Avtec, COR and Tone Remote Control?

[chris.a.terry]

Howdy everyone,
New to the forums but I was turned on from a local radio vendor who said he lurks here for some information.

We recently implemented the Avtec Scout console system. So far so good with the installation however some issues have come up.

Our jurisdiction does not have a functioning microwave system at this time so we are stuck using a UHF link from the PSAP to the controller hilltop which uses COR and HLGT/FT/LLGT to key up our hilltops. I am using the Avtec Outpost to pass the TRC, but I am still having to use the old Gaitronic ITA2000A's for the COR tone.

I believe that these Gaitronic boxes are causing an issue with department paging as well as quality.

Has anyone out there had any experience with Avtec?
Has anyone out there had any experience using Avtec without a microwave PSAP-to-hilltop setup?
Has anyone out there using Avtec been successful in getting their outpost to do COR and TRC at the same time?

I would greatly appreciate any input anyone has and I promise to help out anyone else wherever I can!

[kb4mdz]

Forgive me for speaking out of turn; I'm not much up on the Avtec SCOUT system, but maybe if you elaborate on how your system is constructed, some appropriate info will fall out.

You say you're using the Outpost; but also a UHF link from the PSAP to the hilltop; and then an ITA2000A 'for the COR';

Does the Outpost live at the PSAP, & key up the UHF Link? Or is the Outpost some how at the hilltop? And I don't understand what is meant by 'for the COR tone'. I can infer that the radio on the hilltop has a COR (Carrier Operated Relay; aka Receiver Unsquelched, aka something else; ) that goes into the ITA2000A; but I'm not sure what it's for or how it's meant to operate in your instance.

And FWIW, was your dept. paging OK before the Scout system went in, was there a problem existing already? If the former, then the Scout system may be suspect as having 'interesting artifacts' about its installation. If there was an existing problem before the console installation, it needs to be separated as a different item.

Separate your variables.

[Jim202]

Howdy everyone,
New to the forums but I was turned on from a local radio vendor who said he lurks here for some information.

We recently implemented the Avtec Scout console system. So far so good with the installation however some issues have come up.

Our jurisdiction does not have a functioning microwave system at this time so we are stuck using a UHF link from the PSAP to the controller hilltop which uses COR and HLGT/FT/LLGT to key up our hilltops. I am using the Avtec Outpost to pass the TRC, but I am still having to use the old Gaitronic ITA2000A's for the COR tone.

I believe that these Gaitronic boxes are causing an issue with department paging as well as quality.

Has anyone out there had any experience with Avtec?
Has anyone out there had any experience using Avtec without a microwave PSAP-to-hilltop setup?
Has anyone out there using Avtec been successful in getting their outpost to do COR and TRC at the same time?

I would greatly appreciate any input anyone has and I promise to help out anyone else wherever I can!

As the other poster requested, you need to elaborate as to just what your issue is.

Issues with paging are many. the most common is you hear the tones being sent over the radio, but the pager doesn't respond. Generally this is due to the audio being put into compression and this causes the tones to be distorted enough to not be decoded by the pagers.

It is OK to use radio links, but they can not have any audio compression. If your sending tones from a control station, make sure that they are down at the 3 KHz point for a 5 KHz deviated channel. Then when they come out of the link receiver, they are fed into the normal base transmitter. Again make sure they come out at the 3 KHz level from your normal base. If the tone deviation goes higher, you stand a good chance of them going into compression and causing distortion. Another problems is the roll off of the radios and the way the audio is passed through them. You need to do a frequency sweep of the audio tones and make sure your not rolling off either the high end or the low end. This also causes problems with paging tones. You will probably find that the low end tones are probably very low and the high end tones are normal. This generally is due to the transmitter audio circuit filtering out the low tones. The audio needs to be flat from the time it leaves the page encoder, till it comes out the base transmitter.

Most transmitters are not set up to handle paging tones. Sounds like you may be in this boat. Look at what the tones are using. You will probably need some help and a couple of service monitors. Start with the control point and measure what that transmitter is doing to the tones. You will need to generate a steady tone for maybe 5 to 10 seconds to let the service monitor settle down in the measurement. Start at the lowest paging tone you use and walk up to the highest tone. You will probably find some of your trouble right there at the dispatch point.

