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RSS-118 — Land and Subscriber Stations: Voice, Data and Tone Modulated, Angle Modulation Radiotelephone Transmitters and Receivers Operating in the Cellular Mobile Bands 824–849 MHz and 869–894 MHz
7. Transmitter Tests under Standard Test Conditions
7.1 Power Output and Power Output Rating
7.1.1 Definitions
The transmitter power output is the RF power dissipated in the standard output termination when operating under the rated duty cycle selected by the applicant for approval. The power output rating of the transmitter is the value determined under the conditions of paragraph 7.1.2.
7.1.2 Method of Measurement
The transmitter shall be set up as specified under the standard test conditions and operated unmodulated at the maximum output power at the selected duty cycle designated in accordance with paragraph 5.11. Measurements shall be made to establish the radio frequency power delivered by the transmitter into the standard output termination. All details of the measurement shall be clearly stated in the test report. Power output shall be monitored and recorded throughout the test period and no adjustment shall be made to the transmitter after the test has begun, except as noted below.
If the power output is adjustable, measurements shall be made for the highest and the lowest power levels of the range for the appropriate duty cycle for which approval is requested. The results shall be recorded at the end of the test period.
7.1.3 Minimum Performance Standard
The maximum power output(s) measured under the conditions of paragraph 7.1.2 for each duty cycle for which the transmitter is rated shall be within + 2 dB to 0 dB of the manufacturer's rating(s) of RF power output.
7.2 Out of Band Emission
7.2.1 Definition
Emission on a frequency or frequencies immediately outside the necessary bandwidth which results from the modulation process, but excluding spurious emissions.
7.2.2 Method of Measurement
The spectrum of the transmitter shall be determined with a spectrum analyzer or highly selective receiver as specified in 5.12.2.
- For combined voice and SAT measurements, the transmitter shall have its compressor disabled and shall be modulated with a 2500-Hz sine wave at a level 13.5 dB greater than that required to produce ± 8 kHz peak frequency deviation at 1000 Hz (16 dB greater than that required to produce 50 percent of the maximum deviation of ± 12 kHz), and shall be modulated with a 6000 Hz SAT frequency with ± 2.0 kHz peak frequency deviation.
- For wideband data measurements, the transmitter shall be modulated with a quasi-random 10 kilobit/second data pattern at ±8 kHz peak frequency deviation.
7.2.3 Minimum Performance Standards
No out of band emission shall fall within the cross-hatched area of Figure 1 for voice modulation and Figure 2 for data modulation.
7.3 Spurious Emissions
7.3.1 Definition
Emission on a frequency or frequencies which are outside the necessary bandwidth and the level of which may be reduced without affecting the corresponding transmission of information. Spurious emissions include harmonic emissions, parasitic emissions, intermodulation products and frequency conversion products but exclude out-of-band emissions.
7.3.2 Method of Measurement
The measurement set-up shall be as specified in paragraph 7.2.2, except that standard test modulation (alternately voice and data) shall be applied to the transmitter and a portion of the RF output shall be coupled to a spectrum analyzer or equivalent instrument. The output spectrum shall be carefully searched for spurious emissions over the frequency range from 1 MHz to the third harmonic of the standard test frequency (Fc), excluding within ± 100 kHz from the standard test frequency. In the band 869 MHz to 894 MHz the spurious emissions shall be measured using a bandwidth of 30 kHz. The most significant spurious emissions shall be identified, measured and recorded. The above measurement shall be repeated for the highest and lowest rated power level.
7.3.3 Minimum Performance Standard
- Spurious emissions shall be attenuated below the maximum level of emission of the carrier frequency by at least 43 dB + 10 log10 (mean power of the unmodulated carrier in watts) dB.
- For subscriber units: In addition to the requirements of 7.3.3 (a), the mean power of spurious emissions in the band from 869 MHz to 894 MHz shall not exceed 10 picowatts (-80 dBm).
7.4 Modulation Distortion
7.4.1 Definition
The modulation distortion is the level of the demodulated carrier audio rms noise produced by audio distortion in the transmitter via the audio and RF circuits within the transmitter.
7.4.2 Method of Measurement
The transmitter shall be adjusted per the manufacturer's procedures and instructions for full rated systems deviation. A 1000-Hz test tone adjusted to the manufacturer's specified level shall be applied to the transmitter with the compressor enabled, and the modulation sensitivity shall be set to achieve ±8 kHz peak frequency deviation. The standard test receiver with standard 750 microsecond de-emphasis, with expandor enabled, and with C-message weighted filter shall be tuned to the carrier frequency and used to measure the audio distortion from the modulated transmitter.
