Quantar in mixed mode
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Quantar in mixed mode
Newbie to digital radios here. I'm curious about using a Quantar for both digital and analog operation. I've been experimenting with the Quantar and a couple of XTL5K mobiles. I've tinkered with having the Quantar on one freq w/ Mixed Mode setting (I'll call it Method 1), and also tried setting up two seperate channels w/ close TX freqs (one Astro, one Analog) and enabling the scanning RX function (Method 2). Both methods are working, but when using the 2nd method the analog mobile obviously gets no indication (no busy LED) that the digital channel is being used, and vice versa. On mixed mode, of course you do you do get a busy LED. My customer thinks he needs to be set up with the 2nd method. I can see advantages of having it set that way as far as the console operation back at dispatch is concerned, but I'm not sure about mobile to mobile operation. The obvious answer would be "the mobiles can scan the two channels", but this customer will still have some analog only units out in the field, so those units obviously won't be able to receive/scan the digital channel from the repeater. Or will they? I suppose the analog only radios could have the digital channel programmed in and then scan so they would at least see the carrier (making sure of course they are on hook so they don't here the digital modulation which is just noise to the analog unit). Thoughts? As I said I'm a newbie to the digital ins and outs, so be gentle.
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If at first you don't succeed,.....then maybe skydiving isn't for you.
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If at first you don't succeed,.....then maybe skydiving isn't for you.
You probably notice a little more of a key up delay with your 2nd "scanning method", which may not be much of a problem when there's low/moderate traffic on the system. But if a major event occurs, where the amount of radio traffic goes way up, your users will greatly increase their chances of "doubling" with other users of both modes.
Unfortunately, there's no good Busy Channel Lockout function on the mobiles/portables that works well with mixed mode. The best you can do is program the digital channels in the mobiles/portables as mixed mode RX using an incorrect PL/DPL, so the busy light will illuminate whenever there's any activity on the channel. The users will need to be trained to check that light before transmitting, though.
Most Motorola digital radios will not show a busy light for analog activity on a digital channel unless you use mixed mode RX with an incorrect PL/DPL. Of course if you want the digital capable radios to hear both analog and digital, you can use the correct PL/DPL on RX.
In digital, I'd also recommend taking advantage of the "Smart PTT" feature. On the XTS/XTL5000 series, you can use "Inhibit on Status Symbols", which generally works best to reduce the chances of digital users doubling with other digital users. Use of this option will allow the digital radios to transmit while the wireline connected dispatcher is talking (assuming they're connected via a full-duplex connection with a DIU), but prevent transmission while other digital mobiles are talking.
The other option is "Inhibit on Correct NAC", which is very similar, but will also prevent transmission when the dispatcher is talking. This would be desired if the dispatcher didn't have a full-duplex setup.
Of course either of these options do nothing to prevent the digital users from doubling with analog transmissions. While you might be able to use an "Inhibit on Carrier" option, you'll probably find that this prevents transmissions at undesired times, such as when some weak noise/interference is present on the channel.
I'd do everything you can to prevent doubling on the digital channels, since it's not obvious when this is happening. That is, it's often hard to tell whether a broken/garbled transmission was a result of a "double", or if it was just weak into the repeater.
If there's going to be a lot of traffic on both analog and digital, I would expect some major problems with doubling and whatnot. However, if one of the two modes won't be used all that often, you might be fine. Especially if this isn't a public safety system.
Unfortunately, there's no good Busy Channel Lockout function on the mobiles/portables that works well with mixed mode. The best you can do is program the digital channels in the mobiles/portables as mixed mode RX using an incorrect PL/DPL, so the busy light will illuminate whenever there's any activity on the channel. The users will need to be trained to check that light before transmitting, though.
Most Motorola digital radios will not show a busy light for analog activity on a digital channel unless you use mixed mode RX with an incorrect PL/DPL. Of course if you want the digital capable radios to hear both analog and digital, you can use the correct PL/DPL on RX.
