Mission Hosp. clock system

[AlphaFive]

This is just a unique little novelty, nothing earth shattering. In Asheville if you go to 72.3200 MHz or 72.4000 MHz, you'll find the GPS feed into the Mission Hospital clock system. Now I do not know anything about Satcom, so I don't know if it is uplink, downlink, or sideways link for that matter... The sound is very clear, it consists of a long series of loud high pitched beeps. The transmission is not a constant wave, and is not always active. But, I would say more often than not it is on one of the two frequencies. So, from my limited knowledge point of view, it's pretty cool to hear the satellite communicating with the clocks, and not have to have some kind of extra software hooked up. They're license is WQEN826, with all of the other mobile frequencies associated with it. Take care

 

[ab5r]

As a matter of curiosity, what mode: SSB, FM. FMn or what, please.

 

[AlphaFive]

clock system

I put in the frequency, I'm just waiting to see what registers on the 536, I'll let you know, I never wrote down the mode

 

[AlphaFive]

clock system

72.4000 is registering as FM mode right now, not nfm, or wide, just standard

 

[ecps92]

72 Mhz was not part of the Narrowbanding Requirements, so it is FM

Generally those devices operate under
20K0F1D, 20K0F3D, 20K0F3E

As a matter of curiosity, what mode: SSB, FM. FMn or what, please.

 

[AlphaFive]

clock system

Your right on the money with two of the three designators, for some odd reason this license includes 20KOF1E, which provides for 'encrypted quantized voice', really? encrypted quantized voice? For a clock system, I just do not understand that particular logic. Thank you all for your replies.

 

[Thunderknight]

It is likely a link from a base (master) to be received by the clocks across the facility. So they are a source of master time without wiring to them.
Not a satellite link per se (although the master could have a GPS receiver).

See http://www.primexwireless.com/uploads/files/Choosing_the_Right_Time_Synchronization_Frequency.pdf

 

[AlphaFive]

clock system

That certainly makes perfect sense, looking at the station class codes...that fits

 

[yardbird]

There are several agencies that us the same frequency range for clocks.

Northeast Medical Center in Concord, NC

Stanly County Schools in Albemarle, NC

I am sure if I had time to sit down and search Scanner Frequencies - Phone Numbers - IP Addresses

I could find just about all schools and hospitals will have a license for frequencies in that range.

Also if I am not mistaking the highway patrol has some link frequencies licensed in those rages as well.

Hope this helps

David

 

[kb4mdz]

Look for a signal in that freq. range around the Dalton Library at UNCC. I seem to remember seeing one of those Primex units when I did some LMR service work there.

Off the top of my head, I know I've seen them other places, but can't remember which ones.

 

[SCPD]

ICC in Spindle used to have a similar system, don't know if they still do

 

[kruser]

It is likely a link from a base (master) to be received by the clocks across the facility. So they are a source of master time without wiring to them.
Not a satellite link per se (although the master could have a GPS receiver).

See http://www.primexwireless.com/uploads/files/Choosing_the_Right_Time_Synchronization_Frequency.pdf

The large school district where I live uses 72 MHz clock systems. No satellite but as you said, they very well could use a GPS source for the master clock although I doubt it unless something changed over the past several months.
They did use a signal from WWVB at one time though and that could still be in use but it only synced I think once or twice per day and if no good signal, it would retry hourly until it did get a useable signal.
I forget the specifics of the master clock now but it in itself was fairly accurate even if it did not get a master sync to realtime.

Boeing aircraft also uses such a system as does our local at&t phone CO type buildings. In at&t's case, they do use GPS for a time source but they do not use a radio link like the school district or Boeing.
I think Monsanto may also use a 72 MHz link for its main campus.

We also have paging links here that are in the 72 MHz range. Those run at a higher baud rate than the actual 152/158 MHz POCSAG or FLEX paging transmitters. Probably needed to keep all the transmitters in sync to avoid multipath. Every darn hospital around me has a 152.240 MHz transmitter on its rooftop even though the hospitals are less than a mile apart the way the crow flies in several cases.
I had a PageNet pager on the frequency years ago. If you were not distant or in one of the hospitals parking lots, the timing difference caused a lot of missed pages much in the same way 800 MHz simulcast sites have issues.

To the OP, if you want to hear some sat comms, try for some of the NOAA birds around the 135/136 MHz range. No voice though and the overhead passes are short lived. Maybe 15 minutes unless you have an antenna with auto EL/AZ tracking and the correct circular polarization. Then you can actually get some decent pictures from those old birds. Doppler shift plays a big part in hearing them though. They use an odd bandwidth as well. Wider then FM or NFM but less than FM broadcast radio. I always assumed they used the wide bandwidth to overcome some of the Doppler shift.

 

[AlphaFive]

clock system

Interesting regarding the paging system reference, the license does list a number of paging units. Perhaps this is why there is a designator that provides for encrypted voice. But, that is about 27 steps above my paygrade in understanding. Thank you all again, I learned a lot about something I had no familiarity with...