RTL SDRsharp and close by signals
- Thread starter mike619
- Start date
thewraith2008
Member
- Joined
- Nov 22, 2016
- Messages
- 1,884
Detecting signals at and around the VFO frequency (@ ~2.4MHz bandwidth for a RTL dongle) is what SDR# will do.
You would need to add a plug-in (e.g. Simple DMR) to decode DMR voice traffic.
If you don't know the frequency, then you would need to scan a range of frequencies (e.g. Frequency Scanner plug-in) for activity and use a process of elimination to find it in a field of hay stacks.
You would need to add a plug-in (e.g. Simple DMR) to decode DMR voice traffic.
If you don't know the frequency, then you would need to scan a range of frequencies (e.g. Frequency Scanner plug-in) for activity and use a process of elimination to find it in a field of hay stacks.
Unless they are using the VHF business band, then you'd need to look for that. However, rather than scanning the band (which takes a long time and likely will miss short conversations) you should be looking for spikes, the higher the spike the stronger the signal.
dickie757
Wired
Might be a real challenge unless they are chatterboxes. Are you aquainted with any of the staff that use radios? Social engineer them into telling you who they got the radios from.
If they got them from a shop, they most likely have a license. Look up the property company name in the FCC license search. This will narrow your search time to almost nothing.
Another situation could be.....they are leasing airtime from a shop that holds a MO6 license. If that is the case, you will have to know the shop details to search.
I can think of two other situations...1.they are using GMRS freqs, 2.they have no clue and are using willy nilly teknishun freqs.
All of that legwork will help you zoom in to the right section of spectrum. Low hanging fruit is the GMRS area. Look those up and load them into a scanner or SDR#. Maybe start a spreadsheet of common freqs. Chirp programming software has a bunch of those lists pre-made. Might save some time loading that software.
You have a nice challenge in this one. Good luck!
If they got them from a shop, they most likely have a license. Look up the property company name in the FCC license search. This will narrow your search time to almost nothing.
Another situation could be.....they are leasing airtime from a shop that holds a MO6 license. If that is the case, you will have to know the shop details to search.
I can think of two other situations...1.they are using GMRS freqs, 2.they have no clue and are using willy nilly teknishun freqs.
All of that legwork will help you zoom in to the right section of spectrum. Low hanging fruit is the GMRS area. Look those up and load them into a scanner or SDR#. Maybe start a spreadsheet of common freqs. Chirp programming software has a bunch of those lists pre-made. Might save some time loading that software.
You have a nice challenge in this one. Good luck!
If you have a Linux system, I use this to hunt down signals (I've found stuff I probably never would have been around to hear with it)
github.com
GitHub - shajen/rtl-sdr-scanner-cpp
Contribute to shajen/rtl-sdr-scanner-cpp development by creating an account on GitHub.
github.com
thewraith2008
Member
- Joined
- Nov 22, 2016
- Messages
- 1,884
If using the SDR# Frequency Scanner plug-in:
Use in dynamic noise floor mode.
This will then ignore any continuous carriers that maybe be encountered and saves having to manually lock them out.
Use lockouts, so when you land on a frequency that you determine is not your target, it won't keep stopping on it on further passes.
You could set the scanner activity trigger level higher if you know the target transmissions will be stronger.
This will help reduce/filter the amount of activity seen but doing this maybe too restrictive at first since you are dealing with an unknown.
Use the logging (individual and hit counter) to record where the activity it at.
This can be helpful in determining when the frequency is active and how often.
You can also use with the Audio Recorder plug-in to record this activity.*
You can then review later the recordings to see if that frequency is the one you are seeking.
* If you are expecting DMR then this would only be helpful in determining if it sounds like a DMR signal.
If you know the target is DMR, you can use the scanner in digital mode (with dsd+ or Simple DMR).
This may help reduce/filter the amount of activity seen down to digital modes at least.
Digital mode itself can't identify if P25/DMR etc. Only that voice activity was seen.
Use in dynamic noise floor mode.
This will then ignore any continuous carriers that maybe be encountered and saves having to manually lock them out.
Use lockouts, so when you land on a frequency that you determine is not your target, it won't keep stopping on it on further passes.
You could set the scanner activity trigger level higher if you know the target transmissions will be stronger.
This will help reduce/filter the amount of activity seen but doing this maybe too restrictive at first since you are dealing with an unknown.
Use the logging (individual and hit counter) to record where the activity it at.
This can be helpful in determining when the frequency is active and how often.
You can also use with the Audio Recorder plug-in to record this activity.*
You can then review later the recordings to see if that frequency is the one you are seeking.
* If you are expecting DMR then this would only be helpful in determining if it sounds like a DMR signal.
If you know the target is DMR, you can use the scanner in digital mode (with dsd+ or Simple DMR).
This may help reduce/filter the amount of activity seen down to digital modes at least.
Digital mode itself can't identify if P25/DMR etc. Only that voice activity was seen.
Similar threads
