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

9.4 Intermodulation Spurious Response Attenuation

9.4.1 Definition

The intermodulation spurious response attenuation of the receiver is the measure of its ability to receive a modulated input RF signal frequency in the presence of two unmodulated interfering signals so separated from the assigned input signal frequency and from each other that the n'th order mixing of the two undesired signals can occur in the non-linear elements of the receiver, producing a third signal whose frequency is equal to that of the assigned input RF signal frequency.

9.4.2 Method of Measurement

1. Disable the expandor, terminate the audio output of the receiver in its normally intended load, and make measurements using a C-message weighted filter. Equally couple three RF signal generators to the receiver antenna input terminals. Modulate the first RF signal generator to ± 8 kHz peak frequency deviation with 1000 Hz. Leave the second and third RF signal generators unmodulated.
2. Turn off the second and third RF signal generators. Adjust the frequency of the first RF signal generator to the assigned input RF signal frequency, and adjust the output to give 12-dB SINAD as in 9.1.2. Record this level as the reference sensitivity. Increase the output level of this first RF signal generator to 3 dB above this reference sensitivity.
3. Adjust the second RF signal generator to a channel 60 kHz above the assigned input frequency, and adjust the third RF signal generator to a channel 120 kHz above the assigned input frequency. Turn on the second and third RF signal generators, maintain their outputs at equal levels, and increase these levels until the SINAD measurement from the desired RF signal generator is reduced back to 12 dB. Adjust the frequency of either of the interfering RF signal generators slightly to produce the maximum interfering signal before the final measurement is made. Record the RF signal level of the two interfering signal generators.
4. Repeat the above measurement with the second RF signal generator set to 60 kHz below and the third RF signal generator set to 120 kHz below the assigned input frequency.
5. The smaller of the ratios of the signal level of the second and third RF signal generators to the reference sensitivity level of the first RF signal generator expressed in dB is the measure of intermodulation spurious response attenuation.

9.4.3 Minimum Performance Standard

All intermodulation spurious responses shall be attenuated by at least 55 dB.

9.5 Antenna Conducted Receiver Spurious Emissions

9.5.1 Definition

Antenna conducted receiver spurious output signals are those generated in a receiver and appearing at the receiver antenna terminals. The manufacturer may or may not include the receiver multicoupling, filtering, and pre-amplification equipment for the measurement, depending on whether the receiver is to be certified as a stand-alone component or as a part of an overall multicoupling-preamplification system.

9.5.2 Method of Measurement

The receiver antenna terminals shall be terminated in, or impedance matched to, a spectrum analyzer or frequency selective voltmeter whose nominal input impedance is 50 ohms resistive. The receiver shall be operated in the normal receiver mode on at least three test frequencies, one near the mid-point and the others approximately 10% inside the upper and lower extremities of the band over which the receiver is designed to operate. At each frequency of operation the output shall be searched by carefully tuning the spectrum analyzer or frequency selective voltmeter over the range from the lowest radio frequency generated in the receiver, to three times its operating frequency. All detected outputs shall be investigated and those within 20 dB of the permissible level shall be identified by frequency, measured and recorded. If the receiver incorporates a scanning mode of operation, the above procedure shall be repeated with the receiver operating in the scanning mode.

9.5.3 Minimum Performance Standard

1. No spurious-output signals appearing at the antenna terminals shall exceed 1000 uV across 50 ohms or equivalent output power of 20 nW or -47 dBm.
2. For subscriber units: No spurious-output signals appearing at the antenna terminals and falling within the receive band shall exceed 22.4 uV across 50 ohms (or equivalent output power of 10 pW or -80 dBm).

9.6 Antenna Radiated Receiver Spurious Emissions

At the option of and for the convenience of the user, this test may be used as an alternative to the receiver conducted spurious output test in 9.5 above, except for the requirement for suppression inside the cellular receive band specified in 9.5.3(b).

9.6.1 Definition

Radiated spurious output signals are those generated in a receiver and radiated from the receiver either via the antenna path or via the control, power, and audio cables that may be used with the receiver.

9.6.2 Method of Measurement

The measurement procedure defined in section 10 herein shall be used for measuring receiver radiated spurious emissions.

9.6.3 Minimum Performance Standard

The radiated-spurious power levels from the receiver when measured using the procedure in l0 shall not exceed the levels in Table 2.

Table 2
Maximum Allowable Radiated Spurious Emission

Frequency Range	Maximum Allowable EIRP
25 -70 MHz	-45 dBm
70 - 130 MHz	-41 dBm
130 - 174 MHz	-41 to -32 dBm*
174 - 260 MHz	-32 dBm
260 - 470 MHz	-32 to -21 dBm*
470 -1000 MHz	-21 dBm

* Interpolate linearly on log frequency scale

10. Standard Radiated Signal Measurement Procedure

The measurement and calibration procedures described in this section are intended to provide an accurate means of measuring radiated signals.

10.1 Standard Radiation Test Site

The test site shall be on level ground that is of uniform electrical characteristics. The site shall be clear of metallic objects, overhead wires, etc., and shall be as free as possible from undesired signals such as ignition noise, other carriers, etc. The distance from the equipment under test or the field-strength meter to reflecting objects such as rain gutters, house plumbing, etc., shall not be less than 90 meters (295 feet) for the 30 meter test range nor less than 30 meters (98.4 feet) for the 3 meter test range. If desired, shelters may be provided at the test site to protect the equipment and personnel. All such construction shall be of wood, plastic, or other non-metallic material. All power, telephone, and control circuits to the site shall be buried at least 0.3 meter (1 foot) under ground.

A turntable, essentially flush with the ground, shall be provided that can be remotely controlled. A platform 1.0 meters (3.3 feet) high shall be provided on this turntable to hold the equipment under test. Any power and control cables that are used for this equipment should extend down to the turntable with any excess to be coiled on the turntable.

If the equipment to be tested is mounted in racks and is not easily removed for testing, then the equipment mounted in its rack (or racks) may be placed directly on the turntable.

10.2 Search Antenna

For dipole search antennas, the dipole length shall be adjusted for each frequency of measurement. This length may be determined from a calibration ruler that is normally supplied with the antenna.

The search antenna shall be mounted on a movable non-metallic horizontal boom that can be raised or lowered on a wooden or other non-metallic pole. The cable connected to the search antenna shall be at a right angle to the antenna. The cable shall be dressed at least 3 meters (9.8 feet) either through or along the horizontal boom in a direction away from the equipment being measured. The search antenna cable may then be dropped from the end of the horizontal boom to ground level for connection to the field-strength measuring equipment.

The search antenna shall be capable of being rotated 90 degrees on the end of the horizontal boom to allow measurement of both vertically and horizontally polarized signals. When the antenna length of a vertically mounted antenna does not permit the horizontal boom to be lowered to its minimum specified search range, adjust the minimum height of the boom for 0.25 meter (0.83 foot) clearance between the end of the antenna and the ground.

10.3 Field Strength Measurement

A field strength meter shall be connected to a search antenna. The field strength meter is to have sufficient sensitivity and selectivity to measure signals over the required frequency range at levels at least 10 dB below the levels specified in 9.6.3 above. The calibration of the field strength meter is not critical since a comparison measurement procedure is used.

10.4 Frequency Range of Measurements

When measuring radiated signals from receiving equipment, the measurements shall be made from 25 to at least 1000 MHz.

10.5 30-meter Test Range

Measurement of radiated signals shall be made at a point 30 meters (98.4 feet) from the center of the turntable. The search antenna is to be raised and lowered from 2 to 6 meters (6.6 to 19.7 feet) in both horizontally and vertically polarized orientations.

The field-strength measuring meter may be placed on a suitable table or tripod at the foot of the antenna mast.

When measuring radiated signals from receivers, a vertical antenna, adjusted to 1/4 wavelength and having a ground plane of a half-wavelength radius at the standard input-signal frequency, shall be mounted 3 meters (9.8 feet) above ground over the center of the turntable. A minimum length of low-loss cable shall be used to connect this antenna to the receiver antenna terminal.

10.6 3-meter Test Range

Measurement of radiated signals may be made at a point 3 meters (9.8 feet) from the center of the turntable, provided the following three conditions can be met:

1. A ground screen that covers a least an elliptical area 9 meters (29.5 feet) by 6 meters (19.7 feet) is used with the measuring antenna and the turntable mounted 3 meters (9.8 feet) apart on the major axis and equidistant from the minor axis of the elliptical area.
2. The maximum vertical dimension of the equipment is 3 meters (9.8 feet) or less. When measuring radiated signals from receivers, the maximum dimension shall include the antenna (as in the case of a personal radio) or shall include a 1/4 wavelength ground plane antenna mounted over the radio for those receivers that use remote antennas. The radius of the ground plane shall be half-wavelength at the standard input frequency.
3. The field-strength measuring equipment is either mounted below the ground level at the test site or is located a sufficient distance away from the equipment being tested and the search antenna to prevent corruption of the measured data.

The search antenna is to be raised and lowered over a range from 1 to 4 meters (3.3 to 13.1 feet) in both horizontally and vertically polarized orientations. When the search antenna is vertically oriented, the minimum height of the center of the search antenna shall be defined by the length of the lower half of the search antenna plus 0.25 meter.

10.7 Radiated Signal Measurement Procedures

Radiated signals having significant levels shall be measured on the 30 meter or the 3 meter ranges by using the following procedure:

1. For each observed radiated signal, raise and lower the search antenna to obtain a maximum reading on the field-strength meter with the antenna horizontally polarized. Then rotate the turntable to maximize the reading. Repeat this procedure of raising and lowering the antenna and rotating the turntable until the highest possible signal has been obtained. Record this maximum reading.
2. Repeat (a) for each observed radiated signal with the antenna vertically polarized.
3. Remove the equipment being tested and replace it with a half-wave dipole antenna. The center of the antenna should be approximately at the same location as the center of the equipment being tested.
4. Feed the dipole antenna replacing the equipment under test with a signal generator connected to the antenna by means of a non-radiating cable. With the antennas at both ends horizontally polarized and with the signal generator tuned to the observed radiated signal, raise and lower the search antenna to obtain a maximum reading on the field strength measuring meter. Adjust the level of the signal generator output until the previously recorded maximum reading for this set of conditions is obtained. Record the signal generator power output.
5. Repeat step (d) above with both antennas vertically polarized.
6. Calculate the power into a reference ideal isotropic antenna by:
   1. First reducing the readings obtained in steps (d) and (e) above by the power loss in the cable between the generator and the source antenna; and
   2. Then correcting for the gain of the source antenna used relative to an ideal isotropic antenna.

      The average of different readings thus obtained is the equivalent isotropic radiated power (EIRP) level for the spurious signal being measured.

7. Repeat steps (a) through (f) above for all observed signals from the equipment being tested.
8. As an alternative to the substitution method in steps (c), (d), (e), and (f), when using a calibrated 3 meter radiation test site, the equivalent isotropic radiated power (EIRP) may be determined from the radiated EIRP versus field strength curve. The calibration curve for the radiated EIRP shall be included in the test report.

11. Compliance with Cellular System-Compatibility Standard

Technical requirements for compatibility are outlined in Annex A in a document entitled "Cellular System Land Station - Mobile Station Compatibility Standard".

An attestation shall be provided by the applicant that the equipment submitted for type-approval under this specification complies with all the requirements of the Compatibility Standard. The method by which compliance was determined shall be stated.

Issued under the authority of the Minister of Communications

S.N. Ahmed
Director General
Engineering Programs

Addendum to Annex A

1. Insert the following paragraph: "Carrier ON/OFF Conditions" as 2.1.2.1.

2. Renumber the paragraph titled: "Power Output and Power Control" as 2.1.2.2.

2.1.2.1 Carrier ON/OFF Conditions

The carrier-off condition is defined as a power output at the transmitting antenna connector not exceeding -60 dBm. When commanded to the carrier-on condition on a reverse control channel, a mobile station transmitter must come to within 3 dB of the specified output power (see 2.1.2.2) and to within the required stability (see 2.1.1.2) within 2 ms. Conversely, when commanded to the carrier-off condition, the transmit power must fall to a level not exceeding -60 dBm within 2 ms. Whenever a transmitter is more than 1 kHz from its initial or final value during channel switching, the transmitter carrier must be inhibited to a power level not greater than -60 dBm.

Figure 1
Out of Band Emission (Voice Modulation)

Figure 2
Out of Band Emission (Data Modulation)

Figure 3
The Input Level to Maintain a Constant System Deviation