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PAGE with Astro Spectra/Saber

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tim

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Hi Folks,

I've got a mixed mode repeater here, and was playing with the PAGE function on the Spectra and Saber.

In the analog mode, MDC page works great from/to both units. However in the Astro mode, they don't want to link while in the repeater mode. In direct, they page each other fine. I figure it's something in the response time through the repeater that is the issue.

I've got the scan setup so that the selected channel is priority (no searching of other channels). The MDC info is 500ms pretime, 900ms ACK pretime, 100ms Inter-packet. The Astro response time is 3300ms, minimum response timer 900ms. On the data page, 750ms for frame syc seek, 50ms tx short, 2000ms tx long, 1000, tx resp.

Oh, another question - the CALL feature seems to only do a 1 way page to the desired unit. Wouldn't you likely always want to have some kind of ACK, just to know that the unit got the notification?

Thanks,

Tim
 

Mars

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Hi Folks,

I've got a mixed mode repeater here, and was playing with the PAGE function on the Spectra and Saber.
What kind of repeater? A Quantar or a passive (i.e. Maxtracs back-to-back) repeater?

Oh, another question - the CALL feature seems to only do a 1 way page to the desired unit. Wouldn't you likely always want to have some kind of ACK, just to know that the unit got the notification?
It's operating as it should. That's what a CALL does. If you want to verify or check if the other unit is on the network/repeater, you would use the PAGE feature or the Radio Check (from console) feature.
 
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tim

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20.10.013

But it pages fine through the repeater if the radios are not scanning.
 

Mars

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Well then it's working fine! How is the radio supposed to receive a PAGE packet, if it's not listening on the repeater (because the radio is in scan-mode) when the packet is relayed through the repeater?

PAGE will try a few times, then give up. But again, if the radio is in scan mode, it WILL miss the PAGE packet.

Best way to PAGE a radio which may be in scan mode:

- Set Quantar up with a hang-time of at least 3 seconds
- Keep hitting the PTT button on the PAGEing radio, sending multiple PAGE packets until you receive an acknowledgement.

SCAN is not recommended for mission-critical applications. Use separate radios instead.
 
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tim

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Hmmm, I think we have a failure to communicate! :)

Note that this works fine in Analog MDC page (scanning).

Each radio is scanning, although it is on the desired channel to be paged on. The scan mode is on 'selected channel', so unless another scan member has come into play (under these tests, none has), then it's listening to the desired channel.

I believe it's some timing constant on the radios that I have set wrong.

Totally agree - when I'm IC, I <always> have more than one radio. Scan sux cuz you always miss the most important part of the message! :)
 

Magnus

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If you are in scan, your radio is not listening to the channel you are on, its scanning through the list looking for signals. MDC probably takes longer and has a different preamble time.
 

Mars

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ASTRO paging packets are like 20ms long or something. Very quick. You will not receive them unless you're sitting on the repeater. This is why I suggested you set the hangtime for the Quantar at a minimum of 3 seconds, so your radio will stop on it (while scanning) then perhaps receive the page in a subsequent paging attempt.

Also, if your radio is set up for "selected channel" as the talkback type, it will not send the ACK packet, if you're manually parked somewhere else. Talkback scan is essential in this type of configuration.

Put your scanner on a simplex frequency with the squelch opened up; ASTRO radio on same. Send a page packet from ASTRO radio. Did you hear the page? It's very brief. That's what the secondary radio has to hear on the repeater. If it misses it, paging will not work.

ASTRO signalling has many advantages -- especially on trunking (doesn't tie up a voice channel), but you should not scan conventional ASTRO channels unless it's non-critical (hammy) stuff.

Sorry if I sound condescending or anything like that -- not my intention. It's just important for mission-critical communications to work properly. Scan is not something anyone should ever use in this type of setup. Use multiple radios instead.
 

Alpha

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Try increasing the Astro preamble from 80 to 120 ms - I always do that as a "standard" mod for all the APCO P-25 channels I program and it enhances the reliability of getting the signal through the repeater - it takes a few more ms for the repeater to stabilize than when talking simplex.

Otherwise, what Mars said is true - if it's a repeat channel in "talkaround" mode, ACKS are sent in repeat mode regardless of talkaround status. Only a true simplex channel will send the ACKS back on the same frequency...
 
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tim

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No problem Mars, - this isn't for our public safety system, it's for the guys on the ham repeater here. More playing & learning about Astro stuff.

I'll play around with some of the scan settings in the radios & see if I can make it play. Funny how MDC works fine through both radios & repeater. I know it's a longer data packet (time-wise), but the scan operation of both radios is unchanged between Astro & analog. <shrug>
 
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tim

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Hi Alpha,

Thanks - I tried the preamble up to 120, but still didn't make it work.

In the 'past', when Astro radios were the main radios, did no one 'page' through a repeater while the units were scanning?

Seems since MDC works fine while the users are scanning, they would have complained that the Astro equivalent would have been a 'downgrade' from what they were using.

Obviously, all the users would have had to keep their radios on primary (for response back to the paging unit).
 

cyrus

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Most commercial users have no reason to scan especially in public safety who are the biggest purchasers of P25 systems.
 
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tim

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That might work in the cities, but out here in the boonies, the deputies scan several channels, including their 'innercity' yak channel. The county is so large that it takes 3 repeaters to do all the coverage.

Of course they are just now getting equipment that can do P25. But they plan on using Analog for quite a while.
 

Mars

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I know this is easier said, than done. But for technical reasons:

What you want to accomplish here would be MUCH MORE RELIABLE if it was a trunking setup. The paging packets are sent/received (OSW/ISW) on the control channel, which the radio is monitoring at all idle times, and the scan (active TG status) is also sent via the control channel. You could be scanning and listening for page/call packets, at the same time. The radio is not off in "la-la land" scanning multiple conventional repeaters.

Another benefit with trunking is a page packet doesn't tie up a voice channel, and a call (private call) will bonk if the radio ID (RID) you're attempting to call is not on the network -- letting you now they're not online, or out-of-range. A call on a conventional repeater will go unacknowledged.
 
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