DART Communications

1. General

A DART uses three main types of communications systems:

• Public switched telephone networks (PSTN), also called the local phone system, to include international and countrywide cell phone coverage.
• Satellite (Inmarsat and VSAT) systems.
• Radio (HF/VHF/UHF) networks and systems.

Communications systems are chosen based on DART requirements. These include the following.

• Need for high-volume use.
• Portability.
• Ability to support various modes of communication, including, among others:
  • Standard voice.
  • Computer data (networked or stand-alone e-mail connections).
  • Fax.
  • Text-only messaging and video conferencing.

2. Local Phone System

Services. Services, quality, and availability vary with disaster locations. Following a disaster, if phone service is available, voice-grade lines will be available first (digital- and computer-grade lines may not be immediately available). Available phone circuits may be overloaded, and accessing outside lines may be difficult. Standard phone services are capable of providing ordinary voice and fax modes. Computer modes (e-mail/networking) and extremely high-grade video conferencing modes require specially conditioned phone lines that are not always available.

Operating Range. Nearly all metropolitan areas worldwide offer some degree of telephone services, but these services are not always available in rural areas.

Terrain Effects. Overhead telephone lines suspended on poles are often among the first casualties of natural or human-caused disasters.

Weather Effects. Wet conditions may cause degradation or disconnection of telephone signals. Severe weather may knock down telephone poles, completely disrupting services.

Setup Time. It may take up to 10 minutes to learn and understand different dialing procedures. Because of overloaded circuits and the poor quality of telephone connections, patience may be required when attempting to make connections.

3. Countrywide or International Cell Phones

Services. Cell phone coverage and reliability are normally determined before arriving in-country. The Global System for Mobile Communications (GSM) network provides complete cell phone coverage in countries that have a GSM network. When the GSM network is not available, most countries have local networks available to use with the purchase of cell phone chips (smart cards). The chip refers to an actual internal chip inside the phone. The phone must be equipped with this and the network must support the phone.

Operating Range. Nearly all metropolitan areas worldwide offer some type of cell phone service, but the signal strength is not always reliable in rural areas.

Terrain Effects. Terrain typically does not affect cell phone coverage.

Weather Effects. Weather-related conditions do not affect usage of cell phones.

Setup Time. If using a GSM network or local network cell phone, the setup time will be seconds, the time required to turn the phone on.

4. Satellite Terminal Systems

Services. Common telephone and data services are available from land-based terminals using the portable International Maritime Satellite (Inmarsat) or semifixed Very Small Aperture Terminal (VSAT) satellite network. These services include voice, fax, and e-mail communications. Any device that works with a common telephone device works with satellite systems. In addition to the above-mentioned services, some satellite terminals offer transferring of digital photographs or live video conferencing. Satellite signals may be digitally processed, giving your voice a digitized-sounding characteristic. Table D-1 contains additional information about satellite terminal systems.

Operating Range. Satellite terminal systems operate at any location between latitudes of 70° N. and 70° S. worldwide.

Terrain Effects. The satellite antenna or dish must have a clear, unobstructed view of the sky in the direction of the satellite.

Weather Effects. Heavy rains may impair the signal, and high winds may change the direction of the antenna or change the dish placement.

Frequency Selection. The operating frequency is set and is not under user control.

Setup Time. For portable Inmarsat terminals, setup can take 10 to 15 minutes. For VSAT terminals, setup can take 30 minutes to 3 hours or more (depending on system complexity).

Voltage Requirements. These systems require 90 to 250 VAC 50/60 Hz, 10 to 30 VDC, and generally will operate on any available electricity, including most automobiles.

Shipping Requirements. Depends on system.

5. HF/VHF/UHF Radio Networks and Systems

Services. Transmission of voice and digital data may be accomplished with two stations that are similarly equipped for the desired modes of communications. Table D-1 contains additional information about HF/VHF/UHF systems.

Operating Range. HF radio is most useful for long-distance communications. VHF/UHF are considered line-of-sight dependent, typically 3 to 10 miles. This range may be extended up to 30 to 40 miles with a high-mounted repeater and antenna. Range of special aircraft radios depends on the altitude of the aircraft.

Terrain Effects. Trees, buildings, mountains, etc., may limit range of all radio systems. UHF radio waves are best to penetrate confined spaces, such as collapsed buildings. VHF radio is a better choice for dense foliage, such as jungles. All radio antennas (especially HF) must be mounted in a high location in a clearing for best results.

Weather Effects. With the exception of the most severe rains and wind, weather has only a minor effect on HF and VHF. Some degradation on UHF during heavy rains may be noticed. Quality of HF communications depends on severity of solar activity (which changes throughout the day) in combination with the selected frequency. For this reason, multiple frequencies must be used throughout the day to effectively communicate with HF radio.

Frequency Selection. The Communications Officer determines specific operating frequencies. Use of existing USAID/Embassy frequencies may be authorized and are preferred. Frequency allocation from foreign governments takes time and is not automatic. Organizations such as UN/PVO/NGO/IOs, MARS (Military Affiliate Radio Systems), amateur radio networks, etc., may have prior frequency arrangements that the DART, if authorized, may take advantage of.

Setup Times. Initial base stations or repeaters require 30 minutes to 2 hours to set up. Installation (if required) of taller antennas, additional data modes, or more complex network systems may take several hours. Programming of radio frequencies may require up to 10 minutes per unit.

Voltage Requirements. These systems require 90 to 250 VAC 50/60 Hz, 10 to 30 VDC, and generally will operate on any available electricity, including most automobiles.

Shipping and Handling. Radios are considered by many governments to be controlled items. Special considerations (licenses, declarations, or authorizations) may be required before importation into the affected country.

1. Radio Identification

Radio identifications or call signs will be assigned by the Communications Officer in accordance with international agreements, host government laws, or USAID/Embassy policies. As a security precaution, coordinate with the Embassy in the selection of a call sign that does not indicate you are a ranking official or authority figure.

2. Communications Procedures

The following radio communications procedures should be used.

• Speak clearly, using plain language and no codes.
• Begin the transmission with the call sign of the station you are calling, followed with your call sign.
• If a reply is expected, end your transmission with over.
• If no reply is anticipated, end your transmission with out.
• Use standard phonetics, as provided in table D-2, for call signs, station identifications, and spelling of words and names that may not be easily understood.

Table D-2. Phonetic Alphabet