Las Vegas P25 Repeater output 170.100MHz.

[mangomike]

About three weeks ago I intercepted a new P25 Federal Gov't repeater output, 170.100MHz, NAC 300.
The majority of the traffic intercepted was P25 clear with radio unit identifiers; Gulf 1443, Alpha 1419,
Booking Desk, which also answers to 1400.

I'm assuming the agency using this frequency is CBP. Intercepted traffic also makes references to flights, and number of people to transport. P25/AES-encrypted usage was also detected. All radio units use seven digit P25 ID's with a prefix of 628XXXX. What really surprised me was the repeater input frequency, 169.9125MHz. but each and every time the hit frequency and NAC was the same. I did triple check that this was the correct input frequency, several times over the last three weeks. Also I noticed regular activity, usually on Wednesday afternoons from 12:30 through 2PM. I'm presently in the process of checking Las Vegas Mc Carren Airport flight schedules for direct intentional flights which may correlate with traffic times intercepted.

Channel Designation

TBD

Agency;

CBP?

Repeater-Output Freq.

170.100 MHz.

Repeater-Input Freq.

169.9125 MHz.

P25

NAC 300

P25 Radio ID Prefix

628XXXX


73's

Mike

 

[ecps92]

Little close for the in/out seperation...but not out of the question.

Maybe multiple Repeaters with a common input?

170.1000 has been seen with multiple users.
CBP, NPS, USF&W

169.9125 has been seen with mostly DHS Entities
ICE, DoA

Hope this helps.

About three weeks ago I intercepted a new P25 Federal Gov't repeater output, 170.100MHz, NAC 300.
The majority of the traffic intercepted was P25 clear with radio unit identifiers; Gulf 1443, Alpha 1419,
Booking Desk, which also answers to 1400.

I'm assuming the agency using this frequency is CBP. Intercepted traffic also makes references to flights, and number of people to transport. P25/AES-encrypted usage was also detected. All radio units use seven digit P25 ID's with a prefix of 628XXXX. What really surprised me was the repeater input frequency, 169.9125MHz. but each and every time the hit frequency and NAC was the same. I did triple check that this was the correct input frequency, several times over the last three weeks. Also I noticed regular activity, usually on Wednesday afternoons from 12:30 through 2PM. I'm presently in the process of checking Las Vegas Mc Carren Airport flight schedules for direct intentional flights which may correlate with traffic times intercepted.

Channel Designation

TBD

Agency;

CBP?

Repeater-Output Freq.

170.100 MHz.

Repeater-Input Freq.

169.9125 MHz.

P25

NAC 300

P25 Radio ID Prefix

628XXXX


73's

Mike

 

[mangomike]

Thanks for your input, Bill. In my twenty five plus years of monitoring Fedcom activity I have never encountered such a narrow spread between the repeater input frequency, and the repeater output frequency. Obviously things have changed with this new narrow band equipment.

Mike

 

[ecps92]

Not sure it's a NB thing. if does bear more monitoring.

Even Amateur doesn't go below a 600 khz for spread...

Thanks for your input, Bill. In my twenty five plus years of monitoring Fedcom activity I have never encountered such a narrow spread between the repeater input frequency, and the repeater output frequency. Obviously things have changed with this new narrow band equipment.

Mike

 

[W2NJS]

Mike,

Nice, very nice, report. I wish others would include the detail that was in yours.

 

[Gilligan]

One way to verify if it's an input or another output would be to listen to both freqs from outside the airport and check the signal strengths.

 

[WayneH]

Little close for the in/out seperation...but not out of the question.

I just noticed that. 187.5 kHz apart is way too close. I'm willing to believe the two were/are patched.

The best way to confirm if P25 is repeated is listen to it in raw mode and listen to the end of the transmission. A repeater will have a half-second or more (depends on programming but 2 is generally the default) of idle data. When you hear it you'll know what I mean.

 

[mangomike]

W2NJS, thanks for the flowers. Bill, and Wayne, I agree I need to reconfirm that the 169.9125 is indeed the input or a linked repeater.That is why I originally couldn't believe what I was seeing when I ran the search mode, several times on my scanner, while I used a commercial grade radio to monitor the repeater output of 170.100 MHz.

Even though the signal strength bar meter is not that accurate, I have noticed a difference in signal strength between the 170.100 MHz. displaying 5 bars, and 169.9125 MHz. which is displaying between 2 and 3 bars. Today I was performing mundane domestic activity; errands, groceries, etc.Two sierra units operating on 170.100 MHz. were engaged in a surveillance op. At the time I was about a mile away from their location. I was getting 5 bars on signal strength on the 169.9125 freq. An hour later they were in the same area, and I was arriving at the house, which is about 5 miles away, at which time I was getting 1 to 2 bars on the signal strength. So, I'm pretty confused because 187.5 KHz shouldn't cut it as an input frequency. I will take your advice Wayne and report my findings.

