Requirements for Unity of Application - Japan Patent Office

[Example 14]
[Title of the Invention]
Independent side band (IBS) AM sound multiplex transmission device
[Claims]
1. A transmission device of independent side band (IBS) AM sound multiplex system with a
transmitter and a receiver comprising:
Means (10,12, 14, 16) wherein said transmitter responds to a pair of audio frequency signals,
L and R signals which express left and right multiplex sound information and generates sum
and difference of the L and R signals;
Means (23) generating carrier signals modulated in phase, for expressing said difference
signals modulated inversely by said sum signals according to the modulation function
selected first and provided;
Means (22) for forming ISB AM sound multiplex signals, modulation with amplitude the
above carrier signals, modulated with phase, by said sum signals;
Means (62, 63, 65, 67-70) for responding to the intermediate frequency (IF) ISB AM sound
multiplex signals received by the above receiver, modulating inversely the difference signal
component of the above mentioned signals by the above sum signal component according
to the modulation function selected second, and inducing a pair of audio frequency output
signals expressing respectively the original L and R input signals; characterized in that
modulation function in said transmitter and receiver is selected appropriately, and linearity
and independence of transmitted Land R signals are given, as a result, inter-modulation
distortion is reduced.
2. A transmitter for independent side band (IBS) AM sound multiplex system comprising
means (10, 12, 14, 16) for responding to a pair of audio frequency signals, L and R,
expressing left and right multiplex sound information and sending sum and difference
signals including the component of L and R signals, means (23) for sending carrier signals
modulated in phase, for expressing the above difference signals, modulated inversely, by
said sum signals according to the modulation function, and means (22) for forming ISB AM
sound multiplex signals which has less inter-modulation distortion, by modulation with
amplitude the above carrier signals, modulated in phase, by the above sum signals. (See
Figure 1)
3. A receiver for independent side band (IBS) AM sound multiplex system comprising a means
(62, 63, 65, 67-70) for modulating difference signal component inversely by sum signal
component in the received intermediate frequency (IF) ISB AM sound multiplex signals
according to the modulation function, and inducing a pair of audio frequency output signals
expressing the original L and R signals. (See Figure 2)
[Excerpt from Detailed Description of the Invention and Drawings]
This invention concerns an independent side band AM sound multiplex system, wherein
the linearity and independence of stereo signals are improved by giving the second higher
harmonics correction to the stereo difference signal component; as a result, inter-modulation
distortion is reduced.
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