Central Idaho Amateur
Radio Club
CIARC - Public Service - SAR
Search And Rescue (SAR) Resources
Emergency Services

The Central Idaho Amateur Radio Club makes the repeater system available for emergency services, including Amateur Radio Emergency Service (ARES) and licensed amateur radio operators participating in Search And Rescue (SAR) activities, on a high priority basis. Emergency activity is best coordinated through the CIARC officers but can be coordinated over the air as needed. Emergency use of the repeater system will always take priority over non-emergency use.

If emergency operation is required and contact with CIARC cannot be made to coordinate operation of the repeater system, stations conducting emergency communications should advise other stations that may come on the repeater system that emergency communications are being carried out and the nature of the emergency. All stations not actively participating in emergency communications should yield use of the repeater for emergency communications.

For additional information on the Amateur Radio Emergency Services (ARES) organization, or general public service information, please refer to the Public Service and the Calendar menus.

Membership in CIARC is not a prerequisite for using the CIARC communication infrastructure for Search And Rescue (SAR) or Emergency services.

Radio Communications Infrastructure

The Central Idaho Amateur Radio Club maintains several repeater systems that are available for Search And Rescue use. In addition, several CIARC members own privately maintained repeater systems that augment the capabilities of the CIARC repeaters and are available for CIARC member use. All repeaters are, or will be, linked together using the CIARC 33cm link backbone. These repeater systems and their capabilities are listed below:

Amateur Radio Repeaters available for SAR use
Callsign Location Type On
Offset Access
KC7MCC Brundage Mountain CIARC Yes 147.020 + CTCSS 100.0 Hz Yes No No
KC7MCC No Business Mountain CIARC No 442.500 + CTCSS 100.0 Hz Yes No No
N7IBC McCall Affiliate No 444.125 + CTCSS 100.0 Hz Yes Yes Yes
W7CIA Cascade Affiliate Yes 441.925 + DCS 023 Yes Yes Yes

Linking of repeaters allows a station to communicate on any of the repeater systems and have that communication heard on all of the repeater systems. By linking the repeater systems, repeater coverage is expanded and this allows stations to maintain communications when communication coverage might have been lost on a single repeater by changing channels to a repeater that has coverage.

For example, if a station is located within the coverage footprint of repeater #1 in the following diagram, that station would not be heard in the coverage footprint of repeaters #1, #2, #3 and #4 if repeaters #1, #2, #3 and #4 are not linked. If repeaters #1, #2, #3 and #4 are linked, a station located within the coverage footprint of any of the repeaters is heard on all of the repeaters.

This is very similar to a cellular telephone network. In a cellular telephone network, the system monitors radio signal strength and then the system instructs the individual radios as to what cell channel to use. In a linked amateur radio repeater system, the radio operator must perform the channel selection. Once a station operator becomes familiar with the zones of coverage, channel selection can be made by a familiarity with geographic location rather than based on real-time signal strength observations or reports from other stations of poor signal quality.

For example, imagine a mobile station traveling from location A to location B while communicating with stations located at C and D. Without linking, the mobile station would be heard by station C only when travelling through the coverage footprint of repeater #1 and would never be heard by station D. With linking, the mobile station initially uses repeater #3, then switches to repeater #1 when crossing the overlapping repeater coverage footprint of repeater #1 and #3, then switches to repeater #2 when crossing the overlapping repeater coverage of repeater #1 and #2, all the while maintaining communications with the stations located at C and D.

It should be noted that the coverage zones / cell shapes are influenced by terrain and are almost always irregular shapes.

Several mechanisms for establishing the connections between each of the repeater coverage zones or cells are employed. The most common mode of establishing these connections is to utilize radio frequency linking. Radio frequency linking presents the least amount of dependencies on external infrastructure and is the least prone to failure. Other methods of establishing these connections may include a dedicated telephone line or use of voice over internet protocol (VOIP). The Central Idaho Amateur Radio Club linking capabilities include a combination of radio frequency linking and VOIP linking. It should be noted that VOIP linking allows the Central Idaho Amateur Radio Club repeater system to be interconnected with any other repeater system that has a compatible VOIP linking capability. Where radio frequency linking typically is restricted to line of sight communications between repeater locations, VOIP linking has no such restrictions and provides a world-wide communication capability. VOIP linking is dependent on external internet infrastructure and is subject to failure of that infrastructure.

