Franklin Twp. Trunk - BAD NEWS

[nosoup4u]

btw, 608 does seem to track also. There's no activity at the moment so I don't know if its going to track or not, but like I said before, 520 was tracking fine.

 

[RocketNJ]

Are you referringto Edison's system using 520? If so, did you receive any calls on 472.450? Since that channel would be chan 576 you should not be hearing it. For Somerset/Franklin and Morris 520 is the correct offset for the second table entry.

btw, 608 does seem to track also. There's no activity at the moment so I don't know if its going to track or not, but like I said before, 520 was tracking fine.

 

[rickey456]

I caught some radio tech's on the Franklin & Somerset system just a while ago. I still had the 2ndary config set to 520 and it was tracking the talkgroups fine. 1 tech was on the somerset system, talking to the other tech on the franklin system on t/g 1616 in analog mode. Later on, I was catching clear digital on 40016.

I'm looking at the Trunker readout from this afternoon and there are a number of transmissions to 1616 and 40016. All of these are from units numbered 50001,50003,50004. These could be the radio techs.

At the same time the system is telling me that Cell #1 using/may be using:
f=0x1bb f=0x1d8 f=0x1e2 f=0x2bb f=0x2bf

In response to a message I posted on the trunker group here is a response I received:

This is a smartzone type system. Each "cell" transmits information about neighboring cells. Those hex values are control channels values or alternate control channel values of cell 1.

So you need to calculate the frequency from the hex values like
you did for the frequencies in cell 2. You may even be able to receive cell 1 directly after you find out the frequencies.

 

[nosoup4u]

Disregard my post about the offset, I had misread the post.

Have you tried tracking the somerset system yet? I'm curious what the Base/offset on that system is.

 

[rickey456]

I tried to fnd a signal on the Somerset Co. frequencies last night from home with no luck. I can't track it from here. The only time I had a positive response was a while back when I drove over to Franklin Twp and go a weak control channel on one of the frequencies. May have to go mobile one of these days and get a reading on the system.

 

[nosoup4u]

The control channel has been on 502.6125. Once you get about 10 miles out of Somerville, the signal degrades fairly rapidly. I went from nearly full bars to nothing in the course of a few minutes traveling north on 287 (I had totally lost the signal by the time I hit exit 26).

 

[rickey456]

John

I just put one of my Yupis on the frequency and am receiving a weak signal. Started at 17% and it's now up to 27 as I move around looking for a strong spot. Decoding one voice channel- alomst but no other info - id, etc. I'll play with it a bit more tonight after work.


Up to 47% but still no decode on the sysid. The one voice channel shown seems to be blinking on and off. Can you hear the system from were you are now?

 

[nosoup4u]

I'll run out and bring in my scanner from the car in a bit. I don't think its going to come in though because of all the RF around here. I'm lucky enough to sit about 15 from the server room. I'll let you know.

 

[rickey456]

Let me know what you get. I'll be here for another 10-15 minutes or so and then back about 6:30. I'm getting a 99.6% signal on 502.6125 but I can't get it to decode the sysid or other frequencies. There is only one frequency listed and it's active- blinking on every 1.5 seconds or so. Any suggestions before I leave. Is this the only CC? This freq. is not listed in the database here.

 

[nosoup4u]

I can actually pick it up pretty clearly here. These are the freq.'s that they are licensed for, however some are currently still being used as conventional freq.'s:

471.1625 471.1875 472.3875 472.4125 500.3375 500.6125 500.8875 501.9125 502.5125 502.5375 502.5625 502.6125 502.6875 502.8375

 

[rickey456]

Running late. Will add these freqs to trunker and will see what happens. Will you be around tonight? cu later

 

[nosoup4u]

Sure, I'll be around after 8pm. I'll keep an eye on things for now. Thanks for you help.

 

[W2SJW]

I get 502.6125 at 99% here in Branchburg. I don't have Trunker, and I'd like to know what's needed to interface it with my 96.

 

[rickey456]

Scott

When I left the house this am Trunker was running at 96-97% but it was not decoding the sysid. There was one TG registering and no frequencies showing. Will check it when I get hope. Also going to fire up a second laptop and will run the beta vhf/uhf program on the system. Stay in touch if you're around later tonight.

