Motorola Astro Digitalport Saber Detailed 68p81076c10 A Manual
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2-2 Notations Used in This ManualThroughout the text in this publication, you will notice the use of warnings, cautions, and notes. These notations are used to emphasize that safety hazards exist, and care must be taken and observed. NOTE:An operational procedure, practice, or condition, etc., which is essential to emphasize. You will also find in this publication the use of the asterisk symbol (*) to indicate a negative or NOT logic true signal. CAUTION: Indicates a potentially hazardous sit- uation which, if not avoided, ma y result in equipment damage. To properly word a caution, first identify the gravity of the risk, then describe the nature of the risk, then tell the user how to avoid the risk, and finally communicate this risk clearly to the person exposed to the risk. WARNING: Indicates a potentially hazardous situation which, if not avoided, could result in death or injury. To properly word a caution, first identify the gravity of the risk, then describe the nature of the risk, then tell the user how to avoid the risk, and finally communicate this risk clearly to the person exposed to the risk. DANGER: Indicates an imminently hazardous situation which, if not avoided, will result in death or injury. To properly word a caution, first identify the gravity of the risk, then describe the nature of the risk, then tell the user how to avoid the risk, and finally communicate this risk clearly to the person exposed to the risk. ! C a u t i o n ! W A R N I N G ! D A N G E R
3-1 General Overview of an ASTRO Digital SABER Radio 3 The ASTRO Digital SABER radio is a dual mode (trunked/ conventional), microcontroller-based transceiver incorporating a Digital Signal Processor (DSP). The microcontroller handles the general radio control, monitors status, and processes commands input from the keypad or other user controls. The DSP processes the typical analog signals and generates the standard signaling digitally to provide compatibility with existing analog systems. In addition it provides for digital modulation techniques utilizing voice encoding techniques with error correction schemes to provide the user with enhanced range and audio quality all in a reduced bandwidth channel requirement. It allows embedded signaling which can mix system information and data with digital voice to add the capability of supporting a multitude of system features. The ASTRO Digital SABER radio is available in three models, which are available in the following bands; VHF (136-174MHz), UHF (403- 470MHz or 450-512MHz), and 800MHz (806-870MHz). The ASTRO Digital SABER radio consists of: •Vocoder/Controller (VOCON) Board •Band-Dependent Transceiver Board •Display/Keypad Assembly •In secure models, a hardware, encryption module is also included. It is advantageous to think of the vocoder/controller (VOCON) board as two separate functional units; a vocoder and a controller. The vocoder section consists of a Digital Signal Processor (DSP), Static-RAM (SRAM), FLASH program memory, audio power amplifier (audio PA), and a custom ABACUS/DSP support integrated circuit (ADSIC). This section handles all the analog and signaling functions previously accomplished with analog integrated circuits (ICs) by processing the signals digitally. In addition, it provides advanced digital signal processing functions which include digital modulation and voice encoding techniques while still maintaining compatibility with today’s analog radio systems. The controller section consists of a microcontroller with FLASH program memory, EEPROM, SRAM, and a custom IC; the SLIC. This section handles general radio control and ergonomics through the various user buttons, and rotary knobs. The transceiver is frequency dependent, and one transceiver exists for each of the bands; VHF, UHF (range 1 and 2), and 800MHz. The distinction with these transceivers is the incorporation of the ABACUS IC. The ABACUS is a digital IF/Discriminator which provides a true digital interface to the digital circuitry of the vocoder.
