8
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| Document ID | 24051 |
| Application ID | KJyvPrmmxOWXHUvxHfgRPA== |
| Document Description | 8 |
| Short Term Confidential | No |
| Permanent Confidential | No |
| Supercede | No |
| Document Type | User Manual |
| Display Format | Adobe Acrobat PDF - pdf |
| Filesize | 71.43kB (892906 bits) |
| Date Submitted | 1999-02-19 00:00:00 |
| Date Available | 1999-04-13 00:00:00 |
| Creation Date | 2001-07-04 07:11:46 |
| Producing Software | Acrobat Distiller 4.0 for Windows |
| Document Lastmod | 2001-07-04 07:11:48 |
| Document Title | 8 |
TYPE OF EXHIBIT: INSTRUCTION MANUALS FCC PART: 2.983 (d) (8) MANUFACTURER: RITRON, INC, 505 West Carmel Drive Cam'lel, IN 46032 MODEL: SST-454 TYPE OF UNIT: UHF-FM Handheld Transceiver FCC ID: AIERITOS~450 DATE: December 28, 1996 Included is a draft of the Maintenance and Operating Manual tor RITRON Model Patriot SST-454 UHF-FM Handheld Transceiver. Specifically, this manual includes a technical description of the SST-454 sufficient to establish compliance with the technical standards of the applicable rule part(s). This includes. but is not limited to. the following items required under FCC Part 24983 (d): (1) (2) Type 01 emission. Frequency range. (3) Range of operating power, and means to provide variation in operating powert (5) DC voltage chart. (7) Complete circuit diagrams. (9) Tune-up procedure. (10) A description at all frequency determining and stabilization circuits. (11) A description of the circuits used to suppress spurious radiation, limiting modulation, and limiting power. Signed: Wfi- P/x/ZMJJ Michael A. Pickard - Proiect Engineer 4S EEQHQNIQELC— TABLE OF CONTENTS SST-454 SPECIFICATIONS GENERAL RECEIVER TRANSMITTER INTRODUC'HON General Inspection Model Identification FCC REGULATIONS FCC Licensing Safety Standards BATTERY CARE Charging Battery Replacement Precautions DESCRIPTION OF CONTROLS AND CONNECTORS Fig. 1 Controls and Connectors Belt Clip Installation OPERATION On-OffNqume Receiver Monitor Selective Signaling Squelch Battery Saver Transmit Channel Selection WHAT THE RADIO TONES MEAN Power On/Selt Check “0K” Error Tones Channel Select Tone Squelch Recharge Battery Alert Receiver Squelch Tone Transmit Activate Busy Channel Inhibit Transmitter ‘I'rme-Out N‘IUIM wmmmmma 11 12 12 13 13 13 13 13 13 14 14 14 14 14 14 14 14 15 15 15 15 TROUBLESHOOTING General Battery Error Tones Tone Coded Squelch PROGRAMMING THE RADIO How To Program The Radio How To Find Out What Is Already Programmed Return To Normal Operation Computer Software Copyrights Programming the Radio Using A PC Computer Programmable Features Description of Features SST-454 THEORY OF OPERATION INTRODUCTION POWER SUPPLY AND VOLTAGE DISTRIBUTION Power Strobe Low Battery Voltage Detection REFERENCE OSCILLATOR SYNTHESIZEFI MODULE Pln Numbers Prescaler Divider/Synthesizer Controller VCO/Buller Amplifiers Oscillator Modulation DIGITAL POTENTIOMETERS RECEIVER RF Amplilier 1st Mixer FM Receiver Subsystem Voice/T one Conditioning in Receiver Mode Voioe Band Sub-Audible Audio Amplifier ANTENNA SWITCHING/LOW-PASS FILTER TRANSMITTER Keying +VTX Supply Power Amplifier Voice/T one Conditioning in Transmit Mode Voice Band Sub-Audible MICROCONTROLLER 16 16 16 16 17 18 18 18 18 18 18 19 19 21 21 21 21 21 22 22 22 22 23 23 23 23 23 24 24 24 24 25 25 25 25 26 26 26 26 26 27 10. SST-454 ALIGNMENT PROCEDURE Recommended Test Equipment Radio Preparation Tuning Mode Reierence Frequency Modulation Balance Transmitter Tone Deviation Transmitter Voice Deviation Transmitter Power Receiver Sensitivity and Squelch Synthesizer SST—454 VOLTAGE CHART Measurement Conditions SST-454 Voltages SST-454 Synthesizer Voltages SST-454 SCHEMAflC REFERENCE PARTS LIST SST-454 Synthesizer Schematic Reference List SCHEMATIC AND PART PLACEMENT DRAWINGS fiffl 41 49 52 IMPORTANT MAINTENANCE/REPAIR INFORMATION Surface Mount Repair: RITRON surface mount products require special equipment and servicing techniques. Improper servicing techniques can cause permanent damage to the printed circuit boards and/or components. which is not covered by RITRON’s wananty. If you are not completely familiar with surface mount component repair techniques. FtITFION recommends that you defer maintenance to qualified service personnel. Precautions For Handling CMOS Devices: This radio contains complementary metal-oxide semiconductor (CMOS) devices, which require special handling techniques. CMOS circuits are susceptible to damage by electrostatic or high voltage charges. Damage can be latent, with no failure appearing until weeks or months later. For this reason, take special precautions any time you disassemble the radio. Follow the precautions below, which are even more critical in low humidity environments. 1) Magma - CMOS devices that will be stored or transported must be placed in conductive material so that all exposed leads are shorted together. CMOS devices must not be inserted into conventional plastic “snow" or plastic trays oi the type that are used for other semiconductors. 2) Groung'ug - All CMOS devices must be placed on a grounded bench sunace. The technician that will work on the radio/CMOS circuit must be grounded befre handling the radio. Normally, the technician wears a conductive wrist strap in series with a 100K Ohm resistor to ground. 3) ngthiug - Do not wear nylon clothing while handling CMOS circuits. 4) Power 911 - Remove power before connecting, removing or soldering a PC board that contains CMOS devices. 5) Power/voltage transients - Do not insert or remove CMOS devices with power applied. Check all power supplies to be used for testing CMOS devices, making sure that no voltage trancients are present. 6) Soldering ~ Use a grounded soldering iron for soldering CMOS circuitry. 7) Lead-graightening tools - When straightening CMOS leads. provide ground straps for the tool used. PC Board Removal- Special Tool: FtlTFlON recommends using a knurled nut tool to remove the slotted knurled nuts that secure the charge and audio jacks on top of the radio. Vou will need two sizes of this tool, one for each jack size. Mouser Corporation to is one source, stock number 382-0004 (2.5mm jack) and 382-0006 (3.5mm iack). You can reach Mouser sales and distribution center at 1-800- 346-6873. PraperlyAttach Tile Synthesizer Shield: The synthesizer shield should not be removed, unless a component must be replaced. This shield is soldered to the synthesizer PC board, which is in turn soldered to the main PC board. Reassembly - Speaker Magnet, Battery Voltage on Connector Pin: The speaker magnet will pick up clipped leads and other small metal objects from your bench top, Even tiny objects on the diaphragm will cause the speaker to buzz. Make sure the speaker is free of foreign obiects beiore reassembling the radio. Radio Transmitter Power Measurements: The SST-454 was designed to produce a minimum of 3.00 Watts of Transmitter power at nominal battery voltage (+72 VDC). throughout the radio’s operating frequency range. Measurements are made with the FtITRON SST-SRVBD RF service module connected to the radio antenna terminal. The transmitter was designed with close tolerances to prevent RF power output from exceeding specifications and shortening battery life. SST-454 SPECIFICATIONS GENERAL FCC ID: AIEHIT06-450 FCC Rule Parts: 22, 74, 80, 90 Frequency Range: 450 to 470 MHz standard Max. Freq. Separation: 20 MHz RF Channels: Conventional: 4 Channels. Independent TX/FtX lrequencies. Trunking: 40 Channels in any of 4 combinations of systems or groups. Synthesizer step slze: 5, 6.25, 12.5 KHz Frequency Stablllty: +/-2.5 PPM (-30 to +60 C) TX/HX Tone/Code Signaling: CTCSS (Quiet Call) Digital Coded Squelch (Digital Quiet Call) LTR Trunking Passport npNTs Trunking Power Supply: +7.5 VDC, 800 mAH rechargeable NiCad battery pack Battery Drain: Standby: 60 mA Avg. Standby with Power Saver: 2 mA Receive - 125 mA Transmit - 1500 mA @ 4 Watts 650 mA @ 1 Watt Battery Life: Standard battery (800 mAH) 6 90/515 Duty Cycle 7.9 Hrs, Battery Saver On, TX High Power 13.5 Hrs. Battery Saver On, TX Low Power 5.9 Hrs, Battery Saver Oil, TX High Power 8.6 Hrs, Battery Saver Oil, TX Low Power High capacity battery (1500 mAh) 0 90/515 Duty Cycle 14.7 Hrs, Battery Saver On, TX High Power 25.4 Hrs. Battery Saver On, TX Low Power 11.1 Hrs, Battery Saver Olt, TX High Power 161 Hrs, Battery Saver 0", TX Low Power Dimensions: 4.75"H x 2.2‘W x 1.43"D Weight: 11.5 oz. with battery pack Enclosure Material: Lexan Polycarbonate Environmental: Splash resistant and shock and vibration per HITFlON Drop Test (6 ft. drop onto concrete on all six sides) SST-454 SPECIFICATIONS GENERAL Antenna Fitting: External RF Test Jack: Earphone Jack: MIcrophone/PTI'IChg Jaolc Push Button Controls: LED Indicator: Speaker Beep indicators: On/Volume UF' - Volume Down/Off - Both Volume Buttons - PTT - Channel - QCIDQC Decode Tlme: 1/4" - 32 x 1/4" threaded Antenna connector with RITFlON SST-SRVBD lest device 3.5 mm, disconnects the internal speaker for extemal earphone, speaker/microphone, or headset. Also provides cable connection lor PC programming. 