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參數(shù)資料
| 型號(hào)： | ACE9040 |
| 廠商： | Mitel Networks Corporation |
| 英文描述： | Audio Processor Advance Information |
| 中文描述： | 音頻處理器進(jìn)展信息 |
| 文件頁數(shù)： | 26/33頁 |
| 文件大?。?/td> | 335K |
| 代理商： | ACE9040 |
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26
ACE9040
expander input EIN by using an external summing network
and internally open circuiting the drive to pin RBPO during the
tone (not just muting the speech). This is achieved with bits
COMP[2:1] in the “Initializing mode 0” control message set to
“01”.
Signal dynamic range at input pin EIN is doubled in the 1:2
expander to restore the original signal. Within the operating
signal range each 1 dB change in input level gives a 2 dB
change in output level. The expander output drives pin EOUT
which is coupled by an external capacitor to the input pin
HFGIN. The external connection allows use of an external
compander and removes any d.c. voltage offsets. Bits
COMP[2:1] in the “Initializing mode 0” control message can be
used to select external companding mode and power down
the internal compressor and expander.
The expander’s unity gain level EIN to EOUT is 1V. Above
this level gain is applied to the signal at EIN and below this
level the signal is attenuated to achieve 1:2 dB expansion.
Table 21 gives nominal, Vmax and Vmin levels at EIN and
nominal levels at EOUT corresponding with the TACS and
AMPS systems for 0 dB, maximum and minimum deviation.
The gain of the RXSENSE amplifier should be set so that
the expander operates within these signal levels for a given
demodulated signal range at the RXI input.
Expander pins ERCIN and ERCOUT are used to set the
attack and decay times for the expansion process. For the
usual attack time of 3.0 ms and decay time of 13.5 ms, a
resistor of 180 k
is connected between ERCIN and
ERCOUT pins and a capacitor of 100 nF from ERCIN to GND.
An 82 nF capacitor should be connected between VMIDRX
and GND. Attack and decay time is measured with a 6 dB
step, - 4 dB to - 10 dB relative to the unaffected level. Attack
and decay times are defined respectively at points on the
output envelope where it reaches x 0.57 and x 1.5 of the final
steady state level.
Volume Control and Handsfree Attenuator
Two variable gain stages follow the expander, RXLEVEL
for the volume control and HFATTEN for use with handsfree
mode. Both blocks provide attenuation, expressed as gain to
assist system level design, RXLEVEL from 0 to - 21 dB and
HFATTEN from 0 to - 49 dB. RXLEVEL is controlled by bits
RXV[2:0] in the “Operation mode” control message and
HFATTEN is controlled by bits RHF[2:0] in the “Handsfree
mode” control message.
RX Audio Output: Line Output and Earpiece
Following the handfree attenuator the signal path splits
into two parallel paths: a line output for loudspeaking phones
and drivers for a dynamic earpiece or external handsfree
earpiece. Bits EPH1 and EPH0 in the “Operation Mode” and
“Initializing Mode 0” control messages respectively control the
operation of these outputs, see table 5.
The earpiece output path begins with a variable gain
stage EARSENSE which is controlled by bits EARS[3:0] in the
“Initializing mode 1” control message to give a gain range of -
2·8 to + 3·2 dB. A sidetone signal from the output of the
handsfree attenuator HFGAIN at pin TBPO is added at
EARSENSE's input if bit SD in the “Initializing mode 0” control
message is set to “1”. The output of this block is at pin EAMPI.
The signal at pin EAMPI is amplified by an opamp whose
gain is set by external resistors, allowing overall gain setting
for different models of cellular terminal. A resistor is connected
from EAMPI to the amplifier input pin EAMPFB and a feedback
resistor is connected from the amplifier output EAMPO to
EAMPFB. The ratio of these two resistors sets the gain and the
opamp’s output including feedback resistors should not be
loaded with less than 15 k
. Additional filtering can also be
added to the receive path using the EAMP opamp.
Earpiece
The earpiece drivers have outputs at pins EPOP and
EPON. One of three modes of output drive or a muted output
condition is selected by bits EPH1 and EPH0, see table 5.
A dynamic earpiece, typically of 150
resistance in
series with 800
μ
H, can be driven when connected between
pin EPON and EPOP. The drive mode can be either differen-
tial (EPH1 = 1, EPH0 = 1) or single ended (EPH1 = 1,
EPH0 = 0). The differential output, drives a minimum of 4 Vpp
into the load. The single ended output appears at EPON and
drives a minimum of 2 Vpp into a load referenced to pin EPOP,
which provides an output voltage at mid-supply.
Output drive is setup for an external handsfree earpiece
with EPH1 = 0 and EPH0 = 1. This load, typically of 64
resistance in series with 3.3
μ
F, is driven from pin EPON to
ground and the EPOP output is put into a high impedance
state. The minimum drive into this load is 1.1 Vpp.
The input for the EPOP and EPON output drivers is driven
by the signal at the EAMPO pin for single ended and differen-
tial outputs or from EAMPI directly for a handsfree earpiece,
bypassing the EAMP opamp. The gain from the earpiece
drivers’ common input, to both EPON's inverting and and
EPOP's non-inverting outputs, is nominally + 6 dB.
Line Output
Line output amplifier LODRIVE with its output at pin LO
has a gain of + 5 dB and is used to drive an external audio
power amplifier. LODRIVE can drive a 1 k
load with a
minimum of 1 Vrms. The LO output can be put into a high
impedance state by setting bit HIZ in the “Operation mode”
control message to “0”. During power down EPON and EPOP
and LO are tied to mid-supply voltage.
HANDSFREE OPERATION
In a handsfree telephone the simplest method of prevent-
ing ‘howl round’ caused by acoustic feedback is to attenuate
either the forward or return path until the loop gain is too low
for sustained oscillation. The least active path is attenuated so
the signal level in each path must be detected and compared
so that the quieter can be attenuated.
In the ACE9040 the signal level in both the transmit and
the receive paths are rectified, with smoothing capacitors at
System
Vmax at EIN
Vrms
1.0
1.0
Vmin at EIN
mVrms
43
22
Nominal Input at EIN
(0dB) levels mVrms
245
245
Nominal Output at EOUT
levels mVrms
60
60
dB
dB
- 15
-21
TACS
AMPS
+ 12.5
+ 12.3
Table 21 Expander EIN and EOUT signal levels for TACS and AMPS
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| ACE9050 | System Controller and Data Modem Advance Information |
| ACFA-450 | AM CERAMIC FILTERS |
| ACFA-455 | AM CERAMIC FILTERS |
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相關(guān)代理商/技術(shù)參數(shù) |
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| ACE9040IGFP1N | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:RF/Baseband Circuit |
| ACE9040IGFP1R | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:RF/Baseband Circuit |
| ACE9040IGFP2N | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:RF/Baseband Circuit |
| ACE9040IGFP2R | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:RF/Baseband Circuit |
| ACE9040J/IW/FP1Q | 制造商:Rochester Electronics LLC 功能描述: 制造商:Zarlink Semiconductor Inc 功能描述: 制造商:ZARLINK 功能描述: |
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