CIRCUIT DESCRIPTION
5-11
Figure 5-4 RF Board Block Diagram (Version A/B)
The frequency generation function is performed
by three ICs and associated circuitry. The reference
oscillator provides a frequency standard to the synthe-
sizer/prescaler IC which controls the VCO IC. The
VCO IC actually generates the first LO and transmit-
injection signals and buffers them to the required
power level. The synthesizer/prescaler circuit module
incorporates frequency-division and comparison
circuitry to keep the VCO signals stable. The synthe-
sizer/prescaler IC is controlled by the control logic
through a serial bus. Most of the synthesizer circuitry
is enclosed in rigid metal cans to reduce microphonic
effects.
The receiver back end consists of a two-pole
crystal filter, an IF amplifier, a second two-pole crystal
filter, and the digital back-end IC (ABACUS). The
two-pole filters are wide enough to accommodate 5
kHz modulation. Final IF filtering is done digitally in
the ADSIC.
The digital back-end IC (ABACUS) consists of
an amplifier, the second mixer, an IF analog-to-digital
converter, a baseband down-converter, and a 2.4 MHz
synthesis circuit. The second LO is generated by
discrete components external to the IC. The output of
the ABACUS IC is a digital bit stream that is current
driven on a differential pair for a reduction in noise
generation.
The transmitter consists of an RF PA IC that gets
an injection signal from the VCO. Transmit power is
controlled by two custom ICs that monitor the output
of a directional coupler and adjust PA control voltages
correspondingly. The signal passes through a Rx/Tx
switch that uses PIN diodes to automatically provide
an appropriate interface to transmit or receive signals.
5.6 VHF/UHF RF BOARD (VERSION A/B)
NOTE: The following describes the earlier Version A
and B RF boards described in Section 1.13.1.
5.6.1 FREQUENCY GENERATION UNIT (FGU)
The frequency generation unit (FGU) consists of
three major sections: the high stability reference oscil-
lator (U203), the fractional-N synthesizer (U204,) and
the VCO buffer (U201). A 5V regulator (U202),
supplies power to the FGU. The synthesizer receives
the 5V REG at U204, and applies it to a filtering
circuit within the module and capacitor C253. The
well-filtered 5-volt output at U204, pin 19 is distrib-
uted to the Tx and Rx VCOs and the VCO buffer IC.
The mixer’s LO injection signal and transmit
frequency are generated by the Rx VCO and Tx VCO,
respectively. The Rx VCO uses an external active
VHF/UHF RF BOARD (VERSION A/B)
Содержание 5100 Series
Страница 76: ...PARTS LIST 7 20 MP032 MP030 A200 Part of A200 Part of A200 MP031 MP033 MP034 A100 A030 EP031 J4 J3 EP030 6 ...
Страница 85: ...8 9 Version C Board see Section 1 13 VHF RF BOARD VER C LAYOUT ...
Страница 87: ...8 11 VHF RF BOARD SCHEMATIC VER B PAGE 2 OF 3 ...
Страница 88: ...8 12 VHF RF BOARD SCHEMATIC VER B PAGE 3 OF 3 ...
Страница 95: ...8 19 BOTTOM VIEW TOP VIEW Version C Board see Section 1 13 UHF RF BOARD VER C LAYOUT ...
Страница 105: ...8 29 BOTTOM VIEW TOP VIEW 700 800 MHZ RF BOARD VER C LAYOUT Version C Board see Section 1 13 ...
Страница 112: ...8 36 SEM Module 5500 120 LOGIC BOARD VER C SCHEMATIC PAGE 5 OF 11 ...
Страница 113: ...8 37 Analog Switch 5500 120 LOGIC BOARD VER C SCHEMATIC PAGE 6 OF 11 ...
Страница 118: ...8 42 5500 120 LOGIC BOARD VER C LAYOUT BOTTOM VIEW TOP VIEW Version C Board see Section 1 13 ...
Страница 127: ...8 51 5100 160 LOGIC BOARD VER B TOP VIEW 5100 160 LOGIC BOARD VER B BOTTOM VIEW Version with Motorola UCM ...
Страница 143: ...8 67 5500 420 USER INTERFACE BOARD VER C TOP VIEW Version C Board see Section 1 13 ...
Страница 144: ...8 68 5500 420 USER INTERFACE BOARD VER C BOTTOM VIEW ...
Страница 147: ...8 71 5100 410 USER INTERFACE BOARD VER A TOP VIEW Version w o encryption module Version A Board see Section 1 13 ...
Страница 148: ...8 72 5100 410 USER INTERFACE BOARD VER A BOTTOM VIEW Version w o encryption module ...
Страница 151: ...8 75 5100 450 USER INTERFACE BOARD VER B TOP VIEW Version with EFJ SEM Version B Board see Section 1 13 ...
Страница 152: ...8 76 5100 450 USER INTERFACE BOARD VER B BOTTOM VIEW Version with EFJ SEM ...
Страница 155: ...8 79 5100 460 USER INTERFACE BOARD VER B TOP VIEW Version with Motorola UCM Version B Board see Section 1 13 ...
Страница 156: ...8 80 5100 460 USER INTERFACE BOARD VER B BOTTOM VIEW Version with Motorola UCM ...
Страница 171: ...9 14 OBSOLETE VERSION 5100 410 USER INTERFACE BOARD VER A TOP VIEW Version A Board see Section 1 13 Revision 6 Board ...
Страница 172: ...9 15 OBSOLETE VERSION 5100 410 USER INTERFACE BOARD VER A BOTTOM VIEW Revision 6 Board ...
Страница 173: ...Part Number 001 5100 0017CD 12 04hph Printed in U S A ...