V Med 28

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Tim-B

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Every day on nationwide interop frequecy designated V MED 28 (155.34 MHz) I hear some hospitals around Lafayette doing radio checks. It appears that every day a different hospital takes a turn at being the one to call all the rest for the radio check. Each call to a particular hospital is preceeded by tones that sound like WEEEEEEEEE WEWEWEWEWEWE WEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE WEWEWEWEWE WEEEEEEEEEEEEEEEEEEEEEEEEEEE. Does anyone know what that's all about? What are the tones for and what would they use this radio frequency for? Is it just for backup in the event of a major disaster that reneders phone or computer networks inoperative. These tones are some type of signal that has been around for a while. I remember back in the 80's when Acadian Ambulance units used this same frequency to transmit these tones to a hospital followed by information about patients that they were transporting.
 

nd5y

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Sounds like rotary dial pulse tone encoding (not sure of the exact name).
Back in the 60s-70s it was used for selective calling before DTMF became popular. Instead of a DTMF keypad there was a telephone type rotary dial.

In some places they used that on 155.34 so the hospitals didn't have to listen to all the traffic on the frequency unless their code was dialed up.
 
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ecps92

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SELCALL
https://en.wikipedia.org/wiki/Selcall


Sounds like rotary dial pulse tone encoding (not sure of the exact name).
Back in the 60s-70s it was used for selective calling before DTMF became popular. Instead of a DTMF keypad there was a telephone type rotary dial.

In some places they used that on 155.34 so the hospitals didn't have to listen to all the traffic on the frequency unless their code was dialed up.
 

ecps92

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The Nationwide Interop for 155.2800 as VMED28 would be if there is a PL/CTCSS of 156.7

Any other use, is still considered Local, Regional or State

Every day on nationwide interop frequecy designated V MED 28 (155.34 MHz) I hear some hospitals around Lafayette doing radio checks. It appears that every day a different hospital takes a turn at being the one to call all the rest for the radio check. Each call to a particular hospital is preceeded by tones that sound like WEEEEEEEEE WEWEWEWEWEWE WEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE WEWEWEWEWE WEEEEEEEEEEEEEEEEEEEEEEEEEEE. Does anyone know what that's all about? What are the tones for and what would they use this radio frequency for? Is it just for backup in the event of a major disaster that reneders phone or computer networks inoperative. These tones are some type of signal that has been around for a while. I remember back in the 80's when Acadian Ambulance units used this same frequency to transmit these tones to a hospital followed by information about patients that they were transporting.
 

SteveC0625

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What are the tones for and what would they use this radio frequency for?
155.340 is still used in many, many parts of the US for routine ambulance to hospital communications. If you do any kind of FCC license search on 155.340, you'll find thousands of licensees on this frequency, and many of them dating back to the 1970's, long before the VMEDs and other interop frequencies were designated via DHS's NIFOG which wasn't created until after 9/11/2001.

One advantage of having 155.340 designated as a VMED interop is that a great number of ambulances already this frequency in their radios.

But the VMED designation remains secondary to every day usage in many places.
 

Tim-B

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Since that technology and these licenses have been around for decades does anyone have an idea as to why they are even still using them? We have phones, the internet, virtual private networks, etc. Maybe just for backup in case all of that is out or for coordination between hospitals in case of a major event like katrina?
 

SteveC0625

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Since that technology and these licenses have been around for decades does anyone have an idea as to why they are even still using them? We have phones, the internet, virtual private networks, etc. Maybe just for backup in case all of that is out or for coordination between hospitals in case of a major event like katrina?
None of those technologies are of much use to an ambulance in areas where there is no cell signal. Radio is still highly reliable and cost effective for a large portion of the country. I happen to live in an area where there is very little cell signal outside of villages.

However, in many urban areas, ambulances are routinely using cell phones or data systems for ambulance to hospital communications. But they've still got radios in the vehicles and at the hospitals. Let's remember that when a major incident happens, the first thing to get overloaded and lose reliability for public safety is the cellular network.
 

ecps92

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Also, the need for Medical Control has decreased with "Standing Orders"
Even in the Big Cities the volume has gone down, but not ended the use of UHF

Quick and Dirty entry notifications are generally what occurs

None of those technologies are of much use to an ambulance in areas where there is no cell signal. Radio is still highly reliable and cost effective for a large portion of the country. I happen to live in an area where there is very little cell signal outside of villages.

However, in many urban areas, ambulances are routinely using cell phones or data systems for ambulance to hospital communications. But they've still got radios in the vehicles and at the hospitals. Let's remember that when a major incident happens, the first thing to get overloaded and lose reliability for public safety is the cellular network.
 
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