frequency counter

[ve5wil]

this may be a dumb question, but want to be sure i am buying the right tool.

I want to find the frequencies of two new trunked radio systems in my area, with out having to go though a band scan on the scanner. Am i right in thinking if i had a frequency counter, and can get reasonably close to the repeater, a frequency counter should find the control / voice channels?

thanks

 

[UPMan]

It is very difficult to do that way as the control channel continuously transmits at about the same power level as any voice channels in use. So, when two or more signals relatively close in frequency to each other transmit, frequency counters will not typically lock onto any of the frequencies.


Better tool is a spectrum analyzer. Most cost effective (if you ignore the cost of the laptop) is an SDR dongle plugged into the laptop and the laptop running some version of one of the free applications that allow you to see a broad swath of spectrum activity all at once.


Or, many times you can suss out that info from published FCC data.


What type of trunking is being used? There could be some other reliable methods out there that work on particular types.

 

[ve5wil]

thanks, i should of thought of spectrum analyzer

the two systems wont be listed in publicly accessable documents here in canada, one is the new radio system for our city police, NXDN or DMR 800mhz, the other is a tower site at the local airbase airbase ... should be p25vhf, but their radios say vhf trbo

may have to look into the dongle thing

 

[UPMan]

For this kind of thing you don't need the scientific accuracy of a spectrum analyzer test set. $15 dongle works great. I used this kind of setup extensively during DMR/NXDN development, as most active systems were not yet documented in RRDB (or were incomplete or incorrect).


Being able to click on a peak in the spectrum view and then immediately start getting information about the signal is a pretty efficient use of the $15 (USD).

 

[K2RNI]

Don't even need to spend money or buy anything at all. Simple programing of the frequency search ranges will already do this since you know the bands used.

 

[ve5wil]

im trying to avoid using the scanner, as there are 2 or 3 other systems in the same frequency range. I am trying to nail down those two specifically as the others are already in the RR database.

 

[hardsuit]

ve5wil - the Optoelectronics Digital Scout and Analyze both Conventional and Digital Trunked systems.
bit the Opto Digital Scout is Expensive about $500 and you cant Hear the Audio, it only records the Frequency, tones and Sig Strength. but, It can be used for Digital Transmissions as well.
I only have the Analog one but it used to work Great on Simplex and Conventional Trunking but FEW are transmitting in Analog anymore. It still Reacts to Paging however, Medical still uses Pagers.

 

[Ubbe]

Use the attenuator feature and an antenna that only let you hear the strongest transmitters. I usually only use my finger more or less in the antenna connector when I'm near a transmit site to check what frequencies are active.

/Ubbe

 

[slicerwizard]

im trying to avoid using the scanner, as there are 2 or 3 other systems in the same frequency range. I am trying to nail down those two specifically as the others are already in the RR database.

If you're close to the site, you can remove the antenna and use the attenuator feature to lose the unwanted systems.

Personally, I'd go with a laptop/netbook and a dongle or two. Makes strong signals very easy to nail down.