Chameleonic Radio

Technical Memo No. 8

Requirements for an Experimental Public Safety

Multiband/Multimode Radio: Analog FM Modes

S.W. Ellingson

July 27, 2006

Bradley Dept. of Electrical & Computer EngineeringVirginia Polytechnic Institute & State University

Blacksburg, VA 24061

Contents

1 Introduction 1

2 Frequencies of Interest 1

3 FM Requirements 23.1 Receiver Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . 33.2 Transmitter Specifications . . . . . . . . . . . . . . . . . . . . . . . . 43.3 TIA-603 Requirements Not Considered . . . . . . . . . . . . . . . . . 5

A Summary of VHF Frequencies 9

B Summary of UHF and Higher Frequencies 11

ii

1 Introduction

Virginia Tech is currently developing an experimental multiband/multimode radio for

public safety applications [1]. The purpose of this report is to clarify the requirements

for the analog FM modes of operation. Requirements for these modes of operation

are derived from the standards document TIA-603 [2]. Future reports will specify

requirements for other (e.g., digital) modes of operation.

This report is organized as follows. Section 2 (“Frequencies of Interest”) specifies

all bands which, to the best of our knowledge, are used for public safety applications

(in any mode), and indicates which portions of these bands will actually be imple-

mented. Section 3 (“FM Requirements”) contains a summary of requirements for the

radio’s FM modes, derived from TIA-603. Detailed frequency tables are given for the

VHF and UHF bands in Appendices A and B, respectively.

2 Frequencies of Interest

Appendices A & B summarize the useage of spectrum in all bands relevant to Public

Safety applications, as best as we are able to determine. Appendix A covers the VHF

band (25–300 MHz) whereas Appendix B covers the UHF (300-1000 MHz) and higher

bands. Specific segments of spectrum are labeled with their potential relevance to

public safety applications – either “Yes” (definately applicable), “Maybe” (possibly

applicable; depends on interpretation and geographical location), or “No” (definately

not applicable).

Requirements:

1. In accordance with guidance provided by the project sponsor, the VHF-Lo band

(25–50 MHz) will not be supported.

2. Analog FM operation will be supported in all band segments between 138 MHz

and 862 MHz denoted with a “Yes” or “Maybe” with respect to applicability

to Public Safety applications in Appendices A & B. In this case, the relevant

performance requirements are outlined in Section 3.

1

3. Analog FM operation will be supported in all band segments between 138 MHz

and 862 MHz denoted with a “No” with respect to applicability to Public Safety

applications in Appendices A & B. In this case, the performance requirements

outlined in Section 3 will be interpreted as “desireable,” but not firm require-

ments.

4. Analog FM operation is not required to be supported in any band segments not

identified in Appendices A or B, including frequencies below 25 MHz and above

862 MHz.

3 FM Requirements

General requirements for the analog FM mode of operation shall include the following:

1. The radio shall receive and transmit audio. However, audio is primarily for

purposes of demonstration and performing diagnostics. For research purposes,

primary interest will be in digital audio data; i.e., audio before digital-to-audio

conversion (or vice-versa for transmit).

2. The radio shall have a rudimentary squelch capability. However, squelch is pri-

marily for demonstration purposes and is not required to conform to standards.

3. Noise blanking is not required.

4. Audio compression/expansion is required, and must be capable of being dis-

abled.

5. Subaudible signaling is not required.

More detailed specifications, derived from TIA-603 [2], follow. Note that TIA-603

defines specifications which depend on performance “class” and form factor. TIA-603

recommends Class A performance levels for Private Land Mobile transceivers with

enhanced interference protection characteristics, whereas Class B performance levels

are the minimum recommended for Private Land Mobile Radio transceivers. In this

work, the radio shall be considered “Class B” with the form factor “Portable”.

2

3.1 Receiver Specifications

R1. Reference Sensitivity [3.1.4]. The RF level applied to the antenna terminals

that yields 12 dB SINAD at the audio output.

Requirement: −116 dBm.

R2. Signal Displacement Bandwidth [3.1.5]. The input signal frequency dispace-

ments that reduces the SINAD produced by an RF signal at −110 dBm (i.e.,

6 dB greater than the reference sensitivity) to 12 dB.

Requirement: 40% of the rated system deviation (shown in the column “devia-

tion” in the frequency tables).

R3. Adjacent Channel Rejection [3.1.6]. The ratio of the level of an unwanted

signal in an adjacent channel to the reference sensitivity, when the level of the

unwanted signal is sufficiently high to reduce the SINAD produced by an RF

signal at −113 dBm (i.e., 3 dB greater than the reference sensitivity) to 12 dB.

Requirement: 70 dB when the channel bandwidth is ≥ 20 kHz, otherwise 45 dB.

R4. Spurious Response Rejection [3.1.8]. Essentially the same as Adjacent

Channel Rejection, except the unwanted signal is varied from one-half of the

lowest IF frequency to twice the tuned frequency (or 1 GHz, whichever is less).

