EISPIRATEN

There's a site that has the ACR Aquafix 406 with internal GPS for $477.74. They list one price, but sent me a link with a lower price when I wrote to them. By comparison, REI has the ACR Terrafix 406 with internal GPS for about $595.38 (LA County sales tax included) out the door if you do store pick up; it's more if you choose direct shipping to your home or office. If my math is right, that's a minimum savings of $117.91. The Aquafix is the same as the Terrafix except that the Aquafix is blue and the Terrafix is green.

I'm not sure if I should post the link, although it's probably OK to do so, but just in case, I won't. However, if you were to PM me, and ask me what the best deal I've seen on the internet for an ACR PLB is ...

HJ

P.S. I ordered the unit at about 1:45 PM today. I requested standard UPS Ground shipping. I got an email from UPS at about 2:45 PM today, telling me that the item was in their system and that the delivery date would be this Friday. Not too bad of a turn around.

The ACR Web site has a chart that compares the specs of all of their PLB models.

Good chart.

I guess maybe I should point out that although the Aquafix and Terrafix PLB units are the same (except for the color), the interface cable that comes with the two PLB's it is slightly different, and the Aquafix comes with a mount if you want to put in your boat, vehicle, etc. The Terrafix does not come with a mount. To me those are extraneous issues that I'm not particularly concerned with. I just want a self contained PLB in my backpack.

Regarding the cable, supposedly, if you already have your separate GPS turned on and "dialed in," it might be slightly faster (in terms of getting the GPS coordinates to a SAR satellite) to hook your GPS up to the PLB via the cable since the PLB would not have to hunt for GPS satellites. I think it might be more hassle than it's worth to carry a cable around on the chance that it might be slightly faster, but that's just me. Even if the PLB couldn't get GPS coordinates for some reason, your position can still be determined via calculations based on the doppler shift of your emergency signal. Recall that for the first several years, no PLB's had the GPS interface.

Just some thoughts.

Hikin_Jim wrote: . . . it might be slightly faster . . . to hook your GPS up to the PLB via the cable since the PLB would not have to hunt for GPS satellites.

As an aside, I cannibalized an "AA" battery from my Garmin GPS and didn't replace it for a couple of days. Consequently, my Garmin's internal clock was 2 days behind when eventually I replaced the battery and switched on the handheld. Under these conditions (time error 2 days and location error a dozen miles), the handheld needed 20 minutes to synch time and location.

I would hope that PLBs have internal clocks for fast GPS synch time?

Um, I'm glad you asked that question. And, um, as everyone knows, um, ... the answer is, um ... that I, um ... don't know.

Seriously, that's a good question. Even if your PLB couldn't get an immediate GPS fix, you wouldn't be screwed. A PLB starts xmitting the 406 MHz signal immediately -- with or with out GPS coords. The receiving satellites can calculate your position based on multiple passes and comparing the doppler shifts in your radio signal, so even if GPS coords aren't xmitted in the first pass, they can still get a position on you, although it won't be as accurate as a GPS based position. Even without GPS, the critical events would still happen: the alarm gets sounded, your position is fixed (within about 0.5 miles), and the SAR team starts assembling.

Say the PLB finally gets GPS coords (after 20 minutes as in your example). It takes a while for a SAR team to assemble. Probably the more accurate position would come in while they were still assembling. Even if they were already assembled and dispatched when the more accurate coords came in, the SAR resources would be in the right area; SAR would be in a postion to respond immediately.

This delay, 20 min in this example, is what they're talking about when they say that carrying a cable to attach the PLB to your already operational external GPS may provide more accurate coords more quickly. I personally don't see that it would make a lot of difference unless the PLB got crushed or something and stopped transmitting. If you're in a situation where your PLB has just gotten crushed, maybe immediate SAR response isn't really all that important any longer.

Recall also that a PLB sends a secondary signal at 121.5 MHz which is the international standard homing freq. PLB type units were used successfully before GPS came along.

HJ, good explanation.