3-2 The display module is a two-line, liquid crystal display with associated circuitry. The display module is an integral part of the front cover keypad. This module utilizes chip-on-board technology and is not considered field repairable. The available encryption module connects directly to the VOCON board and interfaces directly to the vocoder digital circuitry. It contains an independent microcontroller, and two custom ICs to perform digital, numerical, encryption algorithms. Analog Mode of OperationWhen the radio is receiving, the signal comes from the antenna/ antenna-switch connector to the transceiver board, passes through the RX/TX switch and the receiver front end. The signal is then filtered, amplified, and mixed with the first local-oscillator signal generated by the voltage-controlled oscillator (VCO). The resulting intermediate frequency (IF) signal is fed to the IF circuitry, where it is again filtered and amplified. This amplified signal is passed to the digital back-end IC, where it is mixed with the second local oscillator to create the second IF at 450kHz. It is then converted to a digital bit stream and mixed a third time to produce a baseband signal. This signal is passed to the VOCON board through a current-driven differential output. On the VOCON board, the ADSIC (ABACUS DSP Support IC) digitally filters and discriminates the signal, and passes it to the digital-signal processor (DSP). The DSP decodes the information in the signal and identifies the appropriate destination for it. For a voice signal, the DSP will route the digital voice data to the ADSIC for conversion to an analog signal. The ADSIC will then present the signal to the audio power amplifier, which drives the speaker. For signalling information, the DSP will decode the message and pass it to the microcontrol unit. When the radio is transmitting, microphone audio is passed from the audio power amplifier (PA) to the ADSIC, where the signal is digitized. The ADSIC passes digital data to the DSP, where pre-emphasis and low- pass (splatter) filtering are done. The DSP returns this signal to the ADSIC, where it is reconverted into an analog signal and scaled for application to the voltage-controlled oscillator as a modulation signal. Transmitted signalling information is accepted by the DSP from the microcontrol unit, coded appropriately, and passed to the ADSIC, which handles it the same as a voice signal. Analog modulation information is passed to the synthesizer along the modulation line. A modulated carrier is provided to the RF PA, which transmits the signal under dynamic power control. ASTRO Mode (Digital Mode) of OperationIn the ASTRO mode (digital mode) of operation, the transmitted or received signal is limited to a discrete set of four deviation levels. The receiver handles an ASTRO-mode signal identically to an analog-mode signal up to the point where the DSP decodes the received data. In the ASTRO receive mode, the DSP uses a specifically defined algorithm to recover information. In the ASTRO transmit mode, microphone audio is processed identically to an analog mode with the exception of the algorithm the DSP uses to encode the information. This algorithm will result in deviation levels that are limited to four discrete levels.
3-3 Transceiver Board OverviewThe receiver front end consists of a preselector, an RF amplifier, a second preselector, and a mixer. Both preselectors in the VHF and UHF radios are varactor-tuned, two-pole filters controlled by the microcontrol unit through the digital/analog (D/A) IC. On the 800MHz receiver front end, these filters are fixed-tuned. The RF amplifier is a dual-gate, gallium- arsenide based IC. The mixer is a double-balanced, active mixer coupled by transformers. Injection is provided by the VCO through an injection filter. See Table 14 for local oscillator (LO) and first IF information. The frequency generation function is performed by three ICs and associated circuitry. The reference oscillator provides a frequency standard to the synthesizer/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 synthesizer/ prescaler IC is controlled by the microcontrol unit through a serial bus. Most of the synthesizer circuitry is enclosed in rigid metal cans on the transceiver board 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 5kHz 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 2.4MHz synthesis circuit to provide a clock to the ADSIC on the VOCON board. 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. Antenna selection is done mechanically in the control top. VOCON Board OverviewThe VOCON board contains the radio’s microcontrol unit with its memory and support circuits, voltage regulators, audio, DSP, ADSIC, and power control circuits. Connected to the VOCON board are the display board, transceiver board, and control top. The microcontrol unit (MCU) controls receive/transmit frequencies, power levels, display, and other radio functions, using either direct logic control or serial communications paths to the devices.The microcontrol unit executes a stored program located in the FLASH ROM. Data is transferred to and from memory by the microcontrol unit data bus. The memory location from which data is read, or to which data is written, is selected by the address lines.
3-4 The SLIC acts as an extension of the microcontrol unit by providing logic functions such as lower address latch, reset, memory address decoding, and additional control lines for the radio. The microcontrol unit controls the crystal-pull circuit to adjust the crystal oscillator’s frequency on the microcontrol unit, so that the E-clock’ s harmonics do not cause interference with the radio’s receive channel. Switched +5V is used for all circuits on the VOCON board except the audio PA, which is sourced from 7.5V. The regulator automatically provides 5V when the radio is turned on. The regulator’s power-down mode is controlled by the microcontrol unit, which senses the position of the on/off/volume control knob. The DSP performs all signalling and voice encoding and decoding as well as audio filtering and volume control. This includes Private- Line®/Digital Private Line™ (PL/DPL) encode and alert-tone generation. The IC transmits pre-emphasis on analog signals and applies a low-pass (splatter) filter to all transmitted signals. It is programmed using parallel programming from the microcontrol unit and the ADSIC. The ADSIC performs analog-to-digital and digital-to-analog conversions on audio signals. It contains attenuators for volume, squelch, deviation, and compensation, and it executes receiver filtering and discrimination. The IC requires a 2.4MHz clock to function (generated by the ABACUS IC) and is programmed by the microcontrol unit SPI bus.
