Sony SPP-930, Руководство по обслуживанию

Страница: 14 / 60

– 14 –
SECTION 3
CIRCUIT OPERATION
FUNCTIONAL OVERVIEW
1.0 Introduction
The basic function of the RF circuits on both handset and base is to provide a full duplex wireless link between the handset and base sections
of the telephone. This is accomplished by setting up two simultaneous communications links between the handset and base RF sections. The
RF receiver and transmitter circuitry essentially provide a link between the microphone and speaker in the handset to the telephone line in the
base set. In this way the phone performs exactly as a corded phone, except without the cord.
The frequency at which the handset (operating at 3V) transmits to the base is centered around 925.65MHz, and the frequency at which the
base(operating at 5V) transmits to the handset is centered around 903.5MHz. This Machine uses a wideband FM modulation scheme to
directly modulate audio signals onto the RF carriers.
The following section will outline the transmit frequencies used by this Machine RF sections as well as the corresponding LO frequencies
which are used for the receivers. This is followed by the Block diagram and a block by block functional description of the modules.
1.1 Frequency Tables
This section outlines the frequencies and corresponding channel numbers used by the RF Module. The handset uses a high side LO while the
base uses a low side LO to down-convert the incoming signal.
l.1.1 Handset
Channel Transmit (MHz) Receive (MHz) RX LO (MHz)
1 925.05 902.3 913.0
2 925.35 902.6 913.3
3 925.65 902.9 913.6
4 925.95 903.2 913.9
5 926.25 903.5 914.2
6 926.55 903.8 914.5
7 926.85 904.1 914.8
8 927.15 904.4 915.1
9 927.45 904.7 915.4
10 927.75 905.0 915.7
1.1.2 Base
Channel Transmit (MHz) Receive (MHz) RX LO (MHz)
1 902.3 925.05 914.35
2 902.6 925.35 914.65
3 902.9 925.65 914.95
4 903.2 925.95 915.25
5 903.5 926.25 915.55
6 903.8 926.55 915.85
7 904.1 926.85 916.15
8 904.4 927.15 916.45
9 904.7 927.45 916.75
10 905.0 927.75 917.05