Like Tree9Likes

project 25 ?

This is a discussion on project 25 ? within the General Discussions forums, part of the Community Boards category; how come project 25 digital radio communications sounds like they are talking through a tube ? thought digital radio communications ...

  1. #1
    Registered User kryptkat's Avatar
    Join Date
    Dec 2002
    Posts
    638

    project 25 ?

    how come project 25 digital radio communications sounds like they are talking through a tube ? thought digital radio communications was supposed to be better. it is not. is it the hardware or transport method ?
    are the chips not fast enough ? what ? meyeaouch !
    Last edited by kryptkat; 09-03-2012 at 07:17 PM.
    <whiteflags> You foolishly believe in people and this feeling must be crushed.

    i have gotta get me a bunch of monsantos gmos == genetically modified orgasms .

  2. #2
    Registered User kryptkat's Avatar
    Join Date
    Dec 2002
    Posts
    638
    i think i will clam these 4 ham calls just for the heck of it.

    im4kat
    im4cat
    p0rn
    me0w

    here is p25 info.
    Project 25 - Wikipedia, the free encyclopedia
    <whiteflags> You foolishly believe in people and this feeling must be crushed.

    i have gotta get me a bunch of monsantos gmos == genetically modified orgasms .

  3. #3
    Registered User
    Join Date
    Oct 2006
    Posts
    2,422
    the point of digital communications in that context is not to produce excellent audio quality, but rather excellent quality of service. reliability is key. they aren't especially concerned about the audio quality so long as the signal gets through, and can be understood.

  4. #4
    RoD
    RoD is offline
    Redundantly Redundant RoD's Avatar
    Join Date
    Sep 2002
    Location
    Missouri
    Posts
    6,331
    Quote Originally Posted by Elkvis View Post
    the point of digital communications in that context is not to produce excellent audio quality, but rather excellent quality of service. reliability is key. they aren't especially concerned about the audio quality so long as the signal gets through, and can be understood.
    Exactly, well put.

  5. #5
    Registered User kryptkat's Avatar
    Join Date
    Dec 2002
    Posts
    638
    excellent quality of service. reliability is key.
    excellent quality better than what ? fm ? reliability better that what ? morse code ?

    i think they got sold a cargo train load of rocks instead of a cargo train load of silver. i took a look at the actual product instead of the sales pitch. was going to do a write up on the vulnerabilities but wiki already did a good job of that. reliability better that what ? fm ?

    reading through wiki on the creation of this project it looked as if the alphabet soup factory had exploded with as many letters all over the place as there were.

    their "talk around" mode they reinvented simplex.

    a special type of 4FSK modulation[9]—for digital transmissions at 4800 baud and 2 bits per symbol, yielding 9600 bits per second total channel throughput. Of this 9600, 4400 is voice data generated by the IMBE codec, 2800 is forward error correction, and 2400 is signalling and other control functions.
    ....
    P25 standards use the proprietary Improved Multi-Band Excitation (IMBE) and Advanced Multi-Band Excitation (AMBE+2) voice codecs which were designed by Digital Voice Systems, Inc. to encode/decode the analog audio signals.
    i found the answer to the question as to why they sound like they are talking through a tube. they are using dial up speeds. with todays technology they should be getting broadband speeds.

    with i phones being made in japan for $8 each they should be able to make a duel band radio or multi band radio with a screen like that of the i phone and a duel core processor for the public safety workers so that they can talk to each other {other agencies }and set up a channel like channel 7 for other or cross communication between the agencies in their band of frequencies using simple fm. why a screen ? so they can send pics. a radio with all public safety bands and cb and ham and other bands....

    me.... wait i am going to use the new call "emm" "eeh" "zero" "double u" . best wishes.
    Last edited by kryptkat; 09-13-2012 at 07:07 AM.
    <whiteflags> You foolishly believe in people and this feeling must be crushed.

    i have gotta get me a bunch of monsantos gmos == genetically modified orgasms .

  6. #6
    Registered User kryptkat's Avatar
    Join Date
    Dec 2002
    Posts
    638
    instead of just selling a few radios and systems a year just force everyone to change to narrow fm and the "new project 25" thus boosting the economy of the electronics industry and radio manufacturing industry is purely marketing genius.
    <whiteflags> You foolishly believe in people and this feeling must be crushed.

    i have gotta get me a bunch of monsantos gmos == genetically modified orgasms .

