Monthly Archives: January 2012

Amateur Radio, APRS

More on TH-D72 battery life.

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I was chatting with two guys in the office about the results from my previous tests with the TH-D72. In the previous tests, the radio was configured to receive all APRS packets.  Now, considering EI4HQ’s scenario, which was to have it with him while walking.  He isn’t going to be very worried about the location of other APRS stations while out walking in the hills.  Also,if another APRS station is within simplex range, Voice Alert will let him know.

So, I just configured the Battery Saver on the TH-D72 to be more aggressive.  Set for 1 second, this means that when the squelch is closed, and no key is pressed for more than 10 seconds, the radio switches the radio off for 1 second, then momentarily turns is back on in order to detect if any signal is present. As an aside, it is suggested in the manual that the battery saver be set to 0.03 seconds in order for APRS to work reliably. This is what it was set to in the previous tests.

Anyway, at 1 second the first packet was logged at 08:44 in the morning and the last at 23:00 that evening.  Giving approximately 14h 15 minutes of runtime.  Setting the battery saver to 2 seconds, with the first packet at 08:35 and second at 00:02 increases that to approximately 15h 25 minutes.

In other words, a 5 to 6.5 hour increase in battery life. That, i think you would agree, is a very useful increase in battery life.

 

 

Amateur Radio, APRS, AREN

TH-D72 Battery Life

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So EI4HQ and I were discussing “toys” and presents in general, and he inquired about the TH-D72 and battery life. I purchased mine in November 2010 (G0HWW twisted my arm) and have used it for various things from AREN events, listening to aircraft, DTN Experiments (PDF), silly IP over AX.25 tunnels, the usual.

Anyway, I said to EI4HQ that I though it was about 8 hours, but I would check.

The radio has a setting to allow it to transmit the position of the radio, automatically at fixed intervals (beacon interval). So, I did three experiments.  I left the radio in the car for the day on all three occasions. Setting the beacon interval to 5 minutes the first day, 10 minutes the second, 20 minutes the third while the second side (transceiver) of the radio was monitoring the local voice repeater(EI7WDR). This was done just to see what the difference was in battery life, and I (and WE7U) was making the assumption that with the longer intervals, that the battery life would be better.

Day 1, first beacon recorded on aprs.fi at 08:50, last at 18:06, total operational time of 9h 16 minutes. Day 2, first beacon recorded at 08:21, last at 17:41, total operational time of 9h 20 minutes. Day 3, first beacon recorded at 08:18, last at 17:18, total operational time of 9h.

Now, today I had to drop down to WIT, so the onboard GPS had to come out of its power save mode for that short journey, which may account for the reduced battery life. Also there could have been more activity on the repeater, actually there was, I had a brief conversation for a few minutes with EI2HI in Cork on the way into work this morning.

However, the results are pretty clear I think (and I would love to see someone else’s results to compare), that the once every few minutes position beacon is not the biggest load on the battery with everything else running.

So what is the battery life?  Without more experimentation, i would guess about 6 hours if I was out walking with it. That, I think, will have to be the next experiment.