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Difference between revisions of "Emergency Medical Services Radio"

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Revision as of 17:05, 22 August 2007

VHF Frequencies

150.7750   EMS (simplex)
150.7900   EMS (simplex)
152.0075   EMS (paging)
155.1600   EMS (also a common SAR frequency)
155.1750   EMS
155.2050   EMS
155.2200   EMS
155.2350   EMS
155.2650   EMS
155.2800   EMS
155.2950   EMS
155.3250   EMS 
155.3400   EMS to Hospital (HEAR)
155.3550   EMS
155.3850   EMS
155.4000   EMS
163.2500   EMS (paging)

These frequencies are also often used for other purposes which may or may not be EMS related such as ambulance dispatch and fire department tactical.

UHF Frequencies

The UHF "Med" channels 1-8 (some regions use different names, such as "Mednet") are used by Emergency Medical Technicians to communicate with the hospital. Information transmitted may be as little as the patient's age, sex, and general condition or as extensive as a full diagnostic workup.

In some areas, Paramedics are only able to give certain treatments under authority of an MD or specially-trained RN. This type of traffic is on the decline as well as Paramedics are given more independent treatment authority.

Analog transmission of electrocardiograms was quite common in the early days of modern EMS, but these modulated 1000 Hz tones are heard less and less as more and more EMS medical traffic is handled via cell phone. The FCC regulations (47 CFR Ch 1 Sec 90.20) reflect the old way in that Med 1-3 (and also Med 11-33) are allocated primarily for transmitting this type of telemetry, although this is rarely done and hence the channels are also used for other purposes (such as voice and paging).

Med channels 9 and 10 (and also Med 91-103) were added later below the original band of 8 and are allocated for dispatch purposes instead of medical control. They also explicitly allow paging, typically the same type as used by fire departments.

The UHF frequencies are assigned in pairs. In semi-duplex mode the higher frequency of the pair is usually used by the mobile while the lower frequency is used by the base (usually a hospital). Some EMS systems have the system configured for full-duplex where both parties can transmit and recieve at the same time. In many areas, they are configured as repeaters on mountaintops with the hospitals transmitting and receiving the same as any mobile. PL tones are selected by the ambulance crew to select which hospital hears the traffic, since many hospitals may be able to hear the same repeater on a particular pair.

Med channels 11-103 are "splinter" frequencies added the most lately. They are situated between the original existing channels and all would probably have to be narrowband to prevent adjacent channel interference if they were used in close proximity. The channels ending in a "1" or "3" (which are .00625 step channels) are narrowband to prevent adjacent channel interference.

Mobile and portable stations above 2.5 watts, licensed before July 6, 2000 must have Med channels 1-8. Those licensed between July 6, 2000 and December 31, 2005 must have Med channels 1-8, plus Med channels 12-82 (those intermediate splinters ending in "2"). Starting January 1, 2006, they must have all 40 channels. Base stations and portables below 2.5 watts are excepted.

Mobile Rx	Mobile Tx	Name	Primary Allocation			Note
463.00000	468.00000	Med 1	Biomedical Telemetry				
463.02500	468.02500	Med 2	Biomedical Telemetry
463.05000	468.05000	Med 3	Biomedical Telemetry

463.07500	468.07500	Med 4	Medical Control (voice)
463.10000	468.10000	Med 5	Medical Control (voice)
463.12500	468.12500	Med 6	Medical Control (voice)
463.15000	468.15000	Med 7	Medical Control (voice)
463.17500	468.17500	Med 8	Medical Control (voice)

462.95000	467.95000	Med 9	Dispatch/Paging
462.97500	467.97500	Med 10	Dispatch/Paging

463.00625	468.00625	Med 11	Biomedical Telemetry			narrowband
463.01250	468.01250	Med 12	Biomedical Telemetry
463.01875	468.01875	Med 13	Biomedical Telemetry			narrowband
463.03125	468.03125	Med 21	Biomedical Telemetry			narrowband
463.03750	468.03750	Med 22	Biomedical Telemetry
463.04375	468.04375	Med 23	Biomedical Telemetry			narrowband
463.05625	468.05625	Med 31	Biomedical Telemetry			narrowband
463.06250	468.06250	Med 32	Biomedical Telemetry
463.06875	468.06875	Med 33	Biomedical Telemetry			narrowband

463.08125	468.08125	Med 41	Medical Control (voice)			narrowband
463.08750	468.08750	Med 42	Medical Control (voice)
463.09375	468.09375	Med 43	Medical Control (voice)			narrowband
463.10625	468.10625	Med 51	Medical Control (voice)			narrowband
463.11250	468.11250	Med 52	Medical Control (voice)
463.11875	468.11875	Med 53	Medical Control (voice)			narrowband
463.13125	468.13125	Med 61	Medical Control (voice)			narrowband
463.13750	468.13750	Med 62	Medical Control (voice)
463.14375	468.14375	Med 63	Medical Control (voice)			narrowband
463.15625	468.15625	Med 71	Medical Control (voice)			narrowband
463.16250	468.16250	Med 72	Medical Control (voice)
463.16875	468.16875	Med 73	Medical Control (voice)			narrowband
463.18125	468.18125	Med 81	Medical Control (voice)			narrowband
463.18750	468.18750	Med 82	Medical Control (voice)
463.19375	468.19375	Med 83	Medical Control (voice)			narrowband

462.95625	467.95625	Med 91	Dispatch/Paging				narrowband
462.96250	467.96250	Med 92	Dispatch/Paging
462.96875	467.96875	Med 93	Dispatch/Paging				narrowband
462.98125	467.98125	Med 101	Dispatch/Paging				narrowband
462.98750	467.98750	Med 102	Dispatch/Paging
462.99375	467.99375	Med 103	Dispatch/Paging				narrowband

Early on, there were four other frequencies, another 5 MHz below Meds 2, 4, 6, and 8 (458.02500, 458.0750, 458.1250, 458.1750). These were used by Paramedics to relay medical and telemetry traffic from the patient's location to the ambulance or rescue vehicle and then again to the hospital or other medical control. Like the Med channels themselves, they are now all in the public safety frequency pool.