Maxon Telecom SP210, SP200 service manual Audio Asic, Audio Signal Path

Page 30

Maxon SP200/210 Radio

SP200/210

5.3 Audio ASIC

The audio ASIC (IC406) processes both the audio signal and the sub-audible tones, including filtering, amplifying, setting attenuations levels etc. It is a programmable device, controlled by the microcontroller, hence alteration of deviation levels is achieved by the ACC-2003 Alignment Software.

The internal block diagram is shown in Figure 5-1. The audio and SAT routes within the ASIC will be described separately.

5.3.1 Audio Signal Path

A1

Buffers discriminator audio input from Pin 30 (INI) and passes it to

 

Analogue Switch 1 (ASW1). It has a gain of x1.

A2

Amplifies the analogue signal from the mic input terminal (IN2) and

 

passes this signal to Analogue Switch 1. It has a gain of 10dB.

ASW1

This is a two-way analogue switch. It is controlled by the serial control

 

interface. Default value is 0, which is Rx (A1).

INTRIM

Sets the deviation for the input analogue signal sensitivity. The control

 

range of this device is –3.5 to +4dB controllable in 16 steps. The

 

control is a 4 bit signal where the default value is 1000, which

 

corresponds to 0dB.

300Hz HPF

Comprises an 8th order filter with a cut-off frequency of 300Hz.

 

Attenuation of the unwanted is at least 30dB.

ASW2

This is a four-way analogue switch, controlled by the serial control

 

interface. It passes the received audio to the de-emphasis circuit or

 

the transmit audio to the pre-emphasis circuit. Alternatively, the pre-

 

emphasis or de-emphasis can be bypassed. The control signal is a 2

 

bit signal with 00 as the default, which is de-emphasis.

DE-EMPHASIS

Applies de-emphasis to the received audio at 6dB/octave. At 1kHz, the

 

gain is x1.

PRE-EMPHASIS

Applies pre-emphasis to the transmit audio at 6dB/octave. At 1kHz,

 

the gain is x1.

RXVOL

Controls the magnitude of the Rx audio signal which is passed, via the

 

volume control (VR5) to the speaker in 16 steps from 0dB attenuation

 

up to 37.5dB attenuation, to Rxout on pin 28.

AMP

This amplifier provides gain, to the Tx audio, in 8 steps from +20dB to

 

+41dB.

LIMITER

Applies limiting at 0dB (2.8V p-p). The output of this stage is controlled

 

in 4 steps from 0dB to –5.4dB attenuation by a 2 bit control signal.

ASW3

This is a two-way analogue switch, controlled by the serial control

 

interface. It passes the Tx audio, or the SAT to the low-pass filter.

VLPF

This is a 6th order low pass filter, which is controlled by the serial

 

control interface. The cut-off point is switched between 2.55kHz and

 

3kHz.

TXTRIM1

Provides deviation adjustment of Tx audio in 16 steps from +3.5dB

 

gain to –4dB attenuation. Uses a 4 bit control signal.

TXSUM

Mixes (Adds) the signal from TXTRIM1 with the SAT signals from

 

COMPIN+, or selects one or other of the signals. Can also apply 50dB

 

muting. Controlled by the serial control interface.

ATTN

Attenuates the signal from TXSUM by either 0dB or 6dB.

TXTRIM2/3

Signal follows two routes (to VCO & TCXO) for final deviation

 

adjustment in 32 stages from +3.75dB to –4dB. Controlled by 5 bit

 

signal.

A3/A4/INV

Final output buffer amplifier for Tx analogue signal. Gain is 0dB. A3

 

output (modout 1 on pin 1) goes to the VCO and A4 (modout 2 on pin

 

2) goes to TCXO, are non-inverting outputs. The inverting output (INV)

 

from A4 is not used.

