Here’s some information about CMED in Massachusetts. I had a hard time finding any sort of general overview, so I’ve tried to create one. I’ve also tried to be fairly obsessive about citing where I found information so all of the links I found are available. I’m not a subject-matter expert (this is stuff I’ve just learned), so corrections are more than welcome!
CMED stands for Central Medical Emergency Direction1, and is a system used in Massachusetts allowing EMS providers (i.e., ambulances and EMTs) to communicate with hospitals. To quote the state EMS Communications Plan1:
The Federal Emergency Medical Services System Act of 1973 established the concept of a Central Medical Emergency Direction (CMED) Center. A CMED Center is an organization that provides specialized communications functions to connect, at a minimum, hospitals and medical first responders.
CMED Centers play a role in coordinating EMS communications by:
assisting EMS field personnel with communication during emergencies managing Medical radio channel usage maintain a clear procedure for EMS communications within a region connecting EMS field personnel to local Emergency Departments and Medical direction providing interoperability with other public safety agencies
So the concept exists at the Federal level, though this article is wholly focused on the Massachusetts system. It’s a radio network allowing ambulances to communicate with hospitals, both to notify them that they’re en route and to potentially receive instructions/authorization from doctors for emergency care EMTs cannot normally provide without a doctor’s orders.
Another explanation comes from the Region II (Central, MA) system2 (more on them in a moment):
CMED (Central Medical Emergency Direction) relies on a network of radio towers set up strategically throughout Central Massachusetts (EMS Region II). Through these towers… an ambulance can contact CMED via radio and request entry notification to a hospital of destination. This provides physician access and ensures that the emergency department is aware of the patient’s pending arrival. CMED also plays an important role in coordinating EMS response to Mass Casualty Incidents and patient distribution from the scene to the hospital. CMED is crucial to the coordination of communications between ambulances and hospitals and ultimately contributes to optimal patient care.
It is primarily a UHF network (though there is apparently some lingering VHF usage).
The system is split up into five regions (known as CMED Centers):
- Region 1: Western MA, Western Massachusetts Emergency Medical Services Inc.
- Region 2: Central MA, Central MA EMS Corp.
- Region 3: Northeast MA, NorthEast Emergency Medical Services, Inc.
- Region 4: Metro Boston, Metropolitan Boston Emergency Medical Service Council, Inc.
- Region 5: Cape & Islands, Cape and Islands Emergency Medical Services System
The Region 2 (Central MA) site has a bunch of information.
The Northeast site is, regrettably, designed in Flash, making it impossible to link to individual pages.
The system is primarily a UHF system, using these frequencies. Somewhat unconventionally, it is a duplex, non-repeater system. The hospital/control transmits simplex on the higher ~468 MHz frequencies, and the ambulances transmit simplex on the lower ~463 MHz frequencies3,4. This makes monitoring difficult, as there are two frequencies in use, one for each side. (Plus, since there are no repeaters, you will likely not hear the ambulance side unless it is nearby.)
Each region runs its own network, but is generally a network of a handful of towers, operated as a remote base from the CMED Center. The communication happens on whichever tower has the best signal.
Statewide, communications begin on CMED-43,5 (463.075 ambulance, 468.075 hospital). (Though it sounds like MED-42 might be used instead in the North Shore part of Region 33,6, possibly to avoid overlap.) CMED Control will then direct ambulances to an open channel as appropriate, and patch in the hospital.
Northeast (Region 3) Info
This being the region in, my coverage is a little biased. 🙂 It’s also where I found the most documented information.
The PL throughout the whole region is 123.03,6.
Per 4, MED-1, MED-5, and MED-7 are used on the North Shore, and MED-1, MED-6, and MED-8 are used in the Merrimack Valley region, though some of this information may be dated. Communication begins on MED-4 (or MED-42 in the North Shore) and units are then directed to one of the available channels. (The channels are referenced as MED-nn, so if you listen you’ll pick up what channels are being used.)
MED-9 is used to dispatch paramedics (ALS) in Lowell and Lawrence4,6.
1 ‘The Massachusetts Emergency Medical Services Communications Plan’, revised 13 May, 2013. http://www.mass.gov/eohhs/docs/dph/emergency-services/radio-communications-plan.doc. This is a treasure trove of information, though it was not aimed at scanner listeners.
2 CMED introduction, http://www.cmemsc.org/index.php/cmed, the Central MA EMS Corp.
3 Massachusetts C-MED, http://scan-ne.net/wiki/index.php?title=Massachusetts_C-MED, Scan New England Wiki.
4 ‘northeast cmed/region 3 info’, posted by cmed325 on Radio Reference, http://forums.radioreference.com/massachusetts-radio-discussion-forum/201303-northeast-cmed-region-3-info.html.
5 ‘CMED: An Overview and Its Practical Applications’, 2009 PowerPoint presentation, found on Metro Boston site, http://www.mbemsc.org/files/provider_info_items/CMED_Training_Presentation_2009.ppt.
6 ‘Region 3 Cmed Narrowband’, post by cmed325 on Radio Reference, http://forums.radioreference.com/massachusetts-radio-discussion-forum/251934-region-3-cmed-narrowband.html.