Transmission rules and regulations
Licensing requirements
It is the responsibility of the owner to comply with the applicable rules and regulations concerning the operation of a radio transmitter. In the United Sates, the FCC regulates the licensing of this equipment.
The TDL450B transceiver use extended frequencies and may contain functions that are not operational in the United States and its territories. Users should check with the radio authority of the country of operation for any restrictions that may apply.
Application for a license is made by submitting FCC Form 600 along with evidence of frequency coordination (if required) and applicable fees. Similar licensing requirements exist worldwide. Penalties for broadcasting without a license can be severe, and may include confiscation of your radio.
For more information, please contact your dealer or our customer service department.
Always obey local licensing requirements and restrictions. It is illegal to transmit in the United States while CSMA is turned off.
Being part of the RF community
Operation of a licensed radio product makes you a member of the RF community. Be aware that virtually all frequencies licensed are provided on a shared basis with other users. Each frequency dedicated specifically to RTK surveying activities has certain restrictions and limitations. For complete information, refer to the appropriate documentation from the licensing agency in your country of operation.
Most frequencies sharing data transmissions and voice transmissions give priority to voice users. Be mindful of the persistent nature of a GPS RTK data transmission and always limit your RF transmission output power when performing close-in survey situations to avoid interference with co-channel users. Trimble recommends using the low RF power setting for construction sites and other line of sight surveys with baselines less than three kilometers (two miles) depending on terrain. Also consider shutting down your radio transmission when not needed.
The TDL450B radio has embedded tools to help you identify the frequencies that are less used where and when you set up your transmitter.
If you are in conflict with a co-channel user, select another frequency to avoid formal actions by government agencies. In most cases, you are required to vacate a frequency upon complaint by a shared channel voice user.
Most survey operations are itinerant in that the system is moved on a frequent basis. For fixed system installations, you should not use frequencies set aside for itinerant operation, but should coordinate a frequency based on the fixed area operation.
Regulations differ from country to country, please be aware of the local regulations before using this radio equipment.
Automatic station identification
For operation in the United States, the FCC requires that the radio transmitters broadcast a station identifier every 15 minutes. The station identifier is the call sign assigned to you on the station license.
The Trimble TDL450B radio supports the broadcast of station identification in a manner that meets the requirements of the FCC. Upon receipt of equipment, use the radio keypad and display to program your FCC call sign into the configuration of the radio. This is only required for transmitters.
The call sign is transmitted every 15 minutes in Morse code. It is not included in any data packet and so is not processed by the receiving radio. However, data transmission is interrupted for up to four seconds, depending on the number of digits of your call sign, while the call sign is being transmitted. If you leave the call sign field blank, the radio programmed with this configuration will not transmit any call sign.
Failure to transmit your station identification is in violation of FCC regulations. If you are operating outside the United States, check with the local authorities if you need to transmit a call sign.
Carrier Sense Multiple Access (CSMA)
CSMA is a technology implemented in the TDL450B radio to meet the FCC transmitter requirements. It is illegal to transmit on any UHF radio within the USA without CSMA enabled. CSMA prevents radio transmission if the frequency is currently being used by a co-channel user. On occasion, you may note that the radio broadcasts stop for short periods of time. This is often due to co-channel interference and the radio is preventing broadcasts due to the FCC-mandated CSMA. The display will tell you that the radio has prevented its transmission because it has detected that the frequency is already being used.
GPS RTK equipment is designed to function with intermittent gaps in the data. Heavy co-channel use may limit the ability of the radio to transmit the required information. In areas of heavy co-channel usage, try changing channels to a less used frequency.