2.5 mm, for external speaker/microphone. headset or FllTFtON model BOA wall charger OnNqume Up Volume Down/Of! PTI' Channel Transmit/channel busy lamp, dual color, Red/Green Green Flashing - Channel busy Red - Transmit enabled Single beep when radio is turned on. followed by increasing audio to adjust volume. Decreasing audio to adjust volume, with two tones when unit is turned off. Alternates between Tone Squelch (single beep) and Carrier Squelch (two beeps). If both buttons are held down until the radio beeps repeatedly, squelch will be disabled. Programmable for a single “transmit beep”. Number 0! beeps indicates channel. per EIA Standards SST-454 SPECIFICATIONS RECEIVER Wide band Narrow band M M Modulation Acceptance: +/- 7.0 KHz +/— 3.75 KHz Sensitivity (12 dB SINAD): 0.3 pV 0:3 uV Adlacent Channel (EIA): —70 dB -60 dB Spurious Raiection: -70 dB -70 dB Image Rejection (EIA): -70 dB -70 dB Intermodulatlon (EIA): —67 dB -60 db Noise Squelch Sensitivity: Programmable per channel, factory set for 12 dB SlNAD Frequency Response: 300 - 3000 Hz, de—emphasized Audio Output 1 Watt into 8 Q. with less than 5 % THD @ the earphone jack Receiving System: Fixed tuned, dual conversion superheterodyne I.F. System: ist - 43.65 MHz 2nd - 450 KHz L.O. injection: Low side TRANSMITTER RF Power Output: Programmable per channel tor high, medium or low power High: 3 Watts minimum @ +7.2 VDC Medium: 2 Watts Low: 1 Watt M Narrow Mode Emission Designator: 16KOF3E 11KOF3E Deviation: +/- 5.00 KHz +/» 2.50 KHz FM Hum and Noise: -43 dB -37 dB Audio Distortion: < 3 % < 6 % Spurious and Harmonics: -50 dBc Audio Response: Meets FCC and EIA requirements Time-out Timer: 30 seconds. programmable SST—454 INTRODUCTION General RITFtON‘s SST-454 handheld is a small, programmable two-way radio, designed to operate in the 450- 470 MHz professional FM communications band. This handheld features push-button operating controls, with the Push-To—Talk and channel buttons on one side of the radio. The on-ott, volume and monitor controls are on top. Each radio can be “dealer or factory" programmed to contain a unique set of operating lrequencies and options. Selective signalling options include Quiet Call (CTCSS), Digital Quiet Call (DCS), LTR Trunking, and Passport npNTS Tmnking. Transmitter power, operating bandwidth and battery saver are among the options programmable on a per channel basis. Inspection Each radio package should include a radio, antenna, rechargeable battery pack, belt clip and any optional accessories ordered. Examine the equipment immediately after delivery and report any damages to your shipping company. Model Identltlcatlon The SST-454 model, serial number and FCC identification are displayed on a label located on the back of the radio beneath the belt clip. Fcc Regulations Licensing The FCC requires the radio owner to obtain a station license for his radios before using them to transmit, but does not require an operating license or permit. The station licensee is responsible for ensuring that transmitter power, frequency and deviation are within the limits specified by the station license. The station licensee is also responsible for proper operation and maintenance at the radio equipment. This includes checking the transmitter frequency and deviation periodically, using appropriate methods. Safety Standards The FCC (with its action in General Docket 79-144, March 13, 1985) has adopted a safety standard for human exposure to radio trequency electromagnetic energy emitted by FCC regulated equipment. FtlTFtON lollows these safety standards, and recommends that you observe the lollowing guidelines: . DO NOT hold the radio such that the antenna is very close to or touching exposed parts of the body, especially the face or eyes, while transmitting. Keep the radio vertical, two to three inches away while talking into the microphone. - DO NOT press the Push-To-Talk except when you intend to transmit. - DO NOT operate radio equipment near electrical blasting caps or in an explosive atmosphere. - DO NOT allow children to play with any radio equipment that contains a transmitting device. - Repair of FtITFtON products should be performed only by RITHON authorized personnel. Battery care The handheld is powered by a rechargeable battery, which fits Into the radio case (see FIG-1). Charging The battery pack can lose its charge during storage and shipment, and should be fully charged before the radio is used. Thereafter, the battery should be charged overnight after each day of use, to ensure peak radio performance for the next day. Using the cube charger (model BC-A), the battery should charge completely in 12 hours. Note: A new battery must be cycled (charged and discharged) several times before it will reach its maximum charge capacity. To charge the battery using a RITRON cube charger - plug the charger cord into the smaller of the two jacks on top of the radio. Then plug the cube into an 110 VAC outlet. The green lamp lights while the battery is charging. and should go off only when the cube is unplugged. Two charger contacts, visible through the bottom of the radio case, allow the battery to be charged using an optional FtITFtON drop-in charger (model BCPS-FS). The battery pack may be charged inside or outsrde of the radio case. To charge the battery using a drop-in charger (model BCPS-FS) - plug the drop-in charger into an 110 VAC outlet. Set the portable or battery into the charger. Each battery contact must rest on a charger contact pin. Typically. a battery packs service life is one year. To ensure maximum service life, follow these gurdelines: - Do not discharge a battery that Is already ”an down," It the battery cannot power your radio, recharge the battery. - Do not overcharge a battery. The standard battery should not be left to charge continuously. . Before storing a battery, charge it for 16 hours. Thereafter, charge the battery for 16 hours once every 30 days. With daily use and recharging, a battery’s service life is about one year. it is time to purchase a new battery: 1) When the radio's transmitter coverage decreases or does not work at all, 2) When the radio quits working after just a few hours of use, despite a full overnight charge or. 3) If the battery is more than two years old. The date of manufacture is stamped on every battery. The first two digits indicate the year, the last two digits the week. Battery Replacement To take the battery out at the radio, remove the battery door pictured in FIG-1. Use the pull-tab to remove the battery. Slide the replacement battery into the radio case. Make sure the spring comacts are inserted between the battery and paper insulator. The contacts must not touch the radio PC board. Flg. 1 Battery Replacement O Q A: Precautlons - Use only HITHON-supplied chargers; other chargers might cause fire. explosion, or other damage to the radio. a Do not Wastcharge" a brand new battery pack. Othenivise, the battery might be damaged. Once the battery has been charged fully using the normal rate, the fast rate may be used therealter. - Do not last-charge a battery pack that is fully charged. This can shorten battery Iile. - Do not charge or replace a battery in an explosive atmosphere. Contact sparking can ignite an explosion. - Do not dispose ol a battery in fire. An explosion might result. - Do not charge the battery in temperatures colder than about 45°F. Electrolyte leakage can occur and ruin the battery. - Charging in temperatures above approximately 95°F will not harm the battery, but can reduce its charge capacity. 