- Produces electrical voltage.
- Voltage drives transducer to produce sound pulse.
- Tells receiver and memory contact made.
- Starts timer for “time of flight” to calculate depth.
THE PULSER AKA BEAM FORMER!!!
PULSER FUNCTIONS:
- Controls PRF, PRP, Amplitude of pulse, frequency for CW and firing patterns for arrays.
- Controls acoustic power of machine.
ACOUSTIC POWER AKA:
OUTPUT POWER, TRANSMIT OR OUTPUT, ENERGY OUTPUT, OUTPUT GAIN.
- CONVERTS US TO ELECTRICAL VOLTAGE AND ELECTRICAL VOLTAGE TO US.
- SENDS INFO FROM VOLTAGE TO RECEIVER.
TRANSDUCER
5 FUNCTIONS OF THE RECEIVER:
- AMPLIFICATION
- COMPENSATION
- COMPRESSION
- DEMODULATION
- REJECTION
CLIPS LARGE VOLTAGE SPIKES OR AMPLIFIES VERY WEAK SIGNALS.
PREAMPLIFIER
- SONOGRAPHER CONTROLS BY ADJUSTING GAIN.
- SMALL VOLTAGES BOOSTED TO MAKE STRONGER.
AMPLIFICATION
COMPENSATION AKA:
SWEPT GAIN TIME GAIN COMPENSATION (TGC) DEPTH GAIN COMPENSATION (DGC) LGC SGC
COMPENSATION FUNCTIONS:
- CREATE UNIFORM IMAGE BRIGHTNESS.
- CAN BE ADJUSTED BY SONOGRAPHER/W TGC SLOPE.
- SQUEEZING SIGNAL AMPLITUDES INTO A NARROWER RANGE.
- RATIO OF GREATEST TO SMALLEST AMPLITUDE THAT CAN BE HANDLED BY US INSTRUMENT.
- SOME DEGREE OF CONTROL.
COMPRESSION!!!
-DYNAMIC RANGE (LOG COMPRESSION, COMPRESSION) RELATES TO COMPRESSION.
LOWER DYNAMIC RANGE = HIGHER CONTRAST
HIGHER DYNAMIC RANGE = LOWER CONTRAST
LARGEST - SMALLEST DYNAMIC RANGE:
- TRANSDUCER/RECEIVER = 100-200 dB
- MEMORY = 40-45 dB
- MONITOR/HARD COPY = 20-30dB
- PROCESS OF CHANGING VOLTAGES TO ANOTHER FORM.
- NOT USER ADJUSTABLE!!!
- 2 PARTS : RECTIFICATION, SMOOTHING
DEMODULATION
WHAT IS RECTIFICATION AND SMOOTHING?
RECTIFICATION: NEG SIGNALS TO POS.
SMOOTHING: NEW SIGNAL IS AVERAGED.
- PROCESS OF SUPPRESSING OR ELIMINATING SMALL VOLTAGE AMPLITUDES.
- HELPS REDUCE NOISE.
- SONOGRAPHER CONTROLS.
REJECTION!!!
-CONTROLLED WITH FILTER CONTROL.
REJECTION AKA:
SUPRESSION
THRESHOLD
FILTER
OVERALL RECEIVER FUNCTION:
MANIPULATES AND PROCESSES VOLTAGES AND SENDS THEM TO MEMORY (SCAN CONVERTER)
