Standard Engineering Installation Package for Dual Frequency Signaling Unit (DFSU).
ARMY COMMUNICATIONS-ELECTRONICS ENGINEERING INSTALLATION AGENCY FORT HUACHUCA AZ
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The U.S. Army Communications-Electronics Installation Agency is responsible for engineering and installation of the Dual Frequency Signaling Unit DFSU communications-electronics C-E equipment at new and existing U.S. Army facilities worldwide. This Standard Engineering Installation Package SEIP will provide engineering and installation data, site survey criteria, quality assurance provisions, and test plan guidance in preparing an Engineering Installation Package EIP for installation of the DFSU. The purpose of the DFSU is to provide enhanced in-band supervisory signaling capability over voice frequency VF communication circuits. The existing conventional in-band signaling equipment utilizes a single frequency SF technique whereby a 2600 Hertz Hz tone is placed on the circuit to indicate the idle state on-hook and the tone is removed from the circuit to indicate the busy state off-hook. Signaling states are conveyed via E receive and M transmit leads to the telephone equipment terminating the circuit. The DFSU operates in much the same way as SF units except that whenever the 2600 Hz tone is removed from the circuit a 2800 Hz tone is applied for a short period 175 milliseconds maximum.
- Radio Communications