Skytrax 9500 Multiplex

General Description

The Series 9500 System provides wireless extension of up to 634 voice or data lines when used in conjuction with a microwave radio. Landline extension is also possible.

The Skytrax is designed to provide optimum economy and flexibility for a broad spectrum of communication system applications - particularly those which contain spurs and multiple drops.

Channel selector switches and passive channel combining allow frequency reassignments and system expansion to be accomplished readily in the field with minimal system disturbance.

The baseband spectrum follows the CCITT recommendations for 612 channels using supergroups 1 thru 10 plus group A. In addition, 2 channels are available between 4 kHz and 12 kHz, plus 20 interstitial channels between supergroups.

In its most economical configuration the Series 9500 multiplex synchronizes on the received 3825 OBS tone. In this self-sync mode each channel stands alone and is independent of all other channels.

In another configuration, using optional sync modules, the Series 9500 multiplex will operate end-to-end with other CCITT multiplex units.


Each Series 9500 modem contains a switch programmable frequency synthesizer which allows it to operate on any 4 kHz and 2540 kHz. Other than the channel selector switch no other adjustments are necessary to change the channel frequency. Since all channels are identical the need for multiple spares is greatly reduced and field change of equipment is easily accomplished.


Signaling is accomplished using a 3825 Hz out-of-band signaling tone. A switch in the 9500 modem allows selection of normal or inverted signaling functions. Front LED's show the status of the E&M signaling at all times. An internal strap provides "E" lead contact protection if required.


Four synchronization modes are available:

Self Sync Mode

In this mode, which requires no common equipment, each channel individually synchronizes on the received 3825 OBS tone. This requires that the OBS tone of the master 9500 be "on" when the channel is active.

Master sync Mode

In this mode, all the channels at a terminal are synchronized to a high stability source. When used end to end with itself or CCITT compatible equipment, the frequency translation will be small, but not zero, and independent of the E&M condition. Master oscillator stabilities available are 0.1, 2, and 5 PPM. The frequency translation error at each end of the link will be the oscillator stability multiplied by the HF line frequency.

Master Sync with Pilot Lock

This is a variation of Mode 2 with the addition of synchronization to a CCITT frequency reference pilot. This provides zero frequency translation error. The Series 9500 can operate end-to-end with CCITT standard equipment and frequencies or we can provide the master and slave pilot modules to make a complete system. The slave unit will revert to Mode 2 upon loss of received pilot. Master and slave modules are interchangeable in the shelf. Two units can be used for hot standby protection with automatic and manual switching provided.

Phase Lock Mode

This mode of operation is used in those special cases where a predictable input-output phase characteristic is required, such as a simulcast transmit system. In this mode, the OBS tone for the channels with phase lock must be "on" at the master site. The same master and slave sync modules used in Modes 2 and 3 are used.


The frequency response and envelope delay of the Series 9500 Skytrax meets and exceeds the requirements for leased quality lines as specified in CCITT M.1020.

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