|
IRIG 106-99 CHAPTER 2 - TRANSMITTER AND RECEIVER SYSTEMS 2.1 Radio Frequency Standards for Telemetry 2.2 Definitions 2.3 UHF Bands 2.4 UHF Telemetry Transmitter Systems 2.5 UHF Telemetry Receiver Systems Footnotes TRANSMITTER AND RECEIVER SYSTEMS 2.1 Radio Frequency Standards for Telemetry These standards provide the criteria to determine equipment and frequency use requirements and are intended to ensure efficient and interference-free use of the radio frequency spectrum and interchange of operations and data between test ranges. The radio frequency spectrum is a limited natural resource; therefore, efficient use of available spectrum is mandatory. In addition, susceptibility to interference must be minimized. Systems not conforming to these standards require justification upon application for frequency allocation, and the use of such systems or frequencies is highly discouraged. The standards contained here are derived from the National Telecommunications and Information Administration's (NTIA) Manual of Regulations and Procedures for Federal Radio Frequency Management. 2.2 Definitions Allocation (of a Frequency Band). Entry in the Table of Frequency Allocations1 of a given frequency band for the purpose of its use by one or more radio communication services or the radio astronomy service under the specified conditions. Assignment (of a Radio Frequency or Radio Frequency Channel). Authorization given by an administration for a radio station to use a radio frequency or radio frequency channel under specified conditions. Authorization. Permission to use a radio frequency or radio frequency channel under specified conditions. Occupied Bandwidth. The width of a frequency band such that below the lower and above the upper frequency limits, the mean powers emitted are each equal to a specified percentage of the total mean power of a given emission. Unless otherwise specified by the International Telecommunication Union (ITU) for the appropriate class of emission, the specified percentage shall be 0.5 percent. The occupied bandwidth is also called the 99 percent power bandwidth in this document. Primary Service. A service which has full rights in a band of frequencies and which can claim protection from harmful interference from other services. Secondary Service. Service which can be obtained on a noninterference operation basis with primary service users. Stations of a secondary service shall not cause harmful interference to stations of a primary service and cannot claim protection from interference from stations of a primary service; however, they can claim protection from harmful interference from other secondary stations to which frequencies were assigned at a later date. 2.3 UHF Bands 2.3.1 Allocation of the L Band (1435 to 1535 MHz) 2.3.1.1 1435 to 1525 MHz 2.3.1.2 1525 to 1530 MHz 2.3.1.3 1530 to 1535 MHz 2.3.2 Allocation of the S Band (2200 to 2300 MHz) 2.3.2.1 2200 to 2290 MHz 2.3.2.2 2290 to 2300 MHz 2.3.3 Allocation of the Upper S Band (2310 to 2390 MHz) 2.3.3.1 2310 to 2360 MHz 2.3.3.2 2360 to 2390 MHz The bands used for telemetry are described unofficially as the L band from 1435 to 1535 MHz, the S band from 2200 to 2300 MHz, and the upper S band from 2310 to 2390 MHz. While these band designations are common in telemetry parlance, they may have no specific meaning to anyone else. Telemetry assignments are made for testing2 of manned and unmanned aircraft, missiles, space vehicles, rocket sleds, and systems carried on such sleds for testing or their major components. 2.3.1 Allocation of the L Band (1435 to 1535 MHz) . This band is allocated in the United States of America and its possessions for government and nongovernment aeronautical telemetry use on a shared basis. The nongovernment use of this band is coordinated by the Aerospace and Flight Test Radio Coordinating Council (AFTRCC). The frequencies in this range will be assigned for aeronautical telemetry and associated remote-control operations3 for testing of manned or unmanned aircraft, missiles, rocket sleds, and other vehicles or their major components. Authorized usage includes telemetry associated with launching and reentry into the Earth's atmosphere as well as any incidental orbiting prior to reentry of manned or unmanned vehicles undergoing flight tests. The following frequencies are shared with flight telemetering mobile stations: 1444.5, 1453.5, 1501.5, 1515.5, 1524.5, and 1525.5 MHz. 2.3.1.1 1435 to 1525 MHz . This frequency range is allocated for the exclusive use of aeronautical telemetry in the United States of America. 