EPIRB interference

[cabo_sailor]

You e-gurus didn't disappoint me on my last question so here is one more. If the fit hits shan, I will activate my new ACR 406 with GPS. I would also activate the DSC Mayday. I don't believe they would interfere with each other since the operational frequencies are no where close. But what about the Delorme Inreach?

Anything else that would interfere with the EPIRB?


Sent from my iPhone using Cruisers Sailing Forum

[Hydra]

See http://files.delorme.com/manuals/InR...ser_Manual.pdf

Page 35:
Iridium Communication
[...]
Frequency Spectrum: 1.61GHz–1.63GHz
[...]
Bluetooth - for Android and iOS
[...]
Frequency Spectrum: 2.40GHz - 2.48GHz unlicensed band
[...]
802.15.4 - for Earthmate PN-60w
[...]
Frequency spectrum: 2.40GHz - 2.48GHz unlicensed band

So, yes, your DeLorme inReach frequencies are remote from the 406MHz of your EPIRB. There should not be any interference.

I hope that the GPS receiver in the inReach doesn't interfere with the GPS receiver in the EPIRB. This should be OK. However, it seems I have had short range (1m) interference between a Navtex receiver and a regular Sangean LW (162kHz) radio...

Alain

[colemj]

There is no issue with GPS receiver interference. If there was, cars would be driving into each other left and right and people would never be able to find anything in any city. Sit your phone and tablet next to each other and see...

Mark

[travellerw]

Originally Posted by colemj

There is no issue with GPS receiver interference. If there was, cars would be driving into each other left and right and people would never be able to find anything in any city. Sit your phone and tablet next to each other and see...

Mark

I think the point is both of those devices are transceivers. You phone or tablet does not transmit on satellite frequencies, it only receives.

I think the risk of the 2 interfering is very low considering they both send out pulses, not continuous transitions. Its possible one of the pulses could get lost, but would be near impossible for all the pulses to be lost.

[colemj]

Originally Posted by Hydra

I hope that the GPS receiver in the inReach doesn't interfere with the GPS receiver in the EPIRB.

I was responding to this.

Mark

[Wotname]

The two transmitters (EPIRB & Inreach) won't interfere with other. Botn are low powered devices and both only transmit momentarily and on different frequecies. Well, the EPIRB also transmits a continious analogue AM on 121.5Mhz but that is neither here nor there.


Can the satellite receivers distinguish between all the EPIRB and Inreach tramsmissions from mulitiple transmiters all over the place -YES

If this wasn't the case, one could not activate 2 EPIRB on boats side by side or use 2 Inreach product nearby!

[ka4wja]

cabo_sailor,
1) As others have written, there's nothing electronic (or VERY little) on-board that will interfere with the transmission of your EPIRB!!
(Although, improper activation/deployment of an EPIRB will adversely effect the ability of the EPIRB signal to get to the satellite!!! And, not having it properly registered will effect the SAR response you will get...and in some areas of the world, you may not get any SAR response at all!!)

Have a look here for some important info:
EPIRB Activation? What happens/How to improve rescue odds

Originally Posted by cabo_sailor

You e-gurus didn't disappoint me on my last question so here is one more. If the fit hits shan, I will activate my new ACR 406 with GPS. I would also activate the DSC Mayday. I don't believe they would interfere with each other since the operational frequencies are no where close. But what about the Delorme Inreach?

Anything else that would interfere with the EPIRB

2) But, as for what else would interfere with an EPIRB, you may be surprised that it is the increased RF background noise on earth, caused by all of our man-made devices, radios, TV's, computers, coffee makers, etc. etc. etc. etc...
And, I'm sorry to say that these increased noise levels are primarily in Europe and Asia!

Now, some of you may think I'm making this stuff up....but I'm NOT....
(see 2015 ITU report)

While we think that the EPIRB band (406.0mhz to 406.1mhz) is "protected", and it is protected from other services using those frequencies, the fact is all of the devices that are in use these days has significantly increased the normal RF noise floor that the COSPAS-SARSAT satellites see, by 15db to 20db!!!
This means that we sailors must make absolutely sure we activate/deploy the EPIRB properly!!

