Lscott

The oscillator in the repeater also could be off frequency a bit too. I have heard of some repeaters where they use an OCXO, Oven Controlled Crystal Oscillator, for very high frequency accuracy. I think the cheap SDR dongles use a simple TCXO, Temperature Compensated Crystal Oscillator, module. The usual specifications for those are +/- 0.5 PPM, Parts Per Million, frequency accuracy more or less. Usually portable or battery operated equipment use the TCXO module since the power requirements are way to much due to the electrically heated oven on an OCXO module. Understanding Ovenized Oscillators.pdf

Good point. I think once the correct frequency is nailed down looking it up in the FCC's database would yield results.

This is turning out to be a bit of a real mystery. I wondering now if the owner even licensed the frequency, and not just stuck up their repeater and said screw the FCC. I'm getting the feeling there is a lot of crap out there on the air that isn't properly licensed and the FCC just ignores it until somebody complains. That's not how it's supposed to work.

A good resource to track down digital licenses in the FCC's database is here: https://digitalfrequencysearch.com/index.php If it's a trunking system on a water tower I'm going to guess it's owned and operated by a company that rents out capacity on their system to various users who don't want to put up their own repeater and or don't have the expertise to do so. A small company, with a single location, with their own repeater would typically be located on site if they have one. Given the frequencies and location I''m certain it had to go through an FCC frequency coordinator and should be in their database. They would need to make sure the antenna height, power level and antenna gain won't interfere with other users in the coverage area. And in this case it seems like that area is going to be rather large too. One company would be Deltacom. https://wireless2.fcc.gov/UlsApp/UlsSearch/licenseFreqSum.jsp?licKey=1925372&pageNumToReturn=2 https://wireless2.fcc.gov/UlsApp/UlsSearch/licenseLocSum.jsp?licKey=1925372 The closest to your frequency of 462.5325 is 462.5375. Given the tolerance of the oscillator in the SDR dongle this could be it. It's off by only 5.0KHz. https://wireless2.fcc.gov/UlsApp/UlsSearch/licenseFreqSum.jsp?licKey=2926515&pageNumToReturn=2 https://wireless2.fcc.gov/UlsApp/UlsSearch/licenseLocSum.jsp?licKey=2926515 Here's another company. This one is sort of odd. They are licensed state wide with a frequency range. No channel frequencies listed. https://wireless2.fcc.gov/UlsApp/UlsSearch/license.jsp?licKey=3770395

I see that "RAS" is showing up. I believe that's a Motorola specific feature to validate a radio on a trunking system. This might explain why you're having problems getting audio and multiple frequencies. If it's a trunking system there might be even more frequencies in use you haven't found yet. https://cwh050.mywikis.wiki/wiki/Restricted_Access_to_System

Do you have a firm read on the frequency? Also any idea about what color code, slot number and talk group is being used. If I get some time I've got my NX-1300DUK5 with me at the office today. I could add the above to the code plug and monitor it. Being at 14 mile and John-R I shouldn't have much of a problem receiving it.

Weather sucks today. I don't imagine you're going out to do any DF'ing.

I've done some technical writing for the company I work at, Power Point slide shows for training/sales, test procedures and manuals, but it's not my primary job. People think it's easy. Nope! It's boring mind numbing work and requires a lot of attention to details. People who do it full time professionally really earn their money. Doing design calculations, simulations and circuit design is much more fun, and it keeps the mind sharp too.

Yeah, programming a DMR radio is a PIA. Then again NXDN and P25 isn’t much different. I’ve done all three of the above.

Maybe. They still have to operate under US rules. Plus they need to communicate with other railroads, yards etc. That's likely going to be on VHF. Railroad - Scanner Frequencies and Radio Frequency Reference.pdf

I would not suspect the railroad. They would either be FM, or they were moving to NXDN, but that's on VHF, not UHF.

I did some checking on AAM and there is only one possible. It's an expired license and the plant is located in Three Rivers. That's a long way away. https://wireless2.fcc.gov/UlsApp/UlsSearch/licenseFreqSum.jsp?licKey=1905276 The frequency listed is 462.3125. Hum, if some radio tech miss typed the frequency entry he could have hit 462.53125, added in the extra "5" after the decimal point. Somebody could be using an unlicensed frequency, never licensed, or continues to use one on a long expired license. It happens. The FCC seems really lax in cracking down on this crap. For example the ding-dongs at the Lakeside Mall, house keeping, are doing it. They are on the same frequency as the Troy GMRS repeater but a different PL tone. Their license expired in 2015, never renewed from what I can see in the FCC database, and they still use the frequency!!! Geez!!?? Oh, if you want to "test" their, illegally operating, GMRS repeater out its 462.575MHz/467.575MHz with a PL of 186.2Hz. You can key it up about 4 to 5 miles away with an HT easy enough. Anyway you narrow the search down and locate the likely source of interference keep us informed! ULS_License - Expired Mall FCC Licenses.pdf ULS License - General Mobile Radio (GMRS) License - KAB1523 - LAKESIDE GENERAL GROWTH PROPERTIES - Administration.pdf

Gives me another frequency to look up.