2.3.1.2 1525 to 1530 MHz. The 1525 to 1530 MHz band was reallocated at the 1992 World Administrative Radio Conference (WARC-92). The Mobile-Satellite Service is now a primary service in this band. The Mobile Service (includes aeronautical telemetry) is now a secondary service in this band. 2.3.1.3 1530 to 1535 MHz . The Maritime Mobile-Satellite Service is a primary service in the frequency band from 1530 to 1535 MHz. 4 The Mobile Service (including aeronautical telemetry) is a secondary service in this band. 2.3.2 Allocation of the S Band (2200 to 2300 MHz) . No provision is made in this band for the flight testing of manned aircraft. 2.3.2.1 2200 to 2290 MHz . These frequencies are shared equally by the United States Government's fixed, mobile, space research, space operation and Earth exploration-satellite services. These frequencies include telemetry associated with launch vehicles, missiles, upper atmosphere research rockets, and space vehicles regardless of their trajectories. 2.3.2.2 2290 to 2300 MHz . Allocations in this range are for the space research service (deep space only) on a shared basis with the fixed and mobile (except aeronautical mobile) services. 2.3.3 Allocation of the Upper S Band (2310 to 2390 MHz). This band is allocated to the radiolocation and mobile services in the United States of America. Government and nongovernment telemetry users share this band in a manner similar to that of the L band. Telemetry assignments are made for flight testing of manned or unmanned aircraft, missiles, space vehicles, or their major components. The frequencies 2312.5, 2332.5, 2352.5, 2364.5, 2370.5, and 2382.4 MHz are also designated for use by both government and nongovernment stations on a co-equal basis for telemetering and associated telecommand operations for expendable and reusable launch vehicles whether or not such operations involve flight testing. Such uses will be limited to 1 MHz bandwidths. 2.3.3.1 2310 to 2360 MHz . These frequencies were reallocated by WARC-92 to the broadcasting-satellite service (sound) and complementary terrestrial sound broadcasting service on a primary basis in the United States of America. This reallocation will take effect in January 1997 or whenever the frequencies are required for this service, whichever occurs later. Aeronautical telemetry will become a secondary service when the reallocation occurs. 2.3.3.2 2360 to 2390 MHz . The Mobile Service (including aeronautical telemetry) is a primary service in this band. 2.4 UHF Telemetry Transmitter Systems 2.4.1 Center Frequency Tolerance 2.4.2 Channel Bandwidth Definitions 2.4.2.1 Standard Bandwidth Signal 2.4.2.2 Wide Bandwidth Signal 2.4.3 Channelization 2.4.3.1 Standard Bandwidth Channels 2.4.3.2 Wide Bandwidth Channels 2.4.4 Output Power 2.4.5 Modulation Polarity 2.4.6 Spurious Emission and Interference Limits 2.4.6.1 Transmitter-Antenna System Emissions 2.4.6.2 Conducted and Radiated Interference 2.4.7 Operational Flexibility 2.4.8 Modulated Transmitter Bandwidth Air- and space-ground telemetry is accommodated in the appropriate UHF bands 1435 to 1535, 2200 to 2300, and 2310 to 2390 MHz as described in paragraph 2.3. 2.4.1 Center Frequency Tolerance. Unless otherwise specified for a particular usage, frequency tolerance for a telemetry transmitter shall be ±0.002 percent of the transmitter's assigned center frequency. |
Between 1 and 5 seconds after initial turn on, the unmodulated transmitter
frequency shall remain within twice the specified limits for the assigned
radio frequency. After 5 seconds, the standard frequency tolerance is
applicable for any and all operations where the transmitter power output is
-25 dBm or greater (or produces a field strength greater than 320 TV/meter at
a distance of 30 meters from the transmitting antenna in any direction.)Between turn on and 1 second following turn on, the unmodulated transmitter output frequency shall be within the occupied bandwidth of the modulated signal at any time when the transmitter output power exceeds -25 dBm. Specific uses may dictate tolerances more stringent than those stated. |
|
2.4.2 Channel Bandwidth Definitions
