Need help with Activity Log
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TOPIC: Need help with Activity Log

Need help with Activity Log 20 Sep 2011 20:33 #7586

  • Jay911
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Hi all,

I'm going over some activity logs I did of a P25 system and I can't quite figure out how the "Iden" lines are laid out. The PDF is only marginally helpful, stating that the "Bfrq" value is in decimal.

This line is from a log on a system which I *know* has a base of 150.8 MHz and a step of 5 kHz.

09/14/2011 06:57:01 "34,B4000502002801CC3480445A" Identifier Update for VHF/UHF Bands Iden:0 Bw:5 Tofs:128 Csp:40 Bfrq:30160000

I understand that "Bw" refers to bandwidth, and I presume 5 is kilohertz. I don't understand what the "Tofs" (transmit offset) is - 128 kilohertz, 128 channels? .. it's not a consistent value on this VHF system in any case, so it doesn't make sense. "Csp" is channel spacing, and I presume that's in kilohertz, but I don't know if that value is of any use to me. The base freq is what is getting me all screwed up. Is that 30.160000 MHz? That completely doesn't make sense, and I can't make any calculations that will get me to my 150.8 MHz base value, nor to any valid LCNs/frequencies.

LCNs reported in the activity log are correct - example, LCN 1034 is reported in the activity log, and I was indeed monitoring 155.97 when the activity log was being written. I've confirmed many other LCNs as being correct. And when the HP1 "figures out" a site's base and step, it writes it correctly into the site, as recorded when I downloaded the favorites file back in from the HP1.

So in the end: Someone please let me know how to decipher the values in the activity log for P25 systems. Thanks in advance!

Re:Need help with Activity Log 28 Sep 2011 19:19 #7669

  • Jay911
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I found some more info about this, particularly by doing my own logs/assessments.

It would appear that the "decimal value" for Bfrq, when looking at a P25 VHF system, is exactly one-fifth that of the actual base. That is, 30.16 * 5 = 150.8.

I confirmed that the other day when monitoring another new VHF P25 system with a base of 138.0. The "Bfrq" in the logs was 27600000.

I had a P25 UHF system I was able to monitor briefly which gave three Bfrq values - 80600000, 84000000, and 90802500. If I divided these by 2, it gave the "real" (confirmed by other sources) bases of 403.0, 420.0, and 454.0125.

Still don't know about the "Tofs" values (8592, 880, and 8592 for the UHF system.. 9182, 9188, and 9788 for the VHF system with the 27.6 Bfrq).

I am (hopefully) about to be able to analyze a new 700 MHz system in my local area. Should be interesting to see how it appears.

Paul or someone else - why do the logs come out this way?
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