Figure 5 Programming lead

USER ADJUSTMENTS

It is possible to adjust the level at which the squelch circuit operates using RV1. This

adjustment can be accessed by carefully removing the fingered lid. Refer to Figure 4

for location of RV1. When adjusting RV1 take care not to adjust the adjacent L8 or

C15.

FREQUENCY PROGRAMMING

The STR450 has an internal memory which can store up to 128 RF channels (16

randomly programmed and 112 sequentially programmed).

The frequency and set-up information is programmed into the unit by a series of 8 byte

data packets over a 1200 baud RS232 interface. Each packet includes a 16 bit sync

code and an 11 bit checksum to eliminate the possibility of spurious reprogramming.

The software supplied with the STR450 receiver is the STRPRG.exe program, which

can be run on a PC with the serial port connected to PL2 of the STR450 receiver via

a suitable lead as shown in Figure 5. If the read-back function is desired, then the

squelch flag output of the receiver must be connected to pin 2 of the PC serial port,

with a 1k pull-up resistor to +5V provided.