Results 1 to 6 of 6
  1. #1

    Default A basic scanner question or two

    How complicated are police scanners?

    Also, when you switch cities don't you have to switch frequencies or something?

  2. #2
    Join Date
    Jun 2011
    Peoples Republic of NY

    Default Re: A basic scanner question or two

    Ans to above.........
    They are as complicated as you want them to be.
    How deep is your wallet ?

    There are thousands of public service frequencies. To make matters worse, there is also narrow band analog as well as digital and digital encrypted channels.

  3. #3

    Default Re: A basic scanner question or two

    Quote Originally Posted by dr_King View Post
    Ans to above.........
    They are as complicated as you want them to be.
    How deep is your wallet ?

    There are thousands of public service frequencies. To make matters worse, there is also narrow band analog as well as digital and digital encrypted channels.
    Is using a radio scanner app on a phone good? Like if I'm traveling through say NYC, I just click the NYC PD channel and listen?

  4. #4
    Advanced Member
    Join Date
    Jan 2006
    Northern New England

    Default Re: A basic scanner question or two

    Quote Originally Posted by napthalene View Post
    Is using a radio scanner app on a phone good? Like if I'm traveling through say NYC, I just click the NYC PD channel and listen?
    Well, what are your goals and what do you want to hear? We need more info before we can help you.

    If you are, for instance, going to be stuck somewhere for a day and may be bored out of your mind and want to monitor everything possible, then a scanner with very capable search and "Signal Stalker" capabilities will make the experience much more enjoyable. I always keep a handwritten log of things as I hear them, then go back later and enter into a spreadsheet and try to identify the users.

    Personally, I never trust what anyone else says are the right frequencies for an area. I will take my time to cross-check the FCC General Menu Reports, the RadioReference database, any local scanner pages, local amateur radio group pages, etc. before deciding what I am going to program into a scanner.

    When I am just scanning for the heck of it, and not looking for specific users, I have scanlists with no CTCSS/DCS assigned to each frequency, so that I can hear all of the activity on that frequency. If I entered only one tone or code into a frequency, I would never know what else might be happening there, and could miss something interesting.

    I will give you a real-life example. Most pre-loaded scanning programs only receive UHF repeater outputs...but then you might miss a ton of activity on the input! If the entity is licensed for both input and output, they could use each frequency for a different reason, with different tones/codes.

    A fictional breakdown of how this might work with a city police department:

    460.500R, CTCSS 100.0 - Main operations channel
    460.500R, DCS025 - Detectives
    460.500S, NAC $101 - Tactical
    465.500S, CTCSS 123.0 - Car-to-car
    465.500S, CTCSS 162.2 - City park and beach patrol
    465.500S, DCS 065 - Tactical shared w/fire and EMS

    So there you go...a casual user might only have the first channel programmed, and is going to miss all of the action on the other frequency/tone combos. And it is all perfectly legal and not "sneaky" on the agency's part (assuming the entity is licensed for both digital and analog voice emissions in this example).

  5. #5

    Default Re: A basic scanner question or two

    Looking for the "Blue Bentley reported on 694 weaving through traffic at speeds of over 100mph" mostly.

  6. #6
    Join Date
    Oct 2014

    Default Re: A basic scanner question or two

    Methuselah is somewhat correct.
    However - FM works on the principal of capture effect.
    The strongest signals are received and the weaker ones are rejected.
    If you try to transmit two signals on the same frequency at the same time, regardless of the (PL) Private Line - which is a term coined by Motorola, the two signals will heterodyne and cause interference, making both signals useless.
    Motorola worked this out a long time ago by using a radio with a hang up microphone that had lights that would indicate when the frequency was in use and when the frequency was clear. But this technology will not work in an environment where someone needs to call for help right now.
    Our Federal Government owns the FCC, they had an unlimited amount of frequencies to use at one time, but gave them away.
    First to television - because television broadcasters were willing to pay for the spectrum.
    Later to cell phone companies - since cell phone companies are willing to pay more money for the spectrum then the television broadcasters, and the cell phone people has a much louder voice - since there are more cell phones in the USA then there is people.

    Today convergence dictates that we now offer not only voice communications but also data streams for the in car computers that dictates that they narrow the footprint of the voice to make room for the data.
    If they narrow it any further it is going to be Amplitude Modulation, because there is not any deviation left to reduce.

    VOIP type systems such as Open Sky allows them to digitally send both voice and data over the same bandwidth, at the same time.
    The problem being that Digital cannot compete with Analog - because with Analog, even if you loose 50% of the signal, you still have a signal. The human ear and brain can decipher what it hears and can figure out when a word is garbled what the user was saying. Digital is all 1's and O's and when you loose part of a data stream, you loose reception and you don't hear anything or you have drop outs that are intolerable when it comes to public service.

    This is the reason why Open Sky does not work in Pennsylvania, too many hills, mountains, and valleys.
    The State has repeater antenna's on top of telephone poles along the road about one every 3 miles in some area's.
    And a system that was supposed to save them money, ended up costing them Billions of Dollars and still doesn't work effectively everywhere. I think their budget for this year, just to keep the system operational is something like 60 million dollars!

    The Frequencies used by the State Police in Pennsylvania are a basic set of frequencies, both in the high VHF - because they reinstalled the old analog equipment back into the cruiser for both car to car and also car to base - because high VHF - 155 MHz works well in hilly environments, while their digital stuff migrated up to around 850 MHz and is dispersed in a checker board fashion, not that it matters, because with VOIP - any patrolman anywhere can talk to any other patrolman in the state and can talk private - one on one, or can talk where a group of people can listen or can talk state wide, depending upon their need.

    Local Police only has a certain bandwidth available to them, most of them here are in the T Band - around 450 - 460 MHz and there is a certain frequency assigned for each locality. In order to pay for FirstNet, the government demands that they upgrade all their equipment to migrate to FirstNet, when a standard is adopted and a company is approved to manufacture the equipment necessary to get everyone on the same system. The mandate is 2024 - not all that far away - 10 years...

    Because government equipment is rotated on a basis of about every 8 years, the Federal Government does not feel that this is going to cause any hardship on any local government or municipality, since the Federal Government gives them grants to buy new equipment.

    Its my personal opinion that when the T band is vacated, that the amateurs are also going to be asked to leave and those frequencies - 420 Mhz - 470 Mhz are going to be sold to the highest bidder - The Cell Phone people, and that they are also going to mandate much of the television broadcasters to migrate back down to the VHF and abandon the channels from Channel 32 to 51 - now occupied by the terrestrial digital television stations..

    With all the money that was spent to make them go digital and to move up into the UHF, where it was quieter, it is only going to be a matter of time before the local terrestrial television stations we take for granted today disappears and we are left with nothing but cable television for reception. Many stations will probably be forced off the air, when there is no where left for their signal to go.

    Radio is quickly going to become a thing of the past in the near future...



Similar Threads

  1. Basic Scanner Question....
    By astro in forum Scanners, Ham Radios, & CB's
    Replies: 1
    Last Post: 06-01-2008, 08:28 PM
  2. Real basic question
    By stimyg in forum Other Countermeasures
    Replies: 1
    Last Post: 10-02-2007, 12:47 PM
  3. Basic Question
    By AndyM in forum Valentine One
    Replies: 28
    Last Post: 08-29-2007, 11:59 AM
  4. hi everyone, i have a basic question
    By 949 in forum Laser Jammers - General
    Replies: 5
    Last Post: 06-05-2007, 09:39 PM
  5. Basic Question About Gun Range
    By jcdc in forum Radar Detectors - General
    Replies: 4
    Last Post: 05-30-2007, 09:22 PM


Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts