Page 45 of 101
DWG ID: 181-0101-00A
Date: 2003-09-26
The Input/Output connector, A3J1, at the top left of the front panel, for units with an I/O
CCA, is for analog and discreet inputs and outputs. See § 7 for pinout and connection
details.
11.7
Input/Output Serial I/O
A 2
nd
serial I/O connector, A3J2, at the top right of the front panel, for units with an I/O
CCA, is for RS232 communications, normally with a PC. Be sure to use a shielded cable
that is properly terminated. See note in § 4.4 FCC Notice concerning shielded cables. The
radio modem is considered a DCE unit. Use a straight through RS232 cable and not a null
modem cable.
12
THEORY OF OPERATION
The TALON UDC units are radio modems utilizing four-level frequency shift keying (4-
LFSK) modulation. The assemblies and subassemblies of the unit consist of:
A1–Radio transceiver (XCVR) assembly (A1A1 CCA with connector and cable).
A1A1–Radio XCVR circuit card assembly (CCA), UHF or VHF frequencies.
A2–Controller CCA.
A2A1–Global Positioning System (GPS) receiver (RCVR) CCA or other function.
A3–I/O CCA having sensor inputs and control outputs.
The basic unit consists of A1 and A2 assemblies with the A2A1 GPS RCVR added as an
option. Other configurations consist of the basic unit of A1 and A2, along with an A3 I/O
CCA, with the A2A1 GPS RCVR added as an option or having some other function.
12.1
Ritron’s VHF Radio XCVR, A1A1
12.1.1
Receiver
12.1.1.1
RF Amplifier and Band-pass Filters
The incoming RF signal from the input connector J101 passes backwards through the
transmitter low-pass filter and the electronic T/R switch to a three pole band-pass filter
formed around L102, L103, and L104. This filter is of Cohn type with 1.5 dB insertion
loss and a bandwidth of 30 MHz. This filter is followed by a low noise amplifier stage
formed around Q101. This amplifier has a gain of about 17 dB with a noise figure of 2
dB and serves to amplify the incoming RF signal above the noise of the following stages.
Following this stage is a three-pole Cohn filter formed around L107 through L109. The
characteristics of this filter are identical to that of the first. The two filter sections are