4-1 Radio Power 4 IntroductionThis section of the manual provides a detailed circuit description of the power distribution for an ASTRO Digital SABER radio. GeneralIn the ASTRO radio, power is distributed to three boards: •transceiver •VOCON •display In the case of a secure model radio, the encryption module is supplied also. Power for the radio is provided through a battery supplying a nominal 7.5Vdc directly to the transceiver. The battery is available in the following forms: •Nickel-Cadmium, High-Capacity (1100mAh), Medium-Size Housing •Nickel-Cadmium, High-Capacity (1100mAh), Medium-Size Housing (FM Approved, Submersible) •Nickel-Cadmium, Ultra-High Capacity (1800mAh), Large-Size Housing •Nickel-Cadmium, Ultra-High Capacity (1800mAh), Large-Size Housing (FM Approved) •Nickel-Cadmium, Ultra-High Capacity (1800mAh), Large-Size Housing (FM Approved, Submersible) •Nickel-Metal-Hydride, Medium-Capacity (950mAh), Small-Size Housing •Nickel-Metal-Hydride, Ultra-High Capacity (1650mAh), Medium-Size Housing (FM Approved, Submersible) B+ from the battery is electrically switched to most of the radio, rather than routed through the on/off/volume control knob, S901/R901. The electrical switching of B+ supports a “keep-alive” mode. Under software control, even when the on/off/volume control knob has been turned to the “off” position, power remains on until the MCU completes its power-down, at which time the radio is physically powered-down.
4-2 B+ Routing for VHF/UHF Transceiver BoardsRefer to Figure 1 and your specific schematic diagram. Raw B+ (7.5V) from the battery (Batt B+) enters the radio on the transceiver board through a 3-contact spring pin arrangement (J3) as B+, where it is routed through two ferrite beads on the VHF (E1, E101) and three ferrite beads on the UHF (E1, E101, E106) to the RF power amplifier module (U105) and ALC IC (U101, pin 13). Battery B+ is fused, and then routed through the connector J1, pins 19 and 20 to the VOCON board (J401, pins 19 and 20). The B+ supply is routed through the VOCON board to the on/off/volume control knob (S901/R901) on the control top/PTT flex at jack J901, pin 1. With the mechanical on/ off switch (S901) placed in the “on” position, switched B+ (B+ SENSE) is routed from the control top flex at connector plug P901, pin 10 and applied to the VOCON board at connector jack J901, pin 10. This signal is also fed to a resistive divider R222, R223 on the VOCON board so that the microcontrol unit (U204) can monitor the battery voltage. The switched B+ voltage supplies power to circuits on the transceiver board. The 5-volt regulator (U202), is applied this voltage through decoupling component C125 to produce a stable 5.0 volt output. Raw B+ (7.5V), which is connected to the ALC IC (U101), is switched through the output (CATH1) to another 5-volt regulator (U106). Regulator U202 supplies those circuits which need to remain on at all times, such as the reference oscillator (U203), fractional-N-synthesizer (U204), D/A IC (U102), and the ABACUS IC (U401). The D/A IC controls dc switching of the transceiver board. The SC1 signal at U102 pin 12 controls transistors Q107, Q111, and the transmit 5 volts (T5). Figure 1 . B+ Routing for VHF/UHF Transceiver Boards Battery 7.5V + RF PA Module U105 5V Regulator U202 VCOB IC U201 ALC U101T5 L105 CR108 RX L122 L121 Vcc RF Amp U1 Mixer U2 Q107 R5 5V Regulator U106 SB+ VHF/UHF Transceiver Board MAEPF-24700-O CR109 5V S Out Fuse To/From VOCON Board SW B+ UNSW B+Raw B+ T5 RX/TX Ref Osc U203ABACUS U401D/A IC U102 Synth U204IF Amp Q601