Depending on what your using for a link radio, it will determine where you pick off the audio to pass it on to the base station. Hopefully your audio is flat at that point. Then you need some way to adjust the level going into the transmitter. Now have the dispatch point start all over again and go with the lowest tone. Measure what the base transmitter does with it. Then walk up to the highest tone. Make a plot of your results and see just how much of a roll off you have. You might have to make some component changes to try and flatten out your results.

This is going to take some time and effort. But from what your saying, it doesn't work now, so anything you do will only make it better.

Jim

[Bill_G]

If the UHF link and ITA2000 combo worked before, it should work now. Probably a levels issue from the Scout. But, you have not told us what the failure is.

[chris.a.terry]

Terribly sorry, everyone. I thought this thing would email me on response but it did not. I'll attempt to answer questions one-by one.

Does the Outpost live at the PSAP, & key up the UHF Link? Or is the Outpost some how at the hilltop?

Yes, the outpost resides in the PSAP right now. It uses the UHF link to key-up the hilltop.

And I don't understand what is meant by 'for the COR tone'. I can infer that the radio on the hilltop has a COR (Carrier Operated Relay; aka Receiver Unsquelched, aka something else; ) that goes into the ITA2000A; but I'm not sure what it's for or how it's meant to operate in your instance.

I'm apologize for my misstatement. The ITA2000A is being used to generate a COR that tells the hilltop to key up.

And FWIW, was your dept. paging OK before the Scout system went in, was there a problem existing already?

That kind of depends on who you ask. I thought the paging worked well enough, ask some field units and they will always say that it could be better. The pagers activated and voice was transmitted, basically no more and no less. Now, pagers will activate and no voice will go or pagers may not activate at all.

Thanks for your quick reply!

[chris.a.terry]

As the other poster requested, you need to elaborate as to just what your issue is.

I'm going to try to!

Issues with paging are many. the most common is you hear the tones being sent over the radio, but the pager doesn't respond. Generally this is due to the audio being put into compression and this causes the tones to be distorted enough to not be decoded by the pagers. It is OK to use radio links, but they can not have any audio compression. If your sending tones from a control station, make sure that they are down at the 3 KHz point for a 5 KHz deviated channel. Then when they come out of the link receiver, they are fed into the normal base transmitter. Again make sure they come out at the 3 KHz level from your normal base. If the tone deviation goes higher, you stand a good chance of them going into compression and causing distortion.

Ok, so if the tone generator is causing a 5khz tone to hit the link then it can distort it?

Another problems is the roll off of the radios and the way the audio is passed through them. You need to do a frequency sweep of the audio tones and make sure your not rolling off either the high end or the low end. This also causes problems with paging tones. You will probably find that the low end tones are probably very low and the high end tones are normal. This generally is due to the transmitter audio circuit filtering out the low tones. The audio needs to be flat from the time it leaves the page encoder, till it comes out the base transmitter.

I never thought to test this. Seems easy enough and I can do that without any special equipment. Thanks!

Most transmitters are not set up to handle paging tones. Sounds like you may be in this boat. Look at what the tones are using. You will probably need some help and a couple of service monitors. Start with the control point and measure what that transmitter is doing to the tones. You will need to generate a steady tone for maybe 5 to 10 seconds to let the service monitor settle down in the measurement. Start at the lowest paging tone you use and walk up to the highest tone. You will probably find some of your trouble right there at the dispatch point.

I have access to a couple of old linemans so I may be able to set up some listening points. Would you suggest before the Gaitronics and after the JPS voter?

Depending on what your using for a link radio, it will determine where you pick off the audio to pass it on to the base station. Hopefully your audio is flat at that point. Then you need some way to adjust the level going into the transmitter. Now have the dispatch point start all over again and go with the lowest tone. Measure what the base transmitter does with it. Then walk up to the highest tone. Make a plot of your results and see just how much of a roll off you have. You might have to make some component changes to try and flatten out your results.

My audio seems to be fairly flat going across the UHF link, but that is just using SSI and a squelch knob. I might have to get the lineman to the hilltop to see what its doing up there.

This is going to take some time and effort. But from what your saying, it doesn't work now, so anything you do will only make it better.

Jim, thanks for your help. It is working right now. Working inconsistently, but working. I can't seem to recreate the issues that I am having so that is why it is hard for me to accurately describe them.

