Instruction manual

ACU-1000 Operations Manual
2-96 Interoperability Now
NOTE: TX Audio Delay is available for all DSP-2 modules, but only for
DSP-1 modules with revision 2.08 or higher firmware installed. To verify
the revision on a DSP-1 module, remove the module and examine the
label on the EPROM. The label reads “DSP-1 1096-201XXX” where
XXX is the revision number. TX audio delay is available for part
numbers 1096-201208 or higher.
2.17.2.7 COR Sampling (DSP and RDI-1)
When a radio connected to the DSP-2 or RDI-1 is operating in half-duplex mode, it cannot
receive while it is transmitting. This means as long as the radio is in the TX mode, the remote
radio user who’s communicating to the ACU-1000 system through this radio will be locked out
and unable to send any commands to the system. To make sure this condition does not last for
extended periods, the module will drop PTT momentarily to allow it to check for an active
COR input, which would indicate the remote user is trying to communicate with the system. If
COR is detected during this “sampling” window, the module will hold the local radio unkeyed
for at least five seconds so the remote user has time to enter a DTMF command. There are
three variable parameters plus ON/OFF functions associated with COR sampling: initial delay
time, sampling interval, and sampling window width. In general, it is desirable to keep the
sampling interval as long as is feasible and the window width as short as is feasible because
each time a sample is taken, a “hole” is put in the transmit audio, and syllables or words can be
missed.
• COR Sampling ON/OFF- The factory default setting for COR Sampling is OFF
(disabled), so no COR sampling will occur unless it’s enabled(ON).
• Initial Delay Time- This configuration item sets how long after the start of the user-
initiated PTT that the first sample window occurs. If the PTT goes inactive before the
initial delay time expires, the initial delay time is reset, and starts running again at the
onset of PTT. Note this time is set separately from the sampling interval, allowing it to
be set longer than the sampling interval. The factory default for the initial delay is 10
seconds.
• Sampling Interval- The first COR sample takes place when the initial delay expires.
The module momentarily ignores the system input holding it in the transmit mode,
drops PTT and samples for an incoming COR. If COR is not detected, and the system
PTT input remains active, the module re-asserts PTT and maintains it for a time less
than or equal to the sampling interval. While PTT is continuously active, samples will
continue to be taken at this interval. The factory default setting is 5 seconds. A shorter
interval will allow quicker take-over of the system by the radio user, but will disrupt
transmit audio more often.
• Sampling Window Width- This sets how long the local radio stays unkeyed while
looking for COR from the local radio. The correct value depends on how fast the local
radio can switch from transmit to receive and how fast COR can be detected. For
Hardwire COR this depends on how fast the local radio’s squelch circuit can respond to
a received signal. For DSP-2 modules using VOX or VMR based COR, it depends on