In digital, I'd also recommend taking advantage of the "Smart PTT" feature. On the XTS/XTL5000 series, you can use "Inhibit on Status Symbols", which generally works best to reduce the chances of digital users doubling with other digital users. Use of this option will allow the digital radios to transmit while the wireline connected dispatcher is talking (assuming they're connected via a full-duplex connection with a DIU), but prevent transmission while other digital mobiles are talking.
The other option is "Inhibit on Correct NAC", which is very similar, but will also prevent transmission when the dispatcher is talking. This would be desired if the dispatcher didn't have a full-duplex setup.
Of course either of these options do nothing to prevent the digital users from doubling with analog transmissions. While you might be able to use an "Inhibit on Carrier" option, you'll probably find that this prevents transmissions at undesired times, such as when some weak noise/interference is present on the channel.
I'd do everything you can to prevent doubling on the digital channels, since it's not obvious when this is happening. That is, it's often hard to tell whether a broken/garbled transmission was a result of a "double", or if it was just weak into the repeater.
If there's going to be a lot of traffic on both analog and digital, I would expect some major problems with doubling and whatnot. However, if one of the two modes won't be used all that often, you might be fine. Especially if this isn't a public safety system.
Thanks for the reply. Unfortunately, this is a public safety system. They are aware of the drawbacks listed though.515 wrote:You probably notice a little more of a key up delay with your 2nd "scanning method", which may not be much of a problem when there's low/moderate traffic on the system. But if a major event occurs, where the amount of radio traffic goes way up, your users will greatly increase their chances of "doubling" with other users of both modes.
Unfortunately, there's no good Busy Channel Lockout function on the mobiles/portables that works well with mixed mode. The best you can do is program the digital channels in the mobiles/portables as mixed mode RX using an incorrect PL/DPL, so the busy light will illuminate whenever there's any activity on the channel. The users will need to be trained to check that light before transmitting, though.
Most Motorola digital radios will not show a busy light for analog activity on a digital channel unless you use mixed mode RX with an incorrect PL/DPL. Of course if you want the digital capable radios to hear both analog and digital, you can use the correct PL/DPL on RX.
In digital, I'd also recommend taking advantage of the "Smart PTT" feature. On the XTS/XTL5000 series, you can use "Inhibit on Status Symbols", which generally works best to reduce the chances of digital users doubling with other digital users. Use of this option will allow the digital radios to transmit while the wireline connected dispatcher is talking (assuming they're connected via a full-duplex connection with a DIU), but prevent transmission while other digital mobiles are talking.
The other option is "Inhibit on Correct NAC", which is very similar, but will also prevent transmission when the dispatcher is talking. This would be desired if the dispatcher didn't have a full-duplex setup.
Of course either of these options do nothing to prevent the digital users from doubling with analog transmissions. While you might be able to use an "Inhibit on Carrier" option, you'll probably find that this prevents transmissions at undesired times, such as when some weak noise/interference is present on the channel.
I'd do everything you can to prevent doubling on the digital channels, since it's not obvious when this is happening. That is, it's often hard to tell whether a broken/garbled transmission was a result of a "double", or if it was just weak into the repeater.
If there's going to be a lot of traffic on both analog and digital, I would expect some major problems with doubling and whatnot. However, if one of the two modes won't be used all that often, you might be fine. Especially if this isn't a public safety system.
Another problem I predicted about having two seperate channels did occur this morning when I tried it. The duplexer isn't tuned for the 2nd (new) freq, so the Quantar PA cuts back when they TX on that channel. The old freq is 1XX.700, and the new one is 1XX.5875. I'm wondering if the duplexer could be tuned in between or not. As I don't know how far off it can be before the Quantar sees a mismatch I'm going to call Moto after lunch to see what they think.
.
.
.
.
If at first you don't succeed,.....then maybe skydiving isn't for you.
.
.
.
If at first you don't succeed,.....then maybe skydiving isn't for you.