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Portable usage in police agencies

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Bill_G
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Portable usage in police agencies

Postby Bill_G » Wed Oct 18, 2017 9:30 pm

Tell me about how your local PD's use their portables.

I chased down a long standing complaint in a small agency this week - echo in the radios after recent installation of voting receiver installation. It's a growing city along the Columbia River experiencing coverage issues particularly by portables. The sales department solution was adding two satellite receivers and a compartor. Good, old school stuff.

The primary repeater has a 4W phone line. One receiver uses a DS0 over a T1 through an existing microwave. The third site uses Multitech IP modems over DSL. Our tech got it all working perfectly including compensating for the delay introduced by the DSL. However, the officers still reported hearing delay in the repeat audio particularly at night. Our tech never heard it himself, but the problem got escalated when dispatch started experiencing the same issues overnight.

It turns out the officers have their portable lashed to their belt with an earpiece plugged in all the time. Dispatch keeps portables on their desk at night turned up to confirm their transmissions went out. Both groups hear the delay between their outgoing and the repeated audio, and are calling that "echo".

Obviously, there is nothing I could do about the 200ms delay. It's necessary to sync the DSL with the other audio. But, it took some listening to understand how they use their radios to discover the problem. Do your people do the same thing? Has it become SOP to keep portables turned up?

Jim1348
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Portable Usage In Police Agencies

Postby Jim1348 » Thu Oct 19, 2017 2:35 am

Bill_G wrote:Tell me about how your local PD's use their portables...Do your people do the same thing? Has it become SOP to keep portables turned up?


Some do and some don't. The earpieces are popular in some places and not so much in others. Honestly, it has a lot to do with what the culture is where and where you start/work. And, there are also all sorts of other variations. A PD near me never had scanning on either their portables or mobiles. So, many guys/gals kept the car radio on the dispatch channel/talkgroup and the portable on, in the car, on the car-to-car channel/talkgroup.

When I was still a deputy sheriff, I was on county radio, but often in places dispatched by their own PSAP. So, I, too, would sometimes keep my car radio on county main and the portable on that agencies main. Even with scanning on conventional, there is still nothing quite like keeping a radio selected on that channel /talkgroup.

I even had a Yaesu dual band rig in my unmarked car. It, too, was handy in any number of ways!

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SteveC0625
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Re: Portable usage in police agencies

Postby SteveC0625 » Thu Oct 19, 2017 4:58 am

Our dispatch center, modest in size - 1.3 million calls per year, only used portables on the dispatch floor for trainers to monitor their trainees late in their FTO time.

We had one permanent monitor receiver on county fire and one on city fire connected to one of the slots on the consoles so that the dispatchers there would always know that QC-II tones and initial voice message went out properly. There was no echo effect as it was all analog conventional at the time. (The receivers were just old L03's with external antennas on the roof, but reliable workhorses for sure.)

They're moving to a P25 700Mhz system now so what they're up to today is unknown.

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Bill_G
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Re: Portable usage in police agencies

Postby Bill_G » Thu Oct 19, 2017 5:13 am

SteveC0625 wrote:Our dispatch center, modest in size - 1.3 million calls per year, only used portables on the dispatch floor for trainers to monitor their trainees late in their FTO time.

We had one permanent monitor receiver on county fire and one on city fire connected to one of the slots on the consoles so that the dispatchers there would always know that QC-II tones and initial voice message went out properly. There was no echo effect as it was all analog conventional at the time. (The receivers were just old L03's with external antennas on the roof, but reliable workhorses for sure.)

They're moving to a P25 700Mhz system now so what they're up to today is unknown.


They will experience about a 1-2-3 delay. (the period of time for three syllables) Depends on the backhaul.

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Bill_G
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Re: Portable Usage In Police Agencies

Postby Bill_G » Thu Oct 19, 2017 5:22 am

Jim1348 wrote:
Bill_G wrote:Tell me about how your local PD's use their portables...Do your people do the same thing? Has it become SOP to keep portables turned up?


