Ontario County now using 700 MHz

[k2hz]

Last evening it was back to "all simul, all the time" operation. I wonder if they have any plans or procedure to limit the use of simul to only when needed or if it is at the dispatcher's discretion. It now seems like there is an effort at times to only use simul to one or both conventional systems when needed and other times it looks
like a dispatcher comes on duty and just sets up simul to everything and leaves it up.

 

[AuntEnvy]

Ahhh, that explains it!

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]


Now I see how you're getting that system.

 

[Nightjock]

Can anyone tell me if this system uses LSM?

 

[GTR8000]

Can anyone tell me if this system uses LSM?

Sort of. For the purposes of keeping it simple, yes.

Technically speaking, Linear Simulcast Modulation (LSM) is specific to Motorola-built systems. This system is manufactured by Harris so it doesn't use LSM specifically, but it is simulcast using CQPSK modulation with linear repeaters.

They are compatible, but not exactly the same.

 

[Thunderknight]

Sort of. For the purposes of keeping it simple, yes.

Technically speaking, Linear Simulcast Modulation (LSM) is specific to Motorola-built systems. This system is manufactured by Harris so it doesn't use LSM specifically, but it is simulcast using CQPSK modulation with linear repeaters.

They are compatible, but not exactly the same.

WCQPSK right?

 

[GTR8000]

WCQPSK right?

Yes, that is what Harris calls it.

 

[Nightjock]

The reason I ask about LSM on this system is I'm wondering if updating to the most recent Uniden 396XT firmware will have any effect on this system. The main improvement in the latest firmware is it improves reception with P25 systems using LSM.

To update my firmware I need a Windows machine, and I'm strictly Mac. That's being discussed in another thread in the Uniden section of the site so I don't want to discuss that aspect here.

Just wondering if the newest firmware will do anything to improve reception of this system.

 

[eng5]

Just wondering if the newest firmware will do anything to improve reception of this system.

It did not for me.

 

[Nightjock]

It did not for me.

Thanks. I'm curious....what sort of signal strength were you getting before the update? I'm seeing full bars on the control channel from Victor.

 

[eng5]

I get full signal at home with the big antenna. I tried a directional antenna, too, but from my location it's hard to point at just one site without also pointing toward another.

I didn't see any improvement in the scanner's ability to decode after the firmware update. The error rate shows below 3, but I still see talkgroups displayed but with no audio, or with choppy unintelligible audio. Sometimes it doesn't stop scanning when there should be traffic on the Fire/EMS talkgroup.