Yeah, their plant is on 14 mile right next to the railroad overpass. I've been by it enough times.

I did some more searching on another site. Assuming the frequency is really 462.5125 I found the following: 462.5125 DMR MO 4 ROCK SECURITY & EVENTS INC. WRAK353 PONTIAC IG SECURITY COMPANY: RADIOS WILL BE USED FOR COMMUNICATION BETWEEN EMPLOYEES 462.5125 DMR MO 4 United Parcel Service, Inc. WPMR963 MADISON HEIGHTS IG APPLICANT IS A DELIVERY SERVICE. THE RADIOS WILL BE USED TO COORDINATE THE ESSENTIAL ACTIVITIES OF THE BUSINESS. 462.5125 DMR MO 5 X-Cel Industries, Inc. WQTT460 Southfield IG Radios used to coordinate activities around a coating facility.

In my experience it's also somewhat buggy too. Maybe by now they have more of the crappy bugs fixed. Also the firmware in the radio had some annoying quirks too. The feature I find most useful is the DMR monitoring mode in the radio. I wish my commercial radios had this, but that wasn't necessary since the market for them ends up with the radios pretty much programmed up once and that's the end of it.

Cool. Like to know what you find.

You can try removing the antenna on the radio. That's a cheap kind of signal attenuater. Do that when the signal gets real strong with the antenna connected. When you get close enough to the source the radio should respond even without the antenna connected. One other trick is flip the radio over so the antenna is horizontal. The source antenna is likely vertical and the cross polarization results in may cases another 20db attenuation. Then rotate in a circle. When the signal is minimum either the end of the antenna is point nearly towards the source or directly away from it. Try that in several locations and that can help pin down the area.

I wondered the same thing. I wouldn't be surprised if radios got swapped around between plants.

What if they don't drive?

Flex-N-Gate is licensed for 462.5125MHz per FCC database. Emission is narrow band FM. Plant location in database is BATTLE CREEK, MI CALHOUN County. https://wireless2.fcc.gov/UlsApp/UlsSearch/licenseFreqSum.jsp?licKey=3494581 I wonder if somebody was miss programming radios for DMR and they ended up at the R.O. location.

I see several company's in that area: Flex-N-Gate (large comlex) Thierry Corp Dixon and Ryan Corp United Resin Corp ArborOakland Group Bowlero Lanes and Lounge (almost on the NW corner)

I would be interested in knowing what you find out. My work office is by 14 Mile and John-R. That's only about a half dozen miles or so from where you're looking.

To get back on track for the thread's topic there is a series of posts on radioreference.com on this exact topic. A few helpful posts shows how to look up Part 95A radios the FCC has certified. I would also imagine changing to Part 95E would also find newly certified radios as well. https://forums.radioreference.com/threads/part-95-gmrs-radio-list.275040/#post-2046099 Then the same person posted an updated procedure: ------------------------------------------------------------------------------------------------------- TThis may be slightly better than what I posted back in 2013. FCC OET Authorization Search Under Application Information: Application Status: select All Granted Statuses Under Equipment Information: Frequency Range in MHz: select 462.55 to 467.725 and uncheck Exact Match Rule Parts (up to three): select 95 and uncheck Exact Match Under Formatting Options: Show results in You can select HTML to view it on the web site or select Microsoft Excel or XML to generate a spread sheet. I just tried the Microsoft Excel format and it generates a file that your browser will want to download. I don't know how that works on a smart phone or Windows. On a Linux PC with Firefox it opens a download dialog box. If you use part 95 instead of part 95A the results could be different. It might include FRS radios too. 95A should include only GMRS radios but some of them (and FRS and CB and MURS) might have only 95 without the letter. I need to check that. Specifying the frequency range 462.55 to 467.725 should exclude MURS, CB, RC and other PRS devices. Today that returned 3969 lines. Some radios have multiple grants or permissive changes so the actual number of devices is way less.

Yes that could also work. Excellent suggestion.