vector Signal Generator (VSG)
Highly customizable signals (shape RF to desired “form”)
Vector Signal Generator (VSG)
Can emulate industry standards
Vector Signal Generator (VSG)
Designed for testing
Vector Signal Generator (VSG)
No actual data sent, modulates pseudo random noise over a carrier
Vector Signal Generator (VSG)
No FEC
Vector Signal Generator (VSG)
Uses Symbol Per Second
Vector Signal Generator (VSG)
- Non-modulated and simplest waveform
- A single frequency
VSG Basic Signal Generation Functions
Continuous Waveform (CW)
Modulates noise, no real data, signal takes the form of various modulation schemes
VSG Basic Signal Generation Functions
Modulated Waveform
CW repeats moving back and forth within a given frequency range
VSG Basic Signal Generation Functions
Sweep
CW pulses on and off at a specific frequency & time interval, or across multiple frequencies (hopping)
VSG Basic Signal Generation Functions
Pulsed
The process of mixing 2 frequencies together to achieve a desired output
Converters
Heterodyning
Takes an input frequency and a local oscillator and creates 4 frequencies, and filters for a desired result:
* Input
* LO
* Input + LO
* Input - LO
Converters
Heterodyning
IF to RF (low frequency to high frequency)
Converters
Upconverter
Adds active gain (higher frequency = more power)
Converters
Upconverter
Allows for flexibility in bands
Converters
Upconverter
RF to IF (high frequency to low frequency)
Converters
Downcoverters
Less attentuation travelling through cables
Converters
Downcoverters
Low Noise Block Downconverters (LNBs) combine what?
Converters
- down conversion
- low-noise amplification
The High Power Amplifier (HPA) adds what kind of gain to overcome Free Space Loss (FSL)?
Amplifiers
Active
Increases chances of data transmission
Amplifiers
High Power Amplifier (HPA)
Raises amplitude of received signals after Free Space Loss (FSL)
Amplifiers
Low-Noise Amplifier
The Low-Noise Amplifier filters out what?
Amplifiers
Out of Band Noise
Antennas add what kind of gain?
Antennas
Passive
Directional
Antennas
Transmit
Greatest factor in success/failure
Antennas
Transmit
Focuses signal on feedhorn
Antennas
Receive
Optimized by RF band
Antennas
Receive
The Transponder Translation Factor (or Frequency) (TTF) is the ratio of what?
Downlink frequency to uplink frequency
What does the Transponder Translation Factor (or Frequency) (TTF) do to polarity?
Flips it to the opposite for downlink
What is a “Spec-A?”
- Visual Representation of the EMS (Frequency Domain)
- Spectrograph (primary trace)
- Spectrogram (waterfall plot)
What are the 2 mission functions of a Spec-A?
- Signal Characterization
- Signal Monitoring
Allows tuning to specific center frequency (think RF address)
Basic Sectrum Analyzer Functions
Center Frequency
Selects frequencies displayed on x-axis (think zoom)
Basic Sectrum Analyzer Functions
Span
Sets the amplitude reference (top line of display)
Basic Sectrum Analyzer Functions
Reference Level
Like Span, but for the Y-axis (based on Ref Level)
Basic Sectrum Analyzer Functions
Scales per Division (Scal/Div)
Applies a filter to the frequencies within a span
Basic Sectrum Analyzer Functions
Resolution Bandwidth (RBW)
Higher RBW makes smoother signals and lower RBW makes sharper signals
Applies a filter to the sampled amplitude seen on frequencies within a span
Basic Sectrum Analyzer Functions
Video Bandwidth (VBW)
Higher VBW creates more noise on the display while lower VBW removes varation
The time it takes for the display to refresh; dependent on setttings and current functions
Basic Sectrum Analyzer Functions
Sweep
Tools used to make specific measurements or perform specific functions
Basic Sectrum Analyzer Functions
Marker/Trace/Measure
What are some spectrum analyzer best practices?
- Center your display
- Fill your display
- Start with a 100:1 ratio of RBW and VBW