10 DESCRIPTION OF CONTROLS AND CONNECTORS Antenna The flexible antenna radiates and receives radio signals. Before using the radio, make sure the antenna base is threaded fully into the radio's antenna bushing. VHF and UHF antennas are not interchangeable. Use only the antenna type packaged with the radio. A VHF antenna is pictured in FIG-2. (The UHF antenna is smaller in diameter.) OnNqume Up This button switches on the radio, then increases the volume if you continue to press. O‘ifNqume Down This button decreases the volume, then shuts oil the radio it you continue to press. channel Select Pressing this button selects the next channel. When the maximum number of channels is reached and you press this button, the radio resets to channel 1. Speaker The speaker allows you to hear calls on your channel. Push-To-Talk Button The PTT activates the transmitter, and must be held down while you talk into the microphone. Release the P'I'I' button to receive. Microphone The microphone converts your voice into electrical impulses, which are carried with your broadcast to receiving radios, Hold the radio about two inches away and talk into the microphone while transmitting. Shouting does not improve the listener's reception. Audio Accessory Jack This jack connects speaker audio to optional accessories, such as a remote speaker/microphone or an earphone. For accessories that have a two-plug connector, the smaller plug is inserted into the charge jack. This Jack is also used to program the radio using the optional PC programming kit. Charge Jack The battery may be charged through this jack using a standard HITRON wall socket charger cube. This jack also connects microphone audio to the optional remote speaker/microphone. Battery Access (Case Bottom) The battery door on the case bottom may be removed to acoess the battery. (Refer to the battery section oi this manual.) Drop-in Charger Contacts Two charger contacts in the bottom of the SST—454 radio case allow the battery pack to be charged using an optional FtlTRON drop-in charger (model BCPS-FS). Jack Cover This rubber cover seals out dust and moisture. etc. Snap the cover into the audio accessory and charge iack openings when the jacks are not being used. 1] Antenna — /— Jack Cover Vol Down/Off Audio Accessory Jack OnIVoI Up Charge Jack Push-to-Talk Channel Selector Microphone Battery Access Door (case bottom) Battery Charger Contacts (Case bottom) Fig. 2 Controls and Accessory Connectors Belt clip installation Il you are going to attach the belt clip to the handheld, loIIow these instructions: 1) The belt clip is fastened to the radio case back with the Philips head screw provided. Use the screw included. since a longer screw might damage the radio’s electronics Do not use petroleum solvents 01 any kind on the radio. These can corrode the case. 2) Place the belt clip on top of the radio case back, with the screw hole in the aligned with the hole in the radio case. 3) Using the screw that came with this accessory, attach the clip to the radio. 12 OPERATION On-oftNolume magnum - press the can/volume up button. To ad' gst the volume - press the volume up button until you reach the desired level. You should hear noise and any broadcasts on the channel. To turn ofimg Lad‘g - press and hold the oft/volume down button until two tones sound. IQ determine whether the radio is on - press the volume down button. If the radio is on, noise or activity on the channel is heard. Receive To hear on s from other users - adjust the volume as desired. The radio can receive broadcasts while the Push-To-Talk button is not being pressed. Whether or not you hear these broadcasts depends upon the squelch settings. There are two types ot squelch used in the SST-454 portable. First is carrier squelch. This lets you hear all broadcasts on yourchannel strong enough for the radio to detect, and silences noise. Second is one of the selective signaling or “tone squelch” formats available on the SST—454 . This allows you to screen out “on-channel” broadcasts that do not carry the correct code programmed tor the radio. Note: It is possible that the beginning of a call might be missed while the radio is in battery saver mode. If this happens, ask the callerto repeat his message. Monitor Mme - press one of the volume control buttons. When you press the volume up or the volume down button, squelch turns oft and all radio traffic on the channel (and noise) sounds in the speaker. Selective signaling Squelch To activate tone squelch - simultaneously press both volume buttons. Hold tor a second or two betore releasing. When tone squelch is turned on, the handheld sounds one beep. When carrier squelch is on, the radio emits a "double beep." Note: If you continue to hold down the volume buttons alter the beep (or double beep), the radio will start beeping repeatedly. This means that all squelch is turned ott. Release the buttons. To restore squelch, press and hold both volume buttons until the radio sounds a beep or double beep. Battery Saver The handheld has a programmable "battery saver" feature that conserves battery power. The battery saver constantly checks the radio‘s transmitter, receiver and controls for activity. it a number of seconds pass without the rece'wer detecting a call. and without the user operating a control, this feature removes power from most oi the radio. During this "oil-time,“ any activity restores full power. Every few tractions ol a second, the battery saver applies power to the receiver, checking for broadcasts. It is possible that the first part of an incoming call might go unheard belore activity is detected and power restored. It this happens, the caller can repeat his message. Once “radio contact" is made, normal unhurried conversation can follow. Transmit 13 Normally, you should not transmit until no one is talking on the channel. To transmit - hold down the Push-To~Talk button and, with the radio a couple of inches away, talk into the microphone. Speak in a normal tone, since talking louder will not improve the listener's reception. Channel Selection Wm - press and release the channel button. The radio will beep a number of times equal to the new channel number. For example, if you select channel 2. the handheld will beep twice. If the highest channel number is selected and you press the channel button, the radio will reset to channel 1. A one channel radio will beep only once when you press the channel button. What The Radio Tones Mean The handheld responds to certain instructions by sounding a beep or series of tones. These tones can tell you whether the radio is working as you expect. Power OnISelf Check “0k” When the handheld is turned on. it runs a quick “self test." Once the internal system checks confirm basic functions, the radio sounds a brief “confirmation tone.” The radio Is then ready to use. Error Tones However, if the self test detects a diagnostic error, an error tune sounds. Alternating tones (the second is longer and lower pitched) indicate the radio frequency synthesizer is malfunctioning. Turn off the radio and try again. A long, low-pitched tone means the battery voltage is too low to operate the radio. In this case, recharge the battery. It you cannot correct a problem, consult an authorized Ritron service facility or Ftitron. Channel Select When you press the channel button, the radio beeps a number of times equal to the channel number selected. Tone Squelch When you press and hold both volume buttons at the same time, a single beep sounds to indicate that tone squelch is on. A “double beep" means that carrier squelch is on. Recharge Battery Alert As the battery voltage approaches the minimum required “operating voltage” the radio will emit a short beep every 10 seconds to alert the user that the battery will soon need recharging. Once the battery charge drops below the required “operating voltage," the radio emits a long, low tone and turns itself off. If you turn the radio back on, it will beep again and shut itseif oft. Recharge the battery. 