Heli-Coder 4 Transmitter Operation Manual | Doc. No. 6051452100 Rev. C
Broadcast Microwave Services, Inc.
11
5.4
Wiring Connections and Signal Interfaces
Reference Figure 12 Typical airborne installation diagram (
without TAA-101 Antenna Actuator
)” and Figure 13 Wire
Hook-Up Diagram for HC4 System” shown later in this document. Also reference section 16 of this manual titled
“CONNECTION AND WIRING DIAGRAMS” during installation for detail related to a typical installation.
Contact BMS regarding issues related to custom or modified installations if applicable. Additional service or fees may
apply.
5.4.1 Power Input (J2)
J2 connects aircraft 28VDC from an available 5 AMP breaker. Use AWG 20 gauge wire or larger.
5.4.2 Radio Frequency Output (RF Out) (J5)
J5 conducts the radio frequency energy out to a transmit antenna. Achieving optimum link performance
includes assuring a maximum RF energy is delivered to the antenna assembly via properly mated connector
assemblies and well installed cables. RF cable should be 50Ω foam dielectric coaxial cable. Belden type FSJ-50A or
equal is recommended. Cable lengths should be as short as practical in the installation to reduce RF loss. Observe
the cable manufacturer’s minimum “bend radius” recommendation during installation. Kinks, pinches, or sharp bends
in high frequency cable will cause significant power losses. Check all connections for proper termination and use
high-quality type N connectors. Hand-tighten connectors; do not use a wrench or pliers as over-tightening will damage
a connector and reduce the system performance by introducing RF loss in the transmission line. Seal mated exterior
connections with self-vulcanizing rubber tape in order to avoid moisture in the connection joint which may also
introduce RF loss or physically damage the connector over time.
It is good practice to avoid the use of 90° elbow adaptors within the RF coax cable run.
5.4.3 Serial Digital Video Input (J12)
J12 is a standard 75Ω BNC jack that is for a Serial Digital Interface. This is the digital video signal that comes out of
most modern video cameras. The signal may be standard definition SDI (SMPTE-270) or high definition HD-SDI
(SMPTE-292). A high quality, double shielded coaxial video cable should be used such as Belden 8281 or equal.
Take care to terminate the cable with a 75Ω BNC plug.
5.4.4 Composite Video (CVBS) Input (J9)
J9 accepts a standard definition composite video signal (PAL or NTSC). Follow the same cabling instructions as in
5.4.3.
5.4.5 ASI Input
J11 accepts an asynchronous serial input (ASI) also known as DVB-ASI (digital video broadcasting). The signal
consists of a compressed MPEG transport stream. The input by-passes the internal encoder built into the HC4 and
goes right into the modulator. This allows use of external video or data encoders whose outputs are an ASI transport
stream.
The input must conform to the ISO/IEC 13818-1 standard
. Follow the same cabling instructions described
in section 5.4.3.
5.4.6 ASI Output
J10 ports out an ASI transport stream consisting of the encoded video currently being transmitted by the HC4. This
output allows external monitoring of the compressed signal and the use of a backup transmitter or other configurations.
Follow the same cabling instructions described in section 5.4.3.
5.4.7 Audio Input
J6 is a multi-pin connector where pins 1-6 are dedicated to two balanced audio channels, each 600Ω impedance. Use
a high quality shielded twisted pair audio cable.
5.4.8 GPS
J1 is an input connector for an external GPS antenna. The recommended antenna is a Garmin GA 35 but other
antennas will work. The output connector is a TNC(f) and should be cabled with a good quality 50Ω coax. Follow the
antenna manufacturer’s instructions for cable/ connector type and cable length.
