MT90812 Mitel Networks Corporation, MT90812 Datasheet - Page 47

• Manufacturer Part Number: MT90812
• Description: Integrated Digital Switch (IDX)
• Manufacturer: Mitel Networks Corporation

Advance Information
A further 9 other standard tones are available for use as call progress and supervisory tones. Also available are
7 programmable tones, which may be single or dual frequency. This totals 32 available tone outputs.
The composite signal output level in the transmit direction is -4 dBm0 ( -Law) and -10 dBm0 (A-law), when the
programmable gains are set at zero dB. Pre-twist of 2.0 dB is incorporated into the composite signal resulting
in a low tone output level of -8.12 dBm0 and a high group level of -6.12dBm0 (for -Law, 6 dB lower for A-Law).
Note that the digitally generated signals will be gain adjusted as programmed in the Connect Memory High for
each outgoing channel. Refer to Section 7.0 for a description of gain control.
Each of the seven programmable locations has two 8-bit registers accessible via the parallel microprocessor
interface used to program the two tone frequencies. If a single tone is desired then one of the registers is
programmed to zero. A tone output is disabled if both low and high coefficient registers are programmed to
zero. The register descriptions of the coefficient registers, Low Tone Coefficient 1-7, and High Tone Coefficient
1-7 (LTC1-7, HTC1-7) are listed on page 64. Of the 7 programmable tone generators the first two can also be
used to provide dual frequency squarewave ringing signals. Tone Ringer enable bits, TRE1 and TRE2, in the
TEDC register, enable the generation of the squarewave ringing signals by the two Tone Ringer circuits. The
Tone Ringer function is described in Section 16.1.
The Tone Generation circuit can be enabled with TGE bit set to 1 in the Tone Generation and Energy Detect
Control Register (TEDC) listed on page 61. With the DTMF circuit reset there is no output generated for all the
32 tones including the Tone ringers and FSK transmitter output.
Frequencies in the fixed and programmable locations tone locations are generated according to one of three
formula’s, depending on what range the coefficient value is in, as shown in Table 14. The coefficients of the
fixed tones cannot be changed. The coefficient is an integer value from 0 to 255.
These single and dual frequency tones are written to the Local Data Memory page at the Tone Block
Addresses. The tones will be selected by writing the corresponding tone’s address to the Connect Memory Low
of the outgoing channel. The address and description of each tone is listed in Table 15.
Outgoing gain control of +3 to -27 dB in steps of 1dB, as well as -
connected to the tone generator output locations. Refer to Section 7.0 for further description of gain control.
All in-band (i.e. 500hz to 3.5khz) harmonics and noise components are at least 35dB below the fundamental
frequencies. Total signal to distortion ratio over this band is at least 30dB.
Coefficient Value
128-255
64-127
1-63
0
Table 14 - Programmable Frequencies Available
(Coef x 15.625) - 1000
250+(Coef x 3.90625)
Coef x 7.8125
Formula Hz
Disabled
Frequency Range Hz
1000.0 - 2984.38
253.91-496.09
500.0 - 992.19
-
dB, is provided for outgoing channels
Resolution Hz
3.90625
7.8125
15.625
MT90812
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