14 PC Programmable Optional Radio Tones Receive Squelch Tone A short tone sounds at the end of each received transmission to indicate that you may transmit. Transmit Activate The radio may be programmed by authorized service personnel to sound a short tone each time you press the Push-To-Talk button to transmit. Busy Channel Transmit Inhibit If a user is transmitting on your radio lrequency without your tone, you will not be allowed to transmit The radio will beep a series of long, low tones while the PTT is held down (like a busy signal). Transmitter Timeout A low tone followed by a higher-pitched tone sounds and the transmitter automatically shuts oil it you hold down the PTT button longer than the programmed Time-out. The radio automatically switches to receive mode, Authorized service personnel can turn off this feature. 15 Troubleshooting Il you have trouble operating the handheld. review the radio controls and operation sections. If you think the radio is malfunctioning, check the table below. Problem GENERAL The radio does not work at all. Operating leatures do not work exactly as expected. Reception is poor. You cannot hear calls lrom other radios. Your calls cannot be heard in other radios. Battery The battery loses its charge sooner than expected. Error Tones An error tone sounds when the radio is lirst switched on. An error tone sounds while you are talking (and the transmitter shuts off). Possible Solgtiggs Make sure that the battery is installed correctly, as shown in FIG-1. Recharge or replace the battery. (See note 1.) The radio has been factory or dealer programmed for customized operation. Move to a different location. (Note 2.) Confirm that the proper antenna is connected to the radio. (See p. 11, 'Antenna.') Turn off tone squelch. (See Note 3.) Be certain your radio receives on the same frequency as the caller transmits. (Note 4.) Recharge the battery. (Note 1.) Make sure that your radio transmits on the receive frequency of the radio(s) you want to call. (Note 4.) Recharge the battery. (Note 1.) Review the battery charging instructions. Conserve the battery. (Note 5.) If the radio is used in extreme cold, warm the radio under your coat. (Note 6.) Replace the battery. (Note 1.) See "Error Tones" in the Operation section. Reler to “Error Tones” 16 Troubleshootlng (Con‘L) mugm Eossigle Solutions Tone Coded Squelch You cannot screen out calls from users outside Make sure that the channel |s programmed of your tone group. with tone squelch. Activate Tone (coded) squelch. (Note 7.) You cannot hear Tone coded messages while in Confirm that the channel is programmed to Tone (coded) squelch. detect the same code as the calling radio(s) transmits. (Note 7.) Others in your tone group cannot hear your Verify that you transmit the same code as tone coded messages. the radio(s) you call are programmed to detect. (Note 7.) Notes 1) 2) 3) 4) 5) 6) 7) Try a battery pack from a working radio. If the radio in question works with that pack, the original battery is suspect. Charge the suspect battery as recommended in this manualt Then, if the charged original battery cannot power the handheld, try charging again with another charger. If the battery still doesn't hold a charge. the pack should probably be replaced. However, if the battery appears to be “good" after you try the second charger, the first charger might be faulty. if you think that an accessory is not operating properly, contact your dealer or RITRON. (Radio accessories come with a 90 day limited warranty.) Reception can often be improved by moving a short disbance. This effect is more noticeable inside of buildings. The range of these portables equipped with a standard battery pack is about two miles (Iine—of—sight). it your radio does not detect calls lrom other radios on the channel. turn off tone squelch. (Press both volume buttons at the same time - a double beep means that tone squelch is off.) If you want to hear a call, you must select a channel that is programmed to receive the caller‘s transmit frequency. If you want to call another unit, you must select a channel that is programmed to transmit the other radio’s receive lrequency. However, if you use a repeater, your channel must be programmed to work with the repeater’s transmit and receive frequencies. (A radio channel can hold two separate operating frequencies, one for receive, the other for transmit.) Maximum power drain occurs while the radio transmits, so don’t hold down the Push-To-Talk button more than necessary. Battery power is used while the handheld is left on to receive calls it practical, switch oll the unit. In extreme cold, a battery's charge capacity is greatly reduced. If you use the radio in very cold weather, periodically warm the poltable underneath your coat if possible. An optional remote speaker/microphone would allow you to keep the radio under your coat while transmitting and receiving. In order for radios to communicate using Quiet Call. they must be programmed with the same tone code. Each code is unique, and your radio will respond only to the code programmed. Press and hold both volume buttons at the same time. A single beep means that tone squelch is on. A double beep means that tone squelch is off. PROGRAMM|NG THE RADIO I7 Each SST-454 may be programmed for 4 channels, with up to 40 frequencies programmed on any single trunking channel. How To Program The Radio SST-454 programming requires an optional Flitron programming kit. This kit allows you to program any frequency within the band and channel spacing of the radio model. This method also lets you customize the handheld with optional operating teatures. How To Find Out What Is Already Programmed If you do not know what lreouencies, tone codes and options are programmed in a radio and want to lind out, you can do a contents readout using the PC Programming Kit. Return To Normal Operation After you linish programming, turn the radio oil and then on again. The radio will beep when it is ready tor normal operation, COMPUTER SOFTWARE COPYRIGHTS The FllTFtON, Inc. products described in this manual include copyrighted RITRON, inc. computer programs. Laws in the United States and other countries grant to RITRON, inc. certain exclusive rights in us copyrighted computer programs, including the exclusive right to distribute copies oi the programs, make reproductions of the programs, and prepare derivative works based on the programs. Accordingly, any computer programs contained in FlITFlON, inc. products may not be copied or reproduced in any manner without the express written permission of FtlTFiON. The purchase of FtITFtON. inc. products does not grant any license or rights under the copyrights or other intellectual property of HlTFtON, inc., except for the non-exclusive, royalty tee license to use that arises in the sale of a product, or as addressed in a written agreement between RITRON, inc. and the purchaser of FllTFtON, inc. products. Programming The Radio Using A PC Computer Ritron‘s programming kit allows programming of the SST-454 model radios using a PC compatible computer. (This kit also allows programming of RTX-454 handhelds.) thron's adapter cable connects the radio to a computer’s serial communications pod. Once the cable is hooked up. the user inserts the diskette provided into his computer‘s floppy disk drive and loads a software program. This program transters data between radio and computer memory, and includes on-screen instructions and help. Radio date may be saved to the computer's hard disk in order to program other radios. The PC Programming Kit Includes: 1) Ritron Transceiver Programming software, which is contained on one 3.5" diskette. 