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A device that collects frequencies

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#1
Hello everyone

I used to be an avid scanner enthusiast back in the nineties and if i remember correctly you could buy a device that is pretty much like a scanner except much faster and all it would do is collect and record all the active frequencies in a given area. Then after a while you could check the device and see what RF activity had taken place. What is this thing called and does it still exist? Thanks everyone!
 

wtp

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#2
kind of

once and a while i set my 396T to scan the 225 to 380 mil air and it has a save feature that only loads a frequency once, no repeats. i know other radios do this but that is my everyday radio. and it is still a radio !
 
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#3
I think this is what you're looking for: Optoelectronics, Inc. It works like you describe, except it's not sensitive like a good radio receiver. It is a nearfield receiver, which means it will pick up strong signals within a quarter mile range (or so). If you slap a pre-amp to the input you can increase the range somewhat, but it is NOT designed to be a sensitive receiver.
 
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#4
Your cheapest bet is to get a $20 RTL-SDR dongle and SDR#. It has a scanner plugin that you can use to log active frequencies into a database. It can scan up to 10MHz of spectrum per second from shortwave to about 1.5GHz.
 

ofd8001

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#5
For some reason the term "Hit Counter" rings a bell. I don't know if that is the proper nomenclature. I remember decades ago an interference issue and the the radio techs used a similar device to snoop out the offending source and the called it a "hit counter".
 
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#6
It's called a Frequency Counter and they're only good for limited range use because they basically get triggered by the most powerful RF signal they can capture (meaning it's got to be relatively close within a few hundred feet or less and not miles and miles). A frequency counter or near-field receiver like the one from Optoelectronics that was linked in a post above is precisely what you'd be looking for but when you consider the incredibly limited functionality of such a device along with the rather high pricing - it's a very very narrow profile device designed for a specific purpose so they can and do charge the premium for it - you should be able to realize that buying a modern physical scanner for a bit less money offers vastly more potential for actual monitoring duties.

A tool like a frequency counter does have a purpose of course but today's scanners have similar capabilities built in with names like Signal Stalker (GRE/Whistler scanners) and Close Call (Uniden) and obviously many many other capabilities that just make them the better deal overall by comparison.

For the kind of money that device is priced at, I'd rather have the best handheld that Uniden or Whistler makes and use the remaining difference in the cost for some tuned antennas or rechargeable batteries or whatever other accessories I'd find useful, personally.

And yes, SDR nowadays offers potential for finding comms as well at a very very low price point, roughly $10-25 for a "cheap USB TV tuner" that when coupled with the proper drivers allows you to turn that tuner into a wideband receiver that when paired up with some SDR application software like SDR$ and that scanning plugin mentioned above can get the job done just as well if not better along with all the other capabilities of already having the info in a computerized format or database you can then work with, print out, edit, etc.

Hope this helps...
 
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#8
A Device That Collects Frequencies

...you could buy a device that is pretty much like a scanner except much faster and all it would do is collect and record all the active frequencies in a given area. Then after a while you could check the device and see what RF activity had taken place...
Another method of what you ultimately want to accomplish is what I would do with a Uniden Bearcat BCD996XT under Butel ARC-XT Pro. For me, to simply know that a frequency was active really didn't tell the whole story for me. If it was in a service that used sub-audible signalling, I wanted to document that, too.

What I would do is program in a number of frequencies and then scan them with PL/DPL finder on. Then, when frequencies came active, I could not only that a frequency was in use, but also the PL/DPL or NAC code if it was APCO P25.

That, too, only told one more piece of the big picture. Next, I would monitor the found frequency and code combination to determine who the user was. It was the sort of thing that I could do when surfing the web on my computer, etc.

Now that public safety in my area has moved to a digital, trunked system, rather than look for conventional activity, I will now use a scanner in the TRUNK SEARCH mode to find new, unknown talkgroups.

It is always interesting to look at the History Log of the Butel and see what new things were active.
 

dlwtrunked

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#9
Hello everyone

I used to be an avid scanner enthusiast back in the nineties and if i remember correctly you could buy a device that is pretty much like a scanner except much faster and all it would do is collect and record all the active frequencies in a given area. Then after a while you could check the device and see what RF activity had taken place. What is this thing called and does it still exist? Thanks everyone!
Although a frequency counter may pick up the strongest frequency, it is not what you want. And a conventional spectrum analyzer generally does not record what it sees for later reviews (like RF Explorer that someone suggest which I do have--and RF Explorer *set for a wide frequency range* will not give you near the resolution that you desire. About the only thing you can do is what I do... run an SDR dongle, AirSpy, or SDRPlay with a PC. However, with the usual software you can cannot capture a great frequency range--AirSpy can do 8 MHz. I then run an auto screen capture program like at
https://sourceforge.net/projects/autoscreen/
and capture the waterfall display every so many seconds into an image file. I use Windows moviemaker program (free) to make these into a video for later review. Not perfect, but it is the closest thing to what you would like.

You could also run to RTLSDR Scanner with a usb dongle setting the program for max signal (later you look for the peaks in the finale display) and attempt wider frequency ranges but there will be gaps in time as it runs on each frequency. Note RDLSDR Scanner has given some people trouble with resources on their PC (I never had an issue). RTLSDR Scanner | Ear to Ear Oak

Now it would be nice if someone wrote some good usb dongle software to help in this. (The other responses I have seen to doing things like this are not really going to do what you want.)
 
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