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
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)...
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!)