7.4.3 Minimum Performance Standard
The maximum modulation distortion shall be 26 dB below modulating tone level.
7.5 Transmit Audio Frequency and Limiting Response
7.5.1 Definition
The transmitter audio frequency response is defined in terms of the degree of closeness to which the frequency deviation of the transmitter follows the prescribed 6 dB per octave pre-emphasis characteristic over a specified continuous audio frequency range, while conforming to the required band limiting condition outside of that range. Deviation shall be treated as voltage when calculating dB.
7.5.2 Method of Measurement
Operate the transmitter with the compressor disabled, and monitor the output with a frequency deviation meter or a standard test receiver without the standard 750-microsecond de-emphasis, with expandor disabled, and without C-message weighted filter (see 5.12.1). Apply a sine wave audio input to the transmitter external audio input port, vary the modulating frequency from 300 to 3000 Hz, and record the input levels necessary to maintain a constant ± 2.9 kHz system deviation.
To test the band limiting condition: adjust the audio input frequency to 1000 Hz, and adjust the input level to 20 dB greater than that required to produce ± 8 kHz deviation. Note the output level on the frequency deviation meter or a calibrated test receiver. Using this output level as reference (0 dB), vary the modulating frequency from 3000 Hz to 20,000 Hz, and record the change in output while maintaining a constant audio input level.
7.5.3 Minimum Performance Standard
Over the frequency range 300 to 3000 Hz, the input level to maintain a constant ±2.9 kHz system deviation shall not vary more than +1 to -3 dB from a true 6 dB/octave pre-emphasis characteristic (with the exception of a permissible 6 dB/octave roll-off from 2500 to 3000 Hz relative to the true level at 2500 Hz), see Figure 3.
Between 3000 Hz and 20,000 Hz the response attenuation shall not exceed the values defined by Table 1.
| Frequency Band | Attenuation Relative to the Maximum Value Allowed at 3000 Hz |
|---|---|
| 3000 - 5900 Hz | 40 log10 (f/3000) dB |
| >5900 - <6100 Hz | 35 dB |
| 6100 - 15000 Hz | 40 log10 (f/3000) dB |
| >15000 - 30000 Hz | 28 dB |
where f is in Hertz
7.6 Modulation Deviation Limiting
7.6.1 Definition
Modulation deviation limiting refers to the ability of the transmitter circuits to prevent the transmitter from producing deviation in excess of rated system deviation.
7.6.2 Method of measurement
The transmitter shall be set to a channel near the center of the band and adjusted by the manufacturer's procedure and instructions for full rated system deviation. Adjust the audio input for ± 8 kHz peak frequency deviation at 1000 Hz with the 2:1 compressor enabled and the SAT disabled. The audio input shall be increased by 20 dB in one step (rise time between the 10-percent and 90-percent points shall be 0.1 second maximum). Both the maximum initial and the subsequent steady state values of the peak frequency deviation, at and following the time of the 20 dB increase, shall be measured and recorded in a 300 to 3000 Hz band.
The measurement shall be repeated in 200 Hz increments from 300 Hz to 3000 Hz with the transmitter test frequency set to each end of the band over which it is designed to operate.
7.6.3 Minimum Performance Standard
The maximum initial and subsequent steady-state, peak frequency deviations shall not exceed the rated system peak frequency deviation of ±12 kHz at any audio frequency in the 300 to 3000 Hz band. This requirement excludes the supervisory audio tone (SAT) and 10 kilobit/second wideband data signals.
7.7 Hum and Noise Level
7.7.1 Definition
The FM hum and noise level is the ratio of residual frequency modulation to test modulation measured on the test receiver.
7.7.2 Method of Measurement
- With the compressor enabled modulate the transmitter with a 1000-Hz tone to ± 8 kHz peak frequency deviation and with a 6000 Hz SAT frequency to ± 2 kHz peak frequency deviation. Monitor the transmitter output with the standard test receiver with standard 750 microsecond de-emphasis filter enabled, with expandor enabled, and with C-message weighted filter (see 5.12.1). Read and record the audio output level from the test receiver.
- Remove modulation from the transmitter and terminate its input with its rated input impedance. Read and record the audio output level from the test receiver.
- The FM hum and noise level in dB is:
20log10 ((Audio output level with transmitter modulated from a.) / (Audio output level with transmitter unmodulated from b.))
7.7.3 Minimum Performance Standard
The FM hum and noise shall be at least 32 dB below the output level.