The worst case is reported.

Requirement: 60 dB.

R5. Intermodulation Rejection [3.1.9]. Essentially the same as Adjacent Chan-

nel Rejection, except there are two unwanted signals with 50 kHz spacing, and

the blocking is the result of third-order intermodulation. The result is the ratio

of the level of one of the unwanted signals to the reference sensitivity.

Requirement: 50 dB.

R6. Receiver Attack Time [3.1.15]. Time required to produce audio power output

after application of a modulated input signal.

Requirement: 150 ms.

3

R7. Receiver Closing Time [3.1.16]. Time between removal of modulated input

signal and squelch closure.

Requirement: 250 ms.

R8. Blocking Rejection [3.1.21]. Essentially the same as Adjacent Channel Rejec-

tion, except the unwanted signal is applied at frequency separations of ±1 MHz,

±2 MHz, ±5 MHz, and ±10 MHz.

Requirement: 70 dB.

3.2 Transmitter Specifications

T1. Carrier Frequency Stability [3.2.2]. Frequency error of the unmodulated

carrier, expressed in parts per million (ppm). Note: The TIA-603 standard

[2] depends on carrier frequency and channel spacing: Between 50 MHz and

862 MHz, values range from 1.5 ppm to 5 ppm for mobile stations; Below

50 MHz, it is 20 ppm.

Requirement: 1.5 ppm.

T2. Carrier Attack Time [3.2.4]. Time required for transmitter to produce 50%

of steady state carrier output power after changing state from “standby” to

“transmit.”

Requirement: 100 ms.

T3. FM Hum & Noise Ratio [3.2.8]. Ratio of the deviation observed for “stan-

dard modulation” to that associated with no modulation (carrier only, presum-

ably residual FM). “Standard modulation” is defined as 1 kHz input tone at a

level that produces 60% of the rated system deviation.

Requirement: See table (rows are frequency, columns are deviation).

±2.5 kHz ±5 kHz25–512 MHz 34 dB 40 dB512–1000 MHz 31 dB 37 dB

4

T4. AM Hum & Noise Ratio [3.2.9]. Ratio of DC voltage detected from an

unmodulated carrier to the detected peak AC voltage.

Requirement: 34 dB.

T5. Sideband Spectrum [3.2.11]. This is a specification on sideband emissions as

a function of frequency offset (i.e., emission mask), and depends on frequnecy

and channel spacing in a complex way.

Requirement: See [2], Section 3.2.11.

T6. Unwanted Emissions: Conducted Spurious [3.2.13]. This is the maximum

allowed level of spurious delivered to the antenna terminals.

Requirement: Less than −13 dBm (50 µW).

T7. Unwanted Emissions: Adjacent Channel Power Ratio [3.2.14]. Self-

explanatory.

Requirement: See tables, [2], Section 3.1.14.

T8. Transmitter Stability into VSWR [3.2.18]. Ability to transmitter not to

produce any spurious output when operated into a load different from the stan-

dard load.

Requirement: Less than −13 dBm (50 µW).

3.3 TIA-603 Requirements Not Considered

The following is a list of TIA-603 requirements which will not be in force for this

work.

Receiver Specifications:

• 3.1.1. Radiated Spurious Output Power

• 3.1.2. Conducted Spurious Output Power

• 3.1.3. Power Line Conducted Spurious Output Voltage

• 3.1.7. Offset Channel Selectivity

5

• 3.1.10. Audio Frequency Response

• 3.1.11. Hum and Noise Ratio

• 3.1.12. Audio Distortion

• 3.1.13. Audio Squelch Sensitivity

• 3.1.14. Squelch Blocking

• 3.1.17. Audio Sensitivity

• 3.1.18. Impulse Blanking Effectiveness

• 3.1.19. Average Radiation Sensitivity

• 3.1.20. Acoustic Audio Output

• 3.1.22. Receiver Opening Time after PTT

Transmitter Specifications:

• 3.2.1. Conducted Carrier Output Power Rating

• 3.2.3. Modulation Limiting

• 3.2.5. Audio Sensitivity

• 3.2.6. Audio Frequency Response

• 3.2.7. Audio Distortion

• 3.2.10. Acoustic Microphone Sensitivity

• 3.2.12. Undesired Emissions: Radiated Spurious

• 3.2.15. Audio Low Pass Filter Response

• 3.2.16. Intermodulation Attenuation

• 3.2.17. Average Radiated Power Output

6

• 3.2.19. Transient Frequency Behavior of the Transmitter

Standards for Unit Characteristics: 3.3 (All).

Standards for Subaudible Signaling: 3.4 (All).

7

References

[1] Virginia Tech, “Development of a Low-Cost Multi-Band / Multi-Mode Radio for

Public Safety Applications” (web site), http://www.ece.vt.edu/swe/chamrad/.

[2] Telecommunications Industry Association, “TIA Standard: Land Mobile FM or

PM – Communications Equipment – Measurement and Performance Standards,”

TIA-603-C, December 2004.