2) Installation instructions (RITRON #01454947) and a registration form. 3) Ritron PC to radio adapter cable, which is terminated at one end with a DB-25F connector, at the other end with a modular plug. The DB-25 plugs into the computers serial port, the modular plug into the SST-SRVBD modular iack. 4) An adapter tor use with SST-454 portables. This adapter mates the modular plug to a 3.5 mm plug, for connection to the handheld’s audio jack. is The PC Programming Kit Requires: A PC compatible computer with DOS 3.2 or later. The computer must have a HS-232 serial port available. A hard disk drive is recommended. Programmable Features The list below indicates whether each feature may be programmed on a per channel basis, or will affect all channels together. Feature we Sta et'tin Per Change Automatic inactivity Turn-oil Y-N Yes Battery Saver Enable Y—N Yes (except trunking) \I Battery Saver Off Time Busy Channel Transmit Inhibit Y-N No 4 Carrier Only, No Tones or Codes Channel identification Mode V-N No Digital Tone Invert RX Y-N No “1 Digital Tone Invert TX Y-N No v Digital Quiet Call (DOS) - - v Disable Monitor Y-N No «J Flash green LED on Carrier Detect Y-N No LTFt Trunking - - ~I Narrow Band Channel Y-N No ~/ Passport npNTS Trunking - - v QC Decode Pre—Ioad Y-N Yes 4 Quiet Call (CTCSS) - - xi Quiet Call Encode Only Y-N No «I Quiet Call Transt Hang Time 0468 ms 188 ms Receive Squelch Tone Y-N No 4 Souelch Tightener Y-N No i Transmit Activate Tone Y—N No «I Transmit Power L-M-H High «1 Transmit Time Out Timer (80 s) Y-N Yes V Turn On To Channel 1 Y-N Yes Turn On To Medium Volume Level Y-N Yes Descriptions of Features Amgmatic luggtm Turn—911 - The radio automatically shuts itself oft it four hours go by without the microcontroller detecting input from the volume, PTT or channel controls. Battem Sayer - Enabling this option allows the radio to go into battery saver mode when the radio remains idle. The power strobe begins atter eight seconds of Inactivity. Batten; §ayer off ”me - This is the time that the radio must remain idle before the battery saver begins cycling. Que! Qhanne Transmit Inhibit - This keeps the radio from broadcasting if the channel is busy, and is oiten used in conjunction with Disable Monitor. It you press the PTT when the channel is busy with a signal not intended for your radio (not carrying your tone code), this leature sounds a "busy“ tone in the speaker and keeps the transmitter turned ott. 19 gngunel Idenm‘ 'gt'on Mode - With this feature enabled, the channel number is “beeped out" when the channel button is pressed. The channel is not incremented. To increment the channel, press the channel button again within three seconds. D'g'ta Quiet Cal EX uvert - The programmed code is inverted for receive mode only. Digital Qu'et gall TX Invert - The code is inverted for transmit mode. D'san e Monitor - This function may be programmed to keep the radio user from listening to other licensees on a shared channel. 00, DQC or trunking must be used with this option (although, not the encode only feature). Que! gall (CTQSfi) - Programming a Quiet Call code allows you to screen out transmissions that do not carry your code. Your code is broadcast when you press the PTT to make a call. gy'gt Call Encode Qu y - The Quiet Call code programmed for the channel is transmitted with your calls. However, Quiet Call is turned off during receive mode, allowing all traffic on the channel to be heard. gs; Decode Prelgad - For a short time after transmitting or receiving a signal with the proper Quiet Call tone, the radio unsquelches when any on-channel signal is present. Until it has time to decode the tone, the radio "assumes" that the correct tone is present. Once the tone is decoded, the radio squelches or unsquelches accordingly. This keeps radio users from missing the first portion of a transmission once radio contact has been made. Quiet 5ng Lansmit Hang me - This is the time that the phase reversed Quiet Call tone is transmitted after the PTl' is released. Recg‘ye Emguency - The radio frequency that receives broadcasts from other units. Beg-give Sgue 9]: one - The receiving radio beeps at the end of each received transmission. Sguelgh T'ghjner - This feature reduces distant “co—channel" or other interference for channels that are not programmed with Quiet Call. Carrier squelch is set for maximum sensitivity at the factory, but may be adjusted to mute weak signals Trgnsm‘t Activate Jone - The radio will automatically beep each time the PTT is pressed. This beep is not heard in the receiving radio(s). (This is a short, high-pitched tone, unlike the long, low-pitched tone of the busy channel transmit inhibit feature.) Transm't Time Out mgr - This feature automatically shuts off the transmitter (ending your call) if you hold down the PTT button continuously for 60 seconds. The radio sounds a tone when the transmitter shuts off. Turn On to Qhannel t - The radio defaults to channel 1 when turned on. Normally, the radio returns to the channel in use at power oft. Tum 529 To Med‘um yglgme Leve - The volume level is at mid-range when the radio is first turned on. Normally, the volume level is low when the radio is turned on. SST-454 THEORY OF OPERATION lNTHODUCTION The SST-454 is a four-channel handheld transceiver built on a single multilayer printed circuit board with a separate synthesizerNOO module and TCVCXO reference oscillator module. Both sides oi the main printed circuit board are populated with components. with the bottom side containing only surface mounted components. The SST-454 is frequency synthesized, with all functions of the radio controlled by microcontroller. POWER 5 LY AND VOLTAGE DISTRIBUTION The SST454 is powered by an internal 6-cell rechargeable battery pack. The battery pack supplies power to the radio via two contact terminals that are connected to the PCB through P302. F301 is a 3A fuse in series with P302 for short circuit protection. The battery pack may be charged through 2.5 mm charge lack J301 via CR302 and F301. Zener diode CR301 prevents the batteries from discharging through the charger accessory, stops a reverse voltage from being applied to the battery pack through J301, and prevents a high voltage from being applied to the radio circuitry. CFt307 prevents a reverse voltage lrom being applied to the radio. SW301 ONNOL UP switched is pressed to switch on the SST-454, turning on voltage pass transistor QSOSB via Fl307. 03055 supplies power to ICBO1, a +5 VDC regulator used to power microcontroller lcsoz. Pin 19 of 16302 turns on QSOSA. which keeps 03058 turned on alter SW301 has been released. Power is removed from the SST-454 by pressing the VOL DNIOFF switch SW302 until a beep is heard from the speaker, at which time Q305A is turned off. +5 VDC regulator l0301 supplies power directly to microcontroller l0302. bilateral audio gates I0304, and PTT detect transistor 0302. Pin 32 of lCaOZ lets 0308 switch the regulated +5 VDC to the receiver, Pin 20 of 10302 is used to switch a regulated +6 VDC to the transmitter. Pin 20 oi ICSOZ turns on 0202, which turns on voltage pass transistor 0204. With 0204 emitter oonnected to the +VBATT battery supply, the collector output is connected to the emitter oi 0202 through voltage Ft205/Fl214, whose values are selected to limit the TX+V voltage to +6 VDC. POWER STROBE The SST-454 handheld includes a power strobe teature. which reduces battery current drain by periodically removing voltage from pan of the radio. The strobe duty cycle is programmable, and can be selectively applied to any programmed channel using the Pius Series PC Programming Kit. The +5VSW power strobe output at Pin 6 of lC302 controls 0307. which smtches the regulated +5 VDC to the audio processing circuitry, Y302 TCVCXO reference oscillator, and the synthesizer module. This includes ICSOSB 2 VDC (Veg) for bias on audio processing Circuitry, ICSOBA audio high pass tilter, 103078 and ICSO7C audio low pass filter for sub-audible frequencies, 10307A audio limiting amplifier, and lC308 digital potentiometers, +5VSW is also applied to 0304, which along with voltage divider Rana/Race generates the +6VSW output used to supply ICGDSB audio summing node amplifier, l0305A audio low pass filter, and the synthesizer module. LOW BATTERY VOLTAGE DETECTION Battery voltage is measured at A/D input Pin 38 of 10302 through voltage divider RBOAIRSOSA The radio will emit a periodic beep if low battery voltage is detected, and will turn the radio oft if the battery voltage drops below +5 VDC. This is to protect the microoontroller and its EE memory from corruption due to low supply voltage. 