Results 1 to 23 of 23

Thread: Embarking on an Amateur Simulcast System -- Need Help

  1. #1
    Join Date
    Mar 20, 2014
    Posts
    507
    Thanks
    65
    Thanked 178 Times in 108 Posts

    Default Embarking on an Amateur Simulcast System -- Need Help

    After waiting years for a site (see some of my old posts) I was recently lucky enough to put machine up in a fairly awesome site. As luck would have it, I have sourced a second site, which should extend the coverage a bunch, but I only have one repeater pair right now. So simulcast it is. I do have the 2 quantars, a couple or three Ciscos, several 4 wire wireline cards and V24 modems, and an ATAC3K with what I believe to be 3 8wire cards, and I would assume modems, if that is needed (The ATAC should arrive in a couple of days.)

    I believe I need to avoid the public interwebs to link the quantars to the ATAC, though I have read mention of a private VPN, which I know very little about, but can read up on if that is a viable solution for linking.

    Anyone have any other ideas on linking. I was thinking maybe RF, like some 420 mobiles, or WIFI like with Ubiquiti or something similar.

    Also, where should I place the ATAC. In the center of a hub and spoke type configuration, or at one of the sites?

    I know I need some GPSDOs, but how many.

    Not that I think I will get a third site (though that is kinda in the works) but how easy will it be to add a third, or more quantars.

    Never mind all the setup I will have to do, which I am sure I will be asking questions about, though I have read a few threads hear dealing with Quantar and ATAC setup, very few deal with Simulcast but are usually multicast.

    This is just the start of this endeavor. Thanks for any suggestions for this early stage of planning.

    Michael


  2. #2
    Join Date
    Mar 08, 2014
    Location
    Florida
    Posts
    605
    Thanks
    326
    Thanked 536 Times in 290 Posts

    Default

    Quote Originally Posted by wiredwrx View Post
    After waiting years for a site (see some of my old posts) I was recently lucky enough to put machine up in a fairly awesome site. As luck would have it, I have sourced a second site, which should extend the coverage a bunch, but I only have one repeater pair right now. So simulcast it is. I do have the 2 quantars, a couple or three Ciscos, several 4 wire wireline cards and V24 modems, and an ATAC3K with what I believe to be 3 8wire cards, and I would assume modems, if that is needed (The ATAC should arrive in a couple of days.)

    I believe I need to avoid the public interwebs to link the quantars to the ATAC, though I have read mention of a private VPN, which I know very little about, but can read up on if that is a viable solution for linking.

    Anyone have any other ideas on linking. I was thinking maybe RF, like some 420 mobiles, or WIFI like with Ubiquiti or something similar.

    Also, where should I place the ATAC. In the center of a hub and spoke type configuration, or at one of the sites?

    I know I need some GPSDOs, but how many.

    Not that I think I will get a third site (though that is kinda in the works) but how easy will it be to add a third, or more quantars.

    Never mind all the setup I will have to do, which I am sure I will be asking questions about, though I have read a few threads hear dealing with Quantar and ATAC setup, very few deal with Simulcast but are usually multicast.

    This is just the start of this endeavor. Thanks for any suggestions for this early stage of planning.

    Michael
    How far apart are these two sites? Are you expecting coverage overlap? What mode, P25 or Analog?

    Sent from my SM-T350 using Tapatalk

  3. #3
    Join Date
    Jul 11, 2012
    Location
    HTX
    Posts
    1,086
    Thanks
    1,002
    Thanked 1,497 Times in 650 Posts
    Country: United States

    Default

    Most of the information here regarding Quantar and AstroTAC linking is still valid. Yes, you can colocate the ATAC at one of your Quantar sites, and even use the same 10 MHz reference for both.

    Latency and jitter are why all of the backhaul has to be over private IP. On analog it will just sound weird, but on P25 it will completely wreck the outbound signal. If all of your sites are in unlicensed microwave range OR if you have a private IP network to piggyback off of you're golden.

    I would strongly recommend that you take the same approach that Motorola, Harris, and other large system vendors take and "stage" your entire system on the bench and make sure everything is working 100% before you start deploying it. You can start by directly linking all of your Quantars to the ATAC with V.24 crossover, then introducing the Cisco routers and IP backhaul into the mix, then finally adding the unlicensed microwave radios or simulating your borrowed IP backhaul network with a lab switch and router.
    "The Girl Scouts found several hungry REACT members at the finish line..."

  4. The Following 3 Users Say Thank You to motorola_otaku For This Useful Post:

    Avery Johannssenn (Aug 18, 2019),crazyboy (Aug 17, 2019),Motoballa (Aug 30, 2019)

  5. #4
    Join Date
    Jun 26, 2019
    Location
    Australia
    Posts
    28
    Thanks
    15
    Thanked 27 Times in 7 Posts
    Country: Australia

    Default

    Quote Originally Posted by wiredwrx View Post
    After waiting years for a site (see some of my old posts) I was recently lucky enough to put machine up in a fairly awesome site. As luck would have it, I have sourced a second site, which should extend the coverage a bunch, but I only have one repeater pair right now. So simulcast it is. I do have the 2 quantars, a couple or three Ciscos, several 4 wire wireline cards and V24 modems, and an ATAC3K with what I believe to be 3 8wire cards, and I would assume modems, if that is needed (The ATAC should arrive in a couple of days.)

    I believe I need to avoid the public interwebs to link the quantars to the ATAC, though I have read mention of a private VPN, which I know very little about, but can read up on if that is a viable solution for linking.

    Anyone have any other ideas on linking. I was thinking maybe RF, like some 420 mobiles, or WIFI like with Ubiquiti or something similar.

    Also, where should I place the ATAC. In the center of a hub and spoke type configuration, or at one of the sites?

    I know I need some GPSDOs, but how many.

    Not that I think I will get a third site (though that is kinda in the works) but how easy will it be to add a third, or more quantars.

    Never mind all the setup I will have to do, which I am sure I will be asking questions about, though I have read a few threads hear dealing with Quantar and ATAC setup, very few deal with Simulcast but are usually multicast.

    This is just the start of this endeavor. Thanks for any suggestions for this early stage of planning.

    Michael
    Hi Wiredwrx,

    No reason why you can't bridge your sites via the internet.

    The IPSec VPN Cisco router configs are not very intuitive, but rock solid once you get them up and running.

    I'm an ex-cisco engineer, and have designed and built some large (for Australia) Cisco router wide area networks incorporating IPSec, DMVPN and GETVPN.

    Happy to pass on pointers or reality-check configs.

    Regards,
    Phil

  6. The Following 2 Users Say Thank You to Phil For This Useful Post:

    Astro Spectra (Aug 17, 2019),Avery Johannssenn (Aug 18, 2019)

  7. #5
    Join Date
    Mar 20, 2014
    Posts
    507
    Thanks
    65
    Thanked 178 Times in 108 Posts

    Default

    Quote Originally Posted by RFI-EMI-GUY View Post
    How far apart are these two sites? Are you expecting coverage overlap? What mode, P25 or Analog?

    Sent from my SM-T350 using Tapatalk
    50 miles apart as the crow flies. I do expect some overlap. P25 almost exclusively.
    Last edited by Astro Spectra; Aug 17, 2019 at 06:42 PM.

  8. The Following User Says Thank You to wiredwrx For This Useful Post:

    mpron (Aug 23, 2019)

  9. #6
    Join Date
    Mar 20, 2014
    Posts
    507
    Thanks
    65
    Thanked 178 Times in 108 Posts

    Default

    Quote Originally Posted by motorola_otaku View Post
    Most of the information here regarding Quantar and AstroTAC linking is still valid. Yes, you can colocate the ATAC at one of your Quantar sites, and even use the same 10 MHz reference for both.

    Latency and jitter are why all of the backhaul has to be over private IP. On analog it will just sound weird, but on P25 it will completely wreck the outbound signal. If all of your sites are in unlicensed microwave range OR if you have a private IP network to piggyback off of you're golden.

    I would strongly recommend that you take the same approach that Motorola, Harris, and other large system vendors take and "stage" your entire system on the bench and make sure everything is working 100% before you start deploying it. You can start by directly linking all of your Quantars to the ATAC with V.24 crossover, then introducing the Cisco routers and IP backhaul into the mix, then finally adding the unlicensed microwave radios or simulating your borrowed IP backhaul network with a lab switch and router.
    Thanks for the advice, will definitely bench it all before deploying it.

  10. #7
    Join Date
    Mar 20, 2014
    Posts
    507
    Thanks
    65
    Thanked 178 Times in 108 Posts

    Default

    Quote Originally Posted by Phil View Post
    Hi Wiredwrx,

    No reason why you can't bridge your sites via the internet.

    The IPSec VPN Cisco router configs are not very intuitive, but rock solid once you get them up and running.

    I'm an ex-cisco engineer, and have designed and built some large (for Australia) Cisco router wide area networks incorporating IPSec, DMVPN and GETVPN.

    Happy to pass on pointers or reality-check configs.

    Regards,
    Phil
    That's awesome. As soon as I figure out what the abbreviations mean, I'll be hitting you up for help

  11. #8
    Join Date
    Mar 08, 2014
    Location
    Florida
    Posts
    605
    Thanks
    326
    Thanked 536 Times in 290 Posts

    Default

    Quote Originally Posted by wiredwrx View Post
    50 miles apart as the cros flies. I do expect some overlap. P25 almost exclusively.
    That is way too much site separation for simulcast. The overlap will have excessive distortion. You would be better off with multicast (with voter) or linking two separate repeaters ( no voter).

