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Thread: Quantar dual reciever?

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    Default Quantar dual reciever?

    Ive noticed the control card on the Quantar has two RX activity indicators and there is two spaces for receivers, I was not able to find any info on this easily in the instruction manual. Has anyone here seen this kind of setup or have any info on it?


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    There's no setup to it, really. You plug in the 2nd receiver, then go into the hardware conf screen in the CPS and it should already be there from auto-detect, AFAIK. We use them for ham receive sites that auto-scan VHF and UHF channels then send back the info on a 403-430 backhaul.

    In the channel params screen you can enter a value in the RX field that is in the range of either receiver and it will auto-select, I think or you have to select which receiver, I can't quite remember. It's been a while since I played with them but as I recall there is really no big deal to getting them to play properly with the new RX. You should be able to figure it out easily.
    Last edited by Alpha; Dec 07, 2012 at 07:27 AM.

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    I will have to play with it at some point. Trapa and I are looking for a way to deal with a coverage gap at a hotel, the easiest way would be to have a second receiver and aim a yagi at the dead spot. This would require the behavior of the Quantar to be voting instead of say first receiver to receive. One would think that it would be that intelligent, but alas, it is Motorola we are talking about.

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    Yeah, why include that as a feature when you can sell 'em a $12,000 voter?

    There is a nice cheap 2-channel ham grade one made by Doug Hall. It actually works pretty well if you balance the audio properly. I have used them in some small-town PD and FD's that have coverage gaps, etc.

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    Im assuming you don't know what the behavior is with two receivers?

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    No, I know exactly how it works, perhaps I was unclear. You DON'T get voting. You can select either receiver in a given channel, and then if you want to you can scan between the two (ore more) channels. That's about it, as I said their solution to what you want to do is for you to buy a link receiver and a voter, for about $15K total. I have done this with a mobile and a Doug Hall unit for about $500.00 total. Simple scanning won't quite do the trick because if you're weak into one receiver, it may stop scan anyway. You might turn the squelch way up but that's not a good solution, you really want a noise quality-based voter of some kind here.

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    Sorry, I derped. Theres some astrotac voters on ebay, might try one.

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    Keep in mind AstroTAC voters don't work with Analog, or at least not very well, so I have heard. You would need an Astro link receiver for it to work at all, AFAIK. The problem is that AstroTAC voters/receivers assume digital to be the default mode. That means the receivers are like modems that are always on-line and trained, and when an analog transmission comes along, it has to drop the link and re-establish it as an analog channel. This causes truncation of the signal (you will lose the first word or two).

    This problem goes back to the previous generation DigiTAC voters. They were the opposite in the way they worked in that they were expecting analog signals, and when someone keyed in SecureNet (digital) it had to drop the analog link and establish a digital one. To prevent truncation they would buffer the signal until the voter had a clear picture of what was going on, then would shift out the digital data after everything got time-aligned.

    The problem is when the AstroTAC, working oppositely, went from it's default digital to analog modes, it does not buffer the signal, so there is a possibility of initial truncation of the user's message. This could be disastrous, as "DON'T SHOOT..." missing the first word is VERY different!

    The need for a full-time continuously established link to the receivers is also why there are few to no hams using AstroTACs - they need a full-time full-duplex path between the voter and the link RX, so you really have to use a dedicated phone line for this link. It doesn't lend itself well to using RF (radio) links due to the full-time nature of the connection, even when the system is idling between transmissions. Most hams are cheap bastards that can't afford dedicated telephone lines between their receive sites and their main TX hub but commercial or government entities have no problem paying monthly for dedicated data lines to their receiver sites.
    Last edited by Alpha; Dec 08, 2012 at 03:09 AM.

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    Do you know if any documentation exists on the V.24 protocol used in this case? I have mused about making a voter in software.

    Edit:
    Also, I am aware of how derp the AstroTAC voter is, its not an issue with the setup.

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    derp dude?

    Astro sync V.24 is basically HDLC framed LDUs.

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    I'm a looken, but I can't see 'em

    Quote Originally Posted by kayfox View Post
    Theres some astrotac voters on ebay, might try one.

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    OK so for those over 21, derp = http://knowyourmeme.com/memes/derp

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    Hey Spectra - what did you use to monitor the V.24 interface? I'm looking for something that can hook in so I can have a look at the protocol and figure out whats going on..

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    HP J2301 but much more interesting would be some hardware to get HDLC into Wireshark because (as you well know) there are both HDLC and P25 tools to play with once it's in the 'shark.

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    Quote Originally Posted by Astro Spectra View Post
    HP J2301 but much more interesting would be some hardware to get HDLC into Wireshark because (as you well know) there are both HDLC and P25 tools to play with once it's in the 'shark.
    Im probably going to take a stab at this after the new year.

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    "Most hams are cheap bastards" I resemble that remark!!!

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    Quote Originally Posted by viper314 View Post
    "Most hams are cheap bastards" I resemble that remark!!!
    Heh, so do I. I can say it 'cos I am one...