Some do and some don't. The earpieces are popular in some places and not so much in others. Honestly, it has a lot to do with what the culture is where and where you start/work. And, there are also all sorts of other variations. A PD near me never had scanning on either their portables or mobiles. So, many guys/gals kept the car radio on the dispatch channel/talkgroup and the portable on, in the car, on the car-to-car channel/talkgroup.

When I was still a deputy sheriff, I was on county radio, but often in places dispatched by their own PSAP. So, I, too, would sometimes keep my car radio on county main and the portable on that agencies main. Even with scanning on conventional, there is still nothing quite like keeping a radio selected on that channel /talkgroup.

I even had a Yaesu dual band rig in my unmarked car. It, too, was handy in any number of ways!


I figured it had something to do with their belt. The portable is lashed down with the earpiece cable threaded through their uniform. It becomes a Borg implant. Always on, always talking in their head. Unfortunately, they are just going to have to turn the volume down when they are in the car.

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Bill_G
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Re: Portable usage in police agencies

Postby Bill_G » Fri Oct 20, 2017 5:03 am

I'm getting sense it's not unusual behavior, but it's not standard behavior. ie: not every agency does it.

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alex
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Re: Portable usage in police agencies

Postby alex » Fri Oct 20, 2017 10:13 am

I have another solution. As opposed to them listening why don't you setup on the console a COR light off a receiver on the same channel. That way if the dispatcher sees an indicator when the radio is transmitting they know the repeater is online? That would solve the echo problem of them having a portable with an ear piece.

The other issue we have up here is people get used to the old systems which run in near-real time. It is hard to explain to the fire fighter, police officer, etc,. why there is now a 1/4 second delay. It wasn't there before... I thought technology was better... etc.
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Bill_G
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Re: Portable usage in police agencies

Postby Bill_G » Sat Oct 21, 2017 6:31 am

The delay in DMR and/or ip backbone systems has been an issue from day one. Rail crews and ship loading crews have stayed analog radio for safety reasons. When you're trying to switch a track, or swing a crane, I get it - you need instant communications. But, dispatching doesn't. Everyone eventually gets used to it.

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alex
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Re: Portable usage in police agencies

Postby alex » Sat Oct 21, 2017 7:23 am

Bill_G wrote:The delay in DMR and/or ip backbone systems has been an issue from day one. Rail crews and ship loading crews have stayed analog radio for safety reasons. When you're trying to switch a track, or swing a crane, I get it - you need instant communications. But, dispatching doesn't. Everyone eventually gets used to it.


I heard a same/similar story long ago from Jason on here that had to with the Disney parade when they switched to Nextel/iDEN and took away the analog radio. They had some incidents where floats wouldn't get the word stop on time and had to go back to analog to resolve the timing issue.
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Bill_G
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Re: Portable usage in police agencies

Postby Bill_G » Sat Oct 21, 2017 8:33 am

alex wrote:I heard a same/similar story long ago from Jason on here that had to with the Disney parade when they switched to Nextel/iDEN and took away the analog radio. They had some incidents where floats wouldn't get the word stop on time and had to go back to analog to resolve the timing issue.


We had a whole crew of dock workers walk off the job because of Trbo delay. We had to switch them back to analog repeater. A steel mill charge crane (the guy that drops the material into the smelter) had similar problems, but we changed them back before it became a work safety issue. It's SOP now to always program some simplex analog channels in new Trbo systems.

RFguy
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Re: Portable usage in police agencies

Postby RFguy » Sat Oct 21, 2017 12:14 pm

Bill_G wrote:It's SOP now to always program some simplex analog channels in new Trbo systems.


Interesting as our SOP is to never give them an analog channel for direct, to keep it digital.

I'm speaking of non-critical users here (shopping malls and the like). They get used to digital and if they have a fall back to analog, they use it as a crutch to avoid learning to adjust to digital quality.

Your applications are different.

joescanner
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Re: Portable usage in police agencies

Postby joescanner » Sun Oct 22, 2017 12:35 pm

Bill_G wrote:I'm getting sense it's not unusual behavior, but it's not standard behavior. ie: not every agency does it.


