Ethernet Connectivity; Receive Audio Paths; Headset Receive Audio - Motorola APX 7500 Detailed Service Manual

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2.3.14 Ethernet Connectivity

The Consolette has an RJ-45 connector on the back panel for LAN communications. The Consolette
is capable of both 10baseT and 100baseT data rates.
The LAN circuit contains a Micrel KSZ8841 Ethernet MAC Controller IC (U704) and supports Auto-
Negotiation at 10/100Mbps Full and Half Duplex communications. The Ethernet Controller IC
communicates to the OMAP microprocessor via the Flash memory bus and has its own dedicated 25
MHz clock. The LAN circuit also includes a Pulse HX1188 transformer (T700) with a 1:1 turns ratio
and rated for 10/100baseT data rates. Termination components R738, R739, R745, R746, C742 and
C743 are located close to the Ethernet Controller IC for impedance matching purposes on the
differential LAN data pairs.
The Ethernet Controller IC and the transformer are located on the Mainboard while the RJ-45
connector is attached to the High Speed backplane board. A high-speed flexible ribbon cable is used
to connect those two boards.

2.3.15 Receive Audio Paths

Audio from the receiver, as well as the various tones produced from the mobile (ex. keyfail tones,
button-press beeps/bonks), are sent from the APX transceiver to the Consolette controller card
(PPLN1689) in PCM audio format via the CAN_AUDIO bus. On the Consolette controller card, CAN
audio is transferred to the SSI by the Nautilus FPGA and routed to the DSP. If "TRC" is selected as
the "Wireline Function" audio parameter in the Consolette CPS, the DSP will filter the TRC guard
tone from the received audio in order to prevent guard tone false detects on the wireline. PCM audio
from the DSP is then converted to analog audio within the Codec (U505), and routed out to Codec
outputs OUTP1 (U505 pin 10), OUTP2 (U505 pin 13), and OUTP3 (U505 pin 15). Receive analog
audio coming from these Codec outputs is identical and they cannot have their gain adjusted
separately within the Codec; however, there is various circuitry external to the Codec on these paths
which allow separate receive audio gain adjustments. The Codec master receive gain adjustment for
all three outputs is in the Consolette CPS labeled "RX Codec Adjustment". This gain adjustment can
vary from -42 dB to +20 dB in 0.5 dB steps. By default, the receive audio level from the Codec
outputs should measure approximately 300 mVrms.
NOTE: The APX Consolette transceiver supports several over-the-air signaling types which can be
enabled in its codeplug: Analog Conventional, Type II Trunking, APCO Conventional, and
APCO P25 Trunking (including F2). Regardless of the signaling type chosen, the audio
provided to the rear panel outputs on the Consolette is always in analog format.

2.3.15.1 Headset Receive Audio

Receive analog audio originating from Codec OUTP1 is the single-ended speaker audio source for
both headset connectors. When a headset is connected to its respective RJ45 connector on the high
speed connector rear panel of the Consolette (J11 for HDST1 and J12 for HDST2), HDST1_SENSE*
(J11 pin 2) and HDST2_SENSE* (J12 pin 2) are grounded. These signals are passed through octal
buffer U1809 before reaching OMAP inputs HDST1_SENSE_OMAP* (U400 pin M8) and
HDST2_SENSE_OMAP* (U400 pin W8). This enables the Consolette to detect the headset
connection(s) and mute the front panel speaker. Codec OUTP1 audio first passes through muting
gate U502 which is controlled by PCIC output HDST_MUTE* (U1301 pin 26). It then passes through
dual op amp package U500 pin 2, which has a gain of approximately 10 dB, before reaching RX
Audio Attenuator U506. U506's attenuation level is mapped to and controlled by the O5 control
head's volume knob via the OMAP's SPI bus; therefore, any volume adjustment for the headset
speakers is done with the O5 volume knob. To avoid needing to adjust the O5 volume knob when
switching between the use of headsets and the front panel speaker, a volume adjustment from the
Audio Parameters page in the Consolette Configuration may be selected. The "Headset Speaker
Volume Ratio" can be chosen to have the headset volume reach maximum volume at 100% (1:1
September 9, 2011
Theory of Operation: System Communications Overview
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