P25 Question Please (SDS 200)

[BOBRR]

Hello,

Please bear with me a bit on this. Age problem now, and I miss many of the
nuances, etc. Really trying to learn this, though.

Getting my SDS 200 going again after about a year of non usage due to medical issues.

Using Sentinel.

Have most everything working, I think, but am very uncertain how to handle the P25 mode used by our PD.

Our local PD uses (per RR) P25e Most of the time, though, I am pretty certain their comms are not encrypted.

About a year ago, I imported directly from RR the data for our FD and PD in
our Municipality in Sudbury, Mass. (Middlesex County, Mass.) into Sentinel. (Please take a look if you have a spare minute)

Sudbury PD is 852.9125 P25e. (from RR)

Assuming their comms are “normal” P25, how do I handle this ?

In Sentinel (or RR) there does not seem to be a choice for P25 for the Sudbury PD. Only NFM (or Auto) choices seems at all applicable.

Is this (the NFM setting) all I need to download to the Scanner ? I tried, but hear nothing; not even static.

e.g., where does the Scanner get the CC info. from ?

*Any other settings I need to change/select in the Scanner ? Or is what Sentinel imported from RR, and downloaded to the SDS 200,
(the NFM setting) all that is required by the scanner ?

If anyone could run me thru this, in excruciating detail, and perhaps explain a little, would be most appreciative.

Thanks, really appreciative,
Bob

 

[nessnet]

Bobrr: If you want, export your hpe file and someone here can take a look
In Sentinel, File / export to hpe file / choose the favorite list in question / (note where it is saved).

Once you have the file saved, attach it to a reply here - note that RR does not allow hpe files to be attached, so change the file extension to .txt to attach and send.

 

[hiegtx]

Hello,

Please bear with me a bit on this. Age problem now, and I miss many of the
nuances, etc. Really trying to learn this, though.

Getting my SDS 200 going again after about a year of non usage due to medical issues.

Using Sentinel.

Have most everything working, I think, but am very uncertain how to handle the P25 mode used by our PD.

Our local PD uses (per RR) P25e Most of the time, though, I am pretty certain their comms are not encrypted.

About a year ago, I imported directly from RR the data for our FD and PD in
our Municipality in Sudbury, Mass. (Middlesex County, Mass.) into Sentinel. (Please take a look if you have a spare minute)

Sudbury PD is 852.9125 P25e. (from RR)

Assuming their comms are “normal” P25, how do I handle this ?

In Sentinel (or RR) there does not seem to be a choice for P25 for the Sudbury PD. Only NFM (or Auto) choices seems at all applicable.

Is this (the NFM setting) all I need to download to the Scanner ? I tried, but hear nothing; not even static.

e.g., where does the Scanner get the CC info. from ?

*Any other settings I need to change/select in the Scanner ? Or is what Sentinel imported from RR, and downloaded to the SDS 200,
(the NFM setting) all that is required by the scanner ?

If anyone could run me thru this, in excruciating detail, and perhaps explain a little, would be most appreciative.

Thanks, really appreciative,
Bob

Bob,

Here's Sudbury as it shows on the county's database page:


The P25, showing in the Mode column simply indicates that the frequency is using digital voice. The lower case e indicates that while they do use encryption, it is not in use all the time. When they are not using encryption, you would be able to hear them. During the times that encryption is in use, you would not.

In Sentinel, to program this frequency manually, you would set the Audio option to Digital.
You would then get a pop-up window asking which type of digital.


For this channel, you would select P25 (which was in the Mode column on the database page), which would then allow you to set the NAC code. The NAC allows you to restrict reception to only the transmissions that include that specific NAC. This serves a function similar to the CTCSS or DCS tones and codes used for analog frequencies. If you are within range of one, or more, agencies that also use the frequency 852.9125, you would only hear your agency, Sudbury, which has the 443 NAC. If, instead, they were using DMR or NXDN, you would choose that, then enter the color code (DMR) or either the RAN or Area for NXDN transmissions.

This is how that should look in Sentinel:


That screenshot is from when I appended Middlesex County to a dummy Favorites list (dummy meaning a list I that I only use to illustrate something, not one that I would use in my scanners).

When you are hearing "just static", either your squelch is set too low, or perhaps that is a time that the PD is using encryption. Normally, the SDS200, as well as other Uniden scanners, does not stop on encrypted signals, other than very briefly, then it moves on. Occasionally, there is something in the encrypted transmissions that the scanner does not recognize as indicating encryption, or that indication may not have been received clearly by the scanner.

