USCG Rescue 21 range

[plenny7]

@plenny7, most good digital communications require an <ACK> or have a checksum at the end of the packet. Not saying it is Packet (AX.25 protocol) but as in a data packet. So the chance of a message getting that garbled is minimal, but not impossible. I understand the checksum can be damages, or there is ACK spoofing going on at the transmitter end.

Too many variables involved. I personally have not looked at the protocols involved in Marine Digital communications, but no doubt it is very standard.

@Brian D , I'm not disputing that at all. On the contrary, SG was stating that with digital you get all or nothing, and that a garbled *analog* message was better than no message at all. I was giving an example of how a garbled *analog* communications is certainly not "better than none".

K0KTW

 

[Brian D]

Got it. I might have misunderstood. Maybe it was garbled between what I saw written and what I read. LOL

Good to have another ham onboard.

 

[Jackdaw]

@plenny7, most good digital communications require an <ACK> or have a checksum at the end of the packet. Not saying it is Packet (AX.25 protocol) but as in a data packet. So the chance of a message getting that garbled is minimal, but not impossible. I understand the checksum can be damages, or there is ACK spoofing going on at the transmitter end.

Too many variables involved. I personally have not looked at the protocols involved in Marine Digital communications, but no doubt it is very standard.

Knock yourself out!

https://www.itu.int/dms_pubrec/itu-r/rec/m/R-REC-M.493-14-201509-I!!PDF-E.pdf

 

[glaufman]

I can hit a repeater at 68mi from my home on my handheld with 2 watts. Yeah, height of the antenna is paramount, not power. Although power has some advantage, but I think mainly in how "clear" one's signal is received. However, gain trumps power any day of the week. If I were to take my antenna and add a reflector or a director to make it a two-element antenna then I have just increased my gain. OK, got it, hard to do on a boat, but not on a fixed land station.

Just to add, a 36' Catalina was headed to Hawaii and had issues 200nm out. Their mayday was picked up in San Diego and Coast Guard was dispatched. But my point is, don't underestimate VHF communications.
http://www.equipped.org/0698rescue.htm

By the way, I also use VHF to talk to LEO satellites (1200mi) with a whip antenna.

Agreed. I've done EME (monbounce for those not familiar) on less than 25w vhf...
In the satellite example mentioned before those antennas have lots of directional gain, whereas my handheld purposely transmits all over... And the SATs have LOTS of the forementioned all important HEIGHT...
On the digital vs analog front... No doubt... With error correction et al digital signals can maintain perfect clarity to a way weaker reception than analog... However, digital will fall off a cliff once it reaches a certain weakness, whereas analog can maintain intelligibility far lower, especially CW (Morse code to the uninitiated) to the ear of a well prcticed operator (I used to be very well practiced)...
73 de N2GPA, son of K2JLD, son of K2JLC( QRT)

 

[Gunni]

I was probably the last guy in the US to give up my Motorola Startac cell phone, it had 2 digital frequencies and an analog frequency. At the time carriers maintained antenna for all three on their towers specifically to deal with poor coverage and long signal distances. Most everyone had been switched out to digital phones. Beyond 5 miles offshore none of those phones would work, the Startac would work to 15 miles out, auto switching to analog service. It would turn itself into a handwarmer and eat the battery in about 30 minutes!

 

[dziedzicmj]

if I remember correctly, the old analogue phone's radio transmitted at 3 or 4 W; the same phones, if they were capable, transmitted at 1/10 of that if using digital. Again, iirc, the max xmit power for cell phones now is 0.6 W. You need way less power for digital transmission.

 

[Brian D]

Apples and oranges. Cell phones transmit in a much higher frequency which requires less power to do the same thing that a lower frequency transmitter can do. But... Lower frequency can "travel" further than VHF which can "travel" further than cell phones. This does not include space communications.

 

[Gunni]

Yes, digital cell is what? 800,900 - 1500-1800 MHz. Low power. My first cell phone (analog) looked like a murse, and had an extending antenna. Hand piece was corded, about 8 feet long so you could get clear of the transmission path!

 

[JimInPB]

... I guess I could upgrade all these radios. But my solution is and has been a ship's sat EPIRB and individual PLBs. Once the kimchee hits the fan and I am stepping off I don't want to be at the mercy of some Coastie watchstander, or the range of my handheld. I want to light up SARSAT real good!

I'm curious why you would prefer have your distress signal picked up by SARSAT, rather than the local USCG?

When I am within 20 miles of the US coast, my preference is to send my signal to the USCG directly.

 

[Gunni]

I'm curious why you would prefer have your distress signal picked up by SARSAT, rather than the local USCG?

Did you read the story I linked of Morning Dew and the loss of 4 lives...despite VHF distress calls received by the USCG?

Then there was the time we were off the Shackleford Banks and witnessed 3 aerial flares, called the USCG watchstander and reported the flares. The watchstander decided to take a poll of any nearby ships (there were none other than us) and the matter faded into the night. SARSAT and NOAA have a much more precise and professional manner for responding to distress signals. There is a very distinct record of the alert, and a formal response method.

 

[JimInPB]

Did you read the story I linked of Morning Dew and the loss of 4 lives...despite VHF distress calls received by the USCG?

Then there was the time we were off the Shackleford Banks and witnessed 3 aerial flares, called the USCG watchstander and reported the flares. The watchstander decided to take a poll of any nearby ships (there were none other than us) and the matter faded into the night. SARSAT and NOAA have a much more precise and professional manner for responding to distress signals. There is a very distinct record of the alert, and a formal response method.

I did not read your previous account.

I have read several accounts of people receiving very delayed response to EPIRB signals & some cases of people receiving no response. These disappointing accounts all occurred outside of US waters. I have never set off an EPIRB or PLB myself, so I have no first hand experience with the response quality.

I have monitored many USCG rescues on the VHF. A close personal friend of mine was successfully rescued by USCG after an offshore mishap a few year ago. That person had only positive things to say about the coasties. Another close friend is a retired USCG master chief. I have done extensive boating with that person. I have had casual relations with several other coasties. I once purchased a boat from a retired Warrant Officer that I previously did some boating with in waters that were considered unnavigable. With the exception of a few new-hires, that were still growing into their paws, I have found the coasties to be very competent & squared away individuals. The new-hires have always been adequately supervised in rescue operations that I am aware of.

It would appear that you & I have had different personal experiences & are working from different bases of information. That would easily explain the differences in our preferences of who to call first when the foul smelling substances get deep.

Thank You for your response.