RSS-181 — Coast and Ship Station Single Sideband Radiotelephone Transmitters and Receivers Operating in the 1,605-28,000 kHz Band

RSS-181 Issue 1

Spectrum Management
Radio Standards Specification

1. Intent

1.1 This specification (amended from time to time) sets forth the minimum performance standards required for the type-approval of radio-telephone non-multiplex transmitters and receivers described by the above specification title. Submission for approval shall be made under one or more of the following categories:

L - Transmitters and receivers for use in coast stations

C - Transmitters not less than 100 watts PEP and receivers for use in compulsorily-fitted ship stations.

V - Transmitters not less than 30 watts PEP and receivers for use in voluntarily-fitted ship stations.

Y - Transmitters less than 30 watts PEP and receivers for use in voluntarily-fitted ship stations.

Note: These letters will be suffixed to the type-approval number according to the category or categories under which the equipment is approved.

1.2 Transmitters and receivers type-approved under this Specification are technically suitable for licensing in accordance with the provisions of the General Radio Regulations, Part II.


2. General

2.1 Those seeking approval of equipment under this Specification shall satisfy the Department at their own expense that the equipment actually meets this Specification.

2.2 Notwithstanding the fact that a particular piece of equipment meets this Specification, the Department reserves the right to require that adjustments be made to that equipment wherever it causes interference within the meaning of the Radio Act.

2.3 The Department reserves the right to revise this Specification.


3. Related Specifications and Procedures

3.1 Radio Standards Procedure 100 - Procedure for obtaining type-approval of equipment.

3.2 Radio Standards Specification 111 - Installation of Maritime Mobile Radiotelephone Equipment for Ship Stations operating in the Medium and High Frequency Bands.


4. Equipment Requirements

4.1 Sideband Emitted - The upper sideband only shall be emitted.

4.2 Power Output Limitation

4.2.1 The transmitter shall automatically limit the maximum output of the transmitter to a level not exceeding 1 dB of the manufacturer's rated peak envelope power (PEP).

4.2.2 Limiting action shall be accomplished in such a manner that when operating in the A3H mode the carrier is not limited in a manner which reduces it below -6 dB relative to the emitted PEP.

4.3 Construction - The equipment construction shall be such as to minimize cabinet radiation.

4.4 Speech Clarifier - In the case when a speech clarifier is provided; the operation of this control shall not change the transmitter carrier frequency.

4.5 Equipment Identification - The following information shall be permanently displayed on each transmitter, receiver or inseparable combination thereof:

  1. Type Approval number
  2. Serial number of equipment
  3. Manufacturer's name
  4. Model identification

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5. Standard Test Conditions (Transmitter)

5.1 Definition - Standard test conditions are those conditions which shall apply to the transmitter while it is being tested for minimum requirements. These conditions apply unless otherwise specified.

5.2 Test Voltage - The test voltage shall be the voltage applied to the input terminals on the equipment. It shall be within 2% of the value stated by the manufacturer to be the working voltage.

5.3 Temperature - Temperature shall be 25°c ± 5°C.

5.4 Two-frequency Test Signal - The two-frequency test signal shall consist of two sinusoidal signals, the frequencies of which are 850 Hz ± 5% and 1950 Hz ± 5%, and the levels of which, when simultaneously applied to the audio input terminals of the transmitter, result in equal amplitude radio frequency output signals.

5.5 Test Modulation - The test modulation shall consist of the standard two-frequency test signal applied at a level sufficient to obtain rated PEP. (See Paragraph 6.1.3)

5.6 Peak Envelope Power (PEP) - PEP is the average power developed by the transmitter during one radio frequency cycle at the highest crest of the modulation envelope.

5.7 Maximum R.f. Power Output Rating (M.P.O.R.) - The maximum power output rating which may be specified by the manufacturer is that peak envelope power (PEP) developed by the transmitter such that the highest power odd-order difference frequency intermodulation product is "X" dB below the rated PEP or when the final amplifier dissipation rating is reached, whichever occurs at the lower power output. The symbol "X" shall have the following numerical values:

Maximum RF Power Output
M.P.O.R. X
Up to 100 watts 32 dB
100 watts up to 5600 watts 32 + 8 log10 (MPOR/100)
5600 watts and over 46 dB

5.8 Test Frequencies - Except where otherwise specified all tests shall be made using at least two frequencies, one near the high end and one near the low end of the frequency range for which the transmitter is to be type-approved. If the transmitter operates in the frequency bands between 1605-2650 kHz, one of the test frequencies shelf be 2182 kHz.

5.9 Output Termination - The standard output termination shall consist of a nominal 50 ohm restive load. Where other output terminations are used for the tests, they shall be specified in the test report and shall be within the impedance range of the equipment as stated by the manufacturer.