 

[BOBRR]

Hi,
What a terrific Forum, and members. Thanks so much.

Followup:

I guess part of my not understanding is that I thought P25 was a "trunked" system, and
required a CC, had various "talk groups," etc.

Not true. Right ?

BTW: is there a RR Wiki, or somewhere, that describes and summarizesall of these modes;
what they are, how to set up, etc. ?

So,
I checked Sentinel, and all the Audio settings are as suggested.
So, perhaps it is that our PD has gone much more to all encrypted ?
No static or any noise; total silence when tuned to it.
But, still have the feeling that I may be missing something.

Went to the Scanner menu to verify that Sentinel loaded everything
into it correctly, and have:

Police Department/Set Audio Type
Digital Only

Digital Only/Set P25 NAC

Input P25 NAC
443 (HEX)

**There is a left going arrow, a right going arrow, and a "to scan" at the bottom of the display.
Anything I need to do here ?

Anything else in the Scanner to check ?
Or, can i assume everything is loaded into the scanner correctly ?

Thanks again for all the help. Sure is a lot to know.
But, it does keep my elderly brain very exercised, which I'm told is good.

Best regards,
Bob


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[RandyKuff]

Hi,
What a terrific Forum, and members. Thanks so much.

Followup:

I guess part of my not understanding is that I thought P25 was a "trunked" system, and
required a CC, had various "talk groups," etc.

Not true. Right ?



................................................................................................................................................................................................................................................................................................................................................................................................................................. ,...................................................................................................................................................≥

P25 are trunked systems... But...
Some conventional channels do use the P25 digital voice encoding for transmissions...
My local police are that way...
Meaning they transmit the same way they used to, but use a digital encoding...
So you would not hear them on an analog scanner like you used to...

 

[IAmSixNine]

To add to what @RandyKuff said P25 is a protocol used for 2-way communications. Its a digital format set of standards.
So you can have P25 conventional communications. P25 Trunking which comes in Phase 1 and Phase 2.

 

[hiegtx]

Input P25 NAC
443 (HEX)

**There is a left going arrow, a right going arrow, and a "to scan" at the bottom of the display.
Anything I need to do here ?

Anything else in the Scanner to check ?
Or, can i assume everything is loaded into the scanner correctly ?

Thanks again for all the help. Sure is a lot to know.
But, it does keep my elderly brain very exercised, which I'm told is good.

Best regards,
Bob

Bob, it sounds like you were looking at the scanner's menu, where you can edit the frequency. More specifically, at the screen where you can enter, or edit, a NAC for a conventional channel that uses P25 (digital) transmissions.

Does this look like the screen you are asking about?

That is a screenshot from ProScan on my laptop. My SDS200 is connected to the PC, via ProScan, so that I can log some specific systems. What you would see on your scanner would be almost identical to this.

The Input P25 NAC at the top of the screen shows that you are at the point, in the menu, where you can verify, change, or enter a NAC for a specific frequency. For this example, on a system in my area, the correct NAC is 128.

In Sentinel, when you program a frequency as using Digital audio, one of the things you can enter is the NAC. In the software, you can click on that field and that will drop down a list of all the possible NAC settings.

On the scanner, you do not have a drop-down to work with. You have to enter each character separately. Notice that in the screenshot, the cursor is on the 1. If I wanted to change that, I would use the scroll knob to cycle through a list of potential figures to use. One I find it, then I would use the Right arrow to move the cursor to the next (middle) item. Again, scroll the know to find it, then once the correct one os shown, again use the right arrow to move to the third figure. Scroll as needed to pick what you need. The Left arrow would be used if you needed to back up to one of the other ones and make a change. Note that since a NAC can have be al numbers, or two numbers and a letter, you use the scroll to set it, figure by figure, If it were all numbers (which it is not), then you could have simply entered the NAC via the keypad, just like you enter a frequency.

Once I had the NAC correctly set, then I can either hit the Enter key, to get back to the Edit menu choices, or use the to Scan, in the middle, to get back to scanning the systems programmed instead of having to back out of that screen, layer by layer, back through the Edit menus, and continuing backwards until I get out of the menu altogether and resume scanning.

 

[BOBRR]

Hi,

Thanks for explanations.
Very clear, as usual.
Really helps.

Regards, and thanks again,
Bob