Batboard

Sometimes when monitoring P25 on my XTS1500, the audio sounds like video game sound effects instead of voices. Is this encryption? The display does not show the channel being received when on scan. Will programming change this? The FW is R14.00.01

Sounds as if what you're hearing is gibberish that is caused by packet loss, which simply means that the data being received can't be converted to analog audio by the radio. Usual direct cause is a weak or weakened signal path between you and the transmitter which might be fixable by moving the radio a short distance in the room.

I am using an outdoor antenna and signal strength is good. I am also using F7E for a NAC.

Encryption sounds like white noise so that is not your issue IMHO

It is common to find PS radio systems using multiple transmitters, in which case they have to be synchronized timewise. If the time synchronized signal at your place is out of phase then you can get distorted signal reception, even though one or both or the signals being received is strong. Then there's the other extreme where the signal is actually too strong and causes overloading in the receiver, so you've got a whole mess of things to investigate. But as Jeff said, it's not encryption if you can understand part of what's being said.

Encryption in P25 has always sounded like digital gibberish to me, not white noise...

Is the received transmission fading to an R2D2 sound or is it like that from the start and none of the transmission is receivable?
In my experience, if I accidentaly don't load all of my keys and I try to listen to a secure call it is not receivable at all and doesn't sound like white noise. It is totally gibberish and painful to listen to.

Like another brought up, are you within the footprint of the system you are listening to? Just because you have a high signal strength you can still get bit errors due to interference from others like NEXTEL.

Oops! Maybe I am conflating securenet over analog? That's the one that sounds like white noise?

Correct. SECURENET 12kbps over analog just sounds like open squelch with a high pitched whine at the end of the transmission.

You can also get that if you try listening to a widepulse system with your radio set to C4FM. Your radio has a crack at demodulating the signal, largely fails, spits rubbish out of the speaker.