The 887170 ADPCM card is a plug-in resource card for the IMACS system. The card has 32 pair of voice compression engines which accept input directly from voice cards or voice traffic on WAN links. The ADPCM card requires a matching card at the other end to decompress the voice channels to normal 64K operation. The ADPCM card is compatible only with the IMACS cross-connect CPU, beginning with CPU software revision 3.6.2 and all hardware supporting the cross-connect (XCON) offerings.

Each pair of compression engines utilize one 64 Kbps DS0 for two compressed channels. Each engine can compress 64 Kbps voice traffic to 24 Kbps, 32 Kbps or 40 Kbps, depending on the compression quality required. The rate of any DS0 is 64 Kbps, so the sum of the compression rates for each engine pair must equal 64 Kbps. A 32 Kbps circuit can only be paired with a 32 Kbps circuit. A 40 Kbps circuit can only be paired with a 24 Kbps circuit and vice-versa. The compression engines work in pairs. Each member of a pair must have the same WAN and time slot. Additionally, both members of the compression engine pair must be active before either port will operate. Each IMACS unit can have up to three ADPCM cards installed (two active ADPCM cards and one redundant card).

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Key Features
  • Provides up to 64 channels of voice compression to reduce long haul bandwidth requirements, compressing up to 2 E1s or T1s of voice traffic.
  • Supports transition signaling as defined by ANSI T1.302-1989.
  • Supports fax and modem operation.
  • Compliant to G.761 for alarm indication and fault handling.
  • Software selectable 24, 32 or 40 Kbps compression rates.
  • Compatible with standard IMACS digital or analog voice cards.
  • 8″ x 7.5″, 20cm x 18.75cm
  • .75 pounds, .34 kilograms
  • 2.88 Watts, 9.83 BTU/hr
  • No physical interfaces, 32 pairs of voice compression engines.
  • ITU G.721, ITU G.723, ITU G726-12/90, ANSI T1.302-1989, ANSI T1.302a-1992, ANSI T1.303-1989
  • Operating temperature 0 to 50 C, 32 to 122 F
  • Storage temperature -20 to 80 C, -4 to 176 F
  • Humidity 0 to 95% humidity, non-condensing
Geek Specs
  • Input voice channels The input can originate from any 2-wire or 4-wire voice card or from a DS0 on a WAN (El/T1 or HDSL) interface.
  • Mu-law & A-law 64Kbps PCM compatible on a per channel basis.
  • Input subrate data SRU data traffic at 19.2Kbps or less can be carried on a 24Kbps sub-channel.
  • Modem data support
    • Transcoder rate
      24Kbps 32Kbps 40Kbps
    • Modem Data
      up to 4.8Kbps
      V.32 to 9.6Kbps
      up to l2Kbps
      V.32 bis to 14.4Kbps
  • FAX support
    • Transcoder rate
      24Kbps 32Kbps 40Kbps
    • FAX
      Group II Group Ill
  • Voice quality As measured by mean opinion score (MOS) analysis, a subjective evaluation
    with a range of 0 (poor quality) to 5 (good quality). Toll quality voice is accorded a MOS of 4.

    • Transcoder rate
      24Kbps 32Kbps 40Kbps
    • MOS
      3.6-3.8 4.0-4.3
  • Echo cancellation None provided; typically not required.
  • Signaling Transmitted in-band utilizing CAS transitional signaling, as per ANSI T1.302
    – 1986 for 32Kbps and modified for use with 24Kbps and 40Kbps.
    Note: robbed bit signaling alarm transmission, as specified in ANSI
    T1 .302a – 1989 is not supported.
  • Maximum card count 3 (2 active, 1 redundant)
  • Transcoder operation Compliant to G.761 Alarm Indication and Fault Handling.

Ordering Information