. Channel bandwidths are defined in the following subparagraphs. 2.4.2.1 Standard Bandwidth Signal . A standard bandwidth signal occupies a bandwidth less than or equal to 1 MHz. 2.4.2.2 Wide Bandwidth Signal. A wide bandwidth signal occupies a bandwidth greater than 1 MHz. 5 2.4.3 Channelization. Channel spacings for all types of telemetry uses are described in the following subparagraphs. 2.4.3.1 Standard Bandwidth Channels . Standard bandwidth channel spacing is in increments of 1 MHz, beginning 500 kHz from the lower band edge such as 1435.5, 1436.5, and 1437.5 MHz. By definition, the band edges of a standard bandwidth channel cannot fall outside the allocated band. 2.4.3.2 Wide Bandwidth Channels. Channels with bandwidths greater than 1 MHz are assigned channels on spacings as standard bandwidth channels. The resulting spectrum is not allowed to fall outside the allocated band. 2.4.4 Output Power. The output power of a telemetry transmitter shall be the minimum possible required for the specific application. The output power shall not exceed 25 watts 6. The output power of a telemetry transmit system and the effective isotropic radiated power (EIRP) shall be the minimum possible required for the specific application. The EIRP shall not exceed 25 watts7 . 2.4.5 Modulation Polarity. An increasing voltage at the input of a frequency modulation (FM) transmitter shall cause an increase in output carrier frequency. An increase in voltage at the input of a phase modulation (PM) transmitter shall cause an advancement in the phase of the output carrier. An increasing voltage shall cause an increase in the output power of an amplitude modulation (AM) transmitter. 2.4.6 Spurious Emission and Interference Limits. Spurious8 emissions from the transmitter case, through input and power leads, and at the transmitter radio frequency (RF) output and antenna-radiated spurious emissions are to be within required limits shown in MIL-STD-461, Electromagnetic Emission and Susceptibility Requirements for the Control of Electromagnetic Interference, when measured by the methods and equipment shown in MIL-STD-462, Electromagnetic Interference Characteristics, Measurement. Other applicable standards and specifications may be used in place of MIL-STD-461 and MIL-STD-462, if necessary. 2.4.6.1 Transmitter-Antenna System Emissions. Emissions from the antenna are of primary importance. For example, a tuned antenna may or may not attenuate spurious frequency products produced by the transmitter, and an antenna or multi-transmitter system may generate spurious outputs when a pure signal is fed to its input. The transmitting pattern of such spurious frequencies is generally different from the pattern at the desired frequency. Spurious outputs in the transmitter output line shall be limited to -25 dBm. Antenna-radiated spurious outputs shall be no greater than 320 TV/meter at 30 meters in any direction. 2.4.6.2 Conducted and Radiated Interference . Interference (and the RF output itself) radiated from the transmitter or fed back into the transmitter power, signal, or control leads could interfere with the normal operation of the transmitter or the antenna system to which the transmitter is connected. All signals conducted by the transmitter's leads (other than the RF output cable) in the range of 150 kHz to 50 MHz, and all radiated fields in the range of 150 kHz to 10 GHz (or other frequency ranges as specified) must be within the limits of the applicable standards or specifications. 2.4.7 Operational Flexibility. Each transmitter shall be capable of operating at all frequencies within its allocated band without design modification 9. 2.4.8 Modulated Transmitter Bandwidth . For the purposes of telemetry signal spectral occupancy, unless stated otherwise, the bandwidths10 used are the 99 percent power bandwidth (occupied bandwidth) and the -25 dBm bandwidth. The -25 dBm bandwidth is the minimum bandwidth which contains all spectral components which are -25 dBm or larger. A power level of -25 dBm is exactly equivalent to an attenuation of the transmitter power by 55 + 10 x log(P) dB where P is the transmitter power expressed in watts. Therefore, the maximum required value for A(f) is 55 + 10 x log(P) dB. The spectra are assumed symmetrical about the transmitter’s center frequency unless specified otherwise. All spectral components attenuated by a value less than 55 + 10 x log(P) dB at the transmitter output must be within the spectral mask calculated using the following equation (refer to appendix A, paragraph 6.0 for additional discussion and examples of this spectral mask):  Equation (2-1) does not apply to spectral components separated from the center frequency by less than one-half of the occupied bandwidth. The -25 dBm bandwidth is not required to be narrower than 1 MHz. 2.5 UHF Telemetry Receiver Systems 2.5.1 Spurious Emissions 2.5.2 Frequency Tolerance 2.5.3 Spurious Responses 2.5.4 Operational Flexibility 2.5.5 Intermediate Frequency Bandwidths As a minimum, UHF receiver systems shall have the following characteristics. 