RED PT500-2, Service Manual

Page: 26 / 62

PT500-2 Service Manual
26
No. Frequency
[Hz]
No. Frequency
[Hz]
No. Frequency
[Hz]
No. Frequency
[Hz]
1 67.0 11 94.8 21 131.8 31 186.2
2 69.3 12 97.4 22 136.5 32 192.8
3 71.9 13 100.0 23 141.3 33 203.5
4 74.4 14 103.5 24 146.2 34 210.7
5 77.0 15 107.2 25 151.4 35 218.1
6 79.7 16 110.9 26 156.7 36 225.7
7 82.5 17 114.8 27 162.2 37 233.6
8 85.4 18 118.8 28 167.9 38 241.8
9 88.5 19 123.0 29 173.8 39 250.3
10 91.5 20 127.3 30 179.9
DCS signaling
：
DCS (Digital code squelch), is a kind of continuous digital code modulated on carrier with
voice signal and used for squelch control. If DCS function is set, the speaker is available
only when receiving the same DCS code to avoid the disturbance of useless signals. The
station has 83 kinds of standard codes including positive and inverse code for your selection,
such as Table 2.
DCS signals produced by MCU (PWM waveform) are sent to VCO and TCXO for modulation
(the HF components of DCS signals are modulated by VCO, while the LF components by
TCXO) after filtered the HF components over 300Hz in low pass filter composed by RC.
CTCSS/DCS signals from receiver are sent to MCU for decoding, and then MCU test if there
are DCS codes with the same setting of the station to decide whether open the speaker or
not.