testing a plb

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andy63
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testing a plb

Post by andy63 » Sat Mar 23, 2019 8:24 pm

ive recently bought an ACR ResQLink plb.. the guide referes you to the online instructions and in the section on testing the device it says the following....
" self test should only be preformed in the first 5 min of any hour "
can anyone tell me why this is ..
thanks..
Andy

Chris Bolton
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Re: testing a plb

Post by Chris Bolton » Sat Mar 23, 2019 9:05 pm

That's odd. Wikipedia redirect 'PLB' to 'Emergency position-indicating radiobeacon station'. This contains an entry for Emergency Locator Transmitters (ELTs) which are are fairly expensive beacons for aviation use. This section says:
According to the U.S. Federal Aviation Administration, ground testing of A-, B-, and S-type ELTs is to be done within the first 5 minutes of each hour. Testing is restricted to three audio sweeps.[37] Type I and II devices (those transmitting at 406 MHz) have a self test function and must not be activated except in an actual emergency.
It's not very clear, but it suggests to me that those types of ELT (which Wikipedia might imply are obsolete) send a live distress message for test purposes, and sending it only during the first 5 min of any hour allows that to be identified as a test. If the beacon continues transmitting after 5 min, it can then be assumed to be a real emergency.

When you test most PLBs they doesn't transmit, just checks the GPS function and battery condition. According to ACR, some new REsQLink devices do transmit to the satellite, so maybe they have to follow the same rule. But it's a US rule, and (whatever the US may think) their laws don't apply to whole world.

I have McMurdo Fastfind, and the antenna is rolled up inside the sealed unit, which you only open if you want to send a real distress message, so it can't send a signal to the satellite when being tested. Does yours deploy the antenna for the test?

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Re: testing a plb

Post by jmmoxon » Sun Mar 24, 2019 8:30 am

You have to deploy the antenna to access the test & activation buttons. I guess that if lots of people were testing them throughout the hour it might obscure a real emergency signal, so better to concentrate that into a short, easily remembered, period.
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andy63
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Re: testing a plb

Post by andy63 » Sun Mar 24, 2019 10:48 am

Chris Bolton wrote:
Sat Mar 23, 2019 9:05 pm
That's odd. Wikipedia redirect 'PLB' to 'Emergency position-indicating radiobeacon station'. This contains an entry for Emergency Locator Transmitters (ELTs) which are are fairly expensive beacons for aviation use. This section says:
According to the U.S. Federal Aviation Administration, ground testing of A-, B-, and S-type ELTs is to be done within the first 5 minutes of each hour. Testing is restricted to three audio sweeps.[37] Type I and II devices (those transmitting at 406 MHz) have a self test function and must not be activated except in an actual emergency.
It's not very clear, but it suggests to me that those types of ELT (which Wikipedia might imply are obsolete) send a live distress message for test purposes, and sending it only during the first 5 min of any hour allows that to be identified as a test. If the beacon continues transmitting after 5 min, it can then be assumed to be a real emergency.

When you test most PLBs they doesn't transmit, just checks the GPS function and battery condition. According to ACR, some new REsQLink devices do transmit to the satellite, so maybe they have to follow the same rule. But it's a US rule, and (whatever the US may think) their laws don't apply to whole world.

I have McMurdo Fastfind, and the antenna is rolled up inside the sealed unit, which you only open if you want to send a real distress message, so it can't send a signal to the satellite when being tested. Does yours deploy the antenna for the test?
hi Chris that , in answer to your point ....yes to do the self test on the gps side of the device you have to deploy the antenna and it goes through a sequence which it describes in the instructions as follows.....

"the second test is a gps self test that actually turns the GPS receiver on , downloads your position and then transmits this data in a self test satellite burst """

the device then indicates whether the test was satisfactory by the sequence of led that flash..

cheers
Andy

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Re: testing a plb

Post by sea monkey » Sun Mar 24, 2019 12:17 pm

Check out http://www.cospas-sarsat.int/en/testing-your-beacon

If the beacon transmits on 406 MHz during its test it will transmit a test message rather than a distress message (and the timing is irrelevant).

However, most beacons also transmit on the legacy 121.5MHz so that SAR aircraft, helis, etc can home in to the beacon during the final stage of a rescue. 406 homing equipment was not standard on SAR units initially but most have it now - it is still useful that the beacon transmits on the legacy frequency for any SAR units with older equipment and as a back up. The first 5 minutes of the hour rule would only apply if your beacon transmits on 121.5MHz during test - I can't find anything that suggests it applies outside the USA.

andy63
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Re: testing a plb

Post by andy63 » Sun Mar 24, 2019 1:55 pm

thanks for the replies..
the plb does transmit on the 121.5mhz frequency , so that may have something to do with the request..
ill try an e mail to the manufacturer, and if I get anywhere ill get back with the reply..
thanks..
Andy

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Re: testing a plb

Post by seawolf856 » Mon Mar 25, 2019 11:51 am

See page 9 of the RescueMe 1 user manual is to see why:

http://oceansignal.com/wordpress/wp-con ... -Web-1.pdf

andy63
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Re: testing a plb

Post by andy63 » Tue Mar 26, 2019 3:47 pm

I got this back from the supplier of my plb.....
which confirms all that's been said.

""Sam replied
Cc: telesales1@force4.co.uk
Mar 26, 12:53pm
Good afternoon Andy,

ACR request this because the self test does actually send a signal to the satellite. Whilst this signal is specific to the self test function and will be received as such, it means that the rescue authority can anticipate that any signal received in the first 5 minutes of the hour may be a test signal, and can monitor them accordingly. As a result of this, any signal received in the remaining 55 minutes of the hour can be assumed to be a legitimate emergency and be acted on immediately. ""

thanks again
Andy

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