4-3 The SC3 signal at U102 pin 14 controls the Rx 5V switch U106, and the receive 5 volts (R5). A voltage on the synthesizer SOUT line at U204 pin 19 supplies power (Vcc) to the VCO buffer at U201 pin 3. During the receive mode, regulator U106 supplies regulated 5V (R5) to the receiver front end. In the battery-saver mode, R5 can be switched on and off by controlling pin 3 of U106. Module U106 is not used during the transmit mode. During the transmit mode, transmit 5 volts (T5) for the ALC IC and other TX circuitry is obtained from U202 via switching transistor Q111. B+ Routing for 800MHz Transceiver BoardsRefer to Figure 2 and your specific schematic diagram. Raw B+ (7.5V) from the battery (Batt B+) enters the radio on the transceiver board through a 3-contact spring pin arrangement (J3) as B+, where it is routed through four ferrite beads (E1, E2, E3, E4) and applied to the RF power amplifier (U502) and the ALC IC (U504 pin 13). Battery B+ is fused and then routed to the VOCON board, where it enters on connector J1 pins 19 and 20. On secure radios, Raw B+ is also routed to the encryption board so that it can perform key management and other functions independently of SW B+. The SW B+ is applied to the 5V regulator (U505) to produce a stable 5.0 volt output. Regulator U505 supplies those circuits which need to remain on at all times, such as the reference oscillator (U304), fractional-n-synthesizer (U302), D/A IC (U503), and the ABACUS IC (U401). The D/A IC controls dc switching of the transceiver board. The SCI signal at U503 pin 12 controls Q503 and transmit 5 volts (T5). The SC3 signal at U503 pin 14 controls the RX 5V switch in Q503 and the Figure 2 . B+ Routing for 800MHz Transceiver Boards Ref Osc U304ABACUS U401D/A IC U503 Synth U302 VCOB IC U303VCO U307 5V Regulator U505 RF PA Module U502 RF Amp U202Mixer U205Q503ALC U504 Rx800MHz Transceiver Board 5V SW B+ Raw B+ UNSW B+ IF Amp Q601 MAEPF-24336-O CR104 L101 CR102Fuse Battery 7.5V + To/From VOCON Board
4-4 receive 5 volts (R5). During the receive mode, switch Q503 supplies regulated 5volts (R5) to the receiver front end. B+ Routing for VOCON Boards and Display ModulesRefer to Figure 3 and your specific schematic diagram. Power for the radio is derived from a 7.5 volt battery, which is applied to the transceiver board through J3. This Raw B+, or unswitched B+ (UNSW B+), is routed to J1 on the transceiver board and then on to J401 on the VOCON board. Here the UNSW B+ is forwarded to the radio’s control top on/off/volume knob through J901 and a flex circuit. The on/off/volume knob controls B+_SENSE to Q206, which in turn controls Q207. Transistor Q207 is a solid-state power switch, which provides SW B+ to the VOCON board’s analog and transceiver 5V regulators, the audio PA, the display module, and back to the transceiver board. In addition, UNSW B+ is routed to the main digital 5V regulator (U409); B+ SENSE provides for enabling or disabling this regulator. In the case of a secure radio model, SW B+ and UNSW B+ are also supplied to the encryption module through J801. Q207 is also under the control of the microcontrol unit (MCU - U204]) through a port on the SLIC IC (U206). This allows the MCU to follow an orderly power-down sequence when it senses the SW B+ is off. This sense is provided through the resistor network of R222 and R223, which provides an input to the A/D port on the MCU. The VOCON board contains two 5V regulators partitioned between the digital logic circuitry and the analog circuitry. The 5V regulator for the digital circuitry is comprised of U409, CR403, L402, C470, and associated components. This circuit is a switched mode regulator. Switched mode regulators use a switched storage device (L402) to supply just enough energy to the output to maintain regulation. This allows for much greater efficiency and lower power dissipation. The analog circuitry of the ADSIC (U406) and the audio PA (U401) is powered through a separate 5V linear regulator (U410). It should also be noted that a system reset is provided by U407. This device brings the system out of reset on power-up. It provides a system reset to the microcomputer on power-down or if the digital 5V regulator falls out of regulation.
4-5 Figure 3 . B+ Routing for Vocoder/Controller (VOCON) Boards 5V Regulator U410 ADSIC U406 DSP56001 U405 256Kx8 FLASH U404 8Kx24 SRAM U402 Audio PA U401 SRAM U202 EEPROM U201 SLIC IV U206Switch Q207 On Off Controls Flex SW_B+ 5V Analog 5V Digital B+_CNTLB+_Sense Vocoder/Controller UNSW_B+ SW_B+ J401 J201 Universal ConnectorOpt_B+ Display Module 8Kx24 SRAM U403 8Kx24 SRAM U414 256Kx8 FLASH U205 256Kx8 FLASH U210 5V Regulator U409 MAEPF-24335-O HC11F1 MCU U204