Central Idaho Amateur Radio Club repeater VOIP linking is supported using Internet Radio Linking Protocol (IRLP) or EchoLink while radio frequency linking is supported using the 33cm / 900MHz amateur radio band.

Should SAR activities occur in an area that has only partial radio coverage through direct access to the Central Idaho Amateur Radio Club repeaters, and the remaining search area is covered by an adjacent repeater system that has VOIP linking capability, then the adjacent repeater system can be connected to the Central Idaho Amateur Radio Club repeater system via VOIP linking to establish a larger integrated communications system. Such capabilities will simplify communications for SAR event coordinators as no relaying between distinct radio systems will be required.

Other capabilities that are available through repeater linking includes remote base operation. A remote base enables the network of linked repeaters to communicate to a repeater or individual station that is not connected to the linked network of repeaters and where that station or repeater has no linking capabilities. A remote base may also enable use of frequencies or bands that are not typically supported by a repeater. This can include use of frequencies that enable beyond line of site communication, including lower VHF frequencies that have greater Fresnel capabilities or HF frequencies that are subject to ionospheric propagation.

In addition, CIARC member stations may have capabilities to extend repeater coverage by implementing a cross-band repeat capability. This capability is often referred to as a mobile extender in public service radio communication. A mobile extender can be implemented by a non-fixed radio and may be conveniently located by SAR event coordinators, as either a mobile or portable station, in order to extend communication capability into a region where communications might otherwise present difficulty. Note that multiple stations using a mobile extender may not hear other stations using the mobile extender and this capability requires that SAR event coordinators be provided with a capability of hearing the primary repeater station that is being extended by the mobile extender capability. Such a configuration requires that all radio traffic be directed through a control point under the direction of SAR event coordinators.

Amateur Radio Emergency Service

The Central Idaho Amateur Radio Club is located within District 3 of the Idaho Amateur Radio Emergency Service (Idaho ARES). CIARC fully supports the ARES and has many ARES members within the CIARC membership. Should additional station resources be required by SAR event coordinators, the Valley County coordinator for Idaho ARES District 3, Tim Bailey, can be contacted to coordinate station staffing with ARES.

Idaho ARES District 3, based in the Boise area, has the capability to use repeaters in the Boise area and on Snowbank Mountain, west of Cascade, to establish communications capabilities with the Central Idaho Amateur Radio Club repeater system, providing an expanded radio coverage footprint for SAR event coordinators.

Digital Communications

Several Central Idaho Amateur Radio Club member stations have capabilities to conduct computer based digital communications where text based communications can be conducted with very high reliability. Digital communications modes are supported by a number of software application programs which provide interoperability independent of computer operating systems. One application program, Fldigi is available as freeware for Linux, Windows or Mac OS X and is intended for, but not limited to, High Frequency operation. Digital communication modes typically require an interface between the radio and a computer sound card.

There is a large suite of digital communications modes available, each with its advantages and disadvantages. Communications modes that are slower and/or offer Forward Error Correction (FEC) provide the most reliable means of communications. Of the available digital communications protocols, use of MT63 is recommended as it provides reasonable speed and is less prone to errors due to the implementation of Forward Error Correction. As a testament to MT63 reliability, MT63 is used by the United States Coast Guard Auxiliary, District 11 North, for its High Frequency text based radio communication due to its inherent immunity to noise induced errors and its reliability.

VHF and UHF packet communication modes are also available. This mode is dependent on a radio relayed line of sight communication capability. Any communications errors require re-transmission from the source. A specialized Terminal Node Controller is required to interface between the computer and radio.

Because digital modes and packet modes have a reliance on specialized equipment, not all amateur radio station operators may have capabilities for these modes.

It is recommended that digital modes that are dependent on a specific computer operating system or specific computer hardware be avoided. These modes do not support interoperability and reliance upon them will present limitations in amateur radio station resources allocation in the field. Such interoperability issues should be avoided at the pre-planning stage in order to avoid critical real-time issues during an SAR event.

Station Deployment

Several station operators have mobile operating capabilities, including ATV mobile radio capabilities, offering the SAR event coordinator additional options in station deployment.