We came up with a TS-32 mod that shortens the un-decode time significantly, but it does narrow the bandwidth and lower the hysteresis. Today's encoders are sufficently accurate for this not to be a problem. This scheme is much better than simply changing the decoder's RC delay. After the mod, we found the un-decode time (at one freq) would drop from about 250 mS to about 80 mS. The decode time remained the same at about 250 mS.
"Decode time" is the interval it takes for the decoder to realize a
user is transmitting the proper PL tone.
"Un-decode time" or release time is the interval it takes for the decoder to realize the user has stopped transmitting.
(1) You'll need three resistors: R60 (20K 1%), R61 (37.4K, 1%, see step
#6), and R62 (20K, 1% or 5%).
(2) Cut the trace leading to pin 6 of IC-A at pin 6.
(3) Connect R62 in parallel with R21. (We found that putting the resistors on the circuit side worked best.)
(4) Connect R60 from Bias-A (we used one end of R1) to IC-A at pin 6.
(5) Connect R61 from IC-A pin 6 to ground (we used the ground connector pin near C1 and C7).
(6) Measure the voltage at IC-A pin 6. It should be 5.30 volts +/- 0.05 volts. If not, change the value of R61.
EE, S-COM Industries
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