Sony ICF-SW7600G - Manual (Page 12)

Receiving SSB (Single Side
Band)/CW (Continuous Wave)
Transmissions
1
5
3
2
1 Turn on the radio, and select AM with FM/AM.
2 Set AM MODE to SSB.
3 Switch LSB/USB to select the desired sideband. To receive CW,
select LSB.
4 Tune in a frequency near the broadcast you want to
receive by way of direct tuning (see page 14), manual tuning (see
page 16) or scan tuning (see page 18).
5 Adjust the tuning with SSB FINE TUNE.
You can adjust the frequency within an approx. ±1.5 kHz range.
The frequency display will not change.
What is SSB (Single Side Band) ?
SSB is very popular among ham and
business radio users and will be found
on ail of Ihe amateur bands because of
its signal intelligibility.
In general, SSB transmissions employ
USB (upper sideband) modulation, and
for amateur bands lower than 10 MHz,
LSB (lower sideband) is often used.
Amplitude Carrier
LSB USB
r\
,
What is CW (Continuous Wave) ?
CW is also popular among ham and
business radio users. In CW
transmission, the amplitude of a carrier
is not modulated whjle that of other
system is modulated. CW conveys
information by interrupting a carrier
using Morse code. It can be heard as a
beat sound only with the unit equipped
with BFO circuits. To understand the
information transmitted by CW, you
need to learn the Morse code.
Frequency
Receiving with the
Synchronous Detection
22
4
3
Turn on the radio, and select AM with FM/AM.
Tune in a frequency you want to receive by way of direct
tuning (see page 14), manual tuning (see page 16), scan tuning (see
page 18) or preset tuning (see page 20).
Set AM MODE to SYNC.
Switch LSB/USB to a sideband that gives clear reception.
When the synchronous detection is locked, the SYNC LOCK
indicator lights.
what is synchronous detection?
There are two big problems in AM
reception: distortion due to fading and
interference from adjacent stations.
Synchronous detection is effective in
solving these problems. Distortion due
to fading is caused by over-modulation,
which occurs when a carrier component
of the received signal is attenuated on
the way. In this receiver, a pure carrier
frequency with no level variation,
perfectly synchronized with the original
carrier, is generated in the synchronous
detector circuit and is mixed with the
received signal to compensate the
attenuated carrier component. In this
way, distortion is remarkably reduced.
On the other hand, AM (SW, MW, and
LW) broadcasting generally uses double­
sideband transmission, in w’hich
modulated signals are transmitted using
both the upper and lower sidebands
(USB and LSB). In most cases, one of the
sidebands is affected by interference
from adjacent stations (beats). In the
synchronous detector circuit, one of USB
and LSB can be received. This allows
clear reception without interference from
adjacent stations.
Amplitude
Carrier
Interference
from adjacent
LSB
n r é \ .
Only this side is
received.
Frequency
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