To find the frequency of the peaks
i measured on the Esmog Spion,
i bought a RTL-SDR kit for 22€ ($26.95).
range: 25MHZ tot 1.7GHz.
i'm an amateur, i don't know if this
thing is very useful, but it shows peaks
at 169 MHz (paging) perfectly matching the Esmog Spion peaks
seen in my TETRA video.
I installed this device in 5-10 minutes
following the walk through on their website.