 

[nosoup4u]

The control channel is off the air now. I'm hoping that they didn't shut it down for the weekend.

 

[rickey456]

just got home and see that the system was turned off. Going thru all of the freqs. you posted earlier looking for another CC. No luck so far

 

[rickey456]

Before the system turned off Trunker was able to collect the following:

sysid 8a27 [1]
CT: 90
Moto Type II Smartnet


I had no frequencies in Trunker but the program read out:

v 0x127
v 0x293

it didn't give me a hex readout for the data channel

 

[rickey456]

Still not on as of 9am this am - no activity on any of the listed frequencies. Maybe the techs got snowed out . Will keep the set on and will see what if anything gets captured during the day

 

[robbinsj2]

Quoting RocketNJ from his post on 1/22/04 12:47 AM:

Here's the original Trunker info for Franklin you posted.
c v 471.8250 1be 42 5a1
v 471.9750 1ca 4e 483
av 472.3250 1e6 6a 394
dv 472.3500 1e8 6c 442
av 472.9000 214 98 376
d 477.4000 278 ffff 0

(snip by robbinsj2)

Now for the second set. Since the other frequency you have listed is 477.400 with hex chan 278, decimal is 632. Doing the math you can see it wouldn't work out with the 471.000/380/12.5 kHz range. It is common for UHF T band and 500 MHz systems to have two sets of base/offset/step. Knowing that Morris County is set for 476.000/520/12.5 kHz for the second range I tested that using the 477.400 freq.

So 632 - 520 = 112. 112 x 0.0125 MHz = 1.4 MHz. 477.400 - 1.400 MHz = 476.000.

If you did not know the second base/offset/step then you would need to know at least two frequencies in the second freq range (476 - 478) in order to calculate it out.
(snip by robbinsj2)

Resurrecting this old thread because I think the second base/offset may be slightly off. 472.9 is hex_214, which is dec_532. Now that frequency should obviously work off the first base/offset pair (proof: it is 44 steps removed from hex_1e8 (dec_488); 472.9-472.35= .55 MHz, .55 MHz / 44 = 12.5 kHz).

But if the second offset is set at 520, wouldn't radios treat dec_532 (hex_214, 472.9 MHz) as being subject to the second pair? Doesn't the upper limit of the first offset have to be 532 or higher, and hence the second offset be 533 or higher?

Once the above is complied with, I think the exact second base, offset, and step are all somewhat academic because only one frequency is calculated from them. Pick any offset >= 533 and back out the base using the channel value. There shouldn't be any problems unless Franklin adds another frequency that works off the same settings as 477.4, at which time there should be enough information to calculate the true base, offset, and step.

I propose the second base/offset could function just fine as Base=476.25 MHz, Offset=540, Step=12.5 kHz. What do the real experts think; is 476.000/520/12.5 okay after all?

I'll reprogram my BC780 and try to tell if it works; most traffic is going out over 471.975 and the CC is currently 477.4, so it may take a while. Unfortunately I can't do a side-by-side comparison with one scanner "before" and one scanner "after" the above.

Jim

 

[robbinsj2]

Whoops, my question was answered back on 1/22/04 at 12:46 PM, in a discussion in this thread on Edison's system:

(snip by robbinsj2)
Since we know that the frequency in question is 478.7125 MHz and it's channel ID is 339H or 825 Dec (you were off by 1), let's assume step is 12.5 kHz since the channel is not divisible by 25 kHz, and the base for the second group is 476.000 MHz (the beginning of the second range of infrastructure tx range in T Band (the 470 T band tx goes from 470.000 to 472.9875 and 476.000 to 478.9875). So with assuming base of 476.000 and step of 12.5 kHz you can calculate out an offset of 608.

Notice we cannot use 520 as in Franklin or Morris? 472.450 MHz which is one of Edison's channels is channel 576 Dec, or 240 Hex. Check my math with Trunker. Since 576 Dec is higher than 520 you can see the system cannot use 520 as the second offset.

The key is the second offset cannot be lower than the channel number of the highest freq in the lower frequency range. In your example of using 520 for the second offset the scanner would not receive 472.450 MHz freq since it would not map out to a channel.

(snip by robbinsj2)

So after all that, the question is ... what do we want to correct the database's base/step/offset to? I'm not confident enough in my math to submit the numbers I list in the previous post.

Jim