8. Transmitter Tests under Environmental Conditions
8.1 Operational Performance Stability
8.1.1 Definition
Operational performance stability is the measured ability of the transmitter to function under environmental conditions of specified variations in power supply voltage, over a specified temperature range, without exceeding permissible carrier frequency stability tolerances and with no more than a specified variation in power output.
8.1.2 Method of Measurement
The measurement procedure outlined below shall be followed:
Step 1: The transmitter shall be installed in a environmental test chamber whose temperature is controllable. Provision shall be made to vary the transmitter power supply voltage and to control the operation of the transmitter. Provision shall also be made to measure the following parameters:
- RF carrier frequency
- RF power output
Note 1: If the transmitter utilizes a self-contained battery power supply, new or fully charged batteries may be installed at the outset of environmental testing and Step 4 of this test procedure shall not apply, or, alternatively, an external power supply can be used.
Note 2: The operating frequency shall be set-up in accordance with the manufacturer's published operation and instruction manual prior to the commencement of these tests. No adjustment of any frequency determining circuit element shall be made subsequent to this initial set-up.
Step 2: With the transmitter inoperative (power switched "OFF"), the temperature of the test chamber shall be adjusted to +25°C. After a one-hour temperature stabilization period at +25°C, the transmitter shall be switched "ON" with standard test voltage applied. The transmitter may be operated in the "standby" mode, for 15 minutes prior to keying the carrier "ON".
Step 3: The carrier shall be keyed "ON", and the transmitter shall be operated unmodulated at full RF power output for a continuous 3 minute period. The following parameters shall be measured in the order indicated:
Note 1: The RF carrier frequency shall be monitored and measurements shall be recorded at the outset and at 30 second intervals.
Note 2: The RF power output shall be measured and recorded during the last minute of operation. This measurement shall be the reference level for minimum performance standards under environmental conditions.
Step 4: With the test chamber temperature maintained at +25°C, the measurement procedure specified in Step 3 shall be repeated with the power supply voltage adjusted to 110% and 90% of standard test voltage. In addition, for portable equipment frequency tolerance measurements shall be made with the external power supply set at 80% of the standard test voltage. All measurements shall be recorded. The transmitter shall be switched "OFF".
Note: For "intermittent" duty cycle equipment, a maximum period of 15 minutes in "standby" mode may be allowed between periods of carrier keyed "ON" operation.
Step 5: The test procedures outlined in Steps 2, 3 and 4 shall be repeated after stabilizing the transmitter at the following environmental temperatures in the order indicated: self contained equipment, +40°C, -10°C; equipment, including portable, intended for use with external power supplies, +60°C, -30°C; base station equipment, +4°C, +49°C or as specified by the manufacturer. All measurements shall be recorded and reported.
8.1.3 Minimum Performance Standards
Under all specified environmental test conditions:
- The RF carrier frequency shall not depart from the standard test frequency in excess of the following tolerances:
Equipment Type Frequency Tolerances (a) Base Station ± 1.5 parts per million (b) Subscriber units ± 2.5 parts per million - The RF power output shall not decrease by more than 4 dB, nor increase by more than 2 dB with reference to the power output measured under paragraph 8.1.2 (step 3(ii)).
9. Receiver Tests under Standard Test Conditions
9.1 Sensitivity
9.1.1 Definition
The usable sensitivity of the receiver is the RF level of the input signal modulated with a 1 kHz frequency to ±8 kHz peak frequency deviation that will result in 12 dB SINAD (C-message weighted), at the audio output of the receiver. SINAD is defined below.
9.1.2 Method of Measurement
Enable the expandor, terminate the audio output of the receiver in the load specified by the manufacturer, and make SINAD measurements using a C-message weighted filter. Apply a -50 dBm RF signal with 1000-Hz modulation at ± 8 kHz peak frequency deviation to the receiver antenna input terminals. Connect an output load distortion meter incorporating a 1000-Hz band notch filter to the receiver-audio output terminals. Reduce the input signal level until the SINAD is 12 dB. The input RF signal level at this point defines the receiver sensitivity.
SINAD is obtained by first measuring the composite of the audio signal with its noise and distortion components, next notching the audio signal with a 1000-Hz notch filter, and then measuring just the noise and distortion components. The input RF signal level that provides a 12 dB ratio between the signal-plus-noise-plus-distortion measured level and the noise-plus-distortion measured level defines the 12 dB SINAD sensitivity for the receiver.
Make the measurement on a channel near the center of the band over which the receiver is designed to operate.
