Installation Manual

4
APPLICANT: LARUS CO.
FCC ID: LYA 9000
The downconverted IF spread-spectrum signal is then applied to the de-spreader. The
receiver control circuits generate early, timely and late codes to correlate the receive signal
plus an uncorrelated signal utilized for AGC control.
The de-spread 70 MHz signal is fed to the Control Module through the multiplexer cable,
where processed further.
Receive IF signal processing. At the controller interface, the extracted 70 MHz signal is
passed through a SAW filter. This filtered signal is the downconverted to 6 MHz through a
mixer/AGC circuit. The downconverted signal is then applied to the demodulator chip.
The demod chip performs the A/D conversion function. The demodulated digital signal is
then converted to four E1 digital streams by the E1 multiplexer.
5. Controller/Telemetry functions.
The controller circuits provide the data interfaces and microcontroller functions for local
control and housekeeping chores.
The signal transmission between the RF and Control module is via a coaxial interface cable
that carries the telemetry signals with the monitoring/control information. The telemetry
signals frequencies within the system are:
RF Module to Control Module: Transmit: 4.43 MHz, Receive: 10.7 MHz
Control Module to RF Module: Transmit: 10.7 MHz, Receive: 4.43 MHz
These telemetry channels are processed in transceivers at each end (e.g., in each the RF
and Control module). They contain information of system operational parameters: transmit
level, spreading code, etc.
This scheme allows the separation of RF and Control unit as much, as 30 feet via the coaxial
interface cable. Extensive filtering of telemetry channels is provided in the transceivers to
eliminate any interference between the IF channels and the telemetry channels that are
simultaneously present in the same cable.
REFERENCE
. MODEL 9000 E1/DS1 Spread Spectrum 5.78 GHz Digital Microwave Radio
System, Volume 1, System Description.