Apple Internal Store

A couple things on this. NYPD dispatch radio is an analog FM system. That means it is relatively easy to configure an inexpensive commercial two way radio to transmit on their frequencies. In fact, many NYC cops own "unauthorized" off duty/backup radio. 1/ https://t.co/ZQY5tlQwl3 

1)The easiest way to prevent this is switch to Astro25 trunking system. Which already exists in NYC by DOITT which used by DSNY,DOC,DHS.....that way they can block/track unauthorized transmissions since APX radios got GPS. It’s also harder to program trunking system

This is incorrect, for a number of reasons. First, P25 is actually MORE vulnerable to jamming than analog systems, and trunked systems add single points of failure and additional complexity. Also, a trunked system with equiv coverage to the current NYPD system would ENORMOUS.

Further, the current NYPD system has over 50 channels, most of which serve a few local precincts. Each has between 2 and 10 single frequency voter sites, to achieve reliable indoor coverage. A trunked system would require each voter site to have receivers for EVERY frequency.

So, converting the NYPD to a digital trunked system would entail enormous expense and complexity, for which they would get increased susceptibility to interference and reduced reliability.

And would a digital trunked system work better than say a cellphone-based system with the existing analog network as a hot backup?

The main features required for public safety dispatch is real-time broadcast audio and high reliability even when normal infrastructure is stressed/degraded. Cellphone systems (even FIRSTnet) aren't ideal for that.