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scan sequence. If the number of non-priority channels is less
than or equal to four, then all non-priority channels will be
scanned between each P1, P2 scan.
As an added example, consider channels 1-8 to be scanned
channels, with P1 being channel 1 and P2 being channel 8. The
scanning order then would be:
Since it takes approximately 15 to 160 milliseconds to scan
each channel, then each Priority channel is sampled every 0.09
to 0.96 seconds and the non-priority channels are sampled at
least once every 0.12 to 1.28 seconds. If Channel Guard is pro-
grammed for a channel, but no carrier is detected, the scan time
for that channel is 15 milliseconds.
SCANNING (Stopped On A Valid SCAN Channel):
Once a carrier is detected, the channel display will indicate
that channel. If the channel is a non-priority channel and there
are no priority channels, then scanning is halted. If only a Pri-
ority 2 (P2) channel is present, then it is scanned every 5 sec-
onds if it has Channel Guard programmed and carrier is
detected and every second otherwise. If there is only a Priority
1 (P1) channel, then it is sampled every 2.5 seconds if it has
Channel Guard and carrier is detected and every 500 millisec-
onds otherwise. If there are P1 and P2 Priority channels, the
sample rate will vary.
In order to show the various scan conditions, the following
conditions are used:
NOTE
The following conditions are shown while listening to
a Non-Priority channel. The "ts" is the "hole" or audio
blanking time in the signal being heard while the radio
is checking the priority channels for activity.
CONDITION 1: P1 and P2 have Channel Guard Programmed
a.
No carriers detected on P1 or P2
P1-P1-P2-P1-P1-P2-P1-P1-P2...
tb (time between samples)
=500 msec
ts (time of sample)
=32 msec
b.
Carrier on P1 detected/wrong Channel Guard
P1-P2-P2-P2-P2-P2-P1-P2-P2-P2-P2-P2-P1...
tb=1 second
ts=32 msec for P2
75-175 msec for P2
c.
Carrier on P2 detected/wrong Channel Guard
P1-P2-P1-P1-P1-P1-P1-P1-P1-P1-P1-P2-P1...
tb=500 msec
ts=32 msec for P1
75-175 msec for P2
d.
Carrier on P1 and P2 detected/both wrong Channel
Guard
P1-P1-P2-P1-P1-P2-P1-P1-P2...
tb=2.5 seconds
ts=75-175 msec
e.
Carrier on P1 and right Channel Guard
Stop scan, display P1
f.
Carrier on P2 and right Channel Guard
Display P2, scan P1
P1-P1-P1-P1-P1-P1...
tb=500 msec
ts=32 msec
g.
Carrier on P2 with right Channel Guard, car-
rier/wrong Channel Guard on P1
P1-P1-P1-P1-P1-...
tb=2.5 seconds
ts=75-175 msec
CONDITION 2: Priority 1 has Channel Guard Programmed,
Priority 2 does not.
a.
No carriers detected on P1 or P2
P1-P1-P2-P1-P1-P2-P1-P1-P2-...
tb (time between samples)
=500 msec
ts (time of samples)
=32 msec
b.
Carrier on P1 detected/wrong Channel Guard
P1-P2-P2-P2-P2-P2-P1-P2-P2-P2-P2-P2-P1-P2-...
tb=1 second
ts=32 msec for P2
75 -175 msec for P1
c.
Carrier on P1 detected/right Channel Guard
Stop on P1, stop scan
d.
Carrier on P2
Stop on P2, scan P1
P1-P1-P1-P1-...
tb=500 msec
ts= 32 msec
e.
Carrier on P2 and P1 with wrong Channel Guard on
P1
Stop on P2, scan P1
P1-P1-P1-P1-P1-P1-...
tb=2.5 seconds
ts=75-175 msec
CONDITION 3: P2 has Channel Guard, P1 does not
a.
No carriers detected on P1 or P2
P1-P1-P2-P1-P1-P2-P1-P1-P2-...
tb (time between samples)
=500 msec
ts (time of samples
=32 msec
b.
Carrier on P2 detected/wrong Channel Guard
P1-P2-P1-P1-P1-P1-P1-P1-P1-P1-P1-P2-P1-...
tb=500 msec
ts=32 msec for P1
ts=32 msec
75-175 msec for P2
c.
Carrier on P2 detected/right Channel Guard
Stop on P2, scan P1
P1-P1-P1-P1-P1-P1-...
tb=500 msec
ts=32 msec
d.
Carrier on P1 detected
Stop on P1, stop scan
CONDITION 4: P1 and P2 with no Channel Guard
a.
No carriers detected on P1 or P2
P1-P1-P2-P1-P1-P2-P1-P1-P2-...
tb (time between samples)
=500 msec
ts (time of sample)
=32 msec
b.
Carrier on P2
P1-P1-P1-P1-P1-P1-...
tb=500 msec
ts=32 msec
c.
Carrier on P1
Stop on P1, stop scan
PUBLIC ADDRESS OPTION
OPERATION
If the Public Address Option is present, the radio may be
used as public address amplifier. Press the programmed flex
key or scroll through the menu to select the PA option (Scan
must be off). The LED display will show "Pub Addr".
When the microphone is keyed, the radio no longer trans-
mits, but allows the microphone audio to feed the speaker.
Adjust the VOLUME for the desired level. Press the pro-
grammed flex key or scroll through the menu a second time
to disable the PA option. The display will return to normal
channel display. Changing channels or turning on Scan will
also turn the operation off.
LBI-39015
The Public Address microphone audio normally feeds an
external speaker. An ON/OFF switch, which is mounted on
or near the radio, allows selecting either the internal or exter-
nal speaker for the receiver audio. The ON/OFF switch
turns the receiver audio on or off to the external speaker.
This switch still functions for the receiver audio with the PA
option disabled.
TYPE 99 OPTION OPERATION
If the Type 99 option is present, selective calling is possi-
ble. Press the programmed flex key or scroll through the
menu to select the T99 decoder option (Scan must be off).
The LED display will show "T99 ON" or "T99 OFF" for 2
seconds. During that time subsequent pressing of the flex
key or Group/SEL buttons will toggle the T99 state between
OFF and ON.
When a T99 call is received, the entire display will alter-
nate between "T99" and the normal channel display and an
alert tone will sound. If a call has been received and the dis-
play is flashing, CLR must be pressed before the T99 option
can be turned off.
DETAILED TYPE 99 OPERATION
AND PROGRAMMING
The optional Type 99 Control Panel provides individual,
group and super group call decode. The Motorola Formatted
two-tone sequential signaling schemes can also be decode.
In Type 99 Tone systems, calls will not be heard from the
receiver until the proper two tones are detected. When the
second tone is decoded and recognized as correct, an alert
tone sounds during the remaining portion of the second tone.
The receiver audio path opens and remains open to receive
messages until the decoder is reset. The display will also
flash to show a call has been received.
The MDX radio can be PC programmed with up to three
separate tables of tones. Either the Ericsson GE Type 99 for-
mat or the Motorola format can be assigned to each tone ta-
ble. The tone decoder can be enabled individually for each
channel. Once enabled, one of the three tone tables can be
selected for each channel. After choosing a tone table, the
call formats must be specified: Individual, Group and Super
Group for the Ericsson GE format or Individual, Group and
Quick-Call (In Motorola tone systems) allows communica-
tion between all radios in a system.
7
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