Where a subscriber unit cannot be measured using the method of measurement described above, the sensitivity may be measured by a radiated measurement equivalent. Documentation shall be provided as to the basis of the measurement used.
9.1.3 Minimum Performance Standard
The RF signal input level measured across the receiver antenna terminals shall not be more than -113 dBm.
9.2 Adjacent and Alternate Channel-Desensitization
9.2.1 Definition
The adjacent channel selectivity and desensitization of a receiver is a measure of its ability to receive a modulated input signal on its assigned channel frequency in the presence of a second modulated input frequency spaced either one channel (30 kHz) above or one channel below the assigned channel.
The alternate channel selectivity and desensitization of a receiver is a measure of its ability to receive a modulated input signal on its assigned channel frequency in the presence of a second modulated input frequency spaced either two channels (60 kHz) above or two channels below the assigned channel frequency.
9.2.2 Method of Measurement
Terminate the audio output of the receiver in its normally intended load, disable the expandor, and make measurements using a C-message weighted filter.
- Connect two RF signal generators equally coupled to the receiver antenna input terminals through a suitable matching network. Set the first RF signal generator to the assigned channel frequency and modulate it with a 1000-Hz tone to ± 8-kHz peak frequency deviation. Switch the second generator off. Adjust the first RF signal generator level to produce a 12 dB SINAD measurement at the audio-output terminal of the receive path.
Record the RF signal level and increase this first RF signal generator output by 3 dB.
- Set the frequency of the second RF signal generator to either 30 or 60 kHz above the frequency of the first RF signal generator and modulate it with a 400-Hz tone to ± 8 kHz peak frequency deviation. Adjust the level of the second RF signal generator to reduce the SINAD measurement back to 12 dB from the first RF signal generator. Record the RF signal level.
- Repeat step (b) with the frequency of the second RF signal generator set to either 30 or 60 kHz below the frequency of the first RF signal generator.
- Calculate the ratios, in dB, of the undesired signal levels measured in steps (b) and (c) to the reference level obtained in step (a). For each case of adjacent-and alternate undesired input signals, the smaller of these ratios for the above-and below-channel undesired signals is the minimum selectivity.
9.2.3 Minimum Performance Standard
The minimum adjacent-channel selectivity shall be 16 dB. The minimum alternate-channel selectivity shall be 60 dB.
9.3 Spurious Response Attenuation
9.3.1 Definition
The receiver spurious response attenuation is a measure of the receiver's ability to discriminate between the assigned input signal frequency and an undesired signal at any other frequency to which it is responsive.
9.3.2 Method of Measurement
- The expandor shall be disabled and the audio output of the receiver shall be terminated in its normally intended load. Measurement shall be made using a C-message weighted filter.
- Two RF signal sources shall be connected to the receiver under test through an appropriate matching or combining network.
- With one RF signal source switched off, the other desired input RF signal source shall be adjusted to the receiving frequency of the unit under test, and a 1000-Hz tone at ± 8 kHz peak frequency deviation shall be applied. Adjust this desired input RF signal source to minimum RF signal level required for a 12 dB SINAD measurement. Record this level as the desired input RF signal source reference level, then increase the input RF signal source by 3 dB, and leave this input RF signal source set at this level and frequency.
- The undesired input RF signal source shall be switched on, and set to a high level (i.e., at least 80 dB above the level of the desired input RF signal source). The undesired input RF signal source shall be modulated with a 400 Hz tone at ± 8 kHz peak frequency deviation.
- The undesired input RF signal source shall be varied over a continuous frequency range from the lowest intermediate frequency or lowest oscillator frequency used in the receiver, whichever is lower, to at least* 1000 MHz, and all spurious responses shall be identified by frequency and recorded.
- At the frequency of each noted spurious response, the level of the undesired RF signal source shall be adjusted and recorded to achieve a 12 dB SINAD measurement from the desired input RF signal source. The corresponding output levels of the undesired input RF signal source level and the desired input RF signal source reference level shall be measured and recorded.
- The spurious-response attenuation is the ratio of the undesired input RF signal source level to the desired input RF signal source reference level, expressed in dB.
* It is preferable but not mandatory that the frequency range be searched to at least 2600 MHz.
9.3.3 Minimum Performance Standard
The spurious response attenuation shall be at least 60 dB (50 dB for portables) for all undesired signals 60 kHz or more removed from the assigned input signal frequency. Subharmonics of the receiver's center frequency shall be excluded from this requirement.
- Date modified:
