Controller Board Audio and Signalling Circuits
1-9
1.14
Electrically Erasable Programmable Memory (EEPROM)
The external 16 Kbyte EEPROM (U0111) contains additional radio operating parameters such as
operating frequency and signalling features, commonly know as the codeplug. It is also used to store
radio operating state parameters such as current mode and volume. This memory can be written to
in excess of 100,000 times and will retain the data when power is removed from the radio. The
memory access signals (SI, SO and SCK) are generated by the µP and chip select (CS) is generated
by address decoder U0141-15.
1.15
Static Random Access Memory (SRAM)
The SRAM (U0121) contains temporary radio calculations or parameters that can change very
frequently, and which are generated and stored by the software during its normal operation. The
information is lost when the radio is turned off.
The device allows an unlimited number of write cycles. SRAM accesses are indicated by the CS
signal U0122-20 (which comes from U0101-CSGP2) going low. U0122 is commonly referred to as
the external RAM as opposed to the internal RAM which is the 3 Kbytes of RAM which is part of the
68HC11FL0. Both RAM spaces serve the purpose. However, the internal RAM is used for the
calculated values which are accessed most often.
Capacitor C0122 serves to filter out any ac noise which may ride on +5V at U0122.
2.0
Controller Board Audio and Signalling Circuits
2.1
General - Audio Signalling Filter IC with Compander (ASFIC CMP)
The ASFIC CMP (U0221) used in the controller has 4 functions;
1) RX/TX audio shaping, i.e. filtering, amplification, attenuation
2) RX/TX signalling, PL/DPL/HST/MDC/MPT
3) Squelch detection
4) Microprocessor clock signal generation (see Microprocessor Clock Synthesizer Description).
The ASFIC CMP is programmable through the SPI BUS (U0221-20/21/22), normally receiving 19
bytes. This programming sets up various paths within the ASFIC CMP to route audio and/or
signalling signals through the appropriate filtering, gain and attenuator blocks. The ASFIC CMP also
has 6 General Control Bits GCB0-5 which are CMOS level outputs and used for NOISE BLANKER
(GCB0) in Low Band radios, EXTERNAL ALARM (GCB1) and DC POWER ON (GCB2) to switch the
voltage regulators (and the radio) on and off. GCB3 controls U0251 pin 11 to output either RX FLAT
AUDIO or RX FILTERED AUDIO on the accessory connector pin 11. GCB4 controls U0251 pin 10 to
use either the external microphone input or the voice storage playback signal. GCB5 is used to
switch the audio PA on and off.
Summary of Contents for 6864115B62-C
Page 1: ...Professional Radio GM Series Detailed Service Manual 6864115B62 C ...
Page 2: ...ii ...
Page 4: ...iv ...
Page 5: ...Professional Radio GM Series Service Maintainability Issue July 2007 ...
Page 8: ...ii ...
Page 22: ...2 10 MAINTENANCE ...
Page 25: ...Professional Radio GM Series Controlhead Service Information Issue July 2007 ...
Page 77: ...Professional Radio GM Series Controller Service Information Issue May 2007 ...
Page 100: ...2 2 TROUBLESHOOTING CHARTS ...
Page 104: ...3 4 Controller schematics parts list ...
Page 154: ...3 52 Controller T12 Schematic Diagrams ...
Page 155: ...Professional Radio GM Series VHF 136 174MHz Service Information Issue May 2007 ...
Page 164: ...1 6 MODEL CHART AND TECHNICAL SPECIFICATIONS ...
Page 176: ...2 12 THEORY OF OPERATION ...
Page 186: ...3 10 TROUBLESHOOTING CHARTS ...
Page 190: ...4 4 VHF PCB SCHEMATICS PARTS LISTS ...
Page 252: ...4 66 VHF 1 25W PCB 8471235L02 Schematics VHF 136 174 MHz IF ...
Page 256: ...4 70 VHF 1 25W PCB 8471235L02 Schematics ...
Page 257: ...Professional Radio GM Series UHF 403 470MHz Service Information Issue May 2007 ...
Page 266: ...1 6 MODEL CHART AND TECHNICAL SPECIFICATIONS ...
Page 366: ...2 12 THEORY OF OPERATION ...
Page 372: ...3 6 Low Band TROUBLESHOOTING CHARTS ...
