EPIRBS now with reach

[dgax65]

Originally Posted by ElectroMike

This seems to be a cool alternative to the personal EPRIBS.

http://www.findmespot.com/Home.aspx

There are some significant differences between Spot and an EPIRB.

An EPIRB signal will be received by COSPAS/SARSAT satellites and will result in automatic alerts at USCG command centers. EPIRB must be tested and certified for use on the internationally recognized COSPAS system. EPIRB are only designed to trigger SAR response from official government organizations. EPIRB do not allow any communication other than beacon and GPS info. EPIRB receivers on geostationary orbit satellites (GEOSAR) provide global detection capability. If the EPIRB has an onboard GPS or a GPS input, it will also transmit it's position to the GEOSAR. That GPS info will be transmitted to the Mission Control Center (MCC) along with the alert. A network of low-Earth-orbit satellites (LEOSAR) also receive the EPIRB signals. These satellites measure the doppler shift of the EPIRB signal to calculate the transmitter's position. Triangulation of EPIRB signals received by the LEOSAR and ground stations (LUT) can provide accurate position fixes, but it may take up to 2-3 hours depending on EPIRB location and satellite orbital position (that's why an EPIRB with an onboard GPS is worth the money).

EPIRB GEOSAR coverage (alerting only, alert and position if using a EPIRB w/ GPS)


EPIRB LEOSAR and ground station (LUT) coverage


Spot is a COMMERCIAL service. Spot units receive position information from GPS satellites. Spot units use commercial satellites to communicate. The signals from Spot units are received at the commercial GEOS facilities. GEOS will alert the closest Coast Guard or applicable SAR organization. When the Spot unit transmits an alert it automatically transmits it's GPS-derived position. Spot has some features that provide greater flexibility than an EPIRB. An EPIRB activation is the last resort (to be deployed only in life-threatening situations, after a MAYDAY has been sent). Spot is a communications device that can send basic messages. It allows alerting of pre-specified individuals without triggering a SAR response. It allows position info to be transmitted and even has a track history feature (for an additional fee). You can even plot the Spot position/track on Google Earth.

Spot coverage is slightly less than the LEOSAR/LEOLUT coverage of COSPAS/SARSAT system (GEOSAR provides global coverage for EPIRB, but will only provide position info from GPS equipped EPIRB).


Basic service for Spot is $100/yr. West Marine has ACR ResQFix 406MHz PLB (EPIRB) for $600 (on sale for $550 a couple of times a year).

Pros

EPIRB:
Internationally recognized and supported technology and infrastructure; mandated by international agreement and maintained by govenrment agencies.
Robust, dependable technology that is tested and certified
Immediate response by SAR agencies
Worldwide alert and poosition coverage (for EPIRB with GPS)
Most 406 MHz EPIRB also have the 121.5MHz homing beacon for localization

Spot
Lower initial cost (lifecycle cost depends on durability of Spot unit)
Functional flexibility-can send non-distress signals, pos/tracks
GPS-derived position accuracy throughout coverage area.
Smal size

Cons:

EPIRB:
Cost-$600 for EPIRB w/ GPS
Single purpose - distress signal only

Spot
No homing beacon
Two step process to get distress signal response
No internationally recognized standard-just a commercial product
Service depends on a commercial organization-GEOS Alliance
Durability?