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GoPac Theory of Operation

M13-0002-00A Rev D.3 11 User Manual

2. THEORY OF OPERATION

The GoPac Power amplifier has been designed

to receive the output from a low power

transmitter and amplify it. The following

discussion assumes that the external

transmitter has output power less than 250mW

and has been verified to abide by all FCC

rules and regulations.

The RF output from the low power transmitter

is applied to the RF Input Connector (J1) as

shown in Figure 1. The signal is passed

through a power coupler (C1). This coupler

feeds two circuits: a variable attenuator (U1),

and a power detector (D1). This power

detector (the first of two) is designed to detect

the presence of an RF signal at J1. If the

signal is too high or too low, the main power

amplifier (A1) will be forced into standby by

the internal controller. This is to prevent the

power amplifier from going into transmit

mode without a signal applied, or with a signal

that is too high for the system to handle.

Power control:

After the RF signal from the coupler (C1) is

applied to variable attenuator (U1), it is routed

to a high gain high power amplifier (A1). The

output of the amplifier is then applied to a

power couple (C2). A portion of the output

power is applied to a second power detector

(D2) that is then fed back through an

automatic gain control loop (AGC). The

output of the AGC loop controls the variable

attenuator. An analog signal from the

microprocessor is applied to the AGC

controller. This signal is compared to the

power level from the main power detector

(D2). If the signal from (D2) is higher than

the signal from the microprocessor, the

attenuator is increased therefore reducing the

total output power, reducing the voltage from

(D2). If the signal from (D2) is lower than the

signal from the microprocessor, the attenuator

is reduced therefore increasing the total output

power, and increasing the voltage from (D2).

This process is performed continuously until a

steady state output power has been reached.

Main RF output:

The RF output from the amplifier is routed

through a low pass filter and an output

isolator. The low pass filter is used to remove

any unwanted harmonics created inside the

power amplifier. The output isolator is used

to protect the power amplifier from being

damaged when devices with poor RF match

are applied.

Summary of content (6 pages)

PAGE 1
GoPac Theory of Operation 2. THEORY OF OPERATION The GoPac Power amplifier has been designed to receive the output from a low power transmitter and amplify it. The following discussion assumes that the external transmitter has output power less than 250mW and has been verified to abide by all FCC rules and regulations. The RF output from the low power transmitter is applied to the RF Input Connector (J1) as shown in Figure 1. The signal is passed through a power coupler (C1).
PAGE 2
GoPac Theory of Operation Figure 1: System Block Diagram M13-0002-00A Rev D.
PAGE 3
GoPac Specifications 3. SPECIFICATIONS RF Performance Frequency band:......................................................1.99 GHz – 2.70 GHz .................................................................................6.40 GHz – 7.10 GHz Frequency tuning step size:.....................................50 KHz (United States) RF Output Power: ...................................................1 to 5W (digital) standard (8W optional) RF Power Modes Standby: ..............................................
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GoPac M13-0002-00A Rev D.
PAGE 5
GoPac Installation 4. INSTALLATION 4.1 transmitter, and the RF input of the GoPac. (Figure 3). UNPACKING & INSPECTION Unpack and visually inspect the unit for LCD, connector, and surface area damage. All claims should be filed with the carrier. Save all shipping and packing materials for possible re-use. 4.2 MECHANICAL INSTALLATION The GoPac comes standard with an Anton Bauer Mounting Bracket Assembly. This allows a camera back transmitter to be quickly attached or removed from the docking station.
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GoPac Installation RF Output (to antenna) Guide pins for mounting camera back transmitter RF Input (from camera back transmitter, e.g.) Figure 2: GoPac Guide Pins & RF Connectors Figure 3: GoPac fitted with RF cables M13-0002-00A Rev D.