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| − | == Setting the P25 Decode Level ==
| + | {{Text_TalkInForumsPlease|uniden-forums|Uniden}} |
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| − | Paul Opitz, the BCD396T product manager, posted the threshold
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| − | table for the BCD396T in an effort to make tuning easier for
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| − | us. L. W. "Dan" Danz posted instructions on how to use this
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| − | table to the BCD396T Yahoo group.
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| − | === The Table ===
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| − | 0) 1.54 1.60 1.66
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| − | 1) 1.52 1.60 1.682
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| − | 2) 1.50 1.60 1.703
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| − | 3) 1.48 1.60 1.724
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| − | 4) 1.46 1.60 1.745
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| − | 5) 1.44 1.60 1.766
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| − | 6) 1.42 1.60 1.787
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| − | 7) 1.40 1.60 1.808
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| − | 8) 1.38 1.60 1.829
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| − | 9) 1.36 1.60 1.8410
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| − | 10) 1.34 1.60 1.8611
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| − | 11) 1.32 1.60 1.8812
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| − | 12) 1.30 1.60 1.9013
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| − | 13) 1.28 1.60 1.9214
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| − | 14) 1.26 1.60 1.9415
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| − | 15) 1.24 1.60 1.9616
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| − | 16) 1.22 1.60 1.9817
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| − | 17) 1.20 1.60 2.0018
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| − | 18) 1.18 1.60 2.0219
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| − | 19) 1.16 1.60 2.0420
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| − | 20) 1.14 1.60 2.06
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| − | ---- | |
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| − | From L. W. "Dan" Danz (WA5SKM)
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| − | Fountain Hills AZ
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| − | There are some initially-confusing things about the P25 Decode Threshold
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| − | level. The manual gives very adequate instructions about how to use
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| − | the AUTO setting, I thought. But I'll provide some insight:
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| − |
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| − | The level numbers are an index into a table of thresholds for decoding
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| − | the digital data. Higher numbers are more permissive (the thresholds
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| − | for decoding are wider) while smaller numbers tighten the threshold
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| − | ranges. The optimum range depends on how the technicians have set up
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| − | the system you are trying to receive.
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| − | DEFAULT
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| − | Means a Level (Index) setting of 8. Thresholds don't change. Must
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| − | likely you can do better.
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| − | MANUAL means you control it all -
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| − | Hold Func and press the scroll knob twice to get the screen.
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| − | Adjust the setting with the knob until you get the best result for
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| − | any given SYSTEM.
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| − | The radio will remember this setting for that System and use it
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| − | every time it has to decode digital audio.
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| − |
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| − | AUTO means the radio attempts to fine tune the P25 audio transmission
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| − | thresholds during receive. You can generally see it doing this. During
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| − | the beta test, we convinced Uniden to implement a slight change to the
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| − | "Auto" functionality. Specifically, we noticed that it was starting
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| − | over at the default setting and then trying to correct it again at every
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| − | transmission; sometimes this meant it took a long time to settle in.
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| − | We went thru a couple of iterations, requiring at first - Set the
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| − | threshold with MANUAL and then AUTO would use that as a starting point.
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| − | This was cumbersome, and soon changed to the ability to control the
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| − | starting point while in AUTO mode by using FUNC-SCROLL while viewing the
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| − | decode screen. Whatever you set at this point will be remembered FOR
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| − | THIS SYSTEM as the starting point for the auto-tuning function for
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| − | subsequent trransmission ON THAT SYSTEM.
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| − | Incidentally, we did suggest the ultimate -- for the radio to
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| − | automagically remember this on its own, continually refining it and
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| − | picking a better starting point if it could. But the engineers thought
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| − | it would results in too many writes to the EEPROM, which has a generous
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| − | capability for making changes to the programming, but the limit would be
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| − | reached if every P25 audio transmission resulted in a write.
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| − | Now I can offer a slight refinement (courtesy of a very helpful Engineer
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| − | at Uniden): If you're having trouble with a P16 (Moto type 2) system
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| − | decoding digital P25 audio, slightly offtune the automatic setting.
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| − | Frequently the radio will auto tune to a setting that is halfway between
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| − | the values that you can set manually. For example, it might finally
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| − | settle to a low threshold of 1.41, but you can't set the starting point
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| − | to that, you can only make it 1.40 or 1.42. Well, the trick that helps
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| − | stop the motorboating is to pick the tighter threshold side. In the
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| − | example, instead of picking 1.40, pick 1.42 (that's a tighter
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| − | threshold). (Think of it as similar to setting the squelch tighter for
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| − | a conventional channel.) Even if you auto-tune to an even value, like
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| − | 1.42, pick the next tighter value (1.44) to start at.
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| − | Works for me. Cuts out 80% of the motorboating that occurred prior to or
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| − | after a transmission. YMMV. You guys having trouble with motorboating
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| − | on the San Mateo system should definitely try this.
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| − | ----
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| − | Posted by --[[User:Al42|Al42]] 21:06, 14 Sep 2005 (CDT)
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