7.1 ,l/,’/’4 REFERENCE OSClLLATOR Reference oscillator Y302 is a 1.5 ppm temperature controlled. voltage controlled oscillator (T CVCXO) operating at 14.4 MHz. The Pin 4 output of the TCVCXO provides a reference for the frequency synthesizer module via Pin 5 of P402. and is multiplied up to 43.2 MHz by Q102 and its associated circurtry to provide a receiver 2nd local oscillator signal. SYNTHESIZER MODULE The SST-454 radio is built around a common phase-looked loop (PLL) that consists of a voltage controlled oscillator (VCO) and a frequency synthesizer. The PLL generates both the receiver 1st local oscillator and transmitter carrier signals. The frequency synthesizer and VCO are both contained in a shielded Synthesizer Module that is mounted to the SST-454 main pcb via P401 and P402. Control signals from microoontroller l0302 and Reference oscillator Y302 are routed to frequency synthesizer lC401 per the following chart: PIN NUMBERS Qiock M3 Latch Q T/R BEE 155W +§§W lC302 62 35 7 64 5 - - - V302 - - — , - 4 2 P402 7 8 6 2 4 5 3 1 [0401 1 8 1 9 1 2 — 20 1 2, 1 4 5 0402, CR401, C428 and associated components provide a filtered supply for the VCO oscillator and buffer amplifiers. PRESCALER DIVIDEH/SYNTHESIZER CONT ROLLER IC401 contains both a prescaler and synthesizer controller. The prescaler squares and divides the VCO output present at pin 11 by either 64 or 65, determined by a synthesizer controller logic signal. The exact number of times the prescaler is instmcted to change divisors is determined by the channel frequency. 10401 contains a digital phase detector that works as follows: when an operating channel is changed or the receive/transmit mode switched, a new synthesizer operating frequency is selected, Microcontroller lCSOZ clocks new data into lC401 internal buffer in syncronization with clock pulses. The channel information is stored in EE memory of l0302 and is loaded into RAM when the radio is initially powered up. Once new data is loaded into the buffer, a single pulse from lC302 appears at l0401 to instruct the synthesizer controller to latch and execute the new data. lC401 utilizes internal circuitry to determine wheather the present VCO output frequency is correct by comparing the phase and frequency of the VCO signal at Pin 11 to the 14.4 MHz reference oscillator at Pin 20. lC401 produces an output signal at Pin 6, a single-ended phase/frequency detector output, proportional to the phase difference between the two input signals. The loop filter C423, 0422. R41 8, Ft419, R417, and 0421 transform the Pin 6 output signal to a DC voltage for application to the VCO tuning varactor CFt402. The synthesizer system is “locked" when the phase and frequency of both the reference and the divided VCO signal are the same. The maximum amount of current this output can sink or source is determined by the value of H420 tied to Pin 8 of IC401. with the output current programmable to 25, 50 or 100% of maximum. VCO/EUFFER AMPLIFIERS 7.2 Q404, L403, CR402 and associated components form the VCO (Voltage Controlled Oscillator), a resonant circuit that oscillates at frequencies lrom 406 MHz in receive (receive frequency — 43.65 MHz) to 470 MHz in transmit, Varying the voltage at CR402 changes the varactor's capacitance, which in turn alters the VCO output frequency. When in transmit mode a +5 VDC T/RSW signal is applied to 0407, which turns on 0406 to draw current through pin diode CR404 and L405. With CR404 biased on, L401 is ellectively shorted to ground, shitting the VCO trequency up 43.65 MHz. 0401 and 0403 are butter amplifiers, with 0403 ieeding in the input of the synthesizer at Pin 11, the receiver tst local oscillator signal at P401 Pin 1 and the transmitter pre-amplilier at P401 Pin 3. OSCILLATOR MODULATION When the SST-454 is in transmit, modulation balance control ICaOSE passes TX audio through to the VCO modulation input at P401 Pin 5. TX audio is applied to varactor CR403 to modulate the VCO. TX audio is also routed to the Pin 1 input of TCVCXO reference oscillator Y302. Low lrequency tones modulate the reference oscillator because the synthesizer is not able to track them. DIGITAL POTENTIOMETE ICaOB contains 6 digital potentiometers programmed by lC-302, sharing the same clock and data outputs used by the synthesizer and a seperarate Digital Pot Latch signal lrorn Pin 33 The digital potentiometers are used in coniunction with ICBOSB, a summing node amplitier used tor modulating the VCO and relerenoe oscillator. lC3OBA, B, D, E, and F can only be changed through serial programming, and can only be performed by an authorized licensed RF technician. ICSOBA and IC3OSB are connected through R351 and R352 to the Pin 6 input ol ICSOSB. ICSOBA and B adiust the DC output of lCSGSB to tune the reference oscillator frequency, with lCaOBA providing a coarse tune and lCSOBB a line tune. Volume control lCSOBC applies the processed voice band signals at lC305A to audio ampiiier l0309 in receive mode. Depressing the ONNOL UP switch SW301 increases the setting oi ICSOSC while VOL DN/OFF switch SW302 decreases it. Transmitter tone deviation control ICSOBD applies the output of the selective signalling low-pass filter l0307C to the Pin 6 input oi lCSDSB through R350. ICSOBD is completely closed in receive mode. Transmitter modulation balance control lCaOBE is used to apply the Pin 7 output 01 ICSOSB to the VCO modulation input at P401 Pin 5. This sets the ratio 01 the modulating signal applied to the VCO and the reterence oscillator. ICSOBE is completely closed in receive mode. Tranmsitter voice deviation control IC308F applies the processed v0|ce hand signals at ICSOSA to the Pin 6 input of icsose through R349. lCSUBF is completely closed in receive mode. As mentioned before, Q308 switches the regulated +5 VDC to the receiver. The +VRX receiver voltage is switched at the strobe duty cycle if programmed for power strobe. RF AMPLIFER A received signal lrorn the antenna passes through a low-pass filter (L213, 0220, 6219, L212, 0218, L211, 0217) and L210 to the receiver headend. L101, L102 and the associated capacitors form a bandpass litter ahead of low-noise RF ampliter 0101. L103 and C109 provide a notch at the receiver image irequency. 87.3 MHz below the receive frequency. The amplifed RF signal is applied to a 4-pole 23 bandpass filter consisting 01 L105, L106, L107, L108 and associated capacitors. This fixed tuned circuit has a 20 MHz bandwidth of 450-470 MHz. 181 MIXER The amplified received input signal is applied to the Pin 8 input of 10102, a ductile-balanced mixer configured for single-ended output. The 1st local oscillator signal from the synthesizer module is applied to the Pin 4 input of IC102, with 0129 coupling the 43.65 MHz output signal at Pins 5 and 6 to YF101, a 43.65 MHz two—pole crystal filter. 