ARRL Certification Program
Emergency Communications
Equipment Operations

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I.8.F - Equipment Operations

DTMF

Consider equipping your radio with a DTMF (Dual Tone Multiple Frequency) microphone. Some radios don't come with it. A DTMF microphone is useful if you need to bring up an emergency autopatch, or if you need to remotely control a repeater.
Consider employing simplex autopatches for field units to access phone lines during emergencies.
Some radios, especially walkies, come with a DTMF decoder that also turns the radio into a DTMF pager.

CTCSS

If you radio is not equipped with CTCSS (Continuous Tone Coded Squelch System), consider getting an encoder and decoder. You can use CTCSS as a kind of off-hour monitor. When the radio receives a signal without the CTCSS sub-audible tone, the receiver will not open and you will not hear audio. When the radio receives a signal with CTCSS tone, it will open the squelch and you can hear the transmission.
CTCSS is useful for:

Monitoring a common calling channel for emergency alerts (activate the CTCSS before calling).
Blocking out interference from intermod.
Activating remote links on repeater system to extend coverage beyond just a local repeater, (and with the CTCSS tone) send the audio onto links to remote repeaters.

AQS

Some radios support the Amateur Quiessence System (AQS). It uses a sequence of tones to perform digital signaling at the beginning of each transmission representing a sequence of numerical digits. You can use it to selectively call another station and quiet the receive in the meantime.
It is found primarily on Yaesu and Icom equipment.

DCS

Some Kenwood radios support Digitally Coded Squelch (DCS). Similar to AQS, it enables you to quiet the receiver and selectively call a radio with a preprogrammed series of three digits.

PASSBAND, NOTCH Filters

Learn the passband and notch filters, and the IF shift features of your radio. You can use them to work around adjacent interference on SSB and CW.
Passband and IF shift are useful if there is a wide signal interfering that is adjacent to your intended receive signal.
A notch filter is useful for CW, if there is an adjacent CW signal.

Hospital Safety Requirements

Hospitals have strict regulations on permitting electronic devices to operate within the building. Stray interference generated by electronic devices can affect the sophisticated and often computer-controlled medical equipment. Have your equipment checked by the safety officer or designated hospital staff person.

QUESTIONS

True or false: DTMF, CTCSS, AQS and DCS can be used to provide selective signalling and calling between two stations.
True or false: Hospitals have strict regulations on permitting electronic devices to operate within the building.

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ARRL Certification Program Emergency Communications Equipment Operations

ARRL Certification Program
Emergency Communications
Equipment Operations