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<br />CTCSS and NAC Coded Squelch <br /> <br />Continuous Tone Coded Squelch (CTCSS) or Network Access Codes (NAG) shall be used on the <br />interoperability calling and tactical channels to mask interference, in accordance with the tables <br />below. Only the CTCSS tones and NAC Codes identified in this channel plan are allowed on the <br />interoperability channels within the state. These tones and codes shall not be changed nor others <br />added by the individual agency, the agency's communications vendor or any maintenance or <br />service provider. <br /> <br />Responding agencies from outside of Texas, and some in-state agencies with legacy equipment, <br />may not have the CTCSS transmit tones installed on VHF wideband interoperability channels. For <br />this reason, all mobile, portable, and temporary base radio receivers should be capable of "monitor" <br />mode operation. <br /> <br />Modulation and Encryption <br />Analoq modulation is mandatory on all interooerability callina channels to facilitate interooerability <br />with legacy radio equipment in the field. Exception: communications on all 700 MHz interoperability <br />channels must be P25 Phase 1 CAI digital modulation. <br /> <br />For most situations, analog modulation is preferred on tactical interoperability channels in all bands <br />except 700 MHz. For occasional pre-planned events, non-encrypted digital modulation is <br />authorized on tactical interoperability channels in all bands. <br /> <br />When used, digital modulation for interoperability channels shall be P ~25 Phase 1 CAI compliant <br />and shall use the following criteria: <br /> <br />· Network access code shall be $61 F for all interoperability channels <br /> <br />. Talkgroup 10 of $0001 <br /> <br />. Manufacturer's 10 of $00 <br /> <br />· Message 10 of $00000000000000000000 for open messages <br /> <br />For occasional pre-planned events where communications security is an issue, encrypted P-25 <br />Phase 1 CAI modes are authorized on tactical channels. Specific encryption algorithms and <br />encryption keys shall be as defined by the event incident commander, and shall conform to the <br />Texas Interoperability Encryption Plan (TIEP), under separate cover. <br /> <br />Temporary Base and Repeater/Mobile Relay Stations <br />Temporary base stations and repeater/mobile relay stations are permitted by the MOU associated <br />with this channel plan, with the following conditions or restrictions: <br /> <br />· Temporary base stations and temporary repeater/mobile relays that are deployed and <br />operating at an incident under interoperability conditions, may employ as much elevation <br />and Effective Radiated Power (ERP) as necessary to successfully support the incident. <br />However; Elevation and ERP should not exceed FCC licensed limitations (see Appendix A <br />for reference copies of state FCC licenses). Suggested on-scene parameters for temporary <br />base or repeater/mobile relay stations are: <br /> <br />o Temporary base and repeater stations should be limited to a maximum transmit antenna <br />height of 15.2m (50 ft), and maximum antenna gain of 3.0 dBd <br /> <br />o Transmit power shall not to exceed 50 watts when measured at the base of the antennat(ERP s 100 W). <br /> <br />7 <br />