Please note that this noise floor increase is from the populated land areas (primarily Europe and Asia) and effects all of the satellites looking down on the earth trying to receive signals...and when discussing the COSPAS-SARSAT LEOSAR satellites, this means once the satellite is out-of-range/beyond line-of-sight of land areas (i.e. middle of the ocean), this increased noise floor is minimal...

This effects all of the satellites using vhf/uhf (and even L-Band / lower end of the microwave band)...

BUT...
Remember these LEOSAR satellites do NOT receive the GPS position data from your EPIRB (assuming you have a GPS-enabled EPIRB), but they only receive the "alert", your EPIRB ID#, and determine your approximate position via Doppler-ranging....and this can mean getting your position estimated within a hundred miles or more, until the next satellite pass (~ 45min to 90min later, or more!)

It is the GEOSAR sats that receive the encoded GPS position data from your EPIRB....and these satellites are looking down on the whole earth....(yes, only small parts of the earth are generating these interfering signals / increased noise floor, but this is also effecting their ability to receive the GPS position data..)

This increased 406mhz satellite received noise floor, effects the LEOSAR sats when they are within line-of-sight of land (over land, coastal areas, near-offshore, etc.), and effects the GEOSAR (and MEOSAT) satellites, as well!

From an ITU report, from earlier this year:

The 406-406.1 MHz frequency band is exclusively allocated to the mobile-satellite service, which is currently used by the Cospas-Sarsat system, the purpose of which is to provide distress alert and location data to assist search and rescue (SAR) operations, using spacecraft and ground facilities to detect and locate the signals of distress beacons operating on 406 MHz.

According to Resolution 205 (Rev.WRC-12), the frequency band 406-406.1 MHz is constantly monitored. Several noise measurements have been conducted using all the three space components. In particular, measurements performed by the LEO component show that the level of noise over certain years (measured in the 406-406.1 MHz band) has increased by 15 to 20 dB above the interference level in some areas. This noise level is especially high over Europe and also in part of Asia. For most of the areas on the Earth (mainly over oceans), a distress beacon can be correctly received and processed by the SARP even for low levels. However, a general concern is raised on the reception and processing of weak distress signals, in certain areas, caused by an increase of noise especially in Europe and Asia.

I'm not trying to be alarmist at all....just thought some would like to know these things...

And, remember it is NOT just the COSPAS-SARSAT satellites that are being effected here, but also all of the satellites that use VHF/UHF, such as military, weather sats, other leosats, etc...and to a lesser extent those using L-Band, such as all of the "mobile satellite systems" (Iridium, INMARSAT, etc.)...
INMARSAT has an engineering team that looks at this issue, and are trying to bring up the subject of "RF Pollution" at World Radio Conferences, 'cause has the potential to seriously effects their business / business plan / capabilities!



3) So, when we talk about RFI nowadays, we need to think beyond our HF (SSB) radios....we need to remember that everything electronic these days, radiate some amount of interfering signal...

And eventually we will find the radio spectrum so crowded with "noise" that it will no longer be usable....(okay, obviously that's an over-statement...but you get the point!)



Fair winds...

John

[ka4wja]

Please note that EPIRB's do work, and do work well...
But, here in this thread you'll find proven scientific reasons why fully understanding them, the GMDSS, the COSPAS-SARSAT system.....and using EPIRB's properly, is so important to actually getting rescued!

I've mentioned this "interference" issue to other professionals (who generally don't believe most BS), and they are genuinely astonished at what all of the cheap, un-certified / un-tested consumer crap is doing to our electro-magnetic spectrum (i.e., clogging up our radio waves!)

So, please have a look at this thread...



And....
With all the talk of EPIRB's in the recent thread regarding the tragedy of the father and 3 teenagers lost just a couple dozen miles offshore SW Florida, in the Gulf of Mexico...I thought some might wish to learn more about EPIRB's, PLB's, etc...
And, more importantly, how they (and the COSPAS-SARSAT system) work!!
http://www.cruisersforum.com/forums/...ds-146617.html




Fair winds..

John