Again, thanks for your quick reply!

[chris.a.terry]

If the UHF link and ITA2000 combo worked before, it should work now. Probably a levels issue from the Scout. But, you have not told us what the failure is.

Thanks for your quick reply, Bill.

I have attempted to "tweak" the levels for paging but Avtec really only gives you one places to adjust the level and I've tried a number of different settings to no avail.

The failure that I am running into is the inability to consistently page my departments. We left an old ModuComm system (which was beginning to fail hard on us) and moved to this IP based system with dreams of modularity and easy expandability. Unfortunately we found that this doesn't really play well when you still have some... legacy... infrastructure. We are working hard to upgrade our infrastructure but I'm going to become a martyr if my VFD's pagers don't go off and sound like I'm in the same room as them!

[kb4mdz]

OK, here's my dire warning. Be careful how you 'tweak'. To truly do this, you need a service monitor, and to know how to use it, and what its measurements mean.

And as an aside, I've seen a few times where the complaint is 'pagers don't work/go off/whatever'. Could be the transmitter a) power b)frequency tolerance, c) tone deviation d)pager sensitivity, e) [insert several other possible problmes here...]

Has anyone done any individual testing on the pagers, for basic RF sensitivity, and decoding? For example, let's say a pager is an older Minitor II; crystal controlled. If the crystal has drifted in frequency by a couple of kilohertz, it will probably alert in high-RF fields, close to the transmitter, but no reliably out on the fringe; whereas a properly tuned & aligned pager should alert well.

So, when were any of the pagers tested?

And tone levels are very important; while there is some latitude in the deviation the tones produce, too low or too high deviation will cause havoc. Too low deviation, and the various filters (in the case of the Minitor II, actual filter circuits that plug in to the pager) won't respond properly, thus won't decode properly. Too high deviation, and the tones get distorted, and also rather difficult for the pagers' circuits to decode.

The country, no, the world, is probably filled with two-tone paging systems that are way out of spec for frequency stability, deviation settings, etc. I'm convinced that too many techs set paging levels by ear, rather than using their test equipment correctly.

I have attempted to "tweak" the levels for paging but Avtec really only gives you one places to adjust the level and I've tried a number of different settings to no avail.

The failure that I am running into is the inability to consistently page my departments. We left an old ModuComm system (which was beginning to fail hard on us) and moved to this IP based system with dreams of modularity and easy expandability. Unfortunately we found that this doesn't really play well when you still have some... legacy... infrastructure. We are working hard to upgrade our infrastructure but I'm going to become a martyr if my VFD's pagers don't go off and sound like I'm in the same room as them!

Back to the Outpost/ITA setup; do you mean the Outpost does the keying of the link radio, and at the hilltop, the COR of the receiving link radio cause the PTT of the main transmitter?

[FMROB]

I'm confused and tired after a long day of IWCE, however I have some points to share.

The AVTEC has numerous areas to adjust level outputs. One being the overall expected TX audio setting (i.e. -10db) for general "local control" purposes. Running through telco rtna and such you will have to adjust for line loss.

The AVTEC also has separate level adjustment for paging tones. At some point in an early firmware version the tone level was reversed from what we consider low and high. -#'s were raising page tones while +#'s were lowering tone levels. It has since been fixed.

The Outpost can handle a variety of control modes from hard PTT and COR, VOX function, and EIA tone control functions. These features are seleectable in the project manager under the individual outpost unit. I guess you could supply hard PTT to your UHF link radio and use COR on the hilltop side to toggle PTT on your page transmitter, however kinda jukey. Like someone said ealier audio has to be flat so no distortion occurs, espicially with DTMF.If you were to fashion a microwave/ethernet link you could co-locate the outpost at the TX site. The avtec is a really great product so you shouldn't have an issue with settings.


- Rob

** As far as using the outpost to do TRC and hard PTT it will do it, however no at once on the same port, as there would be no reason for this (in regards to PTT function). You might be able to use hard PTT and still send other EIA function tones to do oter controls on the same port, haven't had an application to do this yet.

*** Additionally, using the outpost in a non-colocated mode is not a problem. It will send audio through phone lines, in building copper, or over a muxed T1 the same as if it were hooked directly to the back of a radio.

[kb4mdz]

Any new news on this issue? Inquiring minds want..... to put in their two cents worth!!