0103 and associated components amplify the 43.65 MHz IF signal and apply it to the input of the 2nd mixer at Pin 16 of ICtOt. FM RECEIVER SUBSYSTEM A multi-lunction integrated circuit, lC101 and associated components for the FM-receiver subsystem. The subsystem performs the following functions: 1) 2nd mixer, 2) 2nd lF amplifier, 3) FM detector,and 4) noise amplifier. The Pin 4 output of 14.4 MHz reference oscillator Y302 is multiplied up to 43,2 MHZ by 0102 and associated components. This signal is applied to the 2nd local oscillator input at Pin 1 of IC101. The 43.65 MHz signal at Pin 16 and the and local oscillator are mixed, with the resulting 450 KHz output signal appearing at Pin 3. This signal is filtered by a 450 KHz S-pole ceramic filter YF102 and applied to the input of the limiting lF amplifier at Pin 5. IC101 Pin 6 is the decoupled input to the lF amplifier, Pin 7 the limited lF output signal. An internal quadrature detector, whose center frequency is determined by 450 KHz ceramic discriminator Y101, detects the FM lF signal. One input of the quadrature detector is connected internally to the IF signal at Pin 7. while the other detector input is the phase-shifted signal from Y101 at Pin 8. Demodulated audio appears at Pin 9, where a low-pass filter (R114, 0139) removes spurious quadrature output prior to application to the voice/tone conditioning audio circuitry. Demoduiated audio from Pin 9 is applied to the Pin 10 input of a noise filter/amplifier consisting of R110, 0136, 0137, R108, R109 and R111. The Pin 11 output of the noise amplifier is applied to a biased noise detector CR103, with the output connected to an MD input of ICSOZ at Pin 39. The SST-454 is serial programmed to set the squelch threshold and hysteresis. VOICE/T ONE CONDITIONING IN RECEIVE MODE SST-454 audio conditioning filter circuits are shared with the transmitter. The same high-pass filter/amplifier (lCaOGA and associated components) used in receive voice band conditioning is used in the transmit band. Similarly, the low-pass filter (ICSO7C and associated components) used for selective signal tone decode filtering is also used for selective signal encoding. Altering circuit configuration with bilateral switches I0304A, B and C permits the use of the same audio filtering system for both transmit and receive modes. After R114 and 0139 remove the 450 KHz element from the demodulated audio output at Pin 9 of IC101, 0339 couples the audio signal to bilateral switch l0304C for subaudible tone detection and connection to lC-304C for voice band audio processing. VOICE BAND Bilateral switch ICBMA passes the received audio signal to the input of l0306A, which along with its associated components for a high-pass filter/amplifier cichit that attenuates audio signals below 300 Hz. The output of ICGOGA is applied to the input of ICSO7A limiting amplifier. Bilateral switch ICSO4B is switched in receive to insert 0327 into the feedback circuit of l0307A, providing rte-emphasis of the received audio signal. Bilateral switch l03048 also removes R325 from the Pin 14 input to reduce the gain and prevent limiting. The output from l0307A is applied to the input of ICSOSA, which along with its associated components form an 18dB/octave low-pass filter for frequencies above 3000 Hz. The output of lCSOSA is connected to lCSOBC volume control prior to connection to audio amplifier 10309. The output 24 of IC305A is also connected to lC3OBF voice devlation control, which is completely closed in reoeive mode to prevent received signals from modulating the VCO and reference oscillators. Audio frequency tones from Pins 15 and 16 of microcontroller IC302 are applied to the Pin 14 input of l0307A to provide the SST-454 alert tones. SUB-AUDIBLE Bilateral switch lC3040 passes the received audio signal to the input of I0307B, which amplifies the signal and applies it to the Pin 8 input of "33070, a S-pole low-pass filter that attenuates frequencies above 250 Hz. The output at Pin 3 is applied to an AID input of l0302 at Pin 36 for tone decoding. An internal digital signal processing routine programmed into microcontroller l0302 is used to decode the correct selective signalling code. The output at Pin 3 of |cao7c is also connected to tone deviation control lCSOBD, which is completely closed in receive mode to prevent received subaudible tone signals from modulating the VCO and reference oscillators. AUDIO AMPLIFIER Fteceive audio from volume control ICSOBC is applied to the Pin 2 input loses, a 1 Watt audio amplifier. 0359 couples the Pin 5 output to the intemal 89 speaker SP301 via audio jack J303. Microcontroller |C302 Pin 34 switches DC power to the audio amplifier by turning on 031 2, which then turns on pass transistor Q313 to apply battery voltage to Pin 6 of the audio amp. CR306 prevents an inadvertent DC voltage at J303 from damaging the audio amplifier. ANTENNA SWITCHING/LOW‘PASS FILTER A low-pass filter comprised of filter L213, C220, C219, L212, 0218, l211, and C217 removes harmonics from the transmitter output before applying the RF signal to the antenna. Received signals pass through the low-pass filter before entering the receiver RF amplifier circuitryt Two PIN diodes (CR201, CH101) and associated components form the antenna switching circuit. With the SST-454 in receive mode, no voltage is applied to the PIN diodes and they do not conduct. This reverse biases CFt201 to prevent the transmitter amplifier from effecting the receiver tuning and removes CR101 from the receiver input. lnooming signals from the antenna pass through the low-pass filter, then L210 and 0102 to the receiver heedend. When the SST-454 is switched into transmit mode, transmitter supply voltage is switched on by 0202 and Q204 and applied to R208A Current flows through R208, L209. CR201, L210 and then CRtOt to ground, fonrvard biasing the PIN diodes. CR201 passes transmitter RF power to the antenna while CR101 shunts the receiver RF amplifier input to ground. L210 provides sufficient impedence to isolate the transmitter power from the receiver RF amplifier. TRANSMIT KEVING The ST-454 transmitter is keyed when PTT switch SW304 is depressed. Electret condenser microphone M301 is connected in series to ground with the P'IT switch, which when depressed draws current through M301, SW304, CH304 and R318 to turn on pass transistor 0302. 0302 then turns on 0301 to pull the TX Key Pin 2 input of microcontroller I0302 low. The microoontroller TX Enable output at Pin 20 then goes high to turn on 0202, which turns on pass transistor 0204 to apply +6VDC to the transmitter as described previously. The transmitter can also be keyed through J301 with an audio accessory that 25 inserts a microphone and P‘l'l' switch in series to ground, drawing current through CR304. The internal PTT switch SW304 is connected to the Pin 23 PTT input 01 lC302, allowing the radio to distinguish between an internal or external PTl'. This is necessary for certain audio accessories and lor VOX operation. 4 VTX SUPPL Y With the transmitter enabled as described above, the +VTX voltage from 0204 is applied to transmitter RF ampliler 0205 and PWM power control transistor 0201. +VTX supply also forward biases the PlN switching diodes CR201 and CR101 as previously described. The transmitter RF final amplifier Q203 is powered by the battery supply. The Pin 20 TX Enable output of microcontroller ICSO7 can be PC programmed to hold the transmitter on after the PTl' switch has been released to allow tone related tum-oft codes for squelch tail elimination. POWER AMPLIFIER 0205 and associated components amplify the VCO signal and apply it to the input of RF Final ampliler module 0203 at Pin 1. The son output of 0203 is matched to the antenna switching circuitry and applied to the antenna through the low-pass filter. The RF power output is programmable by a licensed RF technician. The SST-454 can be programmed on a channel-by-channel basis for low, medium or high power operation. The PWM power control output at Pin 8 of I0302 is applied to the base of 0201, whose emitter is connected to the Pin 2 Gate control input of 0203. The pulse width from Pin 8 is varied and liltered by R202, 0202, R203, 0203 to adjust the 0203 gate voltage. VOICE/T ONE CONDITIONING IN THANSMIT MODE SST—454 audio conditioning filter circuits are shared with the receiver. The same high-pass filter/amplifier (I0306A and associated components) used in receive voice band conditioning is used in the transmit voice band. Similarly, the low-pass filter 003070 and associated components) used for sub-audible tone decode filtering