  7. #7
    Registered User
    Join Date
    Jun 2011
    Posts
    2,380
    High frequency communications is fine for relatively "useless" communication, such as a person looking up sports scores on their smart phone, for example. But for emergency situations, low frequency communication is a much more stable and successful method.

    I don't know anything about Project 25, other than a brief wiki review. It requires stable communications in all sorts of situations, and they take the actions required to achieve this goal.

    When communicating wirelessly, there are many factors that can affect the wave propagation of the signals, and the idea of Project 25 is to minimize the effects of wave distortion/attenuation.

    Higher frequency waves travel different paths than lower frequency waves, and are subject to deterioration from many complex factors. For instance, environmental: Weather (rain/snow can scatter the signals as they propagate), the current particle ratio in the atmosphere, solar effects, etc. There's also absorption, which means a higher frequency signal is attenuated by physical objects (walls, etc) and, at even high frequencies, by particles in the air.

    Many of these environmental effects might be at play in an emergency situation, so it would behoove the Project 25 committee to take such risks into account. It's all about function over form.

    Once again, this sounds like someone having strong opinions and complaints about something they do not understand, and are ignorant even of the depth/complexity of the factors that must be taken into account.
    Elkvis likes this.

  8. #8
    Registered User
    Join Date
    Oct 2006
    Posts
    2,422
    Quote Originally Posted by kryptkat View Post
    they are using dial up speeds. with todays technology they should be getting broadband speeds.
    broadband speeds only work when you have a lot of bandwidth in which to put the signal. that usually means sending down a physical wire or optical fiber. since these signals have to fit in a ~10khz channel, over the airwaves, dialup speeds are the only thing possible. you seem to have a fundamental misunderstanding of how digital signals are sent via radio.

  9. #9
    Registered User kryptkat's Avatar
    Join Date
    Dec 2002
    Posts
    638
    kittyp0rn dose not work well as a ham call.
    broadband speeds only work when you have a lot of bandwidth in which to put the signal. that usually means sending down a physical wire or optical fiber. since these signals have to fit in a ~10khz channel, over the airwaves, dialup speeds are the only thing possible. you seem to have a fundamental misunderstanding of how digital signals are sent via radio.
    that was priceless!!!! hands elkvis dunce cone. according to you these things do not exist. or are only dial up speeds.


    Broadband - Wikipedia, the free encyclopedia
    Wireless Broadband | Wireless Internet | Cricket Wireless
    Wireless Internet Card | Broadband Modem | Cricket Wireless
    Wireless broadband - Wikipedia, the free encyclopedia
    Satellite Internet Service | FREE Install | Rural Internet

    According to the 802.16-2004 standard, broadband means "having instantaneous bandwidths greater than 1 MHz and supporting data rates greater than about 1.5 Mbit/s."[1]
    since these signals have to fit in a ~10khz channel, over the airwaves, dialup speeds are the only thing possible.
    broadband speed is a differential function of channel throughput not band width. band width of the channel does not matter. the fcc knew this and they changed their rules. you can have one channel 10khz wide and send one data signal through it. or you can have that 10khz channel and send two data streams through it at near 5khz or you could have 10 data streams at 1khz. or you could have 20 at 500hz of bandwidth. now about channel speed. as long as there is no interference between data streams and the carrier signals it will work. you can have 1hz data and send it through on the 10khz or the smaller allocations of the channel. you can divide that 1hz data in to two and have 2hz divide it again and have 4hz then again and get 8hz and so on. until you get to ten gigahertz or more and send it through. with 10ghz that could be lots of data. each data stream is piggy backed on its own carrier and sent through. had you understood that in the first place
    you would not have said " since these signals have to fit in a ~10khz channel, over the airwaves, dialup speeds are the only thing possible. "
    since these signals have to fit in a ~10khz channel, over the airwaves, dialup speeds are the only thing possible.
    as if 10khz channel is a limitation of speed and not bandwidth. <pines ears back> <claws out> that last link is of a satellite broad band system and it is <hiss> technicaly wireless </hiss> <claws in><ears up>

    <grins sheepishly> you made me feel so not clean after that hissy fit i have to take a bath <licks self>
    <whiteflags> You foolishly believe in people and this feeling must be crushed.

    i have gotta get me a bunch of monsantos gmos == genetically modified orgasms .

