Installation Manual
1
APPLICANT: LARUS CO.
FCC ID: LYA 9000
OPERATION OF THE LARUS MODEL 9000, 5.7 GHz DIRECT SEQUENCE SPREAD SPECTRUM
RADIO TRANSMITTER.
1. Summary. This transmitting system (hereafter referred to as
Α
transmitter
≅
) provides point-
to-point transmission of IF/RF carriers, modulated with a serial bit stream designed to
process either four E1 or four T1 multiplexed carriers or digital baseband signals. The unit
under test is designated for E1 carrier traffic. This is not a
Α
pulsed
≅
type transmitting
system; the type of carrier modulation is 16QAM.
The IF transmit frequency is at 140 MHz, where the modulated transmit carrier is
spread and translated up to the radio transmit center frequencies of 5752.5 MHz (TX Low) or
5822.5 MHz (TX Hi). The IF receive frequency is 70 MHz.
The transmit-receive operating mode is full duplex, single channel within the ISM
band, occupying the bandwidths of 5752.5
∀
22.5 MHz and 5852.5
∀
22.5 MHz. For the
frequency plan of this transmitter, see Figure 1.
The Model 9000 system consists of two separate rack-mountable modules: the RF
and Control modules. The
RF Module
contains the transmitter IF/spread circuits (to be
described in detail below.The
Control Module
is utilized for the status, control functions
and baseband/IF modulation/signal processing of the transmitter. It contains the E1/DS1
mux , modulator/demodulator circuits and receive AGC.
The antenna that connects to the bulkhead is not part of the transmitter. It is provided
and installed by the customer in compliance with FCC regulations, as stated in the
Operating and Installation Manual.
2. List of transmitter main functions.
1. 16QAM modulator to modulate the 140 MHz IF carrier with the incoming serial bit
stream of the four multiplexed E1 carriers coming from the E1/DS1 Mux.
2. Spreading circuits that include the Code Multiplier containing the access code,
the chip filter to attenuate unwanted products and to define the spectral shape of
the modulated carrier.
3. IF chain to provide amplification, equalization and gain control/stabilization of
the IF carrier before translating up to the 5.7 Ghz band. The RF drive level to the
output power amplifier is set here as required, consistent with antenna size, or
EIRP.
4. RF chain provides frequency translation of the 140 MHz IF, bandpass filtering
and final amplification of the translated carrier at the 5.7 Ghz band.
5. The transmit power amplifier provides rated power to the antenna through th
diplexer which in turn feeds the receiver at the LNA input.