One-Net/DASDEC User Manual
A-6
v3.0 | r1016
Master Control supports this action via a custom macro, associated with a panel
button, which triggers the SqueezeMax EAS preset, switches audio output to the EAS
device input, and produces a GPI contact closure for triggering alert play-out on the
EAS device. The EAS device goes out of pending alert mode and plays the alert audio
until finished. When the alert is finished, SqueezeMax is taken out of EAS display and
Master Control returns audio back to normal program audio.
The EAS device can also be directly connected to a single SqueezeMax using a serial
connection.
Interfacing to a TV system with Utah Scientific SqueezeMax SD system with Utah
Scientific 2020 switcher, upstream mode.
Refer to description above for the SqueezeMax. An EAS device can interface to mixed
SD and HD SqueezeMax units, but as described above, the alert must be played on all
units at the same time.
For additional information refer to the Digital Alert Systems website’s application notes.
(http://www.digitalalertsystems.com/resources_application_notes.htm#)
EAS PROTOCOL
The EAS device encodes the EAS messages per FCC rules for the EAS protocol. The EAS
protocol from the FCC is described as follows (printed directly from the FCC ruling).
The EAS uses a four-part message for an emergency activation of the EAS. The four
parts are; Preamble and EAS Header Codes, audio Attention Signal, message, and,
Preamble and EAS End Of Message Codes.
The Preamble and EAS Codes must use Audio Frequency Shift Keying at a rate of
520.83 bits per second to transmit the codes. Mark frequency is 2083.3 Hz and space
frequency is 1562.5 Hz. Mark and space time must be 1.92 milliseconds. Characters are
ASCII seven bit characters as defined in ANSI X3.4-1977 ending with an eighth null bit
(either 1 or 0) to constitute a full eight-bit byte.
The Attention Signal must be made up of the fundamental frequencies of 853 and 960
Hz. The two tones must be transmitted simultaneously. The Attention Signal must be
transmitted after the EAS header codes.
The message may be audio, video or text.
The ASCII dash and plus symbols are required and may not be used for any other
purpose. Unused characters must be ASCII space characters. FM or TV call signs must
use a slash ASCII character number 47 (/) in lieu of a dash.
The EAS protocol, including any codes, must not be amended, extended or abridged
without FCC authorization. The EAS protocol and message format are specified in the
following representation. Examples are provided in FCC Public Notices.
____________________________________________________________
[PREAMBLE]ZCZC-ORG-EEE-TTTT-JJJHHMM-LLLLLLLL-
(one second pause)
[PREAMBLE]ZCZC-ORG-EEE-TTTT-JJJHHMM-LLLLLLLL-
(one second pause)
[PREAMBLE]ZCZC-ORG-EEE-TTTT-JJJHHMM-LLLLLLLL-
(At least a one second pause)
