Expand a Multi-Site MPT
The Model 844 4-Port Intersite Link provides enhanced linking capacity to a Zetron Model 827-based MPT 1327 trunked radio system. It provides four 4-wire audio ports and four RS-232 serial data ports. The 4-wire audio and data ports provide a gateway for linking conversation audio and call setup data essential for roaming trunked network operation.
Multisite operation allows mobile units to roam throughout the network without losing any system functionality. Roaming units are located and can receive calls from a telephone or another radio unit. In addition, multisite operation allows a group call to include up to six sites.
MULTISITE � A BRIEF OVERVIEW
The unique advantage of Zetron�s MPT 1327 trunking solution is the capability to build small to medium-sized multisite networks (up to 12 sites) without the need for an expensive central hardware switch. This unique Zetron �switch-less� architecture is made possible by two features implemented in the M827 Trunking Controller and the Model 844:
1. Internal PCM audio and data bus that all M827 and M844 units share
2. Call setup data packets and conversation audio are routed via a simple audio link between sites Multisite operation is implemented by a software option accompanied by the installation of the internal telco option card in at least one M827, or the addition of a M844, in each site to be linked. The M827 optional telco card can be configured as either a PSTN/PABX interface or 4-wire audio link interface. In network applications, sites are connected by leased 4-wire E&M lines provided by the telephone company, or by a multiplexer line shelf card connected to privately owned microwave links or fiber optic backbone.
The M844 easily interfaces to other M827s and M844s in a system over the PCM audio, subscriber, and repeater buses. Each M844 appears on a given Zetron MPT 1327 system as four separate units with the telephone interface enabled and repeater interface disabled. System control data passes between controllers via two data buses. The repeater bus passes real-time call setup information between the control units. Conversely, the subscriber bus transfers database, call detail records, statistics, and other less time sensitive data.
One M827 at the repeater site operates as the bus master to control and synchronize all communications between controllers at a given site. The M844 always functions as a slave signalling unit; as it does not operate in standalone mode. Any radio channel has access to any telephone or intersite link port via the PCM audio bus, regardless of which unit the port is physically located on. Each 4-wire port is equipped with a 1200 baud FFSK modem used to pass call setup, roaming, and registration information between sites. When a dedicated serial link is paired with a 4-wire link, the serial link is used instead to communicate initial call setup and registration information. Each 4-wire link operates independently from the others. The result is that a M844 appears to be four separate telco interfaces to the rest of the system.
Call Detail Records
ALARM REPORTING AND
|Power||10.5 to 16 Volts DC, 12 Watts|
|Temperature||0 to 60� Celsius|
|Size||48 cm W x 4.5 cm H x 26 cm D|
|AUDIO LINK INTERFACE|
|Line Type||4-wire or 4-wire E&M|
|From Telco||-24 dBm to 0 dBm|
|To Telco||-20 dBm to 0 dBm|
|Modem||Internal 1200 baud FFSK modem 4-Wire E&M Private Circuit|
|Speech and Data||Voice audio, DTMF, 1200 baud FFSK|
|Incoming Call||Detection of voltage on E-lead|
|Call Answer||Preferred 2-lead circuit
with user selectable NO or NC relay contact.
M844 has M output lead and E return lead.
|Call Disconnect||Removal of voltage from E lead|
|Speech and Data||4-wire (leased circuit)
or 4-wire E&M (microwave/radio link) required. Line conditioning of
C2 or better, as defined in Bell System Technical Reference Pub
41004, Data Comm
Using Voice Band Private Line Channels, Oct 73, is required. Minimum of one per intersite connection.
|Serial Data Option||RS-232 or external modem over 2- or 4-wire (leased circuit) V28 or similar|
|Link Interfaces||up to 32 per site|
|Radio Channels||up to 24 radio channels per site|
|Sites||up to 12 sites per system|
|Subscribers||5,000 subscribers, expandable to 15,000, 2000 group identities, 500 fleets per system|
|Record Types||Registration, status,
short data (SDM2), mobile-to-mobile, mobile-to-landline,
landline-to-mobile, landline-to-diverted mobile, multisite
multisite land-to-mobile, multisite mobile-to-group, and multisite land-to-group.
|Capacity||Minimum 3656 to a maximum of 7313 records stored internally. Actual record size depends on call type. Landline-to-mobile, mobile-to-landline and multisite calls require twice the storage of other call types.|
|Stored Information||Called/Calling prefix and ID, start date/time, call duration, channel and line assigned, dialed number.|
|Filtering||Programmable minimum call time to store for speech and interconnect. Storage of registration, status, SDM2s, call failures and informational multisite records can be set to on or off.|
|Indicators||Links 1-4, ALARM, BUS, Subscriber Bus Poll, Repeater Bus Sync, Link 1-4 Signaling|
|Backup Battery||Retains data for over 8,000 hours when power is removed from unit. There is no drain on the battery when the unit is operating.|
|Real-Time Clock||Synchronized by Model 827 bus master|
|Programming||Remote programming via computer using M827BASE database program. Access via external modem or local RS-232 programming port. Optionally, any Model 827 in the system can be used as a gateway to program the Model 844.|
BABT Approval Number - 609632
WISCO International, Inc. -
MIAMI, FL U.S.A.
Fax: E-mail: firstname.lastname@example.org