Navy Ships - Strange Programming

[rescue161]

Does anyone else listen to US Navy Ships? I've found that most use the same set of frequencies and talk group assignments. This causes a problem when two ships with the same data are in port at the same time.

They are not using a Smartzone system. Here are some problems:

1. If both are using the same control channel at the same time, each ship has to compete for control over it's radios.

2. If they aren't using the same control channel, then they still have to compete over the other frequencies.

3. A good portion of the time, I see ships that only have ONE user ID for every radio on the ship. Big problem if a radio is ever stolen. If they needed to inhibit the stolen radio, they'd end up wiping out every radio on the ship...

Why did they do the systems like this?

 

[VintageJon]

EXCELLENT point! Why indeed?

73's
Jon

 

[fmon]

As the crow flies, my home is 9 miles across water from NorVA NOB piers, homeport for most of the US Navy ships stopping in Rota. Also, all nuke Aircraft Carriers are refueled and SLEP at the Newport News Shipyard, and the George H Bush CVN 77, is currently being built there as have all 10 other nuke carriers. This yard is less then 6 miles across the James River from my home.

This is a very large concentration of Naval ships, however, I rarely hear any trunking coms due to very low power used by many of these ships (see this link). And I don't have a scanner capable of scanning 380 MHz trunking.

It's rare that I try to scan these ships but I did catch this ship a year or so ago while running trunker. Soon, the signal disappeared and checking departures, three ships, one of which was a Gator Freighter, departed for an operation to the Baltic area. Someone else submitted this data for the Iowa Jima

BTW, I only use stock antennas for this purpose but do receive trunking systems at three times the range of the NOB piers. And the NavBase 400 mhz trunking system booms in on all four of my digital scanners as does the Naval Shipyard 400 system located in Portsmouth.

 

[rescue161]

Well, at least that ship isn't using the exact same frequencies that the ones I monitor do.

They are:

406.8500
407.0750
408.1250
408.7000

There are a few exceptions as in the EDACS 380 systems.

 

[fmon]

Scott,

You roused my curiosity, I'm attempting to get Trunker to lock onto an unknown Mot CC 406.8500. My Pro-96 registers M:36 sysid 661B, which is not in the database.

This is likely a navy ship and supports your previous findings.

 

[rescue161]

Just about all of the ships that are Motorola use those same frequencies. Some are 25 KHx and some are 12.5, you just have to figure it out.

 

[fmon]

Trunker is still unable to lock-on and it's likely because the signal is too low powered. But it sure can't be the same 406.8500 you reported. Yours is 3650 statute miles east of mine.

 

[rescue161]

What I'm saying is that there are numerous ships all with the same info, i.e. the same frequencies and the same talk groups. They pull in and out of here all the time. Right now, there are three ships in port. Two are Motorola systems. One is 661D and the other is 713E. They both have the exact same frequencies and talk groups. The other is an EDACS system in the 380 range.

 

[fmon]

It appears the system on many may be the same except for the fourth character. You have one as 661D and I'm listing one as 661B, Agreed, both may be setup the same otherwise.

BTW, I sent you a PM.

 

[fmon]

By golly Scott, my CC just now change to 407.0750, which is your second frequency above. This is the 661B system, though still to weak to work with Tunker.

 

[fmon]

The following three frequencies are listed in the RR Database for the USS Iwo Jima. I monitored them on the below dates with trunker, and verified with my Pro-96 as M36 with the sysid's as indicated. However, the Iwo in company with the USS Cole and another ship, deployed last weak.
Sysid 6E19 on CC 408.7000 on 11 June 06 INVERT
Sysid 6E19 on CC 407.0750 on 12 June 06 INVERT
Sysid 7206 on CC 407.0750 on 13 June 06 INVERT
Sysid 8833 on CC 406.8500 on 13 June 06 INVERT

Sys 8833 has not given any other data yet on trunker, but the signal is off more then on, typically weak of MA/Com systems in navy ships.