Computer Automation Technology

SQ-1000 Super Squelch Module

When supplied with discriminator audio the SQ-1000 Super Squelch will perform the operation of a Squelch Circuit, COR/CAS Generator, or a Repeater Maker. As quieting occurs, the SQ-1000 will turn on its built-in audio switch and output the audio to a controller or transmitter input. The SQ-1000 also produces a DC logic voltage change to be used by the controller as a CAS or COR input. A dip switch selects whether the logic level is active high or low. The SQ-1000 automatically adjusts closure time with loss of signal. With a strong signal the switch will close in 20 milliseconds. Closure time automatically increases as the signal becomes noisier. A red LED lights whenever a signal is received and the squelch opens. The SQ-1000 connects directly to the audio delay header on most of the CAT controllers. A second header connector on the SQ-1000 permits connection of the AD-1000C Audio Delay.


Board size is 3.0 X 2.0 inches.
This is a plug and play accessory. No soldering required.


COR/CAS Generator
Figure 1 describes how the SQ-1000 is used as a COR/CAS generator with the CAT-200B. In this configuration the SQ-1000 is connected to the transceiver port audio delay header of a CAT-200B. Discriminator noise is sampled by the SQ-1000. When quieting occurs the SQ-1000 produces a DC voltage change that represents a COR input to the controller.


Figure 1


The CAT-1000B connections are identical to the CAT-200 except the COR output must be connected to the COR #2 input pin on the H4 header. The SQ-1000 will support the AD-1000 Audio Delay. Connect the AD-1000 to the J2 connector of the SQ-1000. Set SQ-1000 dipswitch #2 OFF to force the audio output through the delay board.


Figure 2


Repeater Maker
Figure 3 describes how the SQ-1000 is used as a Repeater Maker. Connect two transceivers to the SQ-1000. Assign transceiver #1 as the transmitter and transceiver #2 as the receiver. In this configuration the SQ-1000 monitors the discriminator output of the receiver. When quieting occurs the SQ-1000 COR/CAS logic output is used as a push-to-talk signal to key the transmitter.


Figure 3


Dip Switch
A four-position dipswitch configures various functions of the SQ-1000. Switch #1 determines if the audio output at pin #2 is de-emphasized. Switch #2 controls the audio path. When this switch is on, the audio goes directly out J1 pin #2. When switch #2 is off the audio is diverted to J2 pin #1 to be processed by the optional AD-1000 Audio Delay Board. Switch #3 determines if the COR/CAS output is active high or low. Switch #4 adds a built-in 2200-ohm pull-up resistor to the COR/CAS line.


Theory of Operation
With no signal input the receiver's discriminator output is noise. This noise level adjusted by the squelch control is applied to the combination noise amplifier band pass filter. The noise detector produces a DC voltage proportional to the noise level. This DC level is applied to the microprocessor analog to digital converter. As a signal is received the discriminator noise quiets. This caused a drop in the DC voltage applied to the microprocessor. The microprocessor turns on the squelch switch and the receive audio exits the SQ-1000 at J1 pin #2.


Figure 4


Ordering Information

SQ-1000 Super Squelch Board $89.00