P25 on 155.4875 on a BCD396T.

[steve_eg]

Good evening,

First, let me say that I d/l the new firmware today, and have been able to sporadically pick up relatively clear conversations (I think I need to do some threshold tuning, but that's a topic for another post). The TGID >5000 fix works as advertised!

Now, onto my question-the past couple of days, I've been picking up what appears to be digital traffic on a conventional channel. The frequency is the new NLEC channel, 155.4875.

The traffic sounds digital, and I get a LNK/P25 flash when it's active. This particular channel is in my "Interagency" group, in my conventional county-wide (St. Clair, IL) system.

Is this behavior normal, or am I experiencing something as a result of being close to the local tower (within about 4 miles)?

My county is in the process of migrating to the Starcom21 system, and I'm wondering if they might be doing something to cause this.

Any thoughts?

If this post isn't appropriate for this forum, my apologies-I considered posting it to the Illinois forum, but since this seems to be more of a general question, that could benefit others as well as myself, I thought I'd post it here.

Thanks-

Steve

 

[ChrisP]

I've been picking up what appears to be digital traffic on a conventional channel. The frequency is the new NLEC channel, 155.4875.

The traffic sounds digital, and I get a LNK/P25 flash when it's active. This particular channel is in my "Interagency" group, in my conventional county-wide (St. Clair, IL) system.

Is this behavior normal, or am I experiencing something as a result of being close to the local tower (within about 4 miles)?

Are you questioning the fact you are hearing digital on a conventional channel? There's nothing abnormal about that. Digital modes can be used on conventional frequencies or trunked systems, it doesn't matter.

- Chris

 

[steve_eg]

Chris,

I was just questioning the LNK/P25 that's flashing. Being new to digital systems, I thought that I'd only get that on a P25 system.

Thanks,

Steve

 

[Voyager]

Good evening,

First, let me say that I d/l the new firmware today, and have been able to sporadically pick up relatively clear conversations (I think I need to do some threshold tuning, but that's a topic for another post). The TGID >5000 fix works as advertised!

Now, onto my question-the past couple of days, I've been picking up what appears to be digital traffic on a conventional channel. The frequency is the new NLEC channel, 155.4875.

Maybe because the frequency is wrong? 155.4875 is not a valid frequency - even with the new narrowband ones. Maybe it is 155.4825?
That is a valid one. Being 5 kHz off would cause such a problem.

Joe M.

 

[ChrisP]

Actually from what I have seen, 155.4875 MHz is correct for the new NLEEF narrow-band frequency. And even if it was 155.4825 MHz, the scanner would still be able to pick it up. They don't have that narrow a bandwidth...

- Chris

 

[Voyager]

Actually from what I have seen, 155.4875 MHz is correct for the new NLEEF narrow-band frequency. And even if it was 155.4825 MHz, the scanner would still be able to pick it up. They don't have that narrow a bandwidth...

- Chris

155.4875 MHz is only 2.5 kHz off the NBFM channel 155.490 MHz. It can't be that close. The new SNFM channels are spaced between the 15 kHz existing channels - 7.5 kHz away from those on either side.

If it is 155.4875, it's going to make the 155.490 MHz frequency useless, and vice versa. Someone dropped the ball BIG TIME on that one.

Of course any scanner is going to hear activity on 155.4875, as 155.490 MHz is a popular existing channel.

Joe M.

 

[ChrisP]

155.4875 MHz is only 2.5 kHz off the NBFM channel 155.490 MHz. It can't be that close. The new SNFM channels are spaced between the 15 kHz existing channels - 7.5 kHz away from those on either side.

I hear what you're saying. The 155.4875 MHz frequency does show up on many web sites (including the RR Wiki) as a new narrow-band frequency, and the state of Alaska even holds some licenses on that freq. But, in the lower 48, there are a few states now holding licenses on 155.4825 MHz. I suspect that 155.4825 MHz is correct...

- Chris

 

[Voyager]

155.4875 MHz is only 2.5 kHz off the NBFM channel 155.490 MHz. It can't be that close. The new SNFM channels are spaced between the 15 kHz existing channels - 7.5 kHz away from those on either side.

I hear what you're saying. The 155.4875 MHz frequency does show up on many web sites (including the RR Wiki) as a new narrow-band frequency, and the state of Alaska even holds some licenses on that freq. But, in the lower 48, there are a few states now holding licenses on 155.4825 MHz. I suspect that 155.4825 MHz is correct...

- Chris

Well, Alaska has a history of 'doing their own thing' (with the blessing of the FCC). I think they even have some lower VHF (130-144 MHz) systems up there.

I highly suspect a typo that has been repeated (copied) many times, or something thinking that if it's OK in AK, it's OK everywhere else, too.

Joe M.


Joe M.

 

[loumaag]

According to the actual pool data contained in Part 90.20, 155.4875 is not valid, at least in the lower 48. 155.4825 is the valid frequency.

Those 155.4875 frequencies licensed in AK are part of the State of Alaska trunking system which has freq's all over the place, including those Joe mentioned below the 2 meter Ham band.

As for the Wiki, I am going to find that and fix it, becuase if it says 155.4875, it is wrong.

 

[steve_eg]

I confirmed last night that what I'm picking up is 155.490. It was a police dispatch, and I googled the address, that they gave and it's in St. Charles Co. It's their Sheriff's office and it is running in P25 digital mode.

What really suprised me was the distance that I am from St. Charles-a little shy of 40 miles, and the traffic was clear.

Thanks,

Steve

 

[loumaag]

What really suprised me was the distance that I am from St. Charles-a little shy of 40 miles, and the traffic was clear.

Ya' just gotta love that digital! :wink:

 

[RyltnVFD]

Ya' just gotta love that digital! :wink:

To an extent. It's a good system when it's working properly, but when you can't get a good signal, there's no deciphering voice through the static. There is nothing, or maybe a few beeps, boops, and other assorted robot words.

That's what I don't like about digital.

 

[loumaag]

Ya' just gotta love that digital! :wink:

To an extent. It's a good system when it's working properly, but when you can't get a good signal, there's no deciphering voice through the static. There is nothing, or maybe a few beeps, boops, and other assorted robot words.

That's what I don't like about digital.

Well that is an argument for a different topic (and already covered quite a number of times in these forums), I will just say that evidence does not support your view.

 

[swest90]

I dont what what evidence you are speaking of, But it is surely the case here in Southern California. I used to be able to pick up LAPD no problem with a duck antenna about 30 miles east of LA, same with Glendale, Burbank. Now that they have gone digital and I would guess turned down the power on their sites, now the audio does not come in at all. I now have a stack of 5 external antennas on the roof and all is well. So I would agree with the previous post, When the system is tuned right and if you are within their radius you will pick up the systems well. Any bit outside of that radius and you are screwed. You hear either garbage, or blips and blops of nothing. I much rather listen to a some squelch then lose the conversation in total.

Thanks
Shawn