5.10 Test Receiver - The standard test receiver shall have an audio response characteristic within ± 2dB of the reference level at 1000 Hz between 50 and 6000 Hz.

5.11 Frequency Analyzer - The resolution and accuracy of the frequency analyzer used shall be stated in the test report.

5.12 Assigned Frequency - The assigned frequency is 1400 Hz higher than the carrier frequency.


6. Minimum Standard (Transmitters)

6.1 RATED PEP

6.1.1 Definition - The rated PEP of the transmitter in the peak envelope power delivered to the standard output termination at the manufacturer's specified level of intermodulation distortion products.

6.1.2 Duty Cycle - Transmitter rated PEP may be designated as either continuous, semi-continuous or intermittent according to the following test conditions:

  1. Continuous - Transmitter operated continuously for 24 hours. This rating is limited to transmitters designed for continuous operation.
  2. Semi-continuous - Transmitter operated continuously for eight hours.
  3. Intermittent - Transmitter operated under a cycle of one minute on and four minutes off for a period of eight hours followed by three test cycles of five minutes on, fifteen minutes off.

6.1.3 Method of Measurement - The transmitter shall be operated in the A3J mode (carrier suppressed) at the rated duty cycle and no adjustments shall be made to the transmitter once the test has begun. The transmitter shall be modulated with the standard two-frequency test signal. A sample of the R.F. power output shall be fed to the standard frequency analyzer and the level of the two-frequency signals increased until the highest amplitude odd-order difference frequency intermodulation product is at least "X" dB below PEP. (See Paragraph 5,7) (It may be more than "X" dB below if the manufacturer wishes to decrease the distortion level at the expense of lower PEP output rating.) The average power output (Pavg) is then measured with an R.f. ammeter connected in series with the output termination.

(Pay") is computed from the formula: Pavg = I2 R where:

I - RMS current through R

R - resistance of the standard output termination of the transmitter.

Where an alternate power measurement is made, it should be so specified in the test report.

Rated PEP = 2 X (Pavg)

6.1.4 Minimum Standard - The manufacturer's rating of PEP for any category of equipment shall not be higher than that obtained under the relevant conditions of paragraph 6.1.3, and for:

Category C equipment - shall not be less than 100 watts.

Category V equipment - shall not be less than 30 watts.

Category Y equipment - shall not exceed 30 watts.

6.2 Carrier Level

6.2.1 Definition - The carrier level is expressed as the ratio in dB, at the output of the transmitter, of the amplitude of the carrier to rated PEP.

6.2.2 Method of Measurement

6.2.2.1 Class A3J Emission - With the transmitter operating in the A3J mode, the two-frequency test signal shall be applied to the transmitter input at a level sufficient to produce rated PEP. One test frequency shall then be removed to establish a reference signal level 6 dB below rated PEP. The remaining test signal shall then be removed and the carrier voltage or power output measured.

6.2.2.2. Class A3H Emissions - The transmitter shall then be operated in A3H mode without modulation applied and the carrier voltage or power output measured.

6.2.2.3 Class A3A Emissions - The transmitter shall then be operated in A3A mode without modulation applied and the carrier voltage or power output measured.

6.2.3 Minimum Standards - The power of the carrier for:

Class A3J emissions, shall be attenuated at least 46 dB below rated PEP. (At least 40 dB below level of either tone). It shall not in any case exceed 50 milliwatts in the output termination.

Class A3H emissions, shall not be attenuated more than 6dB below rated PEP. (Not below the level of either tone).

Class A3A emissions, shall be attenuated 16 ± 2 dB below rated PEP. (10 ± 2 dB below level of either tone).

6.3 Frequency Stability

6.3.1 Definition - The frequency stability is the ability of the transmitter to maintain the Test Frequency.

6.3.2 Method of Measurement - The equipment shall have a minimum war-up period of 30 minutes under standby conditions; i.e. filaments and oven power "on". The transmitter shall then be placed in operation at the rated duty cycle with the carrier re-inserted and with no modulation applied. The Test Frequency shall be computed as the mean of all frequency measurements record at one minutes intervals over a one hour period for continuous or semi-continuous duty equipment. For intermittent duty equipment, the frequency shall be measured at one minute intervals during ten cycles of five minutes on and fifteen minutes off. A frequency meter with an accuracy of at least ± 3 Hz shall be used.