is also used for tone encode. Altering circuit configuration with bilateral switches lC304 A, B and 0 permits the use ol the same audio filtering system tor both transmit and receive modes. VOICE BAND M301 microphone audio is passes through CR304, C354 and is switched by IC304A to the input ol IC306A, which along with its associated components lonn a high-pass filter/amplifier circuit that attenuates audio signals below 300 Hz. The output ol I0304A is applied to the input at lC307A limiting ampliter. Bilateral switch ICSMB switches R325 in parallel with R326, raising the gain ol limiting amplifer IC307A for full limiting ol the transmitter voice audio. The output at l0307A is applied to the input of 10305A, which along with its associated components form an 18 dB/octave low-pass filter for frequencies above 3 KHz. The output of ICSOSA is applied to voice deviation control IC308F, which sets the level of the processed transmitter audio applied to summing node amplifer I03055 used to modulate the VCO and relerence oscillator. SUB-A UDIBLE Microcontroller IC302 generates the sub-audible selective signalling encode wevefonns at Pins 17 and 1B and applies them to the input at buffer amplifier lC307B. The output of I0307B is applied to the input of IC307C, a 6-pole low-pass tiller that attenuates frequencies above 250 Hz. R338 and 6345 set the comer frequency of the low-pass filter, with 0346 switched in by Pin 25 of ICSOZ to lower the corner frequency tor lower tones. The output at ICSO7C is applied to tone deviation control ICGOBD, which sets the level of the transmitter sub-audible encode tones applied to summing node ampliter IC3OSB used to modulate the VCO and reference osclllator. 26 MICROCONTROLLER The SST—454 handheld transceiver is electronically controlled by |0302, an B—bit microconfroller. I0302 ROM is flash programmable by authorized RF service technicians to allow in circuit upgrades to the operating system for new or improved features. The microcontroller contains the EEPROM memory used to store the radio channel frequency and configuration information. icaoz has fifteen s-bit AID inputs for processing analog signals. Y301 and and associated components provide an 8 MHz clock oscillator for the microcontroller. ELM DE IPTI 1 RX AUD GATE controls analog switch ICSO4C, connecting received audio from IC101 to the shared audio processing circuitry when LOW and disconnecting receive audio when HIGH. 2 TX KEY input is pulled LOW when either the internal or external P1'l' switch is pressed to initiate transmitter operation 3 POWER ON RESET is momentarily LOW when the radio is first powered up to provide a reset for the microcontroller. 4, 26 SERIAL DATA INPUT links the microcontroller to communications from an external data terminal via J303 RING connection. This allows programming of the SST—454 EEPROM memory used to store channel frequency and configuration information. and the FLASH ROM that contains the radio operating system. 5 T/R SWITCH output is connected to the Synthesizer module to shift the frequency of the VCO oscillator used in both transmit and receive. The output is HIGH in transmit and LOW in receive. 6 STROBE output goes HIGH at a programmable periodic rate to remove the +5VSW supply from various circuits in the radio, thus conserving battery life. In normal transmit or receive mode this output is LOW. 7 SYNTHESIZER LATCH output goes LOW to allow serial data to frequency synthesizer IC401 and goes HIGH to latch the data, allowing the synthesizer to execute the new frequency information. 8 POWER CONTROL is a 15 KHz output whose programmable duty cycle is used to control the transmitter RF power output by adjusting the gate voltage of final amplifier 0203. This output is LOW in receive or standby mode. 9, 10, UNUSED 11 12 ONNOL UP input is pulled LOW when SW301 is depressed to to turn on the radio and raise the receiver speaker audio level. 13 GREEN LED output goes HIGH and lights the green front panel LED when the radio receives an on-frequency signal. 14 RED LED output goes HIGH and lights the red front panel LED when the radio is in transmit mode. m D§§§RIP IQN 15, 16 DTMFIBEEP outputs generate the radio alert tones heard in the speaker, as well as the tones required for DTMF encoding in transmit mode. 27 17.18 19 20 21 23 24 25 27 28, 29, 31 30 32 33 QC ENCODE outputs generate the CTCSS, DQC, LTFt Trunking and Passport Trunking encode waveforms Ior signal processing prior to modulating the VCO in transmit mode. +V SW output is HIGH when the radio is turned on, keeping pass transistor 0305 turned on to supply power to the radio. TX ENABLE output goes HIGH in transmit mode to switch the +VTX transmitter supply voltage on. This output is low in receive and standby. GROUND VDD is connected to the regulated +5VDC to supply power to the microccntroller. PTT input is pulled LOW when the internal PTT switch is depressed. In conjuction with the TX KEY input at pin 2, it initiates the desired transmitter operation required for various SST-454 audio accessories and options. CHANNEL input goes LOW when channel selector switch SWSOS is pressed to change the radio to the next programmed channelr LOW-PASS CUT-OFF output goes LOW to lower the cut-oft frequency of ICSD7C when the radio is on a channel programmed Iora CTCSS tone below 150 Hz. This output is in a tri-state OPEN condition for all other tones. AUDIO INHIBIT disables analog switches ICSD4A, B and C when HIGH to disconnect the shared audio processing circuitry Irom both the receiver and transmitter. UNUSED AUDIO GATE ENABLE controls analog switches I0304A and B to ccntigure the shared audio processing circuitry for receive operation when LOW, and for transmitter operation when HIGH. RX ENABLE output goes LOW in receive mode to switch FIX+V receiver supply voltage on. This output is HIGH in transmit and standby mode. DIGITAL POT LATCH sends a single positive pulse after data has been sent to I0308A to latch the new data and change the digital potentiometers to the new programmed settings. AUDIO AMP ENABLE output goes HIGH to apply power to audio amp I0309 for receiver speaker audio or radio alert tones. DATA output sends serial data to frequency synthesizer 10401 to program frequency information, and to ICC-108 to set the digital potentiometers. TONE IN AID input acoepls the received CTCSS, DQC. LTR or Passport trunking wavetorms at'ter signal processing tor decode analysis. HIGH-PASS AUDIO AID input accepts voice band audio signals for VOX detection in transmit mode and in-band data decode in receive mode. QE$CRIPT QM BATTERY AID input is used to measure the battery voltage tor low and dead battery detection, RSSI A/D input is used to measure the output voltage of the noise detector for squelch detection. 28 40 41 42 43 45 4s, 47. 43, 49, so. 51, 52, 53 54 55 56, 61 57 58. 59 so, as 62 54 PROGRAM SENSE AID input is used to identity the device at the J303 RING connection. TEMPERATURE AID input is used to measure voltage trom the temperature sensor to determine the ambient operating temperature of the radio. VOL DN/OFF input is pulled LOW when SW302 is depressed to lower the receiver speaker audio level and turn off the radio. UNUSED me. supplys power to the microoontroller AID and is connected to the regulated +5 VDC. V“EFL sets the lower relerenoe level lor the ND and is connected to ground. UNUSED VFW sets the upper reference level for the AID and is connected to the regulated +5 VDC. vm is connected to the regulated +5 VDC. GROUND CGMFXC hes a .tuF capacitor bypass lor loop filter phase correction. OSCILLATOR input is connected to an 8 MHz crystal used for clock referenoe. UNUSED inputs are pulled HIGH lor FLASH programming. CLOCK output sends serial data clock pulses to lrequency synthesizer lC401 and digital pctentiometers ICSOB when programming these devices. LOCK DETEGT input connected to the Pin 2, 10401 lock detect output 0? the synthesizer is HlGH when the synthesizer is locked and low pulses when unlocked. 29
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