35.700 mhz p25 ????

Status
Not open for further replies.

2sudsy

Member
Joined
Dec 20, 2004
Messages
28
Location
Detroit, MI
Here in the Grosse Pointe area I have been monitoring the lo VHF bands for the last few weeks now. I came across what sounds like a law enforcement agency on 35.700 mhz. They are using p25 and it sounds like it is part of a trunked system. Most of the activity on this frequency seems to escalate during the night time hours. I hear plate numbers being run to a dispatcher from patrol unites? I've heard unit numbers of the 40 to 50 range.Two weeks ago, again during the late hours of night, I heard a what sounded like a pursuit going West bound on Jefferson and terminating in some Detroit neighborhood near by my home QTH. I made a FCC database search and I came up with nothing. Am I looking in the wrong place?
Rich KB8TVB
 

Thunderknight

Member
Premium Subscriber
Joined
Jan 31, 2008
Messages
1,957
Location
Bletchley Park
There are 143 licenses on 35.700 in the whole country, some expired. They are all in the business/industrial pool.

Since I'm not aware of any company making lowband P25 equipment, I'm thinking you are hearing an image or intermod product. I suppose there is a slight chance it's part of a link, but I think that's unlikely. There are only 4 licenses in Michigan, non to a governmental entity.
 

2sudsy

Member
Joined
Dec 20, 2004
Messages
28
Location
Detroit, MI
Thanks for your help thunderknight and insight. I not positively sure if what I'm hearing is a image because, assuming that the law enforcement agency in queston is on 800 mhz : 35.7 x 25 = 892.5 or 35.7 x 24 =856.8 from that, unless theres a MAJOR problem, I think it's highly unlikely.
I'll do some more monitoring and resource on. Thanks for your help.
Rich KB8TVB
 

SCPD

QRT
Joined
Feb 24, 2001
Messages
0
Location
Virginia
Thanks for your help thunderknight and insight. I not positively sure if what I'm hearing is a image because, assuming that the law enforcement agency in queston is on 800 mhz : 35.7 x 25 = 892.5 or 35.7 x 24 =856.8 from that, unless theres a MAJOR problem, I think it's highly unlikely.
I'll do some more monitoring and resource on. Thanks for your help.
Rich KB8TVB
856.8 IS a trunked frequency often used by police. I can't figure out who it is near you though. Do some more math, it could be conventional digital, similar to LAPD's system. You're definately getting an image though, nobody uses low band VHF any more.
 
Last edited:

2sudsy

Member
Joined
Dec 20, 2004
Messages
28
Location
Detroit, MI
Thanks flintstone 4680 for the info about 856.8 mhz. the only station that comes close to that frequency on the radio reference data base is a simulcast in Kalamazoo and at my QTH that is way out of range even for 800 mhz. I also compared the mystery signal on two scanners just to be sure that there isn't any internal images on my main scanner. At this point I am receiving it on other scanners. Tomorrow I'll ride around my neighborhood to see what the range of this signal.

Thanks again
Rich KB8TVB

P.S. RF is a strange animal and it can to weird things.
 

RayAir

Member
Joined
Dec 31, 2005
Messages
1,799
Here in the Grosse Pointe area I have been monitoring the lo VHF bands for the last few weeks now. I came across what sounds like a law enforcement agency on 35.700 mhz. They are using p25 and it sounds like it is part of a trunked system. Most of the activity on this frequency seems to escalate during the night time hours. I hear plate numbers being run to a dispatcher from patrol unites? I've heard unit numbers of the 40 to 50 range.Two weeks ago, again during the late hours of night, I heard a what sounded like a pursuit going West bound on Jefferson and terminating in some Detroit neighborhood near by my home QTH. I made a FCC database search and I came up with nothing. Am I looking in the wrong place?
Rich KB8TVB
35.700 was designated as "IB" (business) and back in the day Adler's Towing in Pontiac, MI used to use this frequency. I saw one of their tow trucks on the road about a year or two ago and it didn't have a low band antenna so I'm guessing they aren't using it anymore. It would be highly unlikely for you to find public safety using this frequency.

I did hear of a PD in Macomb County using their old low band radios that they still had around for surveillance. Since someone discovered it I'm sure they don't do it anymore.
 

k2epm

Member
Premium Subscriber
Joined
Aug 13, 2003
Messages
49
Location
Long Island, NY
Funny...I was just wondering if anyone uses 35.700 anymore. I realize "low band" has been out of favor for 25 years or so, but what happens to those frequencies when companies / agencies migrate to 800MHz?

Back in the 1970's & 80's my family had an auto repair shop in the Queens section of NYC and we were licensec on 35.700 for our tow trucks to base...it was a simplex system...we had a pretty big tower at the base Our company was Muro's Collision but I think Scuffy's Auto Body also in Queens and Woodmere Taxi out in Nassau County were also on the same frequency.
 

ks4ui

Member
Joined
Sep 15, 2007
Messages
77
Location
Phoenix AZ
IB channels are used by private detectives, these guys are slick and might be operating onauthorized or unauthorized low band radios. Feds have used IB channels when they knew their channels were being monitored. How is it you found them? Suggest you keep on monitoring 35.7 for us.
 

ks4ui

Member
Joined
Sep 15, 2007
Messages
77
Location
Phoenix AZ
I realize the topic is 3 years old but it is still an unusual an interesting one, the use of a VHF lo band channel in the Detroit MI metropolitan area is certainly a little unusual. For the most part, lo band radio assignments were abandoned much more than 3 years ago. The majority of those users actually jumped to VHF hi in the 60s amd 70s.. However the facts that I pointed out are not old and could be interesting for those that like to dial twiddle. Additionally, almost all of the traditional fed agencies have multiple VHF lo band assignments, the FCC data base will not reflect those because the feds receive their authorization from NTIA. Hint, there is low band law enforcement activity in that neck of the woods, have fun.
 

k2epm

Member
Premium Subscriber
Joined
Aug 13, 2003
Messages
49
Location
Long Island, NY
What's the frequency Kenneth

I just googled 35.700 and this thread came up, funny I already commented on it several years ago.

What is being done with low band IB spectrum these days?
 

Darkstar350

Member
Joined
May 19, 2014
Messages
409
Location
Nassau County
Not to "necro post" but i actually happen to have this frequency in one of my radios
I dont think i have got any activity on it recently however i do recall perhaps 2 -3 yrs ago getting P25 on a low band freq
I dont remember the exact frequency but it very well could have been this one
If i remember correctly it was either encrypted or just a low power/ bad decode but i was very curious afterwards so i looked into the subject of P25 on low band and most likely it would be military/govt because they do actually use low band at times(most of the time on analog but anythings possible...)
Either that or i suppose it could be Hams messing around with P25 on low band...
 
Status
Not open for further replies.
Top