Battery Consumption (Analog vs. Digital Modulation Radios)

[Jim1348]

If you have two similar radios, say a Motorola XTS5000 on VHF analog conventional and a Motorola MTS5000 on 800 mHz APCO P-25 trunked system. Assuming the same usage, so many minutes transmitting, so many receiving, will there be a noticeable difference in the amount of power consumption?

[HLA]

a 4 watt transmitter is still a 4 watt output no matter wether it's analog or digital. i think leaving the backlite on more or accessing the menues will be more of a drain.

[Jim1348]

There had been some speculation that the trunked radio might consume more power because it is constantly monitoring the control channel, but it sounds like that is a non-factor then.

[libuff]

There had been some speculation that the trunked radio might consume more power because it is constantly monitoring the control channel, but it sounds like that is a non-factor then.

aren't battery life times based upon a 5/5/90 timescale, 5% transmit, 5% receive, 90% standby, SO... one would assume that if you raise the receive cycle to say 5% 95% 0% that would change the battery life.. i hardly get the battery life from my XTS2500 Trunking radio then i do from my XTS2500 conventional, although its not quite a fair fight, my conventional is MY radio and is kept with fresh conditioned IMPRES batteries, well cared for, whereas my trunking radio is the county's radio, so... no IMPRES, and the battery is a few years old.

although when things were new i don't remember EVER getting a few days out of the trunking radios battery, like i do with my conventional battery..

[Wowbagger]

There are a few tricks one can use to reduce the battery consumption in a trunking system (and cellular is just a special case of trunking), but unfortunately those tricks don't work very well in a PMR environment, especially for an emergency response radio.

The biggest trick is to have the mobile listening only for a brief time, at a known time. Your cell phone isn't listening to the control channel all the time, it actually is listening only ever couple of seconds, for a few milliseconds. The cell site knows when you phone should be listening, and will transmit any data your phone needs at those times.

The result is your phone goes back to listening only 5% of the time, but it takes a couple of seconds for a call to go through. For cellular this isn't a big deal, because people are used to it taking a couple of rings.

That would NOT be acceptable for first responder radios: If dispatch needs to tell you something they need to tell you RIGHT NOW, not two seconds from now. Also, your phone is only listening for one number, whereas your P25 radio is listening for its own ID, your group(s), your announcement groups, and any other control channel messages.

That's just a trade-off you have to make for PMR: you get better response time, more TX power, but you have to have a much bigger battery and charge it more.

This may get better when P25 moves to TDMA - we'll have to see.

[wavetar]

This may get better when P25 moves to TDMA - we'll have to see.

Motorola claims 40% greater battery life with the MotoTRBO radios in TDMA mode, because of the transmitter only being used when required to put information onto it's TDMA slot (which I'm sure you knew, but others may not have).

Todd

[libuff]

This may get better when P25 moves to TDMA - we'll have to see.

Motorola claims 40% greater battery life with the MotoTRBO radios in TDMA mode, because of the transmitter only being used when required to put information onto it's TDMA slot (which I'm sure you knew, but others may not have).

Todd

i could see that... take teh 5/5/90 number, technically cut it in half, get 50/5/45, and your radio is idel 50% of the time instead of 5% of the time, since you are transmitting 1/2 the "time", be it, 1 slot / 2 slots. that should improve battery life, or require smaller batteries, either way...

[Jim1348]

My anecdotal evidence would seem to suggest that the Impress battery with my 800 mHz APCO P-25 digital trunked XTS5000 does not last as long as the battery on my VHF high band HT1000. Granted, we are comparing apples to oranges here, but I been using the MTS5000 in the car to monitor the Minnesota ARMER system even though we aren't switching over until next week. I get two full 8 hour days with just monitoring (scanning) and sometime into the third 8 hour shift I get the battery beeping at me. If I recall correctly, when I have used the HT1000 in a similar capacity I get more battery life out of it, but maybe I am way off base on this.

[MTS2000des]

the digital radios have more processing going on full time. Even in analog radio mode, the DSP is still being used thus an XTS will use more current on standby and RX than a "legacy" radio such as an HT1000 or Genesis radio. An analog Saber with the same NTN4595 1800 mah lasts twice as long on standby/RX than an Astro Saber (conventional analog mode) in every one of my tests.

same is true with cellphones. A CDMA transceiver is on full time, constantly listening for walsh codes...whereas a GSM handset goes to "sleep" and camps on a particular time slot. Since GSM uses less processor power in it's chipsets, the GSM version of a particular phone lasts much longer with the same battery. A Verizon Razr will usually die in a day or two with a standard battery with light use whereas a GSM Razr can go for a week.

It's all in the chips...

[northstarfire0693]

Just my little say in this....
On my county EFJ 5100 in digital P25 trunk mode I get 12-18 hrs of battery life. In analog mode I get 18-24 hrs.