Meh, you've got at least one other customer where it's the norm instead of the exception.

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Re: Portable usage in police agencies

Postby Karl NVW » Thu Dec 21, 2017 11:53 am

FWIW, users get the same so-called "Echo" delay in P25 systems, and for precisely the same reason - delays in the infrastructure transport path. Strange how the laws of physics are so repeatable.
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Jim1348
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Portable Usage In Police Agencies

Postby Jim1348 » Tue Oct 02, 2018 1:24 pm

My post-retirement job is at a small college as a Public Safety Officer. am typically on a NEXEDGE channel, but scan other channels, which are analog. Since I have gotten pretty accustomed to APCO P25, DMR/MOTO TRBO, YSF and now NXDE, the analog channels are horrible to listen to, when they have a weak signal.

What I need to do is find out if they are co-located repeaters and if they are set at the same power levels, same antenna, etc. It might be fun on a quiet late night or weekend to see how analog vs digital compares for range.

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Bill_G
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Re: Portable usage in police agencies

Postby Bill_G » Wed Oct 03, 2018 5:44 am

It would be an interesting experiment Jim, but difficult to perform because of the number of variables. That's why DAQ tests are a subjective mess. I've never built a perfect system. Invariably, someone had a problem. How important the problem was depended on the people paying the bills, and/or how the contract was written.

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Bill_G
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Re: Portable Usage In Police Agencies

Postby Bill_G » Tue Oct 09, 2018 5:03 am

Jim1348 wrote:What I need to do is find out if they are co-located repeaters and if they are set at the same power levels, same antenna, etc. It might be fun on a quiet late night or weekend to see how analog vs digital compares for range.


Thinking about this, I recall I've already done this experiment (as you described) unscientifically on two systems, and the results were no practical difference in range: a dual mode Icom VHF repeater, and a dual mode Tait P25 700 repeater.

The Icom repeater belonged to a railroad on a hilltop with really long legs. It has an easy 50 mile radius depending on terrain and weather. They used it analog conventional, but I set it for dual mode (NXDN), and played with it when there were no crews in the territory. There was no remarkable difference.

The Tait repeater was part of a local public safety P25 trunking system. As part of the initial build, a repeater at each site was programmed to be remotely switched between P25 trunking and local analog repeat. It was an effort to prove to the naysayers that digital did not lose range. And it didn't. The range was the range. Talk in and talk out to the areas important to the customer were the same. And unofficial testing to the fridges showed no difference either.

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escomm
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Re: Portable usage in police agencies

Postby escomm » Fri Oct 19, 2018 5:58 am

I'm awful curious how the deployment of a receive only voting system introduces delay into the transmit

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Bill_G
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Re: Portable usage in police agencies

Postby Bill_G » Fri Oct 19, 2018 3:36 pm

escomm wrote:I'm awful curious how the deployment of a receive only voting system introduces delay into the transmit


By the latency in the slowest link, which is always the ethernet. If the customer uses all T1/DS0, you can use the rough calculation of 6uS per mile to determine the latency. But, if they use ethernet, you use 1mS per hop/router/device. I have no idea *why* ethernet has such delay. It just does even though, in theory, it's faster. I typically see latency on the order of 10mS or more in ethernet voice circuits landing the delay in the audible range.

I just finished one this week, and within 24hrs of cutting them over to the new voting system tied together with gigabit fiber, there were complaints about the "delay". And just like in my original message from a year ago, the officers keep a packset on their hip with an earpiece plugged in all the time. When they talk on their mobile, they hear themselves a part of a second later instead of instantly when the system was a plain old single site repeater. They want me to somehow put a screwdriver in there and reduce the delay. I told them to turn their portables down.

It is disconcerting, but the delay is a function of the network, and the equipment. There is no adjustment. In fact, if anything, I would add delay to overcome frame loss and audio sync issues. The net effect is the return audio from the repeater is several syllables after you speak. In this case, we're using MLC8000's with no adjustments for packet delay in conventional analog comparator mode. So, I can only pray the audio stays sync'd.


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