  10. #10
    Registered User
    Join Date
    Oct 2006
    Posts
    2,422
    it's clear that you don't comprehend radio theory, and you also obviously don't understand how radio signals are regulated and licensed. instead of just spouting ignorant opinions about something of which you clearly have no knowledge, why don't you try to learn about these things and then maybe ask questions about things when you don't understand something, before forming an opinion.

  11. #11
    Master Apprentice phantomotap's Avatar
    Join Date
    Jan 2008
    Posts
    4,262
    O_o

    I think you've confused buzzword bingo with science.

    Marketing speak and technical specifications aren't necessarily referring to the same thing when they say "bandwitdh", "broadband", or "throughput".

    Soma
    Elkvis likes this.

  12. #12
    Registered User kryptkat's Avatar
    Join Date
    Dec 2002
    Posts
    638
    elkvis it is clear that you do not comprehend radio theory and you also obviously do not understand how radio signals are regulated and licensed. instead of just spouting ignorant opinions about something of which you clearly have no knowledge. why you do not try to learn about these things and then maybe ask questions about things when you do not understand something before forming an opinion. back at you.

    * you have failed to show proof that project 25 has excellent quality of service. .... check

    * you failed to show proof that project 25 is more reliable than the older system. .... check

    Quote Originally Posted by elkvis
    since these signals have to fit in a ~10khz channel, over the airwaves, dialup speeds are the only thing possible.
    * i showed with the links that wireless broadband data rates do exist. .... check

    * i showed with the links that wireless broadband does exist. .... check

    * i showed what is possible <other ways to transmit data and a carrier> and other methods to fit more data in the space given but not what is regulated. .... check

    * you have failed to show that project 25 is more or has more stable communications than the older system. .... check

    while project 25 has forward error correction should a lightning strike be near ----> you loose the whole data block<s> . however with crc it retransmits the lost data a system project 25 does not have. digital television does have the forward error correction also looses complete data blocks and the picture is blobbed from two to four seconds and sometimes crashes the tv. but radio does sometimes have one to one communications where it could have crc .
    with the analog tv the disruption only lasted as long as the lightning strike. about a tenth of a second.

    * i put up the definition of what boadband is. .... check

    According to the 802.16-2004 standard, broadband means "having instantaneous bandwidths greater than 1 MHz and supporting data rates greater than about 1.5 Mbit/s."[1]
    you may be able to do a formula one way say multiply while someone else may be able to do that to and also do it a different way say for example divide.
    so how is that buzzword bingo ?

    * i asked a question why does it sound like they are talking through a tube and found the answer . .... check

    <grins sheepishly>
    Last edited by kryptkat; 09-18-2012 at 11:48 AM.
    <whiteflags> You foolishly believe in people and this feeling must be crushed.

    i have gotta get me a bunch of monsantos gmos == genetically modified orgasms .

  13. #13
    Registered User
    Join Date
    Oct 2006
    Posts
    2,422
    As an Extra class amateur radio operator, licensed in the USA for the last 20 years, I have some knowledge of these things. The Project 25 protocol, according to the wikipedia link, must fit in a 12.5KHz-wide channel. the data rate that can be sent through such a channel is limited by the laws of physics. there are formulae that can be used to calculate the maximum data rate with a given amount of bandwidth. I suggest you look it up. Broadband, according to your quoted definition (802.16-2004), is a signal with bandwidth that exceeds 1MHz. Since Project 25 is designed and licensed to use 1.25% of that bandwidth, logic alone, even ignoring technical data of any kind, would dictate that the data rate through such a channel would be greatly reduced, and "broadband speeds" would not be possible.

    the facts are clear as day:

    * the wider the bandwidth of a signal, the more prone to interference and data loss it will be.

    * wireless broadband speeds do exist, but they require much greater bandwidth than Project 25 is licensed or intended to use.

    * Project 25 does not employ a full-duplex signal, so retransmission of lost packets is impossible, because there is no way for the sender to know that a packet was not received successfully. it is very similar to the way UDP packets work over IP networks.

    all of the things you "showed" are irrelevant and do not apply to Project 25 or any related protocols, nor are they relevant to public safety radio communications. the wide signals and high data rates you suggest would not be viable for that sort of communications.

    finally, I'll point out that you're obviously trolling, and you have no intention of carrying on an intelligent conversation, and I'm beginning to suspect that you're simply incapable of that. it seems as if you don't even care about the subject matter. you simply want to start arguments, and have no interest in the facts. to this day, I have never seen a post from you that did not appear to be an attempt at trolling.

    either be a useful, contributing member of this community, or go find a different forum to troll.
    Matticus and phantomotap like this.

