Barrett 2040 - Table of Contents

2
Specification........................................................................................................................5
General Specifications...............................................................................................................5
Receiver Specifications .............................................................................................................6
Transmitter Specifications .........................................................................................................7
Barrett 2040, Barrett 2050 compliance..............................................................................8
FCC RF exposure compliance statement..................................................................................8
FCC RF exposure warning ........................................................................................................9
FCC modulation modes .............................................................................................................9
Industry Canada modulation modes ..........................................................................................9
Introduction.......................................................................................................................11
The use of DSP in the receiver ...........................................................................11
The use of DSP in the transmitter .......................................................................11
Other refinements................................................................................................11
Overview............................................................................................................................12
Control Head............................................................................................................................12
Microprocessor/ RF Audio PCB...............................................................................................12
Microprocessor section .......................................................................................12
RF section ...........................................................................................................12
Power amplifier PCB................................................................................................................13
Technical description.......................................................................................................14
Microprocessor / RF PCB – microprocessor section...............................................................14
Reference oscillator 22.7275 kHz .......................................................................14
Microprocessor....................................................................................................14
DDFS and VCO...................................................................................................14
VCO.....................................................................................................................14
Phase detector ....................................................................................................14
VCO divider ratio .................................................................................................15
Selcall (if enabled)...............................................................................................15
Audio mute ..........................................................................................................15
Audio Filtering .....................................................................................................15
Noise reduction ...................................................................................................15
Microprocessor / RF PCB – RF section...................................................................................15
First mixer............................................................................................................16
Post mixer amplifier Q5.......................................................................................16
First IF filter F1, F2 ..............................................................................................16
Second mixer U48...............................................................................................16
455 kHz IF amplifier ............................................................................................17
AGC.....................................................................................................................17
Carrier insertion generator ..................................................................................17
Third mixer (Product detector) ............................................................................17
Speaker output ....................................................................................................17
Tones ..................................................................................................................18
Transmit ...................................................................................................................................18
Microphone input. Remote head / Front Panel ...................................................18
Line input.............................................................................................................18
Microphone / Line input selection........................................................................18
Compression .......................................................................................................18
Transmit tones.....................................................................................................19
Post DSP (Transmit direction).............................................................................19
455 kHz IF processing.........................................................................................19
Second mixer ......................................................................................................19
First mixer............................................................................................................19
Noise blanker ......................................................................................................19
Power amplifier (PA) PCB .......................................................................................................20
Gain control amp .................................................................................................20