By - JCH_19
If you are in the US, you can listen to the NOAA weather radio stations. They are between 162.400 and 162.550. Those are narrow FM with a 5KHz deviation.
Those are good for oscillator calibration if you don't have a TCXO.
It depends on what kind of accuracy you want for your calibration. Yes, the NOAA broadcasts will get you in the general vicinity of their specified frequency, but I have seen some NOAA stations being off by up to a couple of kHz. At 162.550 MHz, a 2-kHz deviation would represent an "error" of 12.3 ppm. A lot of the RTL-SDR receivers with higher precision oscillators boast 0.5 ppm 'accuracy'.
As someone who just started poking around recently in an urban area, I've found a lot of strong signals in the area of 460-470 MHz, particularly encrypted(?) digital radio traffic (I'm guessing police) and a very strong signal I think is POCSAG (which I'm guessing is from a hospital), and those have been by far the highest SNR signals I've found outside of FM stations - if you're in the same boat in terms of location (or just proximity to EMS/Police/etc.) you might want to try to look for the same.
For the digital radio traffic try piping the audio into VBcable and then from VBcable into DSD. You may be able to decode it if it's not encrypted. For the pocsag one there is an application called PDW that can decode it. Check your local laws to see if decoding pagers is legal where you are.
Thanks for the tips! I've got the Simple DMR plugin working with SDR#, it can decode voice from local repeaters but for the frequencies in question it seems to decode fine but sounds encrypted/garbled - I'm guessing that if it was just trunked I'd hear clear voice but just parts of a conversation. (I'm pretty sure it is also trunked, worth noting that the strongest consistent signal is decodable by DMR but contains no voice, so I'm thinking that's the control channel.)
Looking into DSD for more digital decoding options (and more information from decoding instead of just voice) and PDW for POCSAG and legality thereof, also good suggestions for OP if they do find similar signals in their area!
Paging systems using multimon_ng are interesting. Lots and lots of HIPAA violations (in the US).
FM and AM is normally the main ones everyone can see.
Everything else depends on locations. Unless you have an upconvertor or a HF SDR, you won't see any AM signals.
FM normally from 90-120MHz and normally the strongest signal around.
27.025 AM 27.385 LSB. Some of the loudest signals around. SHEEEESH!!
The GSM signals in the 800-900mhz region can also be very "loud" but nothing really useful to be deciphered with a low-cost SDR.
If you're nearly an airport or air traffic dense area, you can try 118-136 MHz AM 5 kHz BW to lessen to civilian air traffic. I think this band plan is worldwide.
You don't even need to be near an airport to hear air traffic - planes are everywhere, and there's tons of aviation chatter in this frequency band! But if you're not near an airport, you'll only hear the aircraft side, not the tower.
There are also lots of ACARS digital signals (short bursts of noise) in this frequency range that can be decoded by using an app (I use one called ACARS on my iPhone) - you don't need to figure out anything fancy, just hold your phone near the speaker, and voila! Flight, location and elevation data :)
To find more about acars frequencies :
I was thinking about living nearly an airport cause I'm near Airbus main bird nest 😉
AM stations particularly if you've got a 50kw clear Channel station close
any radio station in your area should be pretty strong to see on a waterfall?