    Sent from my SM-T350 using Tapatalk

  12. The Following User Says Thank You to RFI-EMI-GUY For This Useful Post:

    motorola_otaku (Aug 19, 2019)

  13. #9
    Join Date
    Mar 20, 2014
    Posts
    507
    Thanks
    65
    Thanked 178 Times in 108 Posts

    Default

    Quote Originally Posted by RFI-EMI-GUY View Post
    That is way too much site separation for simulcast. The overlap will have excessive distortion. You would be better off with multicast (with voter) or linking two separate repeaters ( no voter).

    Sent from my SM-T350 using Tapatalk
    I see. Hmmmmm, How much is too much? What if I added a third Quantar in between the 2?

  14. #10
    Join Date
    Aug 15, 2019
    Posts
    61
    Thanks
    45
    Thanked 133 Times in 52 Posts
    Country: Australia

    Default

    Quote Originally Posted by wiredwrx View Post
    Hmmmmm, How much is too much?
    More than about 10-13 miles. Slightly more can be doable depending on environmental factors and with careful tuning of launch times, but 50 is completely unworkable.

  15. The Following User Says Thank You to syntrx For This Useful Post:

    motorola_otaku (Aug 19, 2019)

  16. #11
    Join Date
    Aug 15, 2019
    Posts
    61
    Thanks
    45
    Thanked 133 Times in 52 Posts
    Country: Australia

    Default

    Quote Originally Posted by RFI-EMI-GUY View Post
    You would be better off with multicast (with voter)
    This is what I would do. Single input frequency, two different output frequencies at each site.

    Signal from the voter gets transmitted on both output frequencies, and you'd use conventional voting scan on the mobiles to select the best output frequency as you drive around.

  17. The Following 2 Users Say Thank You to syntrx For This Useful Post:

    box (Aug 19, 2019),motorola_otaku (Aug 19, 2019)

  18. #12
    Join Date
    Jun 10, 2012
    Posts
    220
    Thanks
    27
    Thanked 212 Times in 72 Posts

    Default

    Google Inter Symbol Interference (ISI), you should find plenty of good material.

  19. The Following User Says Thank You to noaffiliatefan For This Useful Post:

    wiredwrx (Aug 19, 2019)

  20. #13
    Join Date
    Mar 20, 2014
    Posts
    507
    Thanks
    65
    Thanked 178 Times in 108 Posts

    Default

    Thanks. The coverage from the single site far exceeds that distance.

  21. #14
    Join Date
    Mar 20, 2014
    Posts
    507
    Thanks
    65
    Thanked 178 Times in 108 Posts

    Default

    Quote Originally Posted by syntrx View Post
    This is what I would do. Single input frequency, two different output frequencies at each site.

    Signal from the voter gets transmitted on both output frequencies, and you'd use conventional voting scan on the mobiles to select the best output frequency as you drive around.
    Was thinking about that, but frequency pairs are tough to come by, though maybe I could use a test pair, its not ideal. Now thinking about just adding a receiver site with voting, and keeping the high level machine, or, using directional antenna for transmit to focus the coverage where the simulation software shows no or little coverage with the transmit on the test pair, and using an Omni for receive. Hmmm, still in the thinking stages.

  22. #15
    Join Date
    Jun 10, 2012
    Posts
    220
    Thanks
    27
    Thanked 212 Times in 72 Posts

    Default

    Quote Originally Posted by wiredwrx View Post
    Thanks. The coverage from the single site far exceeds that distance.
    ISI needs to be looked at in terms of topography and desired coverage at the same time. In some cases it may actually be ok - and the idea of adding a site inbetween the two may also be a workable solution.

    You can check simulcast coverage in RadioMobile - CQPSK will do better than C4FM - I don't remember if RM compensates for the long symbol length or not.

  23. #16
    Join Date
    Jul 11, 2012
    Location
    HTX
    Posts
    1,086
    Thanks
    1,002
    Thanked 1,497 Times in 650 Posts
    Country: United States

    Default

    Quote Originally Posted by syntrx View Post
    This is what I would do. Single input frequency, two different output frequencies at each site.

    Signal from the voter gets transmitted on both output frequencies, and you'd use conventional voting scan on the mobiles to select the best output frequency as you drive around.
    If you do elect to go with a multicast voted system designed this way your complexity decreases considerably (no 10 MHz references needed, for starters) and you CAN use public IP for backhaul, with the understanding that there may be some variable delay in site links and users may "hear themselves" when they dekey.
    "The Girl Scouts found several hungry REACT members at the finish line..."