73's

Mike

 

[mangomike]

Wayne, as you have advised me, I have been monitoring 170.100 MHz, and 169.9125 MHz. in the raw. The 170.100 MHz. has the two to almost three second continuous buzz noise at the end of the transmission, while the 169.9125 MHz also has the continuous buzz sound, but is slightly shorter, about one second shorter.

Also, for what it is worth I spent a couple of hours at Las Vegas McCarran International Airport, and the 169.9125 MHz signals are full strength, just as the 170.100 Mhz was also full strength. I also dedicated some time to performing frequency searches while at the airport to determine an input frequency for the 170.100 MHz frequency, but no joy. A few hours later I was in North Las Vegas and can easily pick-up the repeater output; 170.100 MHz, but zip, zero, nothing on the other frequency; 169.9125 MHz.

I would sure love to get a second opinion from a Fedcom monitoring "local", but they are far and few in the Las Vegas area.


Mike

I just noticed that. 187.5 kHz apart is way too close. I'm willing to believe the two were/are patched.

The best way to confirm if P25 is repeated is listen to it in raw mode and listen to the end of the transmission. A repeater will have a half-second or more (depends on programming but 2 is generally the default) of idle data. When you hear it you'll know what I mean.

 

[Hooligan]

I would sure love to get a second opinion from a Fedcom monitoring "local", but they are far and few in the Las Vegas area.


Mike

Never fear -- Hooligan is here!

 

[Squad10]

Never fear -- Hooligan is here!

Elvis has entered the building.

OK, what's the mystery input? 164.XXXX

 

[mangomike]

Okay, Mr Hooligan next time you are in town we'll see if you can find or determine what I have not.

Mike

Never fear -- Hooligan is here!

 

[VNR5338]

Mike
Both freqs are repeater out. CBP

 

[SCPD]

Making this situation more interesting or complicated are the three repeaters with an output of 170.1000 in nearby Death Valley National Park. The input to them is 169.5500. Although the Spring Mountains and Mt. Charleston, the highest peak in the range block the line of site for the highest repeater, Rogers Peak, there is another repeater in the northern portion of the park, which might be receivable from Las Vegas. Its signal may be able to bend over the northern portion of the Spring Mountains, the lowest portion of the range.

The traffic you pick up on 170.1000 must be coming from a very low level repeater. It is a mystery as to why the same frequency would be used so close to Death Valley National Park. One thing for sure the unit numbers you have heard do not match Death Valley NP radio traffic, not even close.

 

[mancow]

I wonder if it would be worth monitoring uhf low 403-420 for possible RF links or are they all mainly wireline IP or microwave now days?

 

[ecps92]

Did Death Valley move to P25 or are they still analog? Any Tones?

Making this situation more interesting or complicated are the three repeaters with an output of 170.1000 in nearby Death Valley National Park. The input to them is 169.5500. Although the Spring Mountains and Mt. Charleston, the highest peak in the range block the line of site for the highest repeater, Rogers Peak, there is another repeater in the northern portion of the park, which might be receivable from Las Vegas. Its signal may be able to bend over the northern portion of the Spring Mountains, the lowest portion of the range.

The traffic you pick up on 170.1000 must be coming from a very low level repeater. It is a mystery as to why the same frequency would be used so close to Death Valley National Park. One thing for sure the unit numbers you have heard do not match Death Valley NP radio traffic, not even close.

 

[Squad10]

Making this situation more interesting or complicated are the three repeaters with an output of 170.1000 in nearby Death Valley National Park. The input to them is 169.5500. Although the Spring Mountains and Mt. Charleston, the highest peak in the range block the line of site for the highest repeater, Rogers Peak, there is another repeater in the northern portion of the park, which might be receivable from Las Vegas. Its signal may be able to bend over the northern portion of the Spring Mountains, the lowest portion of the range.

The traffic you pick up on 170.1000 must be coming from a very low level repeater. It is a mystery as to why the same frequency would be used so close to Death Valley National Park. One thing for sure the unit numbers you have heard do not match Death Valley NP radio traffic, not even close.

With input/output spacing getting closer, I would think thought must be given to desense issues.

 

[radioman2001]

If you run separate TX and RX antenna's with pass cans you can almost go to the next channel away. TX/RX makes combiners that handle down to 50kc spacings. We have one on order for just that. Big losses, but it does work.

 

[Squad10]

If you run separate TX and RX antenna's with pass cans you can almost go to the next channel away. TX/RX makes combiners that handle down to 50kc spacings. We have one on order for just that. Big losses, but it does work.

Fixed equipment yes, My reference was close proximity portable/mobiles on the repeater channel. Maybe a good reason to use talkaround or another simplex channel in priority scan mode most of the time.

 

[WayneH]

I wonder if it would be worth monitoring uhf low 403-420 for possible RF links or are they all mainly wireline IP or microwave now days?

The latter.