[3] B.Z. Kobb, Wireless Spectrum Finder, McGraw-Hill, 2001.

8

A Summary of VHF Frequencies

Provided as a table on the following page. These frequencies were compiled from [2]

and [3].

9

Simplex -or- TIA603B TIA603B TIA603B Reverse (MS Tx) Forward (BS Tx) Spacing Deviation Max. BW Band Relevant? Lo [MHz] Hi [MHz] Lo [MHz] Hi [MHz] [kHz] +/- [kHz] [kHz] Remarks

HF Maybe 25.0000 30.0000 20 5.0 20.0 Includes CB (AM), Military (FM)

VHF Lo Maybe 30.0000 30.5600 20 5.0 20.0 FederalYes 30.5600 32.0000 PMRSMaybe 32.0000 33.0000 Federal & DoDYes 33.0000 34.0000 PMRSMaybe 34.0000 35.0000 Federal & DoDMaybe 35.0000 36.0000 Various, including pagingMaybe 36.0000 37.0000 Federal & DoDYes 37.0000 37.5000 PMRSYes 37.5000 38.0000 PMRS Shared w/Radio AstronomyNo 38.0000 38.2500 Radio AstronomyMaybe 38.2500 39.0000 Federal & DoDYes 39.0000 40.0000 Police RadioMaybe 40.0000 42.0000 Federal & DoDYes 42.0000 43.6900 Various Yes 43.6900 46.6000 Various, including cordless phonesMaybe 46.6000 47.0000 Federal & cordless phonesYes 47.0000 49.6000 Misc, cordless phonesMaybe 49.6000 50.0000 Federal & cordless phones

VHF Hi Maybe 138.0000 144.0000 25 & 30 5.0 20.0 Military, Coast Guard SAR, Federal mobileMaybe 144.0000 148.0000 12.5 & 15 2.5 11.0 Amateur

Maybe 148.0000 149.9000 Federal mobileNo 149.9000 150.0500 SatelliteMaybe 150.0500 150.8000 Federal, variousYes 150.8000 152.8550 Public Safety, misc, "color dots," MURSYes 152.8550 154.0000 Public safety, plus miscYes 154.0000 156.2475 PMRS, "color dots," MURSMaybe 156.2475 157.0375 maritimeMaybe 157.0375 157.4500 maritime (Federal)Yes 157.4500 161.5750 Public Safety, plus lots of other stuffMaybe 161.5750 161.6250 maritimeNo 161.6250 161.7750 Radio & TV news remotesYes 161.7750 162.0125 maratime telecon (near coasts), PS otherwiseYes 162.0125 173.2000 Federal mobile, inc. agencies, weather radioYes 173.2000 173.4000 Private, Local Gov't, some Public safetyYes 173.4000 174.0000 Federal mobile, including agencies

220 MHz Yes 220.0000 222.0000 5 N/A N/A 15 channels for public safety and EMS(Not TIA603B)

B Summary of UHF and Higher Frequencies

Provided as a table on the following page. These frequencies were compiled from [2]

and [3].

11

Simplex -or- TIA603B TIA603B TIA603B Reverse (MS Tx) Forward (BS Tx) Spacing Deviation Max. BW Name Relevant? Lo [MHz] Hi [MHz] Lo [MHz] Hi [MHz] [kHz] +/- [kHz] [kHz] Remarks

UHF Maybe 406.1000 410.0000 25 5 20 Radio Astronomy, some DoD (NTIA)Maybe 410.0000 420.0000 12.5 2.5 11 Federal mobile (NTIA)Maybe 420.0000 450.0000 Amateur 70cm band, Radar, some PMRSYes 450.0000 454.0000 Broadcasting, Some PMRSNo 454.0000 455.0000 Airborne telecom, miscYes 455.0000 456.0000 Broadcasting, Some PMRSNo 456.0000 460.0000 Broadcasting, misc Yes 460.0000 462.5375 PMRS, miscMaybe 462.5375 462.7375 GMRS/FRSYes 462.7375 467.5375 public safety, emegency medical (MED)Maybe 467.5375 467.7375 GMRS repeater inputsYes 467.7375 470.0000 Public safety, "color dots", MEDYes 470.0000 512.0000 TV shared with PMRS

700 MHz Yes 764 776 794 806 25 5 25 Bandwidths from 6.25 kHz to 150 kHz12.5 2.5 12.5

800 MHz Yes 806 809 851 854 25 5 20 NPSPAC809 815 854 860 Shared815 817 860 862 Expansion & Guard Bands

Cellular Maybe 824 849 869 894 N/A N/A N/A

PCS Maybe 1850 1990 N/A N/A N/A

2.4 GHz Maybe 2400 2483.5 N/A N/A N/A

4.9 GHz Yes 4940 4990 N/A N/A N/A Channelization: 10 x 1 MHz, 8 x 5 MHz Aggegation into channels of up to 20 MHz