
MDS 05-4670A01, Rev. E
SD Series Reference Manual (x710 Mode)
48
MODEM 9600M
is selected followed by
MODEM NONE
, analog operation
conforms to the channel constraints for a 12.5 kHz ETSI-compliant
channel. Table 15 defines the relationship between digital modem selec-
tion and analog operation.
Modem transmission/reception characteristics are further qualified by
the
EMP
(emphasis) command. When
EMP ON
is entered, pre-emphasis is
applied on the transmitter and de-emphasis is applied on the receiver.
This setting is typically used in operation with voice radios. To disable
emphasis, select
EMP OFF
.
Audio signal levels are governed by the
RXLEVEL
and
TXLEVEL
com-
mands. Both commands support a range from -20 dBm to 0 dBm. For
RX operation, this means that a received signal at the peak deviation will
be scaled to the specified
RXLEVEL
. For TX operation, this means that a
transmit input signal of the specified
TXLEVEL
will translate into the
specified peak deviation for transmit. Note that
TXLEVEL
can also be set
to
AUTO
to automatically scale the input to the target deviation. Values
outside the expected range will cause clipping of the RF signal.
By default, built-in squelch thresholds automatically mute the receive
audio when a signal is not present. To bypass the squelch controls, enter
the command
SQUELCH BYPASSED
. To restore normal operation, enter
the command
SQUELCH AUTO
.
8.5 Upgrading the Radio’s Firmware
From time to time, GE MDS releases new firmware for its radio prod-
ucts to take advantage of engineering improvements or to add opera-
tional features. New firmware can be installed into existing radios in the
field, bringing them up to date with the firmware shipped with new
units.
Firmware files are available free of charge online at:
www.gemds.com/app/support/downloads
NOTE:
Only firmware specifically designed for this model of radio
can be installed in the unit.
Table 15. Relationship Between Digital Modem Selection
and Analog Operation
Command
Command
Agency
Compliance
Analog
Chan. Size
Peak
Deviation
MODEM 19200
followed by...
MODEM NONE
FCC/IC
25.0KHz
5.0 kHz
MODEM 9600
followed by...
MODEM NONE
FCC/IC
12.5KHz
2.5 kHz
MODEM 9600M
followed by...
MODEM NONE
ETSI
12.5KHz
2.0 kHz
MODEM 4800
followed by...
MODEM NONE
ETSI
12.5KHz
2.0 kHz
Summary of Contents for DS-SD4-1
Page 10: ...viii SD Series Reference Manual x710 Mode MDS 05 4670A01 Rev E ...
Page 69: ...MDS 05 4670A01 Rev E SD Series Reference Manual x710 Mode 59 NOTES ...
Page 70: ...60 SD Series Reference Manual x710 Mode MDS 05 4670A01 Rev E ...
Page 74: ...MDS 05 4670A01 Rev E SD Series Reference Manual x710 Mode I 4 ...