Thanks for replying or I would not even have seen it. Haven't police radios been digital for 20 years or so, and encrypted for half that time?
Not necessarily digital. The 2013 transition was to "narrow band" switching from 25KHz channel spacing to 12.5KHz (or 6.25KHz) channel spacing. Narrow banding can be achieved either by switching to a variety of incompatible digital modulation schemes, or simply reducing the FM deviation of the transmitters and matching IF filters in the receivers. Unlike a similar narrow band change in the 1970's, conversion of existing equipment is not allowed, so all new radios are required for both digital and analog narrow banding.
Whether transmissions are encrypted is totally at the discretion of the license holder. Locally, most everything is NOT encrypted. However, other municipalities are using encryption. Some switch back and forth depending on message content.
For those with older conventional scanners, the non-encrypted speech and data can be decoded with a PC using:
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
When you say "not allowed", that seems to imply there is a non-technical police reason. Or is it an FCC reason?
Amazing how far behind they are. I assume the NYPD is all encrypted because they have done lots of upgrades and restructuring to counter terrorists.
FCC reason. Everything has to be type certified to comply with various FCC rules and regs sections. I forgot which "24 CFR Part XX" sections are applicable. Somewhere in there is some verbiage indicating that an existing radio certified to the older rules and regs cannot be "field modified" and recertified to the new rules. Since there was Federal funds available to pay for the transition to narrow band radios, modifications were both technically and financially a bad idea. I can dig out the specifics later if you want.
It's worse than that. Much of the equipment sold to NYFD after the
911 attacks was not ready for prime time and had to be returned to Motorola. The P25 (Project 25) specifications for most digital radios are from 1989. There have been improvements since then, such as P25 Phase 2 in 2009, but those just created incompatibility problems with older equipment. Of course, each radio manufactory has their own digital standards. There are even some services who are using European standard TETRA trunked system. After 911, the most common request by public safety organizations was interoperability, or the ability to talk to other agencies and services. That's been generally ignored or trashed by proprietary enhancements. I could go on forever on this, but lunch beckons.-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
Looks like NYPD uses encryption on some of their channels, but not on all of them: (5 pages)
On the other foot, encryption hasn't worked too well for some users. The issue is mostly interoperability and "transparency": "Emergency agencies turn off radio encryption"
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
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