  14. #14
    Master Apprentice phantomotap's Avatar
    Join Date
    Jan 2008
    Posts
    4,262
    O_o

    Do you really not understand the vast difference between a device that has MHz of spectrum to play with versus one with only a few KHz?

    These things you are comparing to show.. whatever it is you are trying to argue... have vastly different chunks of the spectrum with which to play.

    But just in case, if you do know a way to fit actual broadband speeds in such a tiny slice of life reliably you absolutely need to write a paper on it.

    Such a work would rewrite information theory for years to come.

    Soma
    Elkvis likes this.

  15. #15
    Registered User kryptkat's Avatar
    Join Date
    Dec 2002
    Posts
    638
    elkvis first you say wireless broadband speeds are not possible then after the wireless broadband speeds are pointed out to you say yes broadband speed are possible and all of a sudden have an extra class amateur licence. did you get that by not answering the questions on the amateur test the same as here where you did not answer the questions now that would be interesting. and change the channel from ~10khz to 12.5khz after looking at the specifications on the wiki page.

    as you know credentials licenses certificates awards can be faked lied about or fabricated. what i would trust is exam conditions with six deputies in a room observing with only a table and chair and a amateur test and pencil and personally observe the test being taken with no search engines or phones or any devices or pagers etc and lets see what you really know. did i say no search engines. i also know that i could give eight or more real ham calls and they would all come back as actual extra class hams and none would be mine. but you would have no way to verify that.

    elkvis i know exactly what you are doing it is called master troll baiting. you put some false accusations then when the victim responds you accuse them of being argumentative. if you want to participate in an intelligent conversation then stop master troll baiting and participate in an intelligent conversation or leave this thread. if you want to continue on this thread then i insist that you answer only this one question first.

    question for elkvis only.

    what causes the project 25 sound of having a flying broom stuck in you back office or like talking through a tube ?

    the slow transfer of dial up speeds is only part of the answer . i want to see if you understand what the problem is. which is the first question that i asked. what i would like is a more detailed answer than dial up speeds. should you not answer it then i will answer it. found an article that comes close.

    end question for elkvis.

    everyone else i found a good site on project 25
    Project 25 Technology Interest Group
    i would like to rephrase the question
    could they change equipment so that the voice clear with project 25. change bands what ever is needed ?
    second question police and fire did not change bands they are still on the same allocated band do you think they should change bands to a more stable and reliable band for public safety ?
    third question i do not see a need for all the stuff. a few examples of actual events. during the twin towers of nine eleven i see no need for having a private channel. during several school shootings the perpetrators were to busy shooting to listen to the police channels. at the zanesville large cat slaughter the big cats were to busy being large cats to listen the police channels. personally think all of the large cats could have been tranquilize and not killed. if they had just taken their time and tried to capture them. what was it 65 large cats. during katrina people were to busy looting to listen to the police channels.
    fourth question can not think of any examples where is needed if you can lets hear it.
    Last edited by kryptkat; 09-23-2012 at 02:17 PM.
    <whiteflags> You foolishly believe in people and this feeling must be crushed.

    i have gotta get me a bunch of monsantos gmos == genetically modified orgasms .

Page 1 of 2 12 LastLast
Popular pages Recent additions subscribe to a feed

Similar Threads

  1. Classes Project (Not class project)
    By adam.morin in forum C++ Programming
    Replies: 3
    Last Post: 02-28-2011, 12:48 AM
  2. Paid project - The Free Marketing Project
    By sharefree in forum Projects and Job Recruitment
    Replies: 0
    Last Post: 10-27-2010, 02:15 PM
  3. Project Help
    By Fatima Rizwan in forum C++ Programming
    Replies: 1
    Last Post: 01-13-2010, 07:52 AM
  4. project
    By xlordt in forum C Programming
    Replies: 0
    Last Post: 10-07-2002, 03:50 AM
  5. your 11th & 12th grade c++ project or similar project
    By sleepyheadtony in forum A Brief History of Cprogramming.com
    Replies: 12
    Last Post: 01-13-2002, 04:14 PM

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21