  24. The Following 3 Users Say Thank You to motorola_otaku For This Useful Post:

    Avery Johannssenn (Aug 20, 2019),RFI-EMI-GUY (Aug 22, 2019),syntrx (Aug 20, 2019)

  25. #17
    Join Date
    Oct 28, 2013
    Posts
    31
    Thanks
    0
    Thanked 18 Times in 11 Posts

    Default

    Simulcast can be done and over RF is an option.

    Will need additional quantar's to complete the links along with V.24 modems and GPS Frequency/PPS sources

    Remote Site to Comparator Hub

    Quantar - Freq's of interest in digital ops
    Quantar - Link freq back to comparator in analog mode
    Modem - V.24 link from Qtar with Freq's of interest

    Modem has to be configured in 4-wire leased line. That will push the audio to the link quantar wireline port.

    This will link to a same link quantar at the comparator site.

    The modems will link up and pass V.24 from the remote site to the comparator hub site.

    You will need a GPS source at the remote and hub sites for timing (and if UHF for frequency reference)


    Complete this for all of your sites and then hit the align simulcast in the comparator.

    C4FM runs great on this for a couple of customers in the Fed world that I used to take care of.

    CoD

  26. The Following 2 Users Say Thank You to ChartoftheDistrict For This Useful Post:

    Avery Johannssenn (Sep 18, 2019),motorola_otaku (Aug 22, 2019)

  27. #18
    Join Date
    Jul 11, 2012
    Location
    HTX
    Posts
    1,086
    Thanks
    1,002
    Thanked 1,497 Times in 650 Posts
    Country: United States

    Default

    In that scenario, does the link Quantar transmit continuously or only when audio is being passed?
    "The Girl Scouts found several hungry REACT members at the finish line..."

  28. #19
    Join Date
    Jan 03, 2015
    Location
    Somewhere in the Lone Star Republic
    Posts
    257
    Thanks
    50
    Thanked 108 Times in 66 Posts
    Country: United States

    Default

    I've been playing around with KISS mode data radios here lately. Things like using them for IP connections (via ax25) and intercommunication with some PLCs I have laying about. Can't remember if the V.24 interface supports 3-wire RS-232 (TXD, RXD, GND) but that would also be an option if they did as well. Something like a the GE iNET or Maxon TPD-2400 (something capable of serial data speeds 9600 bps or higher).

  29. #20
    Astro Spectra's Avatar
    Astro Spectra is offline T¹ ĘS Ų - Moderator
    CS Forums $upporter
    Join Date
    Nov 22, 2012
    Posts
    837
    Thanks
    286
    Thanked 510 Times in 262 Posts
    Country: Great Britain

    Default

    Data radios are async and don't support the V.24 sync used by the Astro infrastructure family.
    It is a fine thing to be honest, but it is also very important to be right

  30. The Following User Says Thank You to Astro Spectra For This Useful Post:

    motorola_otaku (Sep 04, 2019)

  31. #21
    Join Date
    Jul 18, 2013
    Posts
    47
    Thanks
    4
    Thanked 14 Times in 11 Posts

    Default

    I have dealt with P25 Simulcast public safety system that had its back haul on a set of Lynx unlicensed microwave (2.4/5Ghz) They worked pretty good, there was the occasional hiccups in it from time to time. They can be had very cheap these days and would work great for you if you are not in a large metro area.

    Here is some info on the units http://www.airlinx.com/products.cfm/...t/1-162-61.htm

  32. The Following 2 Users Say Thank You to jettajoey For This Useful Post:

    motorola_otaku (Sep 25, 2019),RFI-EMI-GUY (Sep 17, 2019)

  33. #22
    Join Date
    May 12, 2012
    Posts
    532
    Thanks
    898
    Thanked 302 Times in 165 Posts

    Default

    I was assuming this was for Amateur radio, is that correct??????

    If so, I would not worry about frequency coordination, find a clear pair and put em' up. Just realize you may have to change if interference with a coordinated system. If no complaints for some time, coordinate it.
    Radio Referenced...Those who think they know it all are very annoying to those of use who do.

  34. #23
    Join Date
    Oct 28, 2013
    Posts
    31
    Thanks
    0
    Thanked 18 Times in 11 Posts

    Default

    Quote Originally Posted by motorola_otaku View Post
    In that scenario, does the link Quantar transmit continuously or only when audio is being passed?
    Yes,

    The transmit Q-tar at site 1 transmits 100% and the same for the Q-tar a site 2.

    This way the analog audio full-duplex bridge over the RF link carries the V.24 modem traffic end-to-end

    The Telenetic's, Raymar, UDS or similar modems are required for the Synchronous Serial traffic at 9.6 kbps per the Moto spec

    If you don't have quantars laying around for the link, you can use just about any radio configuration for transmit and receive such as a couple of spectra mobiles and mobile duplexers or your favorite swap meet box-o-radio sale.

    CoD

  35. The Following User Says Thank You to ChartoftheDistrict For This Useful Post:

    motorola_otaku (Sep 25, 2019)