DETAILED FUNCTIONAL DESCRIPTION

Issue 1.0

Page 5-2

03/01

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Contents
SP200/210 NSW Australia Tel +61 0 2 9707 Issue No Effective Date Reason for Change Signature Amendment Record SheetAmendment Record Sheet Maxon SP200/210 Radio Table of Contents 10-1 SL100 UHF Parts List11.4 Default Settings 11-8 11-1List of Tables Maxon SP200/210 Radio Issue 03/01 Amendments to this Manual Using this ManualIntroduction Category C Engineering BulletinContact Information Specifications GeneralVibration Environmental Operating Temperature RangePhysical Dimensions Synthesiser ESD EMCAccessories & Options Pre-Install Check AccessoriesOptions Accessories & Options INSTALLATION, Commissioning & Alignment INSTALLATION, Commissioning & AlignmentInstallation ConnectionsCommissioning Recommended Test EquipmentCommissioning Equipment Commissioning KitTest Equipment Set-up using Discrete Test Equipment Discrete Test EquipmentSK 3100 Service Kit Test Equipment Connection Transmitter Performance TestsReceiver Performance Tests Power Adjustment SquelchAudio Output Preparation Tests without DisassemblyAlignment VHFDisassembly and Re-assembly of the Radio Removing and Replacing BatteryRemoving and Replacing the Belt Clip Removing and Replacing the Main Assembly Location of Adjustment PointsPLL Alignment Squelch Sensitivity Transmitter AlignmentTcxo Radiocommunications Test SET Balance Adjustment Audio deviation adjustment Ctcss / DCS deviation Audio Volume Level At maximum volume, nominal distortion is 10%Receiver Alignment Common Circuits Detailed Functional DescriptionIntroduction EepromAudio Signal Path Audio AsicSat Signal Path Miscellaneous Signals and ControllerAudio/SAT Circuits Common RF Circuits Battery Low Indicator CircuitLEDs and indicators PLL SynthesiserCharge Pump and Loop Filter PLL ICOut-of-Lock Detector DC to DC ConverterTransmitter Antenna SwitchAutomatic power control APC circuits PA moduleReceiver Front EndSquelch Mute Circuit First MixerSecond mixer, Second IF, FM detector 16kHz Band Pass FilterNoise detector circuit AF Output Low Pass FilterSpeaker Audio Amplifier Diagnostics TroubleshootingDiagnostic Function TroubleshootingTroubleshooting Chart If ICVoltage Charts Transistors Main CircuitMain Circuit Transistor Voltages Integrated Circuits Integrated Circuit Voltages ReceiveIntegrated Circuit Voltages Transmit Troubleshooting Troubleshooting Troubleshooting Troubleshooting Introduction ProgrammingSMP6100 Getting StartedProgram/Print/Save Select Features MenuScanning Program RadioPrint Data Save Data to DiskMaxon SP200/200 Radio SP200/210 Exploded Mechanical Drawings & Parts Lists Exploded Mechanical Drawings & Parts ListsParts List Spare PartsSL100U2 SL100V2Mechanical Parts For details on servicing, please refer to SectionParts List for Exploded Mechanical Drawing LCD TTR 1866 DpfdpwSML-020MLTT86 SMD PCB LCDSKPT-110VA NUT M7 BsbmPCB VCO PCB RF Aldc Bsbm M2.6SL100 VHF Parts List V2 Control Circuit05B-000-5Z Chip Ceramic 0.012UF GRM39 X7R123K 25V P Diode Switching KDS181S A3Chip Ceramic 0.001UF GRM39 X7R102K 50V P Chip Ceramic 0.0022UF GRM39 X7R222J 50V P2 V2 RF SW Tact SKPT-1101VAThermistor Chip 33KNTCCS32163SH333KC TH1 RES.CHIP Trimmer 1K RH03E1C13XRES.CHIP Trimmer 10K RH03E1C14X Elect Capacitor 10UF 16V 20%Chip Ceramic 43PF GRM40 COG430J 50V P RE Power Module GNOK-M68776-E01 IC9Chip Ceramic 39PF GRM40 COG390J 50V P Chip Ceramic 47PF GRM39 COG470J 50V PTcxo Assembly 4 V2 VCO 5 V2 Front EndSL100 UHF Parts List U2 Control CircuitConnector Waffer Chip Resistor 18K 2 U2 RFChip Resistor 12K Chip Resistor 39KChip Ceramic 10PF GRM40 COG100C 50V P RES.CHIP Trimmer K RH03E1C13XChip Ceramic 0.0015UF GRM39 X7R152K 50V P Chip CeramicChip Ceramic 470PF GRM40 COG471J 50V P Power Mpduleuhf M68732HGNOK IC9Chip Ceramic 2.2PF GRM40 COG2R2C 50V P Chip Ceramic 4.7PF GRM40 COG4R7C 50V PCoil Spring X0.35X7TR TcxoCoil Chip 18NHLL2012-F18NM Coil Spring 2X0.75X3TL SMD4 VCO Maxon SP200/210 Radio RF PCB Circuit Diagrams & PCB LayoutsCircuit Diagrams & PCB Layouts TcxoCircuit Diagrams & PCB Layouts Digital Board Layout Top Side Digital Board Layout Bottom Side RF Board Layout Top Side Issue RF Board Layout Bottom Side P406787a Front End Front-End Board Layout Tcxo Board Layout Spare Parts & Maintenance Policy 10SPARE Parts10.1Spare Parts Surface mount components Component ReplacementSurface mount component replacement Surface mount removalSurface mounted integrated circuit replacement Spare Parts & Maintenance Policy 11.2Test Equipment 11APPENDIX ACC-2003 Alignment BOX11.1Purpose 11.3Calibration ProgramCalibration Program Primary Screen Appendix a ACC-2003 Alignment BOXAsic Control Screen Rx Adjustment of Asic values TXTRIM2TXTRIM3 RX VOL Transmit Adjustments SAT BalanceSAT Deviation Receive Adjustments Audio Output LevelV1 Default Frequency Table 11.4Default Settings11.4.1 V1 Band Default Settings V1 Default Asic Settings11.4.2 V2 Band Default Settings V2 Default Frequency TableV2 Default Asic Settings 11.4.3 U1 Band Default Settings U1 Default Frequency TableU1 Default Asic Settings 11.4.4 U2 Band Default Settings U2 Default Frequency TableU2 Default Asic Settings
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