5-5-90 portable duty cycle

[speedway_navigator]

A previous thread got me thinking about this long time battery standard. In the good old days the portable just sat there waiting for squelch to break and then it looked at CTCSS. With DMR and trunking the receiver is always working so I started wondering if this 5-5-90 is really a valid measurement and how and if the battery / radio makers really do any testing.

Do you guys who admin systems have metrics that show amount of TX time per repeater or TG? I would imagine public safety systems would exceed 5-5-90 since 5% of an hour is 3 min. I looked in my Hytera manuals and don't see any specs on current draw for passing RX audio vs just system monitoring.

 

[mmckenna]

I don't have any data on that.

But on the trunked system, yeah, the radio is listening, but obviously not running the audio amp. Not sure what the current draw is on the radios off the top of my head.

I do have a Kenwood NX-3400 on my system, and it had two battery packs available. I ordered both. The thinner one includes a recommendation that it NOT be used on trunked systems. I can get an 8 hour day out of it, but I don't talk much, and the battery gauge is down at the end of the day.
The larger battery pack is the one they recommend on trunked systems, and I can get two days out of it.

 

[RFI-EMI-GUY]

The basic concept of the three modes of operation are still valid. The idle current is higher on trunked radios because of all of the technology that is running full time. Older conventional radios had battery saver features and sipped current when idle, whereas a P25 radio has to support one or two microprocessors and DSP even in the idle mode.

Administrators of systems should be able to glean average and peak busy hour data from system management reports. The amount of time receiving will be a key factor in calculating battery operating time. Transmission time can be estimated from average message length. It would be important to estimate a worst case based on some past data on busiest talkgroup and plan for either battery capacity or sufficient spare batteries for major incidents.

 

[mmckenna]

Administrators of systems should be able to glean average and peak busy hour data from system management reports.

It's easy enough to pull traffic reports off mine.
But the receiver is running full time on the control channel. I'd bet for most of my users, 5/5/90 is still pretty accurate.

 

[RFI-EMI-GUY]

It's easy enough to pull traffic reports off mine.
But the receiver is running full time on the control channel. I'd bet for most of my users, 5/5/90 is still pretty accurate.

Until the day when the big one drops and everybody is either transmitting or receiving. The time spent on the control channel will be single digit.

When the City of Miami got their first SN II system it idled on pretty smoothly for a year or two and then the Pope came to visit and the users had whole new experience with system busy queues, radio failures, etc.

 

[speedway_navigator]

users had whole new experience with system busy queues, radio failures, etc.

Same thing happened in Ft Lauderdale airport in 2017. From the AAR

"At approximately 2PM, several hundred Broward County School Board bus drivers turned on
their radios for duty (part of routine), which further taxed the already overwhelmed public
safety radio system. This caused increased radio site trunking and loss of "linked" channels
(several linked cities and resources were immediately disconnected from the event.)"

The I35W bridge collapse had system busies too.

 

[RFI-EMI-GUY]

Yeah also the inbound control channel protocol on these systems is slotted aloha which imposes a finite limit on the numbers of inbound requests that can be made. When the limit is reached, subscriber radios show out of range rather than busy and that problem does not show up on the management system.

 

[PACNWDude]

When I run reports on both Unified Event Manager and GenWatch, many of my users are more like 1/1/98.....as the network is under-utilized. This is also why many municipalities and public safety administrators often require reports to show a certain amount of usage for repeaters, TalkGroups, and dispatchers metrics to justify manning and on-going expenses. As others have said, it is still valid to use the 5/5/90 model, and there are always outlier users on a network. In my case, it is a private corporation that is trying to build out radio networks across the country, for internal use, there is no grant money, or need to justify the undersubscribed network, it just has to work when and as needed. Per some security planners, the network is made in case there is ever an active shooter, or more commonly natural disasters, somewhere across the country, where it was expected that radio use would increase dramatically. This is a company with about 30 thousand radios spread across the United States, many is use by private Fire Fighting entities.