2.5.1 Spurious Emissions. The RF energy, radiated from the receiver itself or fed back into power supply, RF input, output, and control leads in the range from 150 kHz to 10 GHz shall be within the limits specified in MIL-STD 461 and tested in accordance with MIL-STD 462 or RCC document 118, volume II, Test Methods for Telemetry RF Subsystems. Other applicable standards and specifications may be used in place of MIL-STD-461 and MIL-STD-462, if necessary. 2.5.2 Frequency Tolerance. The accuracy of all local oscillators within the receiver shall be such that the conversion accuracy at each stage and overall is within ±0.001 percent of the indicated tuned frequency under all operating conditions for which the receiver is specified. 2.5.3 Spurious Responses. Rejection of any frequency other than the one to which the receiver is tuned shall be a minimum of 60 dB referenced to the desired signal over the range 150 kHz to 10 GHz. 2.5.4 Operational Flexibility . All ground-based receivers shall be capable of operating over the entire band for which they are designed. External downconverters may be either intended for the entire band or a small portion but capable of retuning anywhere in the band without modification. 2.5.5 Intermediate Frequency Bandwidths . The standard receiver IF bandwidths are shown in table 2-1. These bandwidths are separate from and should not be confused with post-detection low-pass filtering that receivers provide11. The ratio of the receiver’s -60 dB bandwidth to the -3 dB bandwidth shall be less than 5. |
|
For data receivers, the IF bandwidth should typically be selected so that
90 to 99 percent of the transmitted spectrum is within the receiver 3 dB
bandwidth. In most cases, the optimum IF bandwidth will be narrower than the
99 percent power bandwidth measured using the method outlined in
appendix A, subparagraph 5.2.1.
|
|
|
|
1. Bandwidths are expressed at the points where response is 3dB below the
response at the design center frequency, assuming that passband ripple is
minimal, which may not necessarily be the case. The 3dB bandwidth is chosen,
because it closely matches the noise bandwidth of a "brick-wall" filter of the
same bandwidth. The "optimum" bandwidth for a specific application may be
other than that stated here. Ideal IF filter response is symmetrical about
its center frequency; in practice, this may not be the case. 2. Not all bandwidths are available on all receivers or at all test ranges. Additional receiver bandwidths may be available at some test ranges. 3. (†) Bandwidths are for use with standard bandwidth channels. 4. (‡) Bandwidths are for use with wide bandwidth channels. |
|
Chapter 2 Footnotes 1. The definitions of the radio services that can be operated within certain frequency bands contained in the radio regulations as agreed to by the member nations of the International Telecommunications Union. This table is maintained in the United States by the Federal Communications Commission and the NTIA. 2. A telemetry system as defined here is not critical to the operational (tactical) function of the system. 3. The word used for remote control operations in this band is telecommand. 4. Reallocated as of 1 January 1990. 5. Telemetry systems with bandwidths greater than 10 MHz, operating on the standard telemetry bands, are highly discouraged. 6. An exemption from this power limit will be considered; however, systems with transmitter power levels greater than 25 watts will be considered nonstandard systems and will require additional coordination with affected test ranges. 7. An exemption from this EIRP limit will be considered; however, systems with EIRP levels greater than 25 watts will be considered nonstandard systems and will require additional coordination with affected test ranges. 8. Any unwanted signal or emission is spurious whether it is related to the transmitter frequency (harmonic) or it is not related to the transmitter frequency. 9. The intent is that fixed frequency transmitters can be used at different frequencies by changing crystals or other components. All applicable performance requirements will be met after component change. 10. These bandwidths are measured using a spectrum analyzer with the following settings: 10 kHz resolution bandwidth, 1 kHz video bandwidth, and max hold detector. 11. In most instances, the output low-pass filter should not be used to "clean up" the receiver output prior to use with demultiplexing equipment. |