6.3.3 Minimum Standards - The equipment tested shall not deviate more than the following from the test frequency:

Category L -± 20 Hz
Category C,V,Y -± 40 Hz

6.4 Spurious Emission

6.4.1 Definition - Emission at a frequency or frequencies, outside the band sufficient to ensure the transmission of information, the level of which may be reduced without affecting the corresponding transmission of information; spurious includes harmonic emissions, parasitic emissions and unwanted intermodulation products which are remote from this band.

6.4.2 Methods of Measurement

6.4.2.1 Test A - Emission on frequencies Close to the Band Described Above - (Sideband Splatter Test)

The transmitter shall be modulated with the two-frequency test signal at a level producing 50% of rated PEP. The level of the input signal shall then be increased by 10 dB with the transmitter level control adjusted to meet the requirements of Paragraph 4.2. A sample of the r.f. output shall be fed to the standard frequency analyzer or equivalent instrument and the level of each significant modulation component with reference to the level of either of the fundamental components plotted. (See Figure 1).

6.4.2.2 Test B - Emission on Frequencies Remote from the Band Described Above

The transmitter shall be operated with standard test modulation at rated PEP output. The relative amplitude vs frequency spectrum up to the 10th harmonic of the operating frequency shall be measured across the resistive portion of the load and all spurious outputs outside the frequency range ±8 Khz from the assigned frequency noted.

6.4.3 Minimum Standards

6.4.3.1 Under test A above, no emission shall lie in the cross-hatched area of Figure 1.

6.4.3.2 Under test B, above, all single frequency outputs shall be at least 43 dB below PEP (i.e. 31 dB below the level of either tone). In no case shall the level of any of these undesired outputs exceed 25 milliwatts (average power).

6.5 Audio Frequency Response

6.5.1 Definition - The term audio frequency response denotes the variation in the power output produced with constant amplitude audio frequency signal input over a continuous range Of audio frequencies.

6.5.2 Method of Measurement - Measurements are required on one test frequency only. The transmitter shall be operated in the A3J mode modulated with a 1000 Hz audio input signal level adjusted to produce 1/4 rated PEP. The audio input level shall then be kept constant, and the modulating frequency varied from 100 to 4000 Hz. The transmitter output shall be monitored with an instrument having an accuracy of at least ±0.5 dB. Output reading shall be taken so that a graph of output levels versus modulating frequency can be plotted.

6.5.3 Minimum Standards - The audio frequency response curve for:

6.5.3.1 Categories L, C and V - shall lie between the cross-hatched areas Figure 2.

6.5.3.2 Category Y - shall lie between the cross-hatched areas of Figure 3.

6.6 Residual Noise Level

6.6.1 Definition - Residual noise level is expressed in terms of the ratio of the residual modulation to rated PEP.

6.6.2 Methods of Measurement

6.6.2.1 A3J - The transmitter shall be operated with standard test modulation at rated PEP output. The transmitter output shall be monitored with the standard test receiver (Paragraph 5.10) or by other suitable means. The change in output level shall be recorded when the modulation is removed.

6.6.2.2 A3H - With the audio input signal level established for A3J unchanged, one tone shall be removed and the carrier re-inserted at a level resulting in two equal amplitude radio frequency output signals giving rated PEP power. The change in output level shall be recorded when the modulation is removed.

6.6.3 Minimum Standard - The residual noise level shall be at least 43 dB below rated PEP for A3J and A3H.

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7. Minimum Standards under Environmental Conditions (Transmitters)

7.1 Tolerances - The maximum allowable tolerances on test conditions measurements shall be as follows:

  1. Temperature ± 3 degrees centigrade,
  2. Voltage: ±  2%
  3. Humidity (relative): ±  5%

For the purpose of these tests, equipment temperature shall be considered stabilized when the temperature off the largest internal mass remains within ±  3°C of the specified environmental temperature when the equipment is inoperative or when the crest temperature of the largest internal mass does not vary more than ±  5°C with the equipment operating.

7.2 Measurements under Temperature and Voltage Extremes

7.2.1 Step 1: Low Temperature - Low Voltage - Category L an Y equipment shall be tested at 0°C. All other categories of equipment shall be tested at 20°C. Place the equipment in a chamber at the required low temperature and allow it to stand inoperative (i.e. without primary power supplied) until temperatures have stabilized. The transmitter shall then have a warm-up period of thirty minutes under standby conditions. At the end of this period, the transmitter shall be immediately placed in operation with the primary voltage decreased to 90% of standard test voltage.

  1. Frequency measurements shall then be recorded at one minute intervals for a five-minute period.
  2. The r.f. power output shall be measured.

7.2.2 Step 2: Low Temperature - High Voltage -This test shall follow immediately after Step 1. The transmitter shall be kept in operation with the primary voltage increased to 110% of standard test voltage.

