Business Frequencies- How to Program

[smcclellan06]

Hey all,

I've got a handful of XPR7550e units and I'm currently getting licensed for use on the business frequencies. The frequency coordinator is currently having me monitor the frequencies so I can pick the least congested frequencies to use. I live in an urban environment (decent size city) and as I've been monitoring, there's a lot of traffic on each frequency. I have asked my coordinator for another batch of frequencies to monitor, but I feel that I'm still going to get interference no matter what frequencies I choose.

Anyway, to my actual question: I know that I can program in different DPL tones for privacy in CPS and I plan on operating in digital as opposed to analog. But the way I understand it is that once there's traffic no matter what kind of modulation it is, I cant transmit until the channel is "clear", unless I program each channel's admit criteria as "Always". Would this be the right thing to do? If I program it that way, then I fear that people will be interrupting each other while we're operating.

Any thoughts?

 

[alcahuete]

Anyway, to my actual question: I know that I can program in different DPL tones for privacy in CPS and I plan on operating in digital as opposed to analog. But the way I understand it is that once there's traffic no matter what kind of modulation it is, I cant transmit until the channel is "clear", unless I program each channel's admit criteria as "Always". Would this be the right thing to do? If I program it that way, then I fear that people will be interrupting each other while we're operating.

Any thoughts?

Use Color Code Free instead of Always and it will work fine. What should be most important, however, is that interference is interference. DPL, digital, analog, it all makes no difference. Sure, it won't open your radio up, but it is sure as heck still going to interfere.

It sounds like your coordinator is giving you a bunch of itinerant frequencies or something. A frequency coordinator should be finding you a unique "unused" frequency. After all...that's what frequency coordinators are for and why coordination happens in the first place...so that users are not interfering with each other. My frequencies here in Los Angeles County, for example, are only used 6-8 times throughout the entire state of California, the closest being 80+ miles away. There is no interference at all, because we are the only ones using them.

So it sounds to me like you need a new frequency coordinator, in all honesty.

 

[smcclellan06]

Thanks for the info. I have applied for 5 frequencies and she gave me 10 to monitor for a week to see which ones I want to pick. She told me those were the least congested frequencies in my area and that interference was somewhat likely going to happen in my area. She also said that I could ask for more to monitor of these don’t work out. I guess I’ll be asking for another batch of frequencies.

 

[alcahuete]

Out of curiosity, what are some of the frequencies she gave you?

 

[smcclellan06]

I’ll PM you with those.

 

[N4DES]

Keep in mind that just because you hear someone it doesn't mean it is interference and while you might get coordinated and licensed for a frequency it doesn't make it only yours the term of the license. The FCC database is very fluid and other users will be licensed on top of you at some point in the future, so while a frequency might sound great today it might not be tomorrow.

You also have to worry about the adjacent frequencies as well. I've identified two instances of adjacent channel interference caused by a newly deployed wide-area DMR system 12.5 KHz off the other entities center frequencies. Both ended up paying for re-coordination and reprogrammed their radio due to being encroached upon.