Originally Posted by Thunderknight
You might be so far away that you are only hearing 1 site, and therefore outside of any simulcast issues.
The program I'm using SignalScopePage
has a GUI option to choose which demodulator is to be used; this allows the user to switch back and forth between "FSK4" and "PSK" in real time. When the FSK4 option is selected, the "4 bars" break up into the characteristic simulcast mish mash, but when PSK is selected all is perfectly clean. The presence of simulcast distortion on this signal has also been confirmed on the eye pattern diagram.
The FSK4 option in the program is directly equivalent to hardware FM discrimination. When a P25 signal with simulcast distortion is passed through an FM demodulator/discriminator (as in all current generation scanners) the signal is irrevocably mangled. The solution is to demod the signal as PSK, which requires direct access to the RF signal pre-demodulation.
I admit it does help to be > 2000' in elevation, and there aren't a lot of trees between here and the horizon, but I can confirm perfect reception of the Ontario 700 MHz CC signal here in Cortland county on a rubber duck with zero BER... I've pasted the data for the CC below... [crc:0 is a known bug, there were definitely CRC and/or trellis errors during the reception during the periods when FSK4 was selected]
rf: syid 228 rfid 1 stid 1 frequency 769.556250 uplink 799.556250
net: syid 228 wacn 458ad frequency 769.556250
secondary control channel(s): 769.281250,769.856250,770.106250
stats: tsbks 4386 crc 0
voice frequencies found: 769.28125,769.85625,770.10625
tbl-id: 0 frequency: 769.006250 step 0.012500 offset 30.000000
tbl-id: 1 frequency: 851.012500 step 0.012500 offset -45.000000
adjacent 854.562500: rfid: 41 stid:1 uplink:809.562500 tbl:1
adjacent 770.306250: rfid: 1 stid:1 uplink:800.306250 tbl:0
adjacent 769.256250: rfid: 21 stid:1 uplink:799.256250 tbl:0
adjacent 852.487500: rfid: 21 stid:1 uplink:807.487500 tbl:1
adjacent 769.806250: rfid: 41 stid:1 uplink:799.806250 tbl:0