  1. Frequency measurements shall then be recorded at one minutes intervals for a five-minutes period.
  2. The r.f. power output shall be measured.

7.2.3 Step 3: High Temperature - Low Voltage - Category Y equipment shall be tested at ±40°C and all other categories shall be tested at ±50°C. With the equipment in the chamber at the required high temperature the transmitter shall be operate until the temperature has stabilized, using the appropriate duty cycle. At the end of this period, the primary voltage shall be decreased to 90% of standard test voltage.

  1. Frequency measurements shall then be recorded at one minute intervals for a five-minute period.
  2. The r.f. power output shall be measured.

7.2.4 Step 4: High Temperature - High Voltage - This test shall follow after Step 3. The transmitter shall be kept in operation with the primary voltage increased to 110% of standard test voltage.

  1. Frequency measurements shall then be recorded at one minute intervals for a five-minute period.
  2. The r.f. power output shall be measured.

7.3 Measurements under Humidity Extremes - This test is required for category C equipment only.

7.3.1 Step 1: The equipment shall be placed in the test chamber in a manner similar to that in which it will be used in service. The relative humidity shall be maintained in excess of 95% and the ambient temperature at ±40°C. The equipment shall remain in this atmosphere for a period of 8 hours. During this 8 hour period, no electrical or mechanical power shall be applied to the equipment.

7.3.2 Step 2: At the end of the 8-hour exposure period, equipment shall be removed from the test chamber and any condensed moisture drained off. Within 5 minutes after removal, Standard Test Voltage shall be applied to the equipment. Thirty minutes shall be allowed, following application of primary power, for the equipment warm-up.

7.3.3 Step 3: Immediately following the thirty minute warm-up period:

  1. Frequency measurements shall be recorded at one minute intervals for a five-minutes period.
  2. The rf power output shall be measured.

7.4 Measurements under Vibration Conditions - This test is required for category C equipment only. The equipment shall be secured to the vibration table through its normal attachments or mounting intended for use in service installations, with vibration isolators, if any, in place. Additional straps or other holding means shall not be used. The equipment shall be mounted in the same position (with respect to the direction of gravity) for all vibration tests. Sinusoidal vibratory motion shall be applied to each of the three perpendicular axes of the equipment i.e. lateral, vertical or longitudinal in any sequence under the following conditions:

  1. Constant total excursion of 0.030" from 10 to 30 Hz.
  2. The frequency shall change either linearly or logarithmically with time between 10 and 30 Hz such that a complete cycle (10-30-10 Hz) will take approximately 5 minutes.
  3. The equipment shall be vibrated in each direction for a period of at least 30 minutes.

Throughout the vibration test the equipment shall be operating at the manufacturer's duty cycle, and during the last five minutes of the test the frequency shall be recorded at one minute intervals and the power output measured.

7.5 Minimum Standards under Environmental Conditions

7.5.1 All frequency measurements as recorded should be included in the test report and the maximum deviation in Hertz from the test frequency (para. 6.3.2) noted. The equipment tested shall not deviate more than the following from the test frequency:

Category L ± 20 Hz
Categories C,V,Y ± 60 Hz

7.5.2 The transmitter r.f. power output shall not deteriorate more than 3 dB below the output obtained under standard test conditions.


8. Standard Test Conditions (Receivers)

8.1 Definition - Standard test conditions are those conditions which shall apply to the receiver while it is being tested for minimum requirements. These conditions apply unless otherwise specified.

8.2 Test Voltage - The test voltage shall be the voltage applied to the input terminals on the equipment. It shall be within ± 2% of the value stated by the manufacturer to be the working voltage.

8.3 Input Signal Sources

8.3.1 Signal Levels - Signal input levels are stated in volts across 50 ohms or in equivalent input power.

8.3.2 Input Signal Source (A) - For tests made in the A3J mode, the input signal source shall provide a single sinusoidal rf signal of suitable frequency.

8.3.3 Input Signal Source (B) - For tests made in the A3/A3H mode, the standard input signal source shall provide a carrier signal modulated 30% by a 1000 Hz sinusoidal wave.

8.4 Temperature - Shall be 25°C ± 5°c.

8.5 Output Termination - The standard output termination shall consist of a resistive load equal to the rated output impedance of the receiver.

8.6 Datum Frequency (FD) - The datum frequency (FD) is that radio frequency which would result in an audio output frequency of zero Hz when fully translated by the receiver.

8.7 Test Frequencies - All receiver tests, unless otherwise specified, shall be performed using two frequencies, one near the high end and one near the low end of the frequency range for which the receiver is to be type-approved. If the receiver operates in the frequency bands between 1605-2850 kHz one of the test frequencies shall be 2182 kHz.

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