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Pro-651: And Pro-106 and Squelch Code Question

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robo21

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#1
First a little history. I live in Los Angeles. I have both radios, Pro-651 and Pro-106. I sold my GRE PSR-500 for enough moolah to buy a new 651 and a used 106. I felt like that was a good move. Even the 106 feels like it is an equal to the GRE radio. I do realize that the 651, 106 and 500 are all basically the same. I have had Arc 500 software for the GRE since 2009.

My next door neighbor has the Pro-96 and I turned him onto a deal on a new 651 which he is now loving. He is new to the Arc 500 software.

I downloaded the frequencies for LAPD from this Radio Reference and the download included squelch codes (mostly 466) for each of the police frequencies. My neighbor who considers himself an Expert (with a capital 'E') says that it is better to leave the squelch code blank or on "search" as inputting a code in this field will cause problems such as dropped broadcasts, etc.

I can't imagine that Radio Reference would include codes in the downloads if they weren't necessary so I left the codes in my scan lists and haven't noticed any dropped broadcasts or other problems. If anything when I try his scan list for LAPD I notice issues such as gaps and noise in the broadcasts.

Can anyone shed some light on this subject please?
 
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#2
PL tones are good for only one thing, limiting what you hear. With them set, you will ONLY hear signals with that tone there (and properly decoded). They are necessary when you transmit, but on receive are very optional. If you have unwanted interference (a town to your west and another to your east are both on the same frequency but use different tones AND you only want to hear one of them, programming the tone would eliminate the other from your listening) a tone may help.

Programming a tone may hurt if your scanner has difficulty receiving the signal or decoding the tone since you'll only get audio when you both receive the signal and the tone is properly decoded. It also takes a bit of time for a radio to decode the tone and open up the audio stream. This delay, slight as it may be, can prevent you from hearing short transmissions.

They're in the database, not because they're actually necessary, but because they can be useful in the right circumstances. Just like in the trunking section of the database, they list both the Decimal and Hex values for the talkgroups. Both are not necessary, but if you have a scanner that requires the decimal value and only the hex value is listed, you'd need to perform a conversion. Similarly, if you have a radio that needs the hex value and only the decimal one was listed a conversion would also be required. In either case, a mistake doing the conversion would cause you to not hear that talkgroup.

The process a radio goes through when a tone is programmed and is not programmed is basically as follows:

Not programmed:
1) Signal received?
2) Programmed?
3) Send audio to speaker (simple enough!)

Tone programmed:
1) Signal received?
2) Frequency programed?
3) Tone programed?
4) Decode incorrect? delay and try step again until decode timeout exceeded
5) Timeout exceeded for decode? Scan next
6) Decode correct and Tone correct? (yes, send audio to speaker)
 
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robo21

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Premium Subscriber
Joined
Feb 23, 2008
Messages
38
Location
Los Angeles, CA
#3
PL tones are good for only one thing, limiting what you hear. With them set, you will ONLY hear signals with that tone there (and properly decoded). They are necessary when you transmit, but on receive are very optional. If you have unwanted interference (a town to your west and another to your east are both on the same frequency but use different tones AND you only want to hear one of them, programming the tone would eliminate the other from your listening) a tone may help.

Programming a tone may hurt if your scanner has difficulty receiving the signal or decoding the tone since you'll only get audio when you both receive the signal and the tone is properly decoded. It also takes a bit of time for a radio to decode the tone and open up the audio stream. This delay, slight as it may be, can prevent you from hearing short transmissions.

Thank you very much for the informative reply. So would you recommend removing the codes whatever they may be from the LAPD scan list or should I change the setting to "search?" As far as I know we have no interference from unwanted frequencies.
 

robo21

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Premium Subscriber
Joined
Feb 23, 2008
Messages
38
Location
Los Angeles, CA
#4
What About The Squelch Mode?

Should the squelch mode be set to P25 as has been done by the RR download? Or should it be set to "none" or "search" as my neighbor has suggested?
 
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