PSR-500: Programming a UHF P-25 system

[wwhitby]

I've got two UHF military 3600 P-25 systems nearby. For the TSYS object, i've tried programming them as both P-25 manual and VHF/UHF. On both, I set the base, step size and offset frequency, although I didn't set the table size. I'm not getting any traffic on both of those system, although my PRO-96 is showing them to be active. Analyzing the control channel shows them both to be about 95% or better.

Which would be the correct mode: P-25 manual or VHF/UHF? Also, do you think I need to set the tables, or would the base, offset, and step size be enough?

Thanks,

Warren

 

[LEH]

Warren,

I had the same problem. The correct setting (at least for Langley AFB) is Mot VHF/UHF.

Then when you get to the custom table, you will need to enter the high and low channel value. Many of the table's in the data base don't have these values.

For Langley, with a base of 406.000, step of 12.5 and offset of 380; the low and high are 380 and 759.

If you leave those empty, the system won't work. Been there done that already.

 

[Stick0413]

I was going to ask this question but found the answer. Thanks LEH. I guess the low and high needs to be added in the Eastern Virginia Regional Communications system. I will submit the info now (as others should do with the systems they are having problems with).

 

[wwhitby]

Thanks LEH. I'll have to figure out what the low and high values are.

Do you have any hints on how to do that? This is new territory for me...

Warren

 

[LEH]

First, Stick0413, the Eastern Va system (which includes Norfolk Naval) is 380 and 759 (same as Langley).

Warren, someone may be able to answer this better than me. I am making a WAG here.

From the systems I have seen, the low value is the offset value. For the Langley and Eastern VA, the high is the lo value times two minus 1

hi=((lo X 2) - 1)

I won't promise that will work in all cases.

Like the VA STARS the first lo value is the offset, the high is the lo plus 4096 minus 1 (basically the difference between the lo of the one table and the high of the previous is 4096). At least with the STARS, all the table values are provided.

The 4096 doesn't seem to work for values less than that (4096). Just noticed that 8192 is double the 4096. So this may hold for larger channel numbers (above 4096).

Hey for someone who knows nothing about this, I sure have said alot. Maybe Mickey60 can explain. He's the one who gave me the answer for the Langley system and I"ve embellished from there.

 

[Stick0413]

First, Stick0413, the Eastern Va system (which includes Norfolk Naval) is 380 and 759 (same as Langley).

Warren, someone may be able to answer this better than me. I am making a WAG here.

From the systems I have seen, the low value is the offset value. For the Langley and Eastern VA, the high is the lo value times two minus 1

hi=((lo X 2) - 1)

I won't promise that will work in all cases.

Like the VA STARS the first lo value is the offset, the high is the lo plus 4096 minus 1 (basically the difference between the lo of the one table and the high of the previous is 4096). At least with the STARS, all the table values are provided.

The 4096 doesn't seem to work for values less than that (4096). Just noticed that 8192 is double the 4096. So this may hold for larger channel numbers (above 4096).

Hey for someone who knows nothing about this, I sure have said alot. Maybe Mickey60 can explain. He's the one who gave me the answer for the Langley system and I"ve embellished from there.

Yeah the Eastern Virginia definantly works with this ch low and high. I submited the info to add the info to the custom table on that system.

 

[wwhitby]

LEH, I tried your lo and hi numbers, and they worked for me. I'll have to start researching how you create tables.

Thanks again!

Warren

 

[kikito]

Thanks LEH. I'll have to figure out what the low and high values are.

Do you have any hints on how to do that? This is new territory for me...

Warren

As a rule of thumb, all systems that only have 1 Table, the Low and High values will always be the same: 380 and 759.

For those with multiple tables, you can take the second Offset listed on the database and substract 1 and that will be your High number on the first Table you set. Then the High for the second Table or the last Table if there's more, will be always be the max default of 759.

Using this system as an example: http://www.radioreference.com/modules.php?name=RR&sid=861

The Low/High settings for it would be:

#1 380 - 578
#2 579 - 631
#3 632 - 759

 

[LEH]

kikito,

That works for me. Had I seen that table, I might have figured it out on my own.

The only issue I have here is when you look at the VA STARS tables, the offsets start at 8192.

Now I'll agree that the lo channel value for each system is the offset value and the hi channel value for any previous table (not the first) is one less than the offset of the subsequent channel.

Something like this.

offset lo chan hi chan
table 1 x x x+y
table 2 (x+y)+1 (x+y)+1 (x+y+z)
table 3 (x+y+z)+1 (x+y+z)+1 ....

I hate HTML where spaces are truncated. AHHHHH. This lined up so pretty when I typed it.

If you have the offsets for a multi table, you can figure the lo and high channels. The 4096 value seems to hold true for the STARS table. That is the difference between each of the lo channel values.

 

[n4jri]

It might be good to mention here that actual P25 trunks are not 3600 Baud. If your system is on 3600, you definitely want to make your TSYS a Mot VHF/UHF.

What threw me at first is the need to have an upper value in the table.

If it's really an APCO-25 system, it'll be 9600 baud and the radio will program its own trunking tables from control channel data.

73/Allen (N4JRI)

 

[kikito]

The only issue I have here is when you look at the VA STARS tables, the offsets start at 8192.

Yeah, the instructions I posted earlier were for the older 3600 baud systems.

But for P25 systems, those values are also "fixed" and easy to figure out once you have the channel numbers used on the system as they show up on the Pro96Com program.

There's 16 possible Tables, each with a block of 4096 slots and you'll have to include the values or Offset numbers in your scanner settings for any and all slots that each channel is using on the system. Of course, all of this is only needed for the Pro-96/2096 series due to the "built-in bug".

Just curious, you're not trying to use those kind of values with your new PSR-500 are you?

 

[dc2wheel]

Has anyone tried The PSR-500 on Washington DC Metropolitan Police UHF P25 system yet? I'm curious how it will handle this system's odd multiple base/offset characteristics, though I understand this is a similar issue to the STARS system.

 

[stephend]

PSR-500 Frequency Steps

Can anyone tell me how to change the frequency steps. I'm trying to enter frequencies for a P25 VHF system for Sioux Falls, SD (Site 05). Trying to enter frequency 157.4125. It changes to 157.4250. Thanks

 

[scansomd]

AH HA!! That is probably why I can't scan the NAS PAX River system.
http://www.radioreference.com/modules.php?name=RR&sid=419
Can you clue me in on the low and high values for the above system?

Warren,

I had the same problem. The correct setting (at least for Langley AFB) is Mot VHF/UHF.

Then when you get to the custom table, you will need to enter the high and low channel value. Many of the table's in the data base don't have these values.

For Langley, with a base of 406.000, step of 12.5 and offset of 380; the low and high are 380 and 759.

If you leave those empty, the system won't work. Been there done that already.

 

[LEH]

scansomd,

Try the values I listed, 380 and 759. From what has been posted elsewhere here, these are the default values for a Motorla system.

If this works, don't forget to submit a change to the RR DB so others know what the settings are.

 

[fmon]

scansomd,

Lynn is correct on your lo hi and offset settings, use your base freq and step 25.0.

stephend,

Welcome to forum,

The system is Motorola VHF not P25 so set the scanner to MOT VHF/UHF.
Next set these three tables:

	1	        2	        3
Base:	155.4150 	157.2000 	157.4700 
Spacing:15.0 	        12.5 	        15.0 
Offset:	380 	        436 	        454

Table 1
Ch lo - 380 Ch hi - 435 Base - 155.4150 Offset - 380 Step - 15.0
Tab;e 2
Ch lo - 436 Ch hi - 453 Base - 157.2000 Offset - 436 Step - 12.5
Table 3
Ch lo - 454 Ch hi - 759 Base - 157.4700 Offset - 454 Step - 15.0

Save this, then enter your CC's and disregard if they change step slightly.

 

[fmon]

Gosh, I missed your post DC2,

Program similar to the Sioux Falls above, only you have two tables. STARS is P25 yours is Motorola UHF, so should work better then STARS.

 

[kikito]

Can anyone tell me how to change the frequency steps. I'm trying to enter frequencies for a P25 VHF system for Sioux Falls, SD (Site 05). Trying to enter frequency 157.4125. It changes to 157.4250. Thanks

You can change that by turning on FlexStep. It's on the Expert Global menu (PGM, FUNC + F3) and it's about 18 options down the list. That should allow you to enter those frequencies correctly, just like in our system (ALMR) that also uses "odd" stepping.

I have noticed though that some of the frequencies displayed with Flexstep on, don't seem to come in as clear as the "native" step the PSR